NEET MCQs Inheritance And Variation

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NEET MCQs Inheritance and Variation – Sample

A haemophilic woman marries a normal man, then
a) All the children will be normal b) All the sons will be haemophilic
c) All the girls will be haemophilic d) Half girls will be haemophilic
Disorder inherited as Mendel’s law of inheritance called
a) Mendelian disorder b) Chromosomal disorder
c) Maternal inheritance d) Polygenic inheritance
The term ‘gene’ was coined by
a) Avery b) Bateson c) Johanssen d) Mendel
The phenotypic ratio in the 𝐹2 gereration of dihybrid cross, is
a) 9 : 3 : 3 : 1 b) 1 : 2 : 2 : 4 : 1 : 2 : 1 : 2 : 1
c) 7 : 1 : 1 : 7 d) 12 : 8 : 4
Chromosome is made up of
a) DNA +pectin b) RNA +DNA c) DNA +histone d) Only histone
Select the incorrect statemant from the following.
a) Linkage is an exception to the principle of
independent assortment in heredity
b) Galactosemia is an inborn error of metabolism
c) Small population size result in random genetic
drift in a population
d) Baldness is a sex-limited trait
A pure tall and a pure dwarf plant were crossed to produced offsprings. Offsprings were self crossed, then
find out the ratio between true breeding tall to true breeding dwarf?
a) 1 : 1 b) 3 : 1 c) 2 : 1 d) 1 : 2 : 1
Exposure of X-rays enhances the frequency of
a) Linkage b) Crossing over
c) Pairing of chromosome d) Segregation
A self-fertilizing trihybrid plant forms
a) 8 different gametes and 64 different zygotes b) 4 different gametes and 16 different zygotes
c) 8 different gametes and 16 different zygotes d) 8 different gametes and 32 different zygotes
Genotype is the
a) Genetic constitution b) Genetic constitution of the phenotype
c) Trait expressed d) Expressed genes
Failure of cytokinesis after …A… stage of cell division results in an increase in a whole set of chromosomes
in an organism called …B…
a) A-prophase, B-polyploidy b) A-metaphase, B-polyploidy
c) A-anaphase, B-polyploidy d) A-telophase, B-polyploidy
In previous question find out total seeds (plants) having round seed texture
a) 12 b) 10 c) 9 d) 11
The ratio 1 : 1 : 1 : 1 is obtained from a cross between the parents
a) RRYY×rryy b) RRYY×rryy c) RRYY×Rryy d) RrYy×rryy
Which of the following terms represent a pair of contrasting characters?
a) Homozygous b) Heterozygous c) Allelomorphs d) Codominant genes

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Harmful mutation does not get eliminated from the gene pool because they are mainly
a) Dominant, which have beneficial effect on population and carried by heterozygous individuals
b) Dominant, which have beneficial effect on population and carried by homozygous individuals
c) Carried from one generation to another generation through autosomal chromosomes
d) They show genetic drift
Incomplete linkage is …A… . Complete linkage is …B… . Choose correct option for A and B
a) A-common, B-rare b) A-rare, B-common
c) A-impracticle, B-practicle d) A-practicle, B-impracticle
Mendelism was rediscovered by
I. Morgan
II. De Vries
III. Correns
IV. Tschermark
Choose the correct option
a) I, III and IV b) I, II, III and IV c) II, III and IV d) I, II and III
In gynandromorphs,
a) Some cells of body contain XX and some cells with genotype XY
b) All cells have XX genotype
c) All cells have XY genotype
d) All cells with genotype XXY
Example of interagenic gene interaction is/are
a) Incomplete dominance b) Codominant
c) Multiple alleles d) All of the above
If a cross between two individuals produces offspringe with 50% dominant character (A) and 50%
recessive character (a),then the genotypes of parents are
a) Sex linked genes b) Pseudoallelic genes
c) Intermediate inheritance d) Dominant and recessive genes
Which is correct about traits choosen by Mendel for his experiment on pea plant?
a) Terminal pod was dominant b) Constricted pod was dominant
c) Green coloured pod was dominant d) Tall plants were recessive
Codominance is found in
a) Plants b) Animal c) Both (a) and (b) d) Prokaryote
During Mendel’s investigation, it was first time that …A… and …B… were applied in biology. Here A and B
refers to
a) A-statistical analysis; B-mathematical logic
b) A-statistical analysis; B-physical logic
c) A-statistical analysis; B-chemistry logic
d) A-statistical analysis; B-simple logic
The chromosomal denotation for heterogametic female and homogametic male are
a) ZW and ZZ b) ZO-ZZ c) XX-XO d) Both (a) and (b)
Pure tall plants are crossed with pure dwarf plants. In the F1-generation, all plants were tall. These tall
plants of F1-generation were selfed and the ratio of tall to dwarf plants obtained was 3: 1. This is called
a) Dominance b) Inheritance c) Codominance d) heredity
The best method to determine the homozygosity and heterozygosity of an individual is
a) Self-fertilisation b) Back cross c) Test cross d) Inbreeding
A medical technician, while observing a human blood smear under the microscope notes the presence of a
Barr body close to the nuclear membrane in the WBC. This indicates that the person under investigation is
a
a) Colourblind b) Haemophilic c) Normal female d) Normal male
Find out 𝐴,𝐵 and 𝐶 in the diagram given below in

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a) A-Male, B-Female, C-Gametes b) A-Male, B-Female, C-Sperm
c) A-Female, B-Male, C-Gametes d) A-Gametes, B-Male, C-Female

In Turner’s syndrome
a) Female is fertile b) Male is fertile c) Female is sterile d) Male is sterile
The most likely reason for the development of resistance against pesticides in insect damaging a crop is
a) Random mutations b) Genetic recombination
c) Directed mutations d) Acquired heritable changes
Lampbrush chromosomes sre seen in
a) Interphase b) Zygotene c) Diplotene d) metaphase
In case of incomplete dominance, what will be the phenotypic ratio of 𝐹2generation?
a) Histones b) Hydrocarbons c) Polynucleotides d) Lipoproteins
Examples of dissimilar sex chromosomes are given below
I. XX – XY ⇒ I
II. XX – XO ⇒ II
I and II in the above statement can be
I II a) Man and most
insect
Cockroach and
roundworms

b) Cockroach and
roundworms
Man and most
insect

c) Butterfly Fishes

d) Bird Reptiles

Mutations, which alter nucleotide sequence within a gene are
a) Frameshift mutation b) Base pair substitutions
c) Both (a) and (b) d) None of these
The 𝐹1generation has all tall, and 𝐹2ratio is 3 : 1, it proves
a) Law of dominance b) Independent assortment
c) Law of segregation d) linkage
Mendel’s law were true for situation in which
a) Alleles are affected by their environment b) Alleles shows complete dominance
c) Alleles of a gene alter the affect of a different gene d) A given character is determined by more than one
gene
Blood group-O has
a) No antibodies b) No antigens c) a or b antibodies d) A and B antigens
Wilson detected the colour blindness disease in
a) 1921 b) 1911 c) 1912 d) 1910
In a dihybrid cross between RRYY and rryy parents, the number of RrYy genotypes in 𝐹2generation will be
a) 4 b) 3 c) 2 d) 1
If a cross between two individuals produces offspringe with 50% dominant character (A) and 50%
recessive character (a),then the genotypes of parents are
a) Genic interactions controlling a character b) Multiple genes controlling a character
c) Expression of many characters by a single gene d) Alternative forms of a gene at a given locus
A women with albinic father marries an albinic man.the proportion of her progeny is
a) 2 normal : 1 albinic b) All normal
c) All albinic d) 1 normal : 1 albinic

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When one sex chromosome is lacking in female and males are homogametic, in that condition, the sex
chromosomal representation is
a) ZO-ZZ b) XY-XX c) XX-XO d) ZW-ZZ
Some individuals with blood group –A may inherit the genes for blonde hair, while other individuals with
blood group – A may the gene for brown hair. This can be best explained by the principle of
a) Dominance b) Multiple alleles
c) Independent assortment d) Incomplete dominance
In bugs and cockroaches, the sex determination takes place by
a) XX and XO chromosomes b) XX and XY chromosomes
c) ZZ-ZW chromosomes d) ZO-ZZ chromosomes
The two …A… separate and pass into two daughter nuclei and cells during mitosis. Similarly, each …B…
replicates, with one pair passing into each daughter cell during mitosis. This maintains the similar …C… of
all the cells.
Find out correct option for A, B and C
a) A-chromatid, B-allele pair, C-morphology b) A-chromatid, B-allele pair, C-genetic composition
c) A-organ, B-organ pair, C-individuality d) A-unlinked gene, B-linked gene, C-morphology
The shape of chromosome is determined by
a) Centrosome b) Centromere c) Chromomere d) telomere
Mendel was a
a) Austrian biology teacher b) Austrian monk
c) Austrian scientist d) Austrian mathematician
Who clearly proved and define linkage?
a) Morgan b) Castle c) Bateson d) Punnett
Improvement of human race through hereditary qualities is called
a) Euthenics b) Human heredity c) Human demography d) Eugenics
Test cross involves
a) Crossing between two genotypes with recessive trait
b) Crossing between two F1-hybrids
c) Crossing the F1-hybrid with a double recessive genotype
d) Crossing between two genotypes with dominant trait
When a diploid female plant is crossed with a tetraploid male, the ploidy of endosperm cells in the
resulting seed is
a) Tetraploidy b) Pentaploidy c) Diploidy d) Triploidy
Colour blindness is
a) Sex-linked recessive disease
b) Sex-linked dominant disease
c) Autosomal dominant disease
d) Autosomal recessive disease
A condition, where a certain gene is present in only a single copy in a diploid cell, is called
a) Four different types of gametes produed by the 𝐹1
dihybrid b) Homozygous condition of the 𝐹1-dihybrid
c) Four different types of 𝐹1-dihybrids d) Four different types of gametes produed by the
�
�1-parent
If the blood group of a child is A and of mother is B, then the genotype of mother and father may be
a) BB×AA b) AB×AB c) BO×OO d) BO×AO
symbol in pedigree analysis represents
a) Still birth b) Still death c) Still carrier d) Still mating
Which amino acids are present in histones?
a) Lysine and histidine b) Valine and histidine

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c) Arginine and lysine d) Arginine and histidine

Monosomic trisomy are represented as
a) 2𝑛−1+1 b) 2𝑛−1−1 c) 2𝑛−1 d) 2𝑛+1+1
Which is a sex-influenced disease?
a) Baldness in male b) Haemophilia
c) Xeroderma pigmentosa d) Down’s syndrome
Thalassaemia is
a) Autosomal recessive disease b) Autosomal dominant disease
c) Sex-linked dominant disease d) Sex-linked recessive disease
Mutation is phenomena which results in alternation of
a) Sequence b) Carbohydrates c) Proteins d) Fat
A man with normal vision whose father was colourblind marries with women whose father was also
colourblind. Suppose their first child is daughter then what are the chances of this child to be colourblind?
a) 100% b) 25% c) 50% d) 0%
Gamete mother cells of the chromosome 44 + XY suffers from non-disjunction at first meiotic division.
Which of the following set of gametes would result?
a) 22 + XX, 22 + XY, and 22, 22 b) 22 + XY, 22 + XY, and 22, 22
c) 22 + X, 22 + Y, and 22 + Y, 22 d) 22 + X, 22 + XY, and 22 + Y, 22 + Y
Law of Mendel, which is not completely applicable is?
a) Codominance b) Law of segregation
c) Law of independent assortment d) Law of dominance
Low pitched voice, beared and moustaches, belong to the
a) Sex limited traits b) Sex linked trait c) Nullisomic traits d) Sex influenced traits
Multiple allele can be manifested only when there is the study of
a) Individual organism b) Genus c) Population d) Phylum
𝑁𝑖𝑐𝑜𝑡𝑖𝑎𝑛𝑎 𝑠𝑦𝑙𝑣𝑒𝑠𝑡𝑟𝑖𝑠 flowers only during long days and 𝑁.𝑡𝑎𝑏𝑎𝑐𝑢𝑚 flowers only during short days, if
raised in the laboratory under different photoperiods, they can be induced to flower at the same time and
can be cross fertilized to produce self-fertile offspring. What is the best reason for considering N. sylvestris
and N. tobaccum to be separate species?
a) They are physiologically distinct b) They are morphologically distinct
c) They cannot interbreed in nature d) They are reproductively distinct
The following diagram shows two types of chromosomal mutations

