NEET Biology Principles of Inheritance and Variation MCQs Set 12

Multiple Choice Questions (MCQs) for NEET Biology: Principles of Inheritance and Variation

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Multiple Choice Questions

Question 1: The genotype of a plant showing the dominant phenotype can be determined by
(a) Back cross
(b) Test cross
(c) Dihybrid cross
(d) Pedigree analysis
Show Answer & Explanation

Answer: (b) Test cross

Explanation:
1. A test cross determines the genotype of a plant showing the dominant phenotype.

Teacher's Note:
1. Cross with recessive homozygote.

Question 2: Select the correct statement from the ones given below with respect to dihybrid cross
(a) Tightly linked genes on the same chromosome show very few recombinations
(b) Tightly linked genes on the same chromosome show higher recombinations
(c) Genes far apart on the same chromosome show very few recombinations
(d) Genes loosely linked on the same chromosome show similar recombinations as the tightly linked ones
Show Answer & Explanation

Answer: (a) Tightly linked genes on the same chromosome show very few recombinations

Explanation:
1. Tightly linked genes on the same chromosome show very few recombinations.

Teacher's Note:
1. Recombination increases with distance.

Question 3: A cross in which an organism showing a dominant phenotype is crossed with the recessive parent in order to know its genotype is called
(a) Monohybrid cross
(b) Back cross
(c) Test cross
(d) Dihybrid ross
Show Answer & Explanation

Answer: (c) Test cross

Explanation:
1. Crossing an individual of dominant phenotype with the recessive parent to find its genotype is a test cross.

Teacher's Note:
1. Backcross is with either parent.

Question 4: ABO blood grouping is controlled by gene I which has three alleles and show co-dominance. There are six genotypes. How many phenotypes in all are possible?
(a) Six
(b) Three
(c) Four
(d) Five
Show Answer & Explanation

Answer: (c) Four

Explanation:
1. Six genotypes yield four phenotypes: A, B, AB and O.

Teacher's Note:
1. Codominance gives AB.

Question 5: The fruit fly Drosophila melanogaster was found to be very suitable for experimental verification of chromosomal theory of inheritance by Morgan and his colleagues because:
(a) It reproduces parthenogenetically
(b) A single mating produces two young flies
(c) Smaller female is easily recognisable from larger male
(d) It completes life cycle in about two weeks
Show Answer & Explanation

Answer: (d) It completes life cycle in about two weeks

Explanation:
1. Drosophila is suitable because it completes its life cycle in about two weeks.

Teacher's Note:
1. It also has few chromosomes and many offspring.

Question 6: In Antirrhinum two plants with pink flowers were hybridized. The F1 plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridization? Red flower colour is determined by RR, and white by rr genes.
(a) rrrr
(b) RR
(c) Rr
(d) rr
Show Answer & Explanation

Answer: (c) Rr

Explanation:
1. Two pink plants (Rr x Rr) give 1 RR : 2 Rr : 1 rr, i.e. 1 red : 2 pink : 1 white.

Teacher's Note:
1. Incomplete dominance.

Question 7: Point mutation involves
(a) Deletion
(b) Insertion
(c) Change in single base pair
(d) Duplication
Show Answer & Explanation

Answer: (c) Change in single base pair

Explanation:
1. Point mutation is a change in a single base pair of DNA.

Teacher's Note:
1. Sickle cell is an example.

Question 8: Select the incorrect statement from the following:
(a) Galactosemia is an inborn error of metabolism
(b) Small population size results in random genetic drift in a population
(c) Baldness is a sex-limited trait
(d) Linkage is an exception to the principle of independent assortment in heredity
Show Answer & Explanation

Answer: (c) Baldness is a sex-limited trait

Explanation:
1. Baldness is a sex-influenced trait, not sex-limited, so statement (c) is incorrect.

Teacher's Note:
1. Sex-limited traits appear in only one sex.

Question 9: Haploids are more suitable for mutation studies than the diploids. This is because
(a) All mutations, whether dominant or recessive are expressed in haploids
(b) Haploids are reproductively more stable than diploids
(c) Mutagens penetrate in haploids more effectively than diploids
(d) Haploids are more abundant in nature than diploids
Show Answer & Explanation

Answer: (a) All mutations, whether dominant or recessive are expressed in haploids

Explanation:
1. Haploids have one allele per gene, so every mutation is expressed.

Teacher's Note:
1. Diploids can mask recessive mutations.

Question 10: Which one of the following conditions in humans is correctly matched with its chromosomal abnormality/ linkage?
(a) Down syndrome - 44 autosomes + XO
(b) Klinefelter syndrome - 44 autosomes + XXY
(c) Colour blindness - Y-linked
(d) Erythroblastosis foetalis - X-linked
Show Answer & Explanation

Answer: (b) Klinefelter syndrome - 44 autosomes + XXY

Explanation:
1. Klinefelter syndrome is 44 autosomes + XXY. Down is trisomy 21, colour blindness is X-linked and erythroblastosis foetalis is due to Rh incompatibility.

Teacher's Note:
1. XXY male.

Question 11: In the hexaploid wheat, the haploid (n) and basic (x) numbers of chromosomes are
(a) n = 21 and x = 7
(b) n = 7 and x = 21
(c) n = 21 and x = 21
(d) n = 21 and x = 14
Show Answer & Explanation

Answer: (a) n = 21 and x = 7

Explanation:
1. Hexaploid wheat has 42 chromosomes: n = 21 and basic number x = 7.

Teacher's Note:
1. Basic number x = 7.

