NEET UG Biology Heredity and Variation MCQs

Question: Genetics is the branch of biology which deals with
a) variation
b) inheritance
c) Both (a) and (b)
d) study of characters

Answer: c

Question: The first hybrid progeny obtained by Mendel were called
a) F₁-progeny
b) F₀-progeny
c) F₂-progeny
d) F₃-progeny

Answer: a

Question: The tendency of offspring to differ from their parents is called
a) variation
b) heredity
c) inheritance
d) resemblance

Answer: a

Question: A true breeding line is characterised by the presence of
a) stable trait inheritance due to the continuous selfpollination
b) varying traits in different generations due to the cross pollination
c) single trait in all generations due to allogamy
d) varying trait inheritance in a single generation due to geitonogamy

Answer: a

Question: 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

Answer: b

Question: Mendel investigated characters in garden pea plant manifested in two traits which were
a) similar
b) non-zygote
c) identical
d) opposite

Answer: d

Question: F₁-progeny of a cross between pure tall and dwarf plant is always
a) tall
b) short
c) intermediate
d) None of these

Answer: a

Question: How did Mendel obtained recessive (dwarf) character in F 2-generation?
a) By self-pollinating F₁
b) By self-pollinating F₂
c) By cross-pollinating F₁
d) By cross-pollinating F₂

Answer: a

Question: When alleles of two contrasting characters are present together and one of the character expresses itself during the cross while the other remains hidden gives the
a) law of purity of gametes
b) law of segregation
c) law of dominance
d) law of independent assortment

Answer: c

Question: Mendel crossed tall and dwarf plants. In F₂-generation both the tall and dwarf plants were produced. This shows
a) blending of characters
b) atavism
c) non-blending of characters
d) intermediate characters

Answer: c

Question: The Mendel crossed true breeding tall and dwarf plant varieties in his experiment. Tallness was the dominant character and dwarfness was recessive. The recessive character appeared in
a) F₁
b) F₂
c) F₃
d) F₂ and F₃

Answer: b

Question: During his experiments, Mendel used the term factor for
a) genes
b) traits
c) characters
d) qualities

Answer: a

Question: The phenotypic ratio of a monohybrid cross in F2-generation is
a) 3 : 1
b) 1 : 2 : 1
c) 2 : 1 : 1
d) 9 : 3 : 3 : 1

Answer: a

Question: Graphical representation to calculate the probability of all possible genotype of an offspring in genetic cross is called
a) Bunett square
b) Morgan square
c) Punnett square
d) Mendel square

Answer: c

Question: Choose the incorrect match.
a) Phenotype – Physical appearance of an organism
b) Genotype – Expressed genes
c) Homozygous – Identical alleles of a gene present at the same locus
d) Heterozygous – Genes of an allelic pair are not same

Answer: b

Question: 3:1 ratio in F₂-generation is explained by
a) law of partial dominance
b) law of dominance
c) law of incomplete dominance
d) law of purity of gametes

Answer: b

Question: The genotypic ratio of a monohybrid cross in F2-generation is
a) 3 : 1
b) 1 : 2 : 1
c) 2 : 1 : 1
d) 9 : 3 : 3 : 1

Answer: b

Question: The law of dominance is applicable in inheritance of
a) seed colour in pea
b) flower colour in Mirabilis jalapa
c) starch grain size in pea
d) roan coat colour in cattles

Answer: a

Question: The recessive trait in case of incomplete dominance is seen due to the
a) non-functional enzyme produced by modified gene
b) absence of any enzyme that may otherwise be produced by modified gene
c) normal or less efficient enzyme produced by recessive allele
d) Both (a) and (b)

Answer: d

Question: The law based on fact that the characters do not show any blending and both the characters are recovered as such in F₂-generation although one character was absent in F₁-progeny, is
a) law of purity of gametes
b) law of independent assortment
c) law of incomplete dominance
d) law of dominance

Answer: a

Question: Incomplete dominance is similar to codominance in having identical
a) phenotypic ratio
b) genotypic ratio
c) Both (a) and (b)
d) None of the above

Answer: c

Question: In human blood group inheritance
a) IA and IB are codominant
b) IA and IB are dominant over i
c) IA is dominant over IB
d) Both (a) and (b)

Answer: d

Question: Theoretically in incomplete dominance one allele functions as normal, while another allele may function as
a) normal allele
b) non-functional allele
c) normal but less efficient allele
d) All of the above

Answer: d

Question: If two persons with ‘AB’ blood group marry and have sufficiently large number of children, these children could be classified as ‘A’ blood group : ‘AB’ blood group : ‘B’ blood group in 1 : 2 : 1 ratio. Modern technique of protein electrophoresis reveals presence of both ‘A’ and ‘B’ type proteins in ‘AB’ blood group individuals. This is an example of
a) codominance
b) incomplete dominance
c) partial dominance
d) complete dominance

Answer: a

Question: The types of gametes formed by the genotype RrYy are
a) RY, Ry, rY, ry
b) RY, Ry, ry, ry
c) Ry, Ry, Yy, ry
d) Rr, RR, Yy, YY

Answer: a

Question: Polygenic traits are controlled by
a) one gene
b) two genes
c) three or more genes
d) mutant genes

Answer: c

Question: In Mendel’s experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr) and yellow
colour (YY) was dominant over green colour (yy). What are the expected phenotypes in the F₁-generation of the cross
RRYY´ rryy?
a) Only round seeds with yellow 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

Answer: a

Question: In cross between pure breeding pea plants having yellow round (YYRR) and green wrinkled (yyrr) seeds, find out the
total seeds (plants) having yellow colour in F₂-generation.
a) 12
b) 10
c) 14
d) 11