Give the name or type of mutation in respect to A and B
a) A-Duplication, B-Substitution b) A-Duplication, B-Deletion
c) A-Inversion, B-Deletion d) A-Inversion, B-Substitution

How many different kinds of gametes will be produced by a plant having the genotype AABbCC?
a) Three b) Four c) Nine d) Two
Down’s syndrome and Turner’s syndrome occur in human beings due to
a) Monosomic and nullisomic conditions respectively b) Monosomic and trisomic conditions respectively
c) Trisomic and monosomic conditions respectively d) Trisomic and tetrasomic conditions respectively
What are all the chances of colourblind daughters of a normal man marrying normal women whose father
was colourblind?
a) All sons are normal and all daughters are
colourblind
b) Both the sons and daughters are phenotypically
normal

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c) All the sons are colourblind and all daughters are
normal
d) 50% sons are colourblind and all daughters are
phenotypically normal

In males, pattern baldness is related to both autosomal genes as well as excessive secretion of
a) Oestrogen b) Growth hormone c) Testosterone d) Inhibits
Which of these is not a Mendelian disorder?
a) Cystic fibrosis b) Sickle-cell anaemia c) Colourblindness d) Turner’s syndrome
Which of the following is not true of haemophilia?
a) Royal disease b) Bleeder’s disease
c) X-linked disorder d) Y-linked disorder
If heterozygous dominant (tT) crossed with homozygous dwarf plant, then the percentage of progeny
having dwarf character is
a) 60% b) 40% c) 50% d) 70%
Mutations are generally induced by means of
a) 𝛼−𝑟𝑎𝑦𝑠 b) β−𝑟𝑎𝑦𝑠 c) 𝛾−𝑟𝑎𝑦𝑠 d) UV radiations
Two crosses between the same pair of genotypes or phenotypes, in which the sources of the gametes are
reversed in one cross, is known as
a) Dihybrid cross b) Reverse cross c) Test cross d) Reciprocal cross
A hereditary, disease, which is never passed on from father to son is
a) X-chromosomal linked disease b) Autosomal linked disease
c) Y-chromosomal linked disease d) None of the above
Bateson used the term coupling and repulsion for linkage and crossing over. Choice the correct coupling
and repulsion combination
Coupling Repulsion a) AABB, aabb AAbb, aaBB

b) AABB, aabb AABB, AAbb

c) AAbb, aaBB AaBb, aabb

d) aaBB, aabb AABB, aabb

In blood group typing in human, if an allele contributed by one parent is IAand an allele contributed by the
other parent is i, the resulting blood group of the offspring will be
a) A b) B c) AB d) O
A person having 45 chromosomes and Y-chromosome absent. Is suffering from
a) Down’s syndrome b) Klinefelter’s syndrome
c) Turner’s syndrome d) gynandromorph
Linkage and crossing over are
a) Same phenomena b) Different phenomena
c) Opposite phenomena d) Identical phenomena
The modern concept of gene is
a) A segment of DNA, capable of crossing over b) Functional unit of DNA
c) A segment of RNA d) A segment of chromosome
Females in haplodiploidy sex determination are
a) N b) 2n c) 1
2
n d) 3n
Using imprints from a plate with complete medium and carrying bacterial colonies, you can select
streptomycin resistant mutants and prove that such mutations do not originate as adaptation. These
imprints need to be used
a) Only on plates with streptomycin b) On plates with minimal medium
c) Only on plates without streptomycin d) On plates with and without streptomycin
Phenylketonuria, Huntington’s disease and sickle cell anaemia are caused respectively due to disorders
associated with
a) Chromosome-7, chromosome-11 and chromosome-12
b) Chromosome-11, Chromosome-4 chromosome-12
c) Chromosome-7, chromosome-12 and chromosome-11
d) Chromosome-12, chromosome-4 and chromosome-11

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The arrangement of genes on chromosome is
a) Linear b) Oviod c) Diffused d) Spiral
When two genetic loci produce identical phenotypes in 𝑐𝑖𝑠 and 𝑡𝑟𝑎𝑛𝑠 position, they are considered to be
a) Pseudoalleles b) Multiple alleles
c) The part of same gene d) Different genes
Which of the following matches correctly?
a) Factor –II – Thromboplastin b) Factor –III – Prothrombin
c) Factor –VIII – Antihaemophilic globulin d) Factor –XII – Haemophilic
The longest chromosomes is seen in
a) Allium b) Lilium c) Trillium d) Zea mays
Mendel observed that ….. generation shows always phenotype of dominant parent
a) F4 b) F2 c) F1 d) F0
…A… genes are those which occurs on the same chromosome and …B… genes are those, which are present
on different chromosome.
Choose correct choice for A and B
a) A-linked; B-unlinked gene b) A-unlinked; B-linked
c) A-identical; B-non-identical d) A-non-identical; B-identical
Allelic sequence variations where more than one variant (allele) at a locus in a human population with a
frequency greater than 0.01 is refered to as
a) Incomplete dominance b) Multiple allelism
c) SNP d) DNA polymorphism
The possibility of a female becoming a haemophilia is …A… rare because mother of such a female has to be
at least …B… and the father should be …C…
Choose the correct option for A, B and C
a) A-extremely, B-carrier, C-haemophilic
b) A-extremely, B-carrier, C-carrier
c) A-extremely, B-haemophilic, C-carrier
d) A-extremely, B-haemophilic, C-haemophilic
If the foetus is Rh+ and mother is Rh−, then
a) Foetus will transmit antigen to mother blood
b) Foetus will transmit antibody to mother blood
c) Foetus is attacked by antibodies to mother blood
d) Foetus is attacked by antigen to mother blood
The most popularly known blood grouping is the ABO grouping. It is named ABO and not ABC, because ‘O’
in it refers to having
a) Other antigens besides A and B on RBCs b) Over dominance of this type on the genes for A
and B types
c) One antibody only−either anti-a or anti–b on the
RBCs
d) No antigens A and B on RBCs
Alleles are
a) Alternate forms of a gene b) Homologous chromosome
c) Pair of sex chromosome d) None of the above
Telomere repetitive DNA sequences control the function of eukaryotic chromosomes because they
a) Act as replicons b) Are RNA transcription initiator
c) Help chromosome pairing d) Prevent chromosome loss
Genotypic and phenotypic ratios remains the same in
a) Sex-linked genes b) Pseudoallelic genes
c) Intermediate inheritance d) Dominance and recessive genes
Mendelian disorder may be of
a) Recessive b) Dominant c) Both (a) and (b) d) Can’t be determined

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Sickle –cell anaemia has not been eliminated from the African population because it
a) Is controlled by recessive genes b) Is not a fatal disease
c) Provides immunity against malaria d) Is controlled by dominant genes
A condition characterized by not having an exact number of chromosomes in a multiple of haploid set is
called
a) Polyploidy b) Synploidy c) aneuploidy d) None of these
Choose correct option for 𝐴,𝐵,𝐶 and 𝐷 a) A-tt, B-TT, C-TT, D-TT b) A-Tt, B-Tt, C-Tt, D-Tt
c) A-TT, B-TT, C-Tt, D-TT d) A-Tt, B-Tt, C-Tt, D-TT
When a cross is conducted between black feathered hen and a white feathered cock, blue feathered fowls
are formed. When these fowls are allowed for interbreeding, in F2- generation, there are 20 blue fowls.
What would be the number of black and white fowls?
a) Black 20, white 10 b) Black 20, white 20 c) Black 10, white 10 d) Black 10, white 20
Chromosomes are made up of
a) DNA are protein b) RNA and DNA c) DNA and histone d) Only histones
In pedigree analysis, the square, blackened and horizontal lines represents
a) Female, healthy individual, parents b) Female, affected individual, parents
c) Male, affected individual, parents d) Male, affected individual, progeny
Following pedigree chart shows a) Character is carried by Y-chromosome b) Character is sex-linked recessive
c) Character is sex-linked dominant d) Character is recessive autosomal
Mr. Sidd is suffering from hypertrichosis and phenylketonuria. His father is heterozygous for
phenylketonuria. The probability of Sidd’s sperm having one recessive autosomal allele and holandric
gene is
a) 1
2 b) 1
8 c) 1
10 d) 1
4
F3-generation is obtained by
a) Selfing of F1 b) Selfing of F2 c) Crossing of F1 and F2 d) None of these
In which one of the following, complementary gene interaction rato of 9 : 7 is observed?
a) Fruit shape in Shepherd’s purse b) Coat colour in mouse
c) Feather colour in fowl d) Flower colour in pea
Starch synthesis gene in pea plant is the example of
a) Single gene produce more than one effects
b) Multiple genes produce more than one effects
c) Two genes produce more than one effects
d) Multiple genes produce less than one effects
In 𝐷𝑟𝑜𝑠𝑜𝑝ℎ𝑖𝑙𝑎 , the sex is determined by
a) The ratio of pairs of X-chromosomes to the pairs of autosomes
b) Whether the egg is fertilized or develops parthenogenetically

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c) The ratio of number of X-chromosomes to the set of autosomes
d) X and Y-chromosomes

The 1 : 2 : 1 ratio with the pink flower in the F2-generation indicate the phenomenon of
a) Dominance b) Codominance
c) Incomplete dominance d) Segregation
Sexual reproducation leads to
a) Genetic recombination b) Polyploidy
c) Aneuploidy d) Euploidy
Husband has blood group-A and wife has blood group-B. What is the blood group of children?
a) A b) B c) AB d) A, B, AB and O
Study the following figure and find out the most probable position at which the crossing over takes place a) w and W b) X and y c) y and Z d) w and z
Given diagram shows certain type of traits in human. Which one of the following option could be an
example of this pattern? a) Haemophilia b) Anaemia c) Phenylketonuria d) Thalassaemia
In case of incomplete dominance, what will be the phenotypic ratio of 𝐹2generation?
a) 3 : 1 b) 1 : 2 : 1 c) 1 : 1 : 1 : 1 d) 2 : 2
Haemophilia, a X-linked recessive disease is caused due to deficiency of
a) Blood plasma and vitamin–K b) Blood platelets and haemoglobin
c) Lack of clotting material and vitamin-K d) All of the above
All of this obeys Mendel’s laws except
a) Codominance b) Independent assortment
c) Dominance d) Purity of gametes
in β-thalassaemia, the affected chromosome is
a) 16th b) 14th c) 13th d) 19th
In pea plants, yellow seeds are dominant to green. If a heterozygous yellow seeded plant is crossed with a
green seeded plant, what ratio of yellow and green seeded plants would you expect in 𝐹1generation?
a) 50 : 50 b) 9 : 1 c) 1 : 3 d) 3 : 1
Who was fly men of genetics?
a) Sutton b) Pasteur c) Robert Hooke d) TH Morgan
Mendel’s contribution for genetic inheritance was
a) The idea that genes are found on chromosomes
b) Providing a mechanism that explains patterns of inheritance
c) Describing how genes are influenced by the environment
d) Determining that the information contained in DNA codes for proteins
The genotypic ratio of a monohybrid cross in F2-generation is

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a) 3 : 1 b) 1 : 2 : 1 c) 2 : 1 : 1 d) 9 : 3 : 3 : 1