Question 12: Inheritance of skin colour in humans is an example of
(a) Codominance
(b) Chromosomal aberration
(c) Point mutation
(d) Polygenic inheritance
Show Answer & Explanation

Answer: (d) Polygenic inheritance

Explanation:
1. Skin colour is controlled by many genes, so it is polygenic inheritance.

Teacher's Note:
1. Quantitative trait.

Question 13: A common test to find the genotype of a hybrid is by
(a) Crossing of one F1progeny with male parent
(b) Crossing of one F2 progeny with male parent
(c) Crossing of one F2 progeny with female parent
(d) Studying the sexual behaviour of F1 progenies
Show Answer & Explanation

Answer: (a) Crossing of one F1progeny with male parent

Explanation:
1. The genotype of a hybrid is found by crossing it with a parent having recessive characters (test cross).

Teacher's Note:
1. Back cross to the recessive parent.

Question 14: Two genes R and Y are located very close on the chromosomal linkage map of maize plant. When RRYY and rryy genotypes are hybridized, the F2 segregation will show
(a) Higher number of the parental types
(b) Higher number of the recombinant types
(c) Segregation in the expected 9: 3: 3: 1 ratio
(d) Segregation in 3:1 ratio
Show Answer & Explanation

Answer: (a) Higher number of the parental types

Explanation:
1. Closely linked genes R and Y give more parental types than recombinants.

Teacher's Note:
1. Linkage lowers recombination.

Question 15: 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 F1 generation?
(a) 3 : 1
(b) 50 : 50
(c) 9 : 1
(d) 1 : 3
Show Answer & Explanation

Answer: (b) 50 : 50

Explanation:
1. Yy x yy gives 1 yellow : 1 green (50 : 50).

Teacher's Note:
1. Test cross ratio.

Question 16: A human male produces sperms with genotypes AB, Ab, aB and ab pertaining to two diallelic characters in equal proportions. What is the corresponding genotype of this person?
(a) AABB
(b) AaBb
(c) AaBB
(d) AABb
Show Answer & Explanation

Answer: (b) AaBb

Explanation:
1. A person producing four equal gamete types AB, Ab, aB, ab is AaBb.

Teacher's Note:
1. Heterozygous at both loci.

Question 17: Which one of the following is the most suitable, medium for culture of Drosophila melanogaster ?
(a) Moist bread
(b) Agar agar
(c) Ripe banana
(d) Cow dung
Show Answer & Explanation

Answer: (c) Ripe banana

Explanation:
1. Ripe banana is the usual medium for culturing Drosophila.

Teacher's Note:
1. Fruit flies feed on fermenting fruit.

Question 18: Phenotype of an organism is the result of
(a) Mutations and linkages
(b) Cytoplasmic effects and nutrition
(c) Environmental changes and sexual dimorphism
(d) Genotype and environment interactions
Show Answer & Explanation

Answer: (d) Genotype and environment interactions

Explanation:
1. Phenotype results from the interaction of genotype and environment.

Teacher's Note:
1. P = G + E.

Question 19: In which mode of inheritance do you expect more maternal influence among the offspring ?
(a) Autosomal
(b) Cytoplasmic
(c) Y-linked
(d) X-linked
Show Answer & Explanation

Answer: (b) Cytoplasmic

Explanation:
1. Cytoplasmic inheritance gives maternal influence because the egg supplies the cytoplasm.

Teacher's Note:
1. Mitochondrial genes are maternal.

Question 20: How many different kinds of gametes will be produced by a plant having the genotype AABbCC?
(a) Three
(b) Four
(c) Nine
(d) Two
Show Answer & Explanation

Answer: (d) Two

Explanation:
1. AABbCC has only one heterozygous locus (Bb), so 2 types of gametes.

Teacher's Note:
1. 2^n with n heterozygous loci.

Question 21: Which one of the following is an example of polygenic inheritance?
(a) Flower colour in Mirabilis jalapa
(b) Production of male honey bee
(c) Pod shape in garden pea
(d) Skin colour in humans
Show Answer & Explanation

Answer: (d) Skin colour in humans

Explanation:
1. Skin colour in humans is a polygenic trait; the others are single-gene or other examples.

Teacher's Note:
1. Polygenic means many genes.

Question 22: 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 bet
Show Answer & Explanation

Answer: (c) Crossing the F1 hybrid with a double recessive genotype

Explanation:
1. A test cross involves crossing the F1 hybrid with a double recessive genotype.

Teacher's Note:
1. Recessive homozygote.

Question 23: If a colourblind woman marries a normal visioned man, their sons will be
(a) All normal visioned
(b) One-half colourblind and one-half normal
(c) Three-fourths colourblind and one-fourth normal
(d) All colourblind
Show Answer & Explanation

Answer: (d) All colourblind

Explanation:
1. A colour-blind woman (XcXc) x normal man (XY) gives all sons colour blind (XcY) and carrier daughters.

Teacher's Note:
1. Criss-cross inheritance.

Question 24: Cri-du-chat syndrome in humans is caused by the
(a) Fertilization of an XX egg by a normal Y-bearing sperm
(b) Loss of half of the short arm of chromosome 5
(c) Loss of half of the long arm of chromosome 5
(d) Trisomy of 21st chromosome
Show Answer & Explanation

Answer: (b) Loss of half of the short arm of chromosome 5

Explanation:
1. Cri-du-chat syndrome is due to loss of part of the short arm of chromosome 5.

Teacher's Note:
1. A deletion syndrome.

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