Answer: a

Question: Which of the following option (s) is/are correct for starch synthesis in pea seeds controlled by single gene which has
two allelic forms B and b?
a) BB is round seed with large starch synthesis
b) bb is wrinkled seed with large starch synthesis
c) Bb is round seed with less starch synthesis
d) All of the above

Answer: a

Question: In a cross between plants having yellow round (YYRR) and green wrinkled (yyrr) seeds, what will be the ratio between
seeds having yellow and green seed colour?
a) 3 : 2
b) 3 : 1
c) 9 : 7
d) 7 : 9

Answer: a

Question: Mendel’s result on inheritance of characters were rediscovered by
a) de Vries
b) Correns
c) von Tschermak
d) All of these

Answer: d

Question: Who proposed the chromosomal theory of inheritance?
a) Sutton and Mendel
b) Boveri and Morgan
c) Morgan and Mendel
d) Sutton and Boveri

Answer: d

Question: In Morgan’s experiment, white and yellow genes were linked tightly, while white and miniature wing were loosely linked. The per cent recombination shown by these genes were
a) 50% each
b) 72% and 8.3%, respectively
c) 0.3% and 53%, respectively
d) 1.3% and 37.2%, respectively

Answer: d

Question: Phenylketonuria in human
a) manifests through phenotypic expressions
b) is characterised by mental retardation
c) leads to hair reduction and skin pigmentation
d) All of the above

Answer: d

Question: The chromosomes as well as genes occur in pair and the two alleles of a gene pair are located on
a) homologous chromosomes
b) non-homologous chromosomes
c) single chromosome
d) All of the above

Answer: a

Question: Which one of the following pairs is wrongly matched?
a) XO type of sex-determination – Grasshopper
b) ABO blood grouping – Codominance
c) Starch synthesis in pea – Multiple allele
d) TH Morgan – Linkage

Answer: c

Question: Choose the incorrect pair with respect to sex determination in different organisms.
a) Grasshopper = XO type
b) Birds = ZZ-ZW type
c) Drosophila = XX-XO type
d) Human = XX-XY type

Answer: c

Question: A human male contains the karyotype of …A… and a human female has …B… chromosomes.
A B A B
a) 44 + XX 44 + XY
b) 44 + XY 44 + XX
c) 44 + XO 44 + XX
d) 44 + XX 44 + XO

Answer: b

Question: If there are four different types of nitrogenous bases (A, T, G and C) then how many different types of transitions and
transversion are possible?
a) Transition = 8, Transversion = 4
b) Transition = 4, Transversion = 4
c) Transition = 8, Transversion = 4
d) Transition = 4, Transversion = 8

Answer: d

Question: Sickle-cell anaemia is a classical example of
a) frame-shift mutation
b) point mutation
c) Both (a) and (b)
d) None of the above

Answer: b

Question: Colour blindness in humans
a) results in defect in either red or green cone of eyes
b) is caused due to the mutation in gene found on X-chromosome
c) affects males more frequently than females
d) All of the above

Answer: d

Question: In haemophilia, the affected protein is a part of a cascade of protein which is involved in the
a) formation of RBCs
b) formation of WBCs and platelets
c) coagulation of blood
d) anticoagulation

Answer: c

Question: In sickle-cell anaemia,
a) Both parents are heterozygous carriers, but are unaffected
b) Single pair of allele controls the disease
c) Only Hb⁸ Hb⁸ s s show diseased phenotype
d) All of the above

Answer: d

Question: Thalassemia in humans
a) is an autosome linked recessive blood disorder
b) can transmit from parents to offspring when both parents are unaffected carriers (heterozygous)
c) caused due to the mutation or deletion of one of the a or b-globin chain
d) All of the above

Answer: d

GENE INTERACTION :-

Gene interaction is the modification of normal phenotypic expression of a gene due to either its alleles or non- allelic genes.

Gene interaction is of two types:-

   (i) Intragenic interaction

   (ii) Intergenic interaction

Intragenic interaction :-

In intragenic interaction , two alleles of a gene which are present on the same gene locus on the two homologous chromosomes ,react to produce modified phenotype.

Eq :- 1. Incomplete dominance

   2. Codominance

   3. Multiple alleles

Intergenic interaction :- It is the modified effect of a gene under the influence of a non - allelic gene.

Eq :- 1. Complementary genes

   2. Supplementary genes

Complementary genes :-

If two genes present on different loci produce the same effect when present alone but interact to form a new trait when present together are called complementary genes. Complementary gene ratio is 9 : 7

Supplementary Genes :- 

Supplementary genes are two non allelic genes in which one type of gene produces its effect whether the other is present or not and the second gene produces its effect only in the presence of the first, usually forming new trait. Supplementary gene ratio is 9 : 3 : 4

INHERITANCE :-

There are two types of inheritance

1. Qualitative inheritance / Monogenic inheritance

2. Quantitative inheritance / polygenic inheritance

Monogenic inhenitance :-

* A single dominant gene inflences a complete trait.

* Intermediate forms are not produced

Polygenic inheritance :-

* Full trait is shown when all dominant alleles present.

*Each dominant allele expresses a part or unit of the trait.

* Intermediate forms are produced

Ex:- Human skin colour

VARIATIONS :-

* Variations are differences found in morphological, physiological, Cytological and behavioural traits of individuals belonging to same species.

* Hereditary variations are transmitted from generation to generation where as environmental variations are temporary and do not relate with last or next generation.

M.C.Q.