Baldness is more common in men than in woman. It could be explained on the basis that
a) Genes of baldness are located on X-chromosomes only
b) Baldness genes are located on Y-chromosomes
c) Genes of baldness are autosomal but influenced by androgens
d) None of the above
How many pairs of contrasting characters in pea pod were chosen by Mendel?
a) 3 b) 5 c) 7 d) 9
A mutagen pollutant is
a) Organophosphates b) Resins
c) Chlorinated hydrocarbons d) Nitrogen oxides
Both chromosome and gene (Mendelian factors) whether dominant or recessive are transmitted from
generation to generation in which form
a) Changed b) Unaltered form c) Altered form d) Disintegrated
Pedigree analysis is very important in human beings because
a) It helps genetic counselers to avoid disorders
b) It shows origin of traits
c) It shows the flow of traits in family
d) All of the above
Genes when present in homozygous condition results in non – viable progeny, the factor responsible for
such conditions are
a) Polygenes b) Linked genes c) Lethal genes d) Epistatic genes
Turner’s syndrome caused due to the absence of
a) One X-chromosome (44 with XO) b) One Y-chromosome
c) One X-and Y-chromosome d) Two X-chromosome
The recessive genes located on X-chromosome in humans are always
a) Lethal b) Sub-lethal c) Expressed in males d) Expressed in females
Strength of the linkage between the two genes is
a) Proportionate to the distance between them
b) Inversely proportionate to the distance between them
c) Depend on the chromosomes
d) Depend upon the size of chromosomes
Fruitfly is excellent model for genetics because of
I. Small life cycle (two week)
II. Can be feed on simple synthesis medium
III. Single mating produce large number of progeny
IV. Clear differentiation of sexes
V. Many heredity variation can be seen with low power microscopes
Choose the correct option
a) I, II and III b) III, IV and V c) I, IV and V d) All of these
In Guinea pigs, black short hair (BBSS) is dominant over white long hair (bbss). During a dihybrid cross,
the 𝐹2-generation individuals with genotypes BBSS, BbSS, BBSs and BbSs are in the ratio of
a) 9 : 3 : 3 : 1 b) 4 : 2 : 1 : 2 c) 1 : 2 : 1 : 2 d) 1 : 2 : 2 : 4
When both parents are of blood type AB, they can have children with
a) A, B, AB and O blood types b) A, B, and AB blood types
c) A and B blood types d) A, B and O blood types
Test cross is
a) Recessive F1-plant crosses with dominant F2-plant
b) Recessive F2-plant crosses with dominant F3-plant
c) Dominant F2-plant crosses with recessive parent plants
d) Dominant F2-plant crosses with heterozygous parent plants

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The phenomenon of a single gene regulating several phenotypes is called
a) Multiple allelism b) epistasis
c) Incomplete dominance d) Pleiotropism
If two pea plants having red (dominant) coloured flowers with unknown genotypes are crossed, 75% of
the flowers with unknown genotypes are crossed, 75% of the flowers are red and 25% are white. The
genotypic constitution of the parents having red coloured flowers will be
a) Both homozygous b) One homozygous and other heterozygous
c) Both heterozygous d) Both hemizygous
A woman has a haemophilic son and three normal children. Her genotype and that of her husband with
respect to this gene would be
a) XX and XhY b) XhXh and XhY c) XhXh and XY d) XhX and XY
The proportion of plants that were dwarf and tall in F2- generation ofo Mendel experiment
a) 1
4th and 3
4th b) 3
4th and 1
4th c) 2
3rd and 1
3rd d) 1
3rd and 4
3rd
Night blindness is
a) Genetic disease b) Nutritional deficiency disease
c) Generally found in male d) Generally found in female
Two genes R and Y are located very close on the chromosomal linkage map of maize plant. When RRYY
and rryy genotypes are hybridized, then 𝐹2-segregation wii show
a) 1 : 2 : 1 b) 3 : 1 c) 9 : 3 : 3 : 1 d) 1 : 1 : 1
Who argued that pairing and separation of chromosomes would lead to the segregation of a pair of factor
they carried?
a) Sutton b) Boveri c) Both (a) and (b) d) Morgan
Sex chromosomes of male are
a) Homozygous b) Heterozygous c) Hemizygous d) autosomes
Trisomy of which chromosome is involved in Down’s syndrome?
a) 15th b) 21st c) 20th d) 19th
Which of the following symbols are used for representing chromosome of birds?
a) ZZ-ZW b) XX-XY c) XO-XX d) ZZ-WW
Sudden and heritable change in a character of an organism is called
a) Mutation b) Heterosis c) Inbreeding d) selection
Heterozygous purple flower is crossed with recessive white flower. The progeny has the ratio
a) All purple b) All white
c) 50% purple, 50% white d) 75% purple, 25% white
The Mendel crossed true breeding tall and dwarf plant varieties in his experiment. The tall character was
dominant and recessive character was dwarf. The recessive character was appeared in
a) F1 b) F2 c) F3 d) F2 and F3
Night blindness can be corrected by giving vitamin- …A… but colour blindness can’t be cured because it is
…B… disease.
Choose the correct option for A and B
a) A-A; B-genetic b) A-B; B-autosomal c) A-C; B-non-genetic d) A-D; B-genetic
Heredity is
a) Transmission of characters b) Mixing of characters
c) Blending of inheritance d) Deleting of characters
Which of these statements about Huntington’s disease is true?
a) Genetic tests to detect the presence of the allele responsible for Huntington’s disease do not exist at this
time
b) The onset of Huntington’s disease is typically between birth and three years of age
c) There is currently no effective treatment of Huntington’s disease
d) Huntington’s disease is caused by the expression of a recessive allele

Page| 12

Centromere is required for
a) Transcription b) Crossing over
c) Cytoplasmic cleavage d) Movement of chromosomes towards poles
Which of the following condition in humans is correctly matched with its chromosomal
abnormality/linkage?
a) Klinefelter’s syndrome –44 autosomes + XXY b) Colour blindness –Y- linked
c) Erythroblastosis foetalis –X- linked d) Down’ s syndrome – 44 autosomes+ XO
Rrrr progeny : Red (dominant) flowered heterozygous crossed with white flower
a) 350→red∶350→white b) 450→red∶250→white
c) 380→red∶250→white d) None of these
A hereditary disease which is never passed on form father to son is
a) X- chromosomal linked disease b) Autosomal linked disease
c) Y- chromosomal linked disease d) None of the above
A man with blood group-B marries a woman with blood-A and their first child is having blood group-B.
What is the genotype of child?
a) IaIb b) IaIo c) IbIo d) IbIb
Linked gene are present on
a) Same chromosome b) Different chromosome
c) Heterologous chromosome d) Paired chromosome
The structure that become double in synthesis phase of cell division is/are
a) RNA b) Centriole c) DNA d) None of these
Genetics is the branch of biology which deals with
a) Variation b) Inheritance c) Both (a) and (b) d) Study of characters
Giant chromosomes are found inside
a) nucleus of man b) oocytes of frog
c) salivary glands of silk moth d) salivary glands of Drosophila
Who is known as father of physiological genetics or father of biochemical genetics?
a) Slatyer b) Charles Elton c) Taylor d) Archibald Garrod
The graphical representation to calculate the probability of all possible genotypes of offspring in a genetic
cross, is called
a) Pedigree analysis b) Karyotype c) Punnett square d) Chromosome map
Rh factor can produce disease
a) AIDS b) Turner’s syndrome
c) Erythroblastosis foetalis d) Sickle-cell anaemia
To determine heterozygousity of a cross, one has to perform
a) Back cross b) Reciproacal cross c) Test cross d) Any of these
Which of the following type of mutation involves the reverse order of genes in a chromosome?
a) Deletion b) Duplication
c) Inversion d) Reciprocal translocation
The chromosomal number in the meiocytes of housefly is
a) 8 b) 12 c) 21 d) 23
The alternate forms of a gene is called
a) Recessive character b) Dominant character
c) Alleles d) Alternative gene
Haemophilia is related to
a) Albinism b) Sickle-cell anaemia c) Colour blindness d) thalassemia
Identify a Mendelian disorder from the following.
a) Down’s syndrome b) Turner’s syndrome

Page| 13

c) Phenylketonuria d) Klinefelter’s syndrome

When a tall plant with round seeds (TTRR) crossed with a dwarf plant with wrinkled seeds (ttrr), the 𝐹1
generation consists of tall plants with round seeds. What would be the proportion of dwarf plant with
wrinkled seeds in 𝐹1-generation?
a) 1
4 b) 1
16 c) 0 d) 1
2
The term ‘Genetics’ was proposed by
a) Mendel b) Bateson c) Motgan d) Johanssen
Sex chromosomes are also known as
a) Autosomes b) Allosomes c) Genome d) karyotype
Mendel obtained recessive character in F2 by …A… the …B… plants. Here 𝐴 and 𝐵 refers to
a) A-self-pollinating; B−F1 b) A-self-pollinating; B−F2
c) A-cross-pollinating; B−F1 d) A-cross-pollinating; B−F2
In a family father had a trait but mother did not. All their sons and daughter had this trait. The same trait
was found in some grand daughters, through daughter were married to the normal persons.
Choose the correct pedigree chart for the condition

If genes of an allelic pair are not-same. This condition is called
a) Homozygous b) Heterozygous c) Diallelic d) Polyallelic
Which type of pollination method was adopted by Mendel in his experiment?
a) Artificial b) Cross pollination c) Natural d) Both (a) and (b)
Select the correct statement from the ones given below with respect to dihybrid cross.
a) Tightly linked genes on the same chromosome
show higher recombinations
b) Genes far apart on the same chromosome show
very few recombinations
c) Genes loosely linked on the same chromosome
show similar recombinations as the tightly linked
ones
d) Tightly linked genes on the same chromosome
show very few recombinations
Grain colour in wheat is determined by three pairs of polygene. Following the cross
AABBCC(dark colour)×aabbcc(light colour) , in 𝐹2 generation. What proportion of the progeny is likely to
resemble either parent?
a) Half b) Less than 5 per cent c) One –third d) None of these
Chromosomal abbreviation commonly found in the
a) Cancer cells b) Normal cells c) Healthy cells d) Autosomal cells
In short horned cattle, genes for red( R) and white( r) coat colour occur. Cross between red (RR) and
white (rr) produced (Rr) roan. This is an example of
a) Incomplete dominance b) Codominance
c) Complementary genes d) Epistasis
Female is haemophilic definitely if
a) Mother is carrier b) Father is carrier
c) Father is affected d) Both mother and father affected

Page| 14

Polyploidy leads to rapid formation of new species because of
a) Isolation b) Development of multiple sets of chromosomes
c) Mutation d) Genetic recombination
Law of segregation is also called law of
a) Probability b) Purity of gametes
c) Independence of gametes d) Punnett hypothesis
Test cross is a cross between
a) Hybrid×Dominant parent b) Hybrid×Recessive parent
c) Hybrid×Hybrid parent d) Two distantly related species
XX and XY chromosomal sex determination, females are
a) Homogametic b) Heterogametic
c) Can not determine d) All of the above
Heterogametic male condition does not occur in
a) Birds b) Humans c) Drosophila d) Honey bee
In a typical Mendelian cross which is a dihybrid cross, one parent is homozygous for both dominant traits
and another parent is homozygous for both recessive traits. In the 𝐹2 generation, both parental
combinations and recombinations appear. The phenotypic ratio of parental combinations to
recombinations, is
a) 10:6 b) 12:4 c) 9:7 d) 15:1
The genotype of a plant showing the dominant phenotype can by
a) Test cross b) Dihybrid cross c) Pedigree analysis d) Back cross
If a man who is colourblind marries a women, who is pure normal for colour vision, the chances of their
sons have colour blindness is
a) 100% b) 50:50 c) 0% d) 75 : 25
When a tall pea plant (TT) is crossed with dwarf plant (tt) what will be the F2-generation?
a) All tall plants b) All dwarf plants
c) Both tall and dwarf plants in 1 : 1 ratio d) Both tall and dwarf plants in 3 : 1 ratio
Broadly the genetic disorders may be classified in …A… group Mendelian disorder and …B… disorders.
Mendelian disorder are mainly determined by …C… in single gene.
Choose the correct option for A, B and C
a) A-two, B-chromosomal, C-genetic b) A-two, B-chromosomal, C-inversion
c) A-two, B-chromosomal, C-alteration d) A-three, B-chromosomal, C-deficiency
…A… individual show …B… phenotype but they are the …C… of the disease as there is 50% probability of
transmission of mutant gene to its progeny
Choose the correct option for A, B and C
a) A-homozygous, B-affected, C-carrier b) A-homozygous, B-unaffected, C-carrier
c) A-heterozygous, B-unaffected, C-carrier d) A-heterozygous, B-affected, C-carrier
If male is TT and female is tt than they contribute pollen and egg respectively with
a) T and T gametes b) tt and TT gametes c) TT and tt gametes d) T and t gametes
Number of linkage group in Pisum sativum is
a) 2 b) 5 c) 7 d) 9
In Mendel’s experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr),
yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the
F2- generation of the cross RRYY×rryy?
a) Only round seeds with green cotyledons b) Only wrinkled seeds with yellow cotyledons
c) Only wrinkled seeds with green cotyledons d) Round seeds with yellow cotyledons and wrinkled
seeds with yellow cotyledons
BB = for black colour alleles
bb = for brown colour alleles

Offspring of a cross between a black mouse and brown mouse allowed to interbreed than find out the
percentage of black coat in them
a) 75%
b) 50%
c) Cross is not possible because black and brown mouse are different species
d) 100%

NEET MCQs: Inheritance & Variation – : ANSWER KEY :

1) b 2) a 3) c 4) a
5) c 6) d 7) a 8) b
9) a 10) b 11) d 12) a
13) d 14) c 15) a 16) a
17) c 18) a 19) d 20) c
21) c 22) a 23) a 24) d
25) a 26) b 27) c 28) a
29) c 30) c 31) c 32) c
33) a 34) c 35) c 36) b
37) b 38) d 39) a 40) d
41) d 42) a 43) c 44) a
45) b 46) b 47) b 48) a
49) d 50) c 51) a 52) a
53) a 54) d 55) b 56) c
57) a 58) a 59) a 60) a
61) d 62) b 63) c 64) d
65) c 66) c 67) b 68) d
69) c 70) d 71) c 72) d
73) d 74) c 75) c 76) d
77) a 78) a 79) a 80) c
81) c 82) b 83) b 84) a
85) d 86) a 87) a 88) c
89) c 90) c 91) a 92) d
93) a 94) a 95) d 96) a
97) d 98) c 99) c 100) c
101) c 102) b 103) c 104) c
105) c 106) a 107) a 108) b
109) d 110) a 111) c 112) c
113) a 114) d 115) d 116) a
117) b 118) c 119) a 120) d
121) a 122) a 123) b 124) b
125) c 126) a 127) c 128) b
129) d 130) c 131) a 132) c
133) b 134) d 135) d 136) b
137) c 138) d 139) c 140) d
141) a 142) b 143) a 144) c
145) b 146) b 147) a 148) a
149) c 150) d 151) a 152) a
153) c 154) d 155) a 156) a
157) a 158) c 159) a 160) c
161) c 162) c 163) d 164) c
165) c 166) c 167) c 168) b
169) c 170) c 171) c 172) c
173) b 174) b 175) a 176) a
177) b 178) c 179) d 180) b
181) a 182) b 183) d 184) b
185) b 186) b 187) a 188) a
189) a 190) a 191) c 192) d
193) c 194) c 195) d 196) c
197) d 198) a 199) b 200) a

NEET MCQs: Inheritance & Variation Page| 57 – ANSWER KEY – HINTS AND SOLUTIONS :
1 (b)
Haemophilia is a recessive X-linked disease. A
female with defected single X-chromosome is
normal but, carrier of disease, and male with
defected single X-chromosome is haemophilic.

2 (a)
Genetic disorder may be grouped into two
categories
(i) Mendelian Disorders These genetic disorder
are mainly caused by alternation and mutation in
the single gene. They are transmitted to offsprings
following the principle of inheritance. Mendelian
disorder can be dominant or recessive. 𝑒.𝑔.,
haemophilia, colour blindness, sickle-cell
anaemia, cystic fibrosis, phenylketonuria,
thalassaemia.
(ii) Chromosomal Disorders Chromosomal
disorder are caused due to excess, absence, or
abnormal arrangement of one or more
chromosome, 𝑒.𝑔., Turner’s syndrome, Down’s
syndrome, etc
3 (c)
The term gene was coined by Johanssen.
4 (a)
A dihybrid cross involves two pairs of contrasting
characters, e.g., yellow round seeded plant and
wrinkled. Green seedes plant(both pure lines)
homozygous. When a dihybrid cross is made
between two pure line of homolzygous parents,
then the 𝐹1 generation shows hybrids with
dominant phenotypic effect. When 𝐹1
heterozygous plants are self-ferilized to
produce𝐹2 generation, four types of combinations
are obtained of which two are similar to parental
combination and other two are new
combinations. The phenotypic dihybrid ratio of
these four combinations in 𝐹2 generation comes
out to be 9 : 3 : 3 : 1, while the genotypic dihybrid
ratio is 1 : 2 : 2 : 4 : 1 : 2: 1 : 2 : 1.
5 (c)
Chromosome is made up of DNA and histone
proteins.
6 (d)
Baldness is not a sex-limited trait. Balaness is a
sex influenced trait.
Linkage is an exception to the principle of
independent assortment in heredity.
Galactosemia is a hereditary disease that is
caused by the lack of a liver enzyme required to
digest galactose.
Small population size results in random genetic
drift in population.
7 (a)
The 𝐹1 offsprings of pure tall and pure dwarf are
heterozygoous tall, which on selfing produces 1 :
1 ratio of breeding tall to breeding dwarf.
8 (b)
Exposure of ‘X’ rays enhance the frequency of
crossing over
9 (a)
The genotype of trihybrid would be AaBbCc. Eight
different types of gametes ABC, ABc, AbC, Abc,
aBC, aBc, abC, abc would be formed. The number
of zygotes would be 82=64.
10 (b)

Page| 60

The genetic composition of an organism, i.e., the
combination of all alleles possessed by an
organism is called genotype
11 (d)
In polyploidy there are more than one set of
chromosomes is presen’t in an organisms. It only
happens when cytokinesis doesn’t take place in
proper way
12 (a)
12
A dihybrid cross in pea
plant between yellow round (smooth) seeded and green wrinkled seeded plant. The cross proves the
principle of independent assortment
13 (d)
When the F1-hybrid (Rr Yy) of a dihybrid cross is
test crossed (crossed with double recessive
parent rryy), the F2-offspring appear in the
phenotypic and genotypic ratio of 1 : 1 : 1 : 1
confirming that F1-offspring was heterozygous in
both the traits. It is a cross between RrYy×rryy.
14 (c)
Allelomorphs or simply called allele represents a
pair of contrasting characters
15 (a)
Harmful mutation does not get elimated from the
gene pool because most of the harmful mutations
are recessive and they carried by heterozygous
condition in the individual. If they (mutation) are
dominant then they easily get eliminated by the
death of an organism
16 (a)
A-Common, B-Rare
17 (c)
Mendel died in 1884 long before his work came to
recognized. It was in 1900 when three worker
independently rediscovered the principles of
heredity already worked out by Mendel.
They were Hugo de Vries of Holland, Carl Correns
of Germany and Eric Tiron and Tschermark of
Austria
18 (a)
In gynandromorphs, some cells of body contain
XX and some cells XY genotype.
19 (d)
Post Mendelian Discoveries
Gene interaction is the influence of alleles and
nonalleles ion the normal phenotypic expression
of genes. It is two types, intragenic (allelic) and
intergenic (nonallelic). In the intragenic
interaction the two allels (present on the same
gene locus on the two homologous chromosome)
of a gene interact in such a way as to produce a
phenotypic expression different from typical
dominant-recessive phenotype, 𝑒.𝑔., incomplete
dominance, codominance, multiple alleles.
In intergenic or non-allelic interaction, two or
more independent gene present on the same or
different chromosomes interact to produce
different expression, 𝑒.𝑔., epistasis, duplicate
genes, complementary genes, supplementary
genes, lethal genes, inhibitory genes, etc.
20 (c)

Page| 61

Intermediate inheritance is incomplete
dominance in which dominant factor of a
heterozygote does not completely mask the
expression of recessive allele. In incomplete
dominance, genotypic and phenotypic ratio
remain the same and is 1 : 2 : 1.
21 (c)
Green pod colour is dominant.
7 dominant traits, 7 recessive traits total 14 traits
or 7 oppossing pairs of traits
Characters Dominant
Traits
Recessive
Traits
Seed shape
Seed colour
Flower
colour
Pod shape
Pod colour
Flower
position
Stem
height
Round
Yellow
Violet

Full
Green
Axial

Tail
Wrinkled
Green
White

Constricted
Yellow
Terminal

Dwarf

22 (a)
IA IB are the dominant form of I gene, I is
recessive form
23 (a)
A-statistical analysis; B-mathematical logic
24 (d)
ZW and ZZ and ZOZZ.
ZW and ZZ Type of Sex Determination This
mechanism operates in certain insects (butterflies
and moths) and in vertebrates (fishes, reptiles
and birds). The male has two homomorphic sex
chromosomes (ZZ) and is homogametic and the
female has two heteromorphic sex chromosomes
(ZW) and is heterogametic. There are thus two
types of eggs with Z and with W and only one type
of sperms. i.e., each with Z

WZ-ZZ types of sex determination
25 (a)
If a character is expressed equally in the
homozygous and heterozygous conditions, it is
called dominant and the other character is said to
be recessive. In given question, ‘Tall’ character is
dominant over ‘dwarf’, hence, the cross shows
dominance and segregation of traits.
26 (b)
The best method to determine homozygosity and heterozygosity of an individual is back cross.
Crossing of F1 (dominant phenotype) to any one of the parent called back cross and when phenotype of
crossing parent is recessive than this is called test cross. The progeny of such cross can easily be analysed
to predict the genotype of test organism

27 (c)
Presence of one Barr body indicates the person
under investigation is a normal female.
28 (a)
A-Male, B-Female, C-Gametes.
XY and XY type sex determination seen in many
insect and mammals including humans. Males
have X and Y chromosome along with autosome
and females have pair of ‘X’ chromosome along
with autosome
Parents Phenotypes Male
Female

Page| 62

             Genotypes     44A + XY

44A + XX
Gametes 22A + X 22A+Y
22A + A22A + X
22A+ X 22A+X
Children 22A + X 44A + XX 44 A + XY
Female
22A + Y 44 A + XY 44 A + XY
Male
Sex ratio Female : Male = 1 : 1
In plants The flowering plants are mostly bisexual
and lack sex chromosomes. The unisexual
flowering plants tent to have XX-XY type of sex
chromosomal mechanism for sex determination.
The female plants are XX and male plants are XY.
XX and XO Type of Sex Determination
Found in insect like grasshopper, cockroaches and
bugs. Males have only X sex-chromosome and
autosomes, female have pair of X-chromosome
and autosome
Parents Phenotypes Male Female
Genotypes 𝐴𝐴+𝑋𝑂 𝐴𝐴+𝑋𝑋
Gametes 𝐴+𝑋,𝐴+𝑂 𝐴+𝑋,𝐴+𝑌
�
�𝟏-generation

XX-XO type of sex determination
29 (c)
Female is sterile.
Disorders Autosomal/Sex
Linked
Symptoms Effects
Down’s
syndrome
Autosomal
aneuploidy
(trisomy, +21)
Mongolian eyefold
(epicanthus), open
mouth, protruded
tongue, projected
lower lip, many
loops on finger tip,
palm crease
Retarded
mental
development
IQ (below 40)
Turner’s
syndrome
Sex
chromosomal
monosomy 44

XO
Short stature
females (<5’),
webbed neck, body
hair absent
menstrual cycle
absent. Sparse
pubic hair,
underdeveloped
breasts narrow lips
puffy fingers
Sterile
hearing
problem
Klinefelter’s
syndrome
Sex
chromosomal
aneuploidy
(tri/tetrasomy
of X
chromosome)
44+XXY
44+XXXY
The males are tall
with long legs,
testes small, sparse
body hair, Barr
body present,
breast enlargement
Gynaecomast
ia azospermia
sterile

Page| 63

Cause Absence of one of the X-chromosomes, resulting in the karyotype 44+XO
Symptoms
(a) Sterile female with rudimentary ovaries
(b) Shield-shaped thorax
(c) Webbed neck
(d) Poor development of breasts
(e) Short stature, small uterus, puffy fingers
(iii) Klinefelter’s syndrome
Cause Presence of an additional copy of X-chromosome resulting in the karyotype 44+XXY
Symptoms
(a) Sex of the individual is masculine but possess feminine characters
(b) Gynaecomastia, i.e., development of breasts
(c) Poor beard growth and often sterile
(d) Feminine pitched voice
30 (c)
The environmental stress (as pesticides) does not
cause the direct changes in genome, instead, it
simply selects rather persisting mutations, which
result in phenotypes that are better adapted to
the new environment (e.g., certain pesticides).
31 (c)
A Lampbrush chromosomes is made up of two
homologous chromosomes held at several places
by chiasmata. The chromosomes are found in
oocytes of many invertebrates and all vertebrates
except some mammals. Lampbrush chromosomes
are found during the extended diplotene phase of
first meiotic division.
32 (c)
A gene consists of a polynucleotide sequence that
encodes a functional polypeptide or RNA
sequence.
33 (a)
XY and XY type sex determination seen in many
insect and mammals including humans. Males
have X and Y chromosome along with autosome
and females have pair of ‘X’ chromosome along
with autosome
Parents Phenotypes Male
Female
Genotypes 44A + XY
44A + XX
Gametes 22A + X 22A+Y
22A + A22A + X
22A+ X 22A+X
Children 22A + X 44A + XX 44 A + XY
Female
22A + Y 44 A + XY 44 A + XY
Male
Sex ratio Female : Male = 1 : 1
In plants The flowering plants are mostly bisexual
and lack sex chromosomes. The unisexual
flowering plants tent to have XX-XY type of sex
chromosomal mechanism for sex determination.
The female plants are XX and male plants are XY.
XX and XO Type of Sex Determination
Found in insect like grasshopper, cockroaches and
bugs. Males have only X sex-chromosome and
autosomes, female have pair of X-chromosome
and autosome
Parents Phenotypes Male Female
Genotypes 𝐴𝐴+𝑋𝑂 𝐴𝐴+𝑋𝑋
Gametes 𝐴+𝑋,𝐴+𝑂 𝐴+𝑋,𝐴+𝑌
�
�𝟏-generation

XX-XO type of sex determination
34 (c)
Frameshift mutations are the mutations caused by
insertion (i.e., addition) or deletion of one or
more nitrogen bases in the DNA or RNA. This type
of mutation alters the nucleotide sequences in all
the genes and hence, the genetic code is changed
totally, fro the point of mutation which results in
the change in biochemical behaviour of the genes.
Base pair substitution mutations involve
substitution of a aitrogen base by another base or
by some derivative of nitrogen base.
35 (c)

Page| 64

According to law of segregation, the heredity
character in the form of alleles segregate from
each other during gamete formation, i.e, each
gamete carry only one allele of each gene. This is
also called law of purity of gametes. When tall and
dwarf plants are crossed only tall plants are
produced in 𝐹1 generation. By selfing of these 𝐹1
plants tall and dwarf plants produced in 3 : 1
ratio.
36 (b)
Mendel’s law are able to predict accurately the
pattern of inheritance for a situation in which
alleles shows the complete dominance. Effect of
environment, other alleles did not explained by
the Mendel. Mendel did not know about the
polygenic traits also
37 (b)
Blood group-O has no antigens but A and B
antibodies.
38 (d)
Colour blindness disease was detected by Wilson
in 1910.
39 (a)
In the dihybrid cross between RRYY and rryy
parents, the number of RrYy genotypes in 𝐹2
generation will be four.
40 (d)
Allelism refers to presence of alternative forms of
a gene at a given locus. Alleles or allelomorphs are
the two contrasting aspects of the same character
present at a locus of homologous pair of
chromosomes. Now –a-days, the same aspect in
duplicate (TT or tt) of a character is also
considered an allele.
41 (d)
The women with albinic father has gene for
albinism. When this women marries with albinic
men, they produce normal and albinic in 1 : 1
ratio.
42 (a)
ZO and ZZ type of sex determination. This
mechanism occurs in certain buttterfiles and
moths. The female is heterogametic and produces
two types of eggs half with Z and half without Z
chromosome. The males have homomorphic sex
chromosomes and is homogametic. It forms only
one kind of sperms, each with Z-chromosome
Parents Phenotypes Male Female
Genotypes AA + ZZ AA +ZO
Gametes A+Z, A+Z A +Z, A+O
�
�𝟏-generation

ZO-ZZ type of sex determination
43 (c)
Mendel’s law of independent assortment states
that,”the alleles of different genes segregate
independently of each other during meiosis”.
44 (a)
XX and XO chromosome.
XY and XY type sex determination seen in many
insect and mammals including humans. Males
have X and Y chromosome along with autosome
and females have pair of ‘X’ chromosome along
with autosome
Parents Phenotypes Male
Female
Genotypes 44A + XY
44A + XX
Gametes 22A + X 22A+Y
22A + A22A + X
22A+ X 22A+X
Children 22A + X 44A + XX 44 A + XY
Female
22A + Y 44 A + XY 44 A + XY
Male
Sex ratio Female : Male = 1 : 1
In plants The flowering plants are mostly bisexual
and lack sex chromosomes. The unisexual
flowering plants tent to have XX-XY type of sex
chromosomal mechanism for sex determination.
The female plants are XX and male plants are XY.
XX and XO Type of Sex Determination
Found in insect like grasshopper, cockroaches and
bugs. Males have only X sex-chromosome and
autosomes, female have pair of X-chromosome
and autosome
Parents Phenotypes Male Female
Genotypes 𝐴𝐴+𝑋𝑂 𝐴𝐴+𝑋𝑋
Gametes 𝐴+𝑋,𝐴+𝑂 𝐴+𝑋,𝐴+𝑌
�
�𝟏-generation

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XX-XO type of sex determination
45 (b)
A-Chromatid, B-Allele pair, C-Genetic composition
46 (b)
The position of centromere determines the shape
of chromosome.
47 (b)
After schooling Mendel joined Augustinian
monastery of St. Thomas at Brunn (then in
Austria now Brunn in Czechoslovakia) in 1843 at
the age of 21. At the age of 25 (1847), he was
made a prist in that monastery
48 (a)
It was TH Morgan who clearly proved and define
linkage on the basis of the breeding experiments
in fruitfly. In 1911, Morgan and Castle proposed
‘chromosomal’ theory of linkage’
49 (d)
Francis Galton(1885) gave the term eugenics.
Eugenics is the improvement of human race by
the application of principles of genetics. The other
meaning of eugenics is ‘science of being well
born’.
50 (c)
The test cross involves the crossing of F1hybrid
with a double recessive genotypic parent. By test
cross, the heterozygocity and homozygocity of the
organism can be tested.
51 (a)
Tetraploid endosperm is obtained, when a diploid
female and tetraploid male plants are crossed.
52 (a)
Colour Blindness
(i) It is a sex-linked recessive disorder
(ii) It results in defect in either red or and green
cone cells of eye resulting in failure to
discriminate between red and green colour
(iii) The gene for colour blindness is present on X
chromosome
(iv) It is observed more in males (XcY) because of
presence of only one X-chromosome as compared
to two chromosomes in famales
53 (a)
When the 𝐹1-hybrid is crossed with recessive
parent, both phenotypes appear in progeny and
this is called test cross. It gives 1 : 1 ratio in
monohybrid cross and 1 : 1 : 1 : 1 ratio in dihybrid
cross.
54 (d)

Thus, the genotype of parents will be BO×AO.
55 (b)
Symbol in pedigree chart represents still death
56 (c)
Histones are basic proteins found in the
eukaryotic chromosomes. These are rich in basic
amino acids lysine and arginine. There are
basically five types of histones, i.e.,
H1,H2A,H2B,H3 and H4 which have been studied
in almost all eukaryotic cells.
57 (a)
In monosomic condition, one chromosome is
missing from the somatic chromosome
complement. It is denoted by 2n-1. When somatic
cells of an organism contain three copies of one
chromosome, the condition is known as trisomy.
It is denoted by 2n+1. Therefore, monosomic
trisomy is represented as 2n-1+1.
58 (a)
Baldness is common in humans. Hereditary
baldness is carried by a dominant autosomal
gene. It develops only in men and never in
women.
59 (a)
Thalassaemia
(i) It is an autosome-linked recessive disesase
(ii) It occurs due to either mutation or deletion
resulting in reduced rate of synthesis of one of
globin chains of haemoglobin
(iii) Anaemia is the characteristic of this disease
(iv) Thalassaemia is classified into two types

𝛂-thalassaemia Production of α-globin
chain is affected. It is controlled by the
closely linked genes HBA1 and HBA2 on

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chromosome 16. It occurs due to mutation
or deletion of one or more of the four
genes.

𝛃-thalassaemia Production of β-globin
chain is affected. It occurs due to mutation
of one or both HBB genes on chromosome
11
60 (a)
The term ‘mutation’ was introduced by Hugo de
Vries in 1901 and his mutation theory of
evolution called mutation theory of evolution.
Mutation is new sudden inheritable change in
organism due to permanent change in their
genotype
61 (d)
Because in sex linked inheritance the chance of
girl or female to be affected is almost nill.
Generally, the females are carriers and in
heterozygous condition
62 (b)
Non-disjunction is the condition in which the
separation of chromosome doesn’t take place
during cell division. In 44+XY non-disjunction
there is non-separation of XY gene is there, which
leads to the formation of sperm having genotypes,
22+XY and 22
63 (c)
Linkage prevents independent assortment.
64 (d)
Sex influenced trait.
Finalization of sex at the time of fertilization is
known as sex determination. All sex linked
character show criss-cross inheritance and firstly
it was studied and discovered by TH Morgan
(1910). Sex related trait may be divided into three
types
(i) Sex Linked Traits They are those traits the
determining genes of which are found on the sex
chromosomes. All the sex-linked traits present on
a sex chromosome are inherited together
(ii) Sex Limited Traits They are autosomal traits
which are expressed in a particular sex in
response to sex hormones although their genes
also occur in the other sex, e.g., milk secretion in
mammalian females, pattern baldness in males.
The gene for baldness behaves as an autosomal
dominant in males and autosomal recessive in
females
(iii) Sex Influenced Traits The traits are not due to
particular genes but are by products of sex
hormones, e.g., low pitched voice, beard
moustaches. In males, pattern baldness is related
to both autosomal genes as well as excessive
secretion of testosterone
65 (c)
Since in an individual only two alleles can be
present, multiple alleles can be found only when
population studies are made
66 (c)
Biological concept of species says that only the
members of a species can breed freely in nature to
produce fertile offsprings. The plant tobacco
(𝑁𝑖𝑐𝑜𝑡𝑖𝑎𝑛𝑎) has two different species,
�
�𝑖𝑐𝑜𝑡𝑖𝑎𝑛𝑎 𝑡𝑜𝑏𝑎𝑐𝑐𝑢𝑚 and 𝑁𝑖𝑐𝑜𝑡𝑖𝑎𝑛𝑎 𝑠𝑦𝑙𝑣𝑒𝑠𝑡𝑟𝑖𝑠.
These two species cannot reproduce freely.
67 (b)
In duplication there is increase in size of genes by
duplication of it segment of a chromosome.
Mainly seen in case of plants. But in deletion there
is loss of genes or segment of chromosome
68 (d)
The types of gametes produced by a plant depend
upon the number of hetrozygous pair.
Number of types of gametes=2𝑛
N=Number of heterozygous pair
21=2
The gametes are-ABC and AbC.
69 (c)
In trisomic condition, diploid organism have extra
chromosome represented by the chromosomal
formula2𝑛+1 . One of the pairs of chromosomes
has an extra member, so that a trivalent may be
formed during meiotic prophase, e.g., Down’s
syndrome (45+XX or 45+XY), Klinefelter’s
syndrome (44 + XXY).
In monosomic, diploid organism has one
chromosome of a single pair missing with
genomic formula 2𝑛−1. Monosomics can from
two kind of gametes, (n) and (n-1),
e.g., Turner’s syndrome (44 + X).
70 (d)

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When a normal man marries a normal woman,
whose father was colourblind then their 50%
sons are colourblind (50% sons normal) and all
the daughters are phenotypically normal(carrier
woman also are phenotypically normal).
The female parent is carrier as it receives a
defective X-chromosome from her father.
71 (c)
Testosterone in male secreted by Leydig cells. In
the male testosterone is essential for
development of secondary sexual character and
related to baldness also
72 (d)
The disorder cystic fibrosis, sickle cell anaemia,
colour blindness and haemophilia are caused due
to the abnormality in gene (Mendelian factor).
Turner’s syndrome is due to chromosomal
abnormality. It is characterized by 44 autosomes
and only one X-chromosome.
73 (d)
Haemophilia is a X-linked disorder not Y-linked.
74 (c)
(Homozygous tall) × (Homozygous dwarf)

Phenotypic ratio 1 : 1 (50% tall, 50% dwarf)
Genotypic ratio 1 : 1
75 (c)
γ−rays generally induce mutations.
76 (d)
Since genotypes/phenotypes of both parents are
same but only sources of gametes are reversed,
these crosses are called reciprocal crosses.
77 (a)
Man has only one X-chromosome that is inherited
to his daughter. Therefore, a hereditary disease,
which is X-chromosomal linked, is never passed
on from father to son.
78 (a)
Bateson gave the coupling and repulsion
hypothesis for linkage and crossing over.
Similar genes remain together they don’t go for
crossing over. Bateson called them coupling
gones.
While on the other hand dissimilar gene segregate
crossing over takes place. Bateson called them
repulsion parents gene
79 (a)
The blood group type in human provides an
example of multiple allelism (i.e., presence of
more than two allele for one gene). There are
three A, B and O blood groups allele usually given
the symbolIA,IB and Ii.IA and IB are codominant
to each other but both are dominant to Ii. The
offspring of parents having IA and I1 allele with be
IAIi having blood group-A.
A-IAIi
B-IBIi
AB-IAIB
O-IiIi
80 (c)
A person having 45 chromosomes instead of 46
due to lack of Y-chromosome is suffering from
Turner’s syndrome.
81 (c)
Opposite phenomena.
Strength of linkage between two genes inversely
proposed to the distance of two gene means if two
genes are closely placed then they have high
percentage of linkage and if they placed for then
there is low percentage of linkage.
Linkage and recombination are two opposite
phenomena. In linkage two genes remains united
and in recombination the two get apart due to
crossing over during gametogenesis (meiosis)
82 (b)
Johanssen (1909) proposed the term gene. Genes
are made up of DNA, i.e., a DNA segment
associated with proteins, which can be copied in
the form of RNA and is responsible for hereditary
characters. Genes have full control over protein
synthesis.
83 (b)
2n (diploid).
Haploid diploid mechanism of sex determination
(haplodiploidy).

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Hymenopterous insect such as bees, wasps ants
show unique phenomena in which an unfertilized
egg develops into male and female develops from
fertilized egg.
In honeybee, the quality of food determines
whether a diploid larva will become a fertile
queen or a sterile worker female. A larva fed on
royal jelly a secretion from the mouth of mussing
workers grows into a queen, whereas a larva fed
on pollen and nectar grows into a worker bee

84 (a)
For the given case, the imprints need to be used
only on plates with streptomycin.
85 (d)
Phenylketonuria (PKU) is homozygous recessive
autosomal disorder associated with metabolism
and the gene for it is present on chromosome-12.
Huntington’s disease (Huntington’s chorea) is a
dominant autosomal disorder due to an allele on
short arm of chromosome-4. Sickle cell anaemia is
due to codominant autosomal allele HbS present
on chromosome-11.
86 (a)
The genes are arranged in a linear fashion on the
chromosome.
87 (a)
According to 𝑐𝑖𝑠−𝑡𝑟𝑎𝑛𝑠 effect of Lewis, when
two genetic loci produce identical phenotypes in
�
�𝑖𝑠 and 𝑡𝑟𝑎𝑛𝑠 position, they are considered to be
pseudoalleles and phenomenon as pseudoallelism.
88 (c)
Factor-II − Prothrombin
Factor –III − Thromboplastin
Factor –VIII − Antihaemophilic globulin
Factor –XII − Hageman factor
89 (c)
The longest chromosome is seen in Trillium
(30𝜇).
90 (c)
F1.
Mendel cross-pollinated a pure tall pea plant
(100-120 cm hight) and a pure dwarf pea plant.
(only 22 to 44 cm hight). He called them parental
generation, expressed now-a-days by symbol P.
This hybridization popularly called as
monohybrid cross

Page| 69

population with a frequency greater than 0.01. In
simple terms, if an inheritable mutation is
observed in a population at high frequency, it is
referred to as DNA polymorphism.
93 (a)
A-Extremely, B-Carrier, C-Haemophilia
94 (a)
The Rh factor causes erythroblastosis foetalis,
when a woman who is Rh− marries a man, who is
Rh+ , their first child will be safe (which is Rh+)
but during pregnancy some blood of foetus and
mother mixes due to which the mother develops
antibodies against her foetus antigen which is
Rh+.
95 (d)
Landsteiner divided human population into four
groups based on the presence of antigens found in
their RBCs. Each group represented a blood
group. Thus, there are four types of blood groups
A, B, AB and O. Blood group-O does not contain
any antigen on RBCs, hence can be given to any
person, that’s why, this blood group is called
universal donor.
96 (a)
Alleles or allelomorphs are alternative forms of
the same gene, e.g., for height of plant ‘T’ and ‘t’.
Homologous chromosomes are a pair of
chromosomes having similar genes, which control
the same characters.
97 (d)
Telomeres are ends of chromosome, that have
repetitive DNA sequences and are stable and
resistant to exonuclease digestion hence, essential
for chromosome stability.
98 (c)
Intermediate inheritance also called the
incomplete dominance. In that inheritance the
phenotypic and genotypic ratio are same. The
classical examples are = four O’ clock plant and
snapdragon.
Mirabilis jalapa shows incomplete dominance

The ratio of pink and white flower will be 1 : 1
99 (c)
Mendelian disorder may be dominant or recessive
100 (c)
In African population, sickle cell anaemia provides
immunity against malaria.
101 (c)
Aneuploidy is the variations in individual
chromosomal number. Actually, loss or gain of
individual chromosomes upsets the balance and,
hence normal development is not possible.
103 (c)
Black feathered hen = BB
White feathered cock = bb
Blue feathered fowl = Bb

104 (c)
Histones are special type of basic protein
associated with DNA and form chromosome. RNA,
protein, carbohydrate, fat, doesn’t find in
chromosomes
105 (c)
In pedigree
Square represents male blackened square or
circle represents affected individual.
Horizontal line represents-parents
The study of inheritance of genetic traits in
several generations of a human family in the form
of a family tree diagram is called pedigree
analysis.
Advantages
(i) It helps in genetic counselling to avoid
disorders

Page| 70

(ii) It shows the origin of a trait and flow of a trait
in a family
(iii) It is important to know the possibility of a
recessive allele that can cause genetic disorders
like colour blindness, haemophilia, etc.
Signosed in the pedigree are

106 (a)
In the given pedigree chart only males are
affected. So, it can be easily inferred that the given
trait is connected to Y-chromosome. The genes,
which are present on the Y-chromosome are
called holoandric genes
107 (a)
In the gametogenesis meiosis occur. The diploid
chromosome become haploid, so the probability
of side is sperm lacking one recessive autosomal
allele and holandric gene is half
108 (b)
F3-generation obtained by selfing of F2
generation.
Mendel cross-pollinated a pure tall pea plant
(100-120 cm hight) and a pure dwarf pea plant.
(only 22 to 44 cm hight). He called them parental
generation, expressed now-a-days by symbol P.
This hybridization popularly called as
monohybrid cross

This three generations of pea plants after crossing
a pure tall plant with a dwarf one. The plants of
F1-generation are all tall, of F2-generation three
tall and one dwarf. One third of the tall plants are
pure, while the remaining behave as hybrids
�
�𝟏-generation Seeds collected from the parental
generation called first filial generation or F1
generation
�
�𝟐-generation F1-plants pollinated among them
self (self breeding or inbreeding) and seed
produced by F1-plants called F2-generation. They
were in ratio 3:1 (three tall and one dwarf).
�
�𝟑-generation Mendel allowed F2-plant to form
seed by self-pollination called F3-generation.
Mendel observed that tall and dwarf plant behave
differently
(i) Dwarf plant produced dwarf plant on self
pollinated
(ii) In tall plants one third plants breed true so
they were pure
(iii) Other two third plant behave like parents and
give tall to dwarf plants 3 : 1 indicate that their
parents have dwarf genes also
109 (d)
W Bateson and R C Punnett observed
complementary gene interaction for flower colour
in sweet pea (𝐿𝑎𝑡ℎ𝑦𝑟𝑢𝑠 𝑜𝑑𝑜𝑟𝑎𝑡𝑢𝑠). In
complementary interaction, two separate pairs of
genes interact to produce the phenotype in such a
way that neither of the dominant genes is
expressive unless the other one is present. In 𝐹2
generation, complementary genes produce a ratio
of 9 : 7.
110 (a)
Occasionally a single gene product may produce
more than one effect. For example starch
synthesis in pea seeds is controlled by one gene. It
has two allele (B and b). Starch is synthesized
effectively by BB and have bigger grains. In
contrast bb homozygous have lesser efficiency in
starch synthesis and produce smaller grains
111 (c)
In 𝐷𝑟𝑜𝑠𝑜𝑝ℎ𝑖𝑙𝑎, sex is determined by the ratio
number of X-chromosomes to the set of
autosomes.
112 (c)
The genotypic and phenotypic ratio of 1 : 2 : 1
with red, pink and white flowers are produced in
�
�𝑖𝑟𝑎𝑏𝑖𝑙𝑖𝑠 𝑗𝑎𝑙𝑎𝑝𝑎, when red flowered plants (RR)

Page| 71

are crossed with white flowered (rr). It occurs
due to allelic gene interactions, called, incomplete
dominance. In which, both of the allelomorphic
genes will have partial or incomplete dominance
and F1-hybrid will show mixture of characters of
two parents.
113 (a)
Meiosis is an important stage in sexual
reproduction. During meiosis, genetic
recombination occurs as a result of crossing over.
114 (d)
Blood group of children may be A, B, AB and O.
115 (d)
The genes, which are present very far from each
other tend to get unlinked and they arethe most
chances for crossing over
116 (a)
Given diagram depicits the sex linked inheritance
in given options haemophilia is the sex-linked
character
117 (b)
Incomplete dominance or blending inheritance is
the phenomenon, in which the two genes of
allelomorphic pair are not related as dominant or
recessive but each of them expresses itself
partially, thus the 𝐹1 hybrids exhibit a mixture or
blending of characters of both the parents. In 𝐹2
generation, the phenotypic ratio obtained is 1 : 2 :

118 (c)
Haemophilia is a disease, which is caused due to
lack of blood clotting factor. It appears only in
human male which can be transferred to their
grandson through his carrier daughter.
119 (a)
In the given option only codominance does not
obey Mendel’s laws.
The phenomenon of expression of both the alleles
in heterozygote is called codominance. As the
result the phenotype is different from both
homozygous genotype.
Examples
Blood group is the good example
codominance
ABO blood groups are controlled by gene
I. The gene (l) has three allele
IA,IB,i,IA,IB produce slilghtly different
form of sugar while i does not produce
any kind of sugar.
IA,IB are dominant alleles where as i is
recessive alleles
Since, there are three different allele,
there are six different combination of
these three alleles are possible and four
phenotypes (A, B, AB and O)
Genetic Basis of Blood Groups in Human
Population
Allele
from
Parent
1
Allele
from
Parent
2
Genotype
of
Offspring
Blood
Types of
Offspring
IA IA IAIA A
IA IB IAIB AB
IA i IAi A
IB IA IAIB AB
IB IB IBIB B
IB i IBi B
i i ii O
When IA and IB are present together they both
express their own types of sugars this is because
of co-dominance. ABO blood grouping also
provides a good example of multiple alleles.
Here, you can see that there are more than two,
i.e., three alleles governing the same character.
Since, in an individual only two alleles can be
present multiple alleles can be found only when
population studies care made. Dominance is not
an autonomous features of a gene. It depends on
much on the gene product
120 (d)
11th.
Thalassaemia
(i) It is an autosome-linked recessive disesase
(ii) It occurs due to either mutation or deletion
resulting in reduced rate of synthesis of one of
globin chains of haemoglobin
(iii) Anaemia is the characteristic of this disease
(iv) Thalassaemia is classified into two types
𝛂-thalassaemia Production of α-globin
chain is affected. It is controlled by the
closely linked genes HBA1 and HBA2 on
chromosome 16. It occurs due to mutation
or deletion of one or more of the four
genes.
𝛃-thalassaemia Production of β-globin
chain is affected. It occurs due to mutation

Page| 72

of one or both HBB genes on chromosome
11
122 (a)
TH Morgan.
Father of experimental genetics is TH Morgan. He
is also called the fly man of genetics because of
selecting fruit fly (Drosophila melanogaster) as
research material in experimental genetics
123 (b)
Mendel gave the laws of inheritance, which
provides the mechanism that explains the pattern
of inheritance
124 (b)
The genotypic ratio can be find out of a dominant phenotype by test cross or by simply Punnett square.

Phenotypic ratio Tall : Dwarf
Genotypic ratio TT : Tt : tt
1 : 2 : 1
A Punnett square used to understand to typical monhybrid cross conducted by Mendal between true
breeding tall plants and true-breeding dwarf plants
Crossing of F1 (dominant phenotype) to any one of the parent called back cross and when phenotype of
crossing parent is recessive than this is called test cross. The progeny of such cross can easily be analysed
to predict the genotype of test organism

125 (c)

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Genes for baldness are located on autosomes and
influenced by androgens, thus, this is more
common in men than in women.
126 (a)
The number of characters studied by Mendel was
seven which were present on four chromosomes.
Three contrasting characters with respect to pea
pod are (i) pod shape,(ii) pod colour, (iii)pod
position.
127 (c)
Chlorinated hydrocarbons are mutagen pollutants
which can cause mutation in gene.
128 (b)
Both genes and chromosomes (Mendelian
factors) whether dominant or recessive are
transmitted from generation to generation in the
pure or unaltered form. It is also called law of
purity of gametes
129 (d)
The study of inheritance of genetic traits in
several generations of a human family in the form
of a family tree diagram is called pedigree
analysis.
Advantages
(i) It helps in genetic counselling to avoid
disorders
(ii) It shows the origin of a trait and flow of a trait
in a family
(iii) It is important to know the possibility of a
recessive allele that can cause genetic disorders
like colour blindness, haemophilia, etc.
Signosed in the pedigree are

130 (c)
Some genes control phenotypic traits and at the
same time they also influence the viability of the
individuals. The influence of these genes on
viability is such that it may cause death of
individual carrying them. Such genes are called
lethal genes.
131 (a)
Absence of one X-chromosome (44 with XO).
Disorders Autosomal/Sex
Linked
Symptoms Effects
Down’s
syndrome
Autosomal
aneuploidy
(trisomy, +21)
Mongolian eyefold
(epicanthus), open
mouth, protruded
tongue, projected
lower lip, many
loops on finger tip,
palm crease
Retarded
mental
development
IQ (below 40)
Turner’s
syndrome
Sex
chromosomal
monosomy 44

XO
Short stature
females (<5’),
webbed neck, body
hair absent
menstrual cycle
absent. Sparse
pubic hair,
underdeveloped
breasts narrow lips
puffy fingers
Sterile
hearing
problem

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Klinefelter’s
syndrome
Sex
chromosomal
aneuploidy
(tri/tetrasomy
of X
chromosome)
44+XXY
44+XXXY
The males are tall
with long legs,
testes small, sparse
body hair, Barr
body present,
breast enlargement
Gynaecomast
ia azospermia
sterile

Some Examples of Aneuploidy
(i) Down’s syndrome-21 trisomy
Symptoms
(a) Short statured with small round head
(b) Partially open mouth with protruding furrowed tongue
(c) Palm is broad with characteristic palm crease
(d) Slow mental development
(ii) Turner’s syndrome
Cause Absence of one of the X-chromosomes, resulting in the karyotype 44+XO
Symptoms
(a) Sterile female with rudimentary ovaries
(b) Shield-shaped thorax
(c) Webbed neck
(d) Poor development of breasts
(e) Short stature, small uterus, puffy fingers
(iii) Klinefelter’s syndrome
Cause Presence of an additional copy of X-chromosome resulting in the karyotype 44+XXY
Symptoms
(a) Sex of the individual is masculine but possess feminine characters
(b) Gynaecomastia, i.e., development of breasts
(c) Poor beard growth and often sterile
(d) Feminine pitched voice
132 (c)
The recessive genes located on X-chromosome in
humans are always expressed in males because a
female may be homozygous or heterozygous,
while male is always hemizygous (i.e., only one
allele is present).
133 (b)
Strength of linkage between two genes inversely
proposed to the distance of two gene means if two
genes are closely placed then they have high
percentage of linkage and if they placed for then
there is low percentage of linkage.
Linkage and recombination are two opposite
phenomena. In linkage two genes remains united
and in recombination the two get apart due to
crossing over during gametogenesis (meiosis)
134 (d)
Fruitfly is excellent model for genetics because
(i) Life cycle is very short (14 days)
(ii) Can be feed on simple synthesis medium
(iii) Single mating produces large number of
progeny
(iv) Clear differentiation of sexes
(v) Variation can be seen simply by hand lens or
simple microscope
(vi) They (fruitfly) are easy to handle
136 (b)
If both parents have blood group-AB then the
possible blood groups of children are A, B and AB.
137 (c)
Test cross is a cross in which the dominant F1-plant crosses with the homozygous recessive parents plant.

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Crossing of F1 (dominant phenotype) to any one of the parent called back cross and when phenotype of
crossing parent is recessive than this is called test cross. The progeny of such cross can easily be analysed
to predict the genotype of test organism

138 (d)
The ability of a gene to have multiple effects is
known as pleiotropy and this phenomenon
pleiotropism. The basis of pleiotropy is the
interrelationship between the metabolic
pathways that may contribute towards different
phenotypes.
139 (c)
When two pea plants having red (dominant)
coloured flowers with unknown genotype are
crossed, the 75% red and 25% white flowered
plants will be produced by following the law of
Mendel. This is possible only if the parents are
heterozygous.

141 (a)
1
4
th and 3
4
th.
Mendel cross-pollinated a pure tall pea plant
(100-120 cm hight) and a pure dwarf pea plant.
(only 22 to 44 cm hight). He called them parental
generation, expressed now-a-days by symbol P.
This hybridization popularly called as
monohybrid cross

Page| 76

Night blindness is nutritional deficiency disease
generally happens due to deficiency of vitamin-A
143 (a)
The genotypic ratio of monohybrid cross is 1 : 2 :
1, whereas the phenotypic ratio is 3 : 1.
9 : 3 : 3 : 1 is the phenotypic ratio of dihybrid
cross (the cross made to study the inheritance of
two pairs of factors or alleles of two genes).
144 (c)
Chromosomal Theory of Inheritance
Walter Sutton and Theodore Boveri noted that the
behavior of chromosomes was parallel to the
behaviour of genes and used chromosome
movement to explain Mendel’s laws.

Law of segregation interpreted on the basis of
genes or factors (solid and hollow) situated on
two homologous chromosomes.
Comparison between the Behaviour of
Chromosomes and Genes
Chromosomes Genes
Segregate at the
time of gamete
formation such
that only one of
each pair is
transmitted to a
gamete
Independent
pairs segregate
independently
of each other
Segregate of
gamete
formation and
only one of
each pair is
transmitted to
a gamete
One pair
segregates
independently
of another pair
Sutton and Boveri argued that the pairing and
separation of a pair of chromosomes would lead
to the segregation of a pair of factors they carried.
Sutton united the knowledge of chromosomal
segregation with Mendelian principles and called
it the chromosomal theory of inheritance.
Experimental verification of chromosomal theory
of inheritance was given by Thomas Hunt Morgan.
Morgan worked with tiny fruitfly (Drosphila
melanogaster)
145 (b)
The females have homozygous XX sex
chromosomes, while males have heterozygous XY
chromosome. Y-chromosome is shorter than X
chromosome.
146 (b)
The Down’s syndrome (Mongolian idiocy) arises
due to trisomy of 21st chromosome, i.e., total 47
chromosomes will present in such person. The
main features are mental deficiency, short stature,
round face, flaccid muscles, protruding tongue,
etc.
147 (a)
ZW-ZZ system of sex determination occurs in
certain insects (gypsy moth) and vertebrates such
as fishes, reptiles and birds and plants such as
Fragaris elatior.
148 (a)
The Sudden and heritable change in the genetic
make up of an individual is called mutation. The
term mutation was introduced by Hugo de Vries.
149 (c)
According to law of purity of gametes, when the
gametes are formed, they carry only one allele of
the gene considered.

150 (d)
The recessive trait shown by F2 and F3-generation
both but firstly it was observed in F2-generation.
Mendel cross-pollinated a pure tall pea plant
(100-120 cm hight) and a pure dwarf pea plant.

Page| 77

(only 22 to 44 cm hight). He called them parental
generation, expressed now-a-days by symbol P.
This hybridization popularly called as
monohybrid cross

This three generations of pea plants after crossing
a pure tall plant with a dwarf one. The plants of
F1-generation are all tall, of F2-generation three
tall and one dwarf. One third of the tall plants are
pure, while the remaining behave as hybrids
�
�𝟏-generation Seeds collected from the parental
generation called first filial generation or F1
generation
�
�𝟐-generation F1-plants pollinated among them
self (self breeding or inbreeding) and seed
produced by F1-plants called F2-generation. They
were in ratio 3:1 (three tall and one dwarf).
�
�𝟑-generation Mendel allowed F2-plant to form
seed by self-pollination called F3-generation.
Mendel observed that tall and dwarf plant behave
differently
(i) Dwarf plant produced dwarf plant on self
pollinated
(ii) In tall plants one third plants breed true so
they were pure
(iii) Other two third plant behave like parents and
give tall to dwarf plants 3 : 1 indicate that their
parents have dwarf genes also
151 (a)
A-A; B-Genetic disorders
152 (a)
Heredity (L. Hereditas – Heirship or inheritance)
is the transmission of genetically based characters
from parents to their offspring.
The process by which characters are transferred
from one generation to the next generation is
called inheritance
153 (c)
Huntington’s chorea is a fatal disease of man. It is
characterized by uncontrolled jerking of body and
progressive degeneration of central nervous
system. The mean age for the onset of these
symptoms is between 35 to 40. This disease is
caused by an autosomal dominant gene.
154 (d)
Movement of chromosomes towards poles
requires centromere.
155 (a)
Klinefelter’s syndrome is represented by 44
autosomes + XXY.
157 (a)
Man has only one X-chromosomes that is inherted
to has daughter. Therefore, a heredftary disease,
which is X-chromosomal linked, is never passed
on from father to son.
159 (a)
Chromosomal theory of linkage states that
(i) Linked gene present on same chromosome
(ii) They lie in linear sequence in chromosome
(iii) There is tendency to maintain the parental
combination
(iv) Strength of linkage between two gene is
inversely proposal to the distance of two gene and
vice-versa
160 (c)
In the diploid organism (plants and animals) the
chromosome or DNA number becomes double
just before the cell division
161 (c)
Genetics is the branch of biology which deals with
the inheritance and variations
162 (c)
Balbiani first observed these chromosomes in the
salivary glands of midge Chironomus in 1881.
These polytene chromosomes are considered as
somatic giant tubules and also reported from fat
bodies some other dipterans also, e.g., Drosophila,
Chironomus, Sciaca, Rhyncosciara, etc.
163 (d)
Sir Archibald Edward Garrod was an English
physician, who pioneered the field of inborn
errors of metabolism. He was born on November
25, 1857, in London and died on March 28, 1936,
in Cambridge.
164 (c)

Page| 78

Punnett square is a table, in which all possible
combinations of gametes and progeny are
displayed in a grid structure.
165 (c)
Erythroblastosis foetalis is a haemolytic disease of
newborn children. Erythroblastosis foetalis can
occur when father is Rh positive and mother is Rh
negative. An Rh negative woman can be sensitized
when she bears an Rh+ child and Rh+ children
may have erythroblastosis.
166 (c)
When 𝐹1 hybrid is crossed with its recessive
parents, it is called as test cross.By test cross, the
herterozygosity and homozygosity of the
organism can be tested. The test cross ratio in
monohybrid cross is 1 : 1 and in dihybrid cross,
ratio wii be 1 : 1 : 1 : 1.
167 (c)
Inversion involves a reverse order of genes in a
part of chromosome.
168 (b)
The gamete mother cells (2𝑛) are called
meiocytes, which undergo meiosis to form
gametes (𝑛) . The chromosome number in the
melocytes(2𝑛) of housefly is 12.
169 (c)
Genes which codes for a pair a contrasting traits is
called alleles. They are slightly different forms of
the same gene, 𝑒.𝑔., TT, tt, tT
170 (c)
Haemophilia and colour blindness are both X
linked recessive diseases. The gene for both is
found on X-chromosome only.
Albinism, Sickle-cell anaemia and thalassemia are
autosomal diseases.
171 (c)
Mendel described the inheritance of recessive and
dominant genes. Phenylketonuria (PKU) is an
autosomal recessive mutation of gene on
chromosome-12.
172 (c)

Thus, there is no dwarf plant with wrinkled seeds
in F1-generation.
173 (b)
The term genetics (Gk. Genesis=descent) was
coined by Bateson in 1906. Genetics is the study
of principles and mechanism of heredity and
variations.
174 (b)
In human beings, 46 chromosomes are found, in
which only one pair XY takes part in sex
determination. These are known as sex
chromosomes or allosomes, rest 22 pairs are
known as autosomes.
175 (a)
Mendel obtained the recessive character in F2 by
self pollinating the F1-plants.
Mendel cross-pollinated a pure tall pea plant
(100-120 cm hight) and a pure dwarf pea plant.
(only 22 to 44 cm hight). He called them parental
generation, expressed now-a-days by symbol P.
This hybridization popularly called as
monohybrid cross

Page| 79

produced by F1-plants called F2-generation. They
were in ratio 3:1 (three tall and one dwarf).
�
�𝟑-generation Mendel allowed F2-plant to form
seed by self-pollination called F3-generation.
Mendel observed that tall and dwarf plant behave
differently
(i) Dwarf plant produced dwarf plant on self
pollinated
(ii) In tall plants one third plants breed true so
they were pure
(iii) Other two third plant behave like parents and
give tall to dwarf plants 3 : 1 indicate that their
parents have dwarf genes also
176 (a)
Criss-cross Inheritance It is a type of sex-linked
inheritance, where a parent passes the traits to
the grand child of the same sex through offspring
of the opposite sex, that is, father passes the traits
to grandson through his daughter (diagynic),
while the mother transfers traits to her grand
daughter through her son (dia-andric).
It was first studied by Morgan (1910) in case of
eye colour in Drosophila. Criss-cross inheritance
is applicable to most sex-linked disorders in
humans, 𝑒.𝑔., red green colour blindness,
haemophilia
177 (b)
Heterozygous.
The diploid condition in which the alleles at a
given locus are identical is called homozygous or
pulls. In homozygous condition, organism have
two similar genes or alleles for a particular
character in homologous pair of chromosomes,
�
�.𝑔., TT or tt.
Organisms containing two different alleles or
individual containing both dominant and
recessive genes of an allele pair, 𝑒.𝑔., Tt is known
as heterozygous or hybrid
178 (c)
Mendel conducted artificial pollination/cross
pollination using true breeding pea lines A true
breeding line is one that having undergone
continuous self pollination, shows stable trait
inheritance and expression for several generation
179 (d)
Morgan and his group found that when genes
were grouped on the same chromosome, some
genes were very tightly linked (showed very low
recombination), while others were loosely linked
(showed higher recombination).
180 (b)
Polygene results in quantitative inheritance,
which is characterized by occurrence of
intermediate forms between the parental type. In
case of crossing between AABBCC (dark colour)
and aabbcc (light colour), in 𝐹2-generation seven
phenotypes will obtain with ratio 1 : 6 : 15 : 20 :
15 : 6 : 1. The total number of progeny is 64, out of
which only two will be likely resemble with either
parents. Hence, their proportion in 𝐹2-generation
would be 3.12, i.e., less than 5%
181 (a)
In cancer cells there is uncontrolled cell division.
In them chromosomal abbreviation is commonly
found
182 (b)
The given case is the example of codominance.
183 (d)
Males and female are haemophilic definately. If
their father and mother both are haemophilic

184 (b)
Polyploidy is the phenomenon, which leads to
increase in the number of chromosomes thus,
increasing in the number of genes. Due to
cumulative effect of genes, new characters appear,
which results into formation of new species.
185 (b)
Mendel is called father of genetics. There are three
laws of Mendel in respect of inheritance:

Law of dominance
Law of segregation or Law of purity of
gametes or Law of splitting of hybrids.
Law of independent assortment
186 (b)

Page| 80

Test cross is a cross between 𝐹1 hybrid with its
recessive parent.
187 (a)
Homogametic.
XY and XY type sex determination seen in many
insect and mammals including humans. Males
have X and Y chromosome along with autosome
and females have pair of ‘X’ chromosome along
with autosome
Parents Phenotypes Male
Female
Genotypes 44A + XY
44A + XX
Gametes 22A + X 22A+Y
22A + A22A + X
22A+ X 22A+X
Children 22A + X 44A + XX 44 A + XY
Female
22A + Y 44 A + XY 44 A + XY
Male
Sex ratio Female : Male = 1 : 1
In plants The flowering plants are mostly bisexual
and lack sex chromosomes. The unisexual
flowering plants tent to have XX-XY type of sex
chromosomal mechanism for sex determination.
The female plants are XX and male plants are XY.
XX and XO Type of Sex Determination
Found in insect like grasshopper, cockroaches and
bugs. Males have only X sex-chromosome and
autosomes, female have pair of X-chromosome
and autosome
Parents Phenotypes Male Female
Genotypes 𝐴𝐴+𝑋𝑂 𝐴𝐴+𝑋𝑋
Gametes 𝐴+𝑋,𝐴+𝑂 𝐴+𝑋,𝐴+𝑌
�
�𝟏-generation

XX-XO type of sex determination
In most of cases the female produce similar sex
chromosome called homomorphic. In most of
cases the male produce dissimilar sex
chromosome called hetermorphic
188 (a)
In birds, usually female is designated as ZW, being
heterogametic and male is designated as ZZ being
homogametic.
189 (a)
A cross of round yellow seeds (both dominant)
and green wrinkled seed (both recessive) plants
produced 9 : 3 : 3 : 1 ratio of plants
(phenotypic)in 𝐹2 generation. The ratio of
parental to recombinant is 10 : 6 here because the
9 and 1 are of parental type and 3 & 3 are
recombinant.
190 (a)
In genetics, a test cross, first introduced by Gregor
Johann Mendel, is used to determine weather an
individual exhibiting a dominant trait is
homozygous or heterozygous for that traits. More
simply, test cross determines the genotype of an
individual with a dominant phenotype. The test
cross is defind as being a type of back cross
between the recessive homozygote parents and 𝐹1
generation.
191 (c)

So, all sons in the progeny will be normal.
192 (d)
When a tall pea plant (TT) is crossed with dwarf
plant (tt), the F1progeny shows all plants hybrid
tall and on selfing of F1progeny, the F2generation
shows both tall and dwarf plant in the ratio 3 : 1.
Out of three tall plants, one is pure tall (TT) and
two are hybrid tall (Tt).
193 (c)
A-Two, B-Chromosomal, C-Mutation
194 (c)
A-Heterozygous, B-Unaffected, C-Carrier
196 (c)
Linkage group will be equal to haploid number of
chromosomes. 𝑃𝑖𝑠𝑢𝑚 𝑠𝑎𝑡𝑖𝑣𝑢𝑚 has seven pairs of
chromosomes, therefore linkage group is also
seven.
197 (d)

Page| 81

When a cross (dihybrid) is made between plants
bearing round yellow (RRYY) and wrinkled green
(rryy) seeds, all the plants in F1-generation are
with yellow round seeds (showing the genotype
RrYy).
198 (a)
Black colour is dominant over the recessive so by
cross it is easily infered that 75% of the offspring
are black and 25% are brown

199 (b)
There are only very few characters, which are
present on the Y-chromosome of male. Like
hypertrichosis. Given pedigree analysis is the
example of Y-linked inheritance because all male
progeny is affected
200 (a)
Haemophilia.
Genetic or chromosomal symbol used for person
who is having sickle-cell anaemia Ps−Hbs Hbs.
Sickle-cell Anaemia
(i) It is an autosome-linked recessive trait
(ii) The disease is controlled by a single pair of
allele Hbs and Hbs
(iii) Only the homozygous individuals for Hbs, i.e.,
HbsHbs show the diseased phenotype
(iv) The heterozygous individuals are carriers
(HbAHbS)
(v) Due to point mutation, glutamic acid (Glu) is
replaced by valine (Val) at the sixth position of β
globin chain of haemoglobin molecule
(vi) A single base substitution at sixth codon of
the beta globulin gene from GAG to GUG. GAG
code for glutamic acid and GUG code for valine.
(vii) HbS behaves as normal haemoglobin except
under the oxygen stress where erythrocytes lose
their circular shape and become sickle-shaped. As
a result, the cells cannot pass through narrow
capillaries. Blood capillaries are clogged and thus,
affect blood supply to different organs
omal
dominant in males and autosomal recessive in
females
(iii) Sex Influenced Traits The traits are not due to
particular genes but are by products of sex
hormones, e.g., low pitched voice, beard
moustaches. In males, pattern baldness is related
to both autosomal genes as well as excessive
secretion of testosterone

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