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PRINCIPLE
UNNIITT OF INHERITANCE AND VARIATION 29
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CHAPTER 5
PRINCIPLE OF INHERITANCE
AND
VARIATION
MULTIPLE-CHOICE QUESTIONS
1. All genes located on the same chromosome:
a. Form different groups depending upon their relative distance
b. Form one linkage group
c. Will not from any linkage groups
d. Form interactive groups that affect the phenotype
2. Conditions of a karyotype 2n +1, 2n –1 and 2n + 2, 2n – 2 are called:
a. Aneuploidy
b. Polyploidy
c. Allopolyploidy
d. Monosomy
3. Distance between the genes and percentage of recombination shows:
a. a direct relationship
b. an inverse relationship
c. a parallel relationship
d. no relationship
4. If a genetic disease is transferred from a phenotypically normal but
carrier female to only some of the male progeny, the disease is:
a. Autosomal dominant
b. Autosomal recessive
c. Sex-linked dominant
d. Sex-linked recessive
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30 BIOLOGY, EXEMPLAR PROBLEMS
5. In sickle cell anaemia glutamic acid is replaced by valine. Which one
of the following triplets codes for valine?
a. GGG
b. AAG
c. GAA
d. GUG
6. Person having genotype IA IB would show the blood group as AB. This
is because of:
a. Pleiotropy
b. Co-dominance
c. Segregation
d. Incomplete dominance
7. Z Z / ZW type of sex determination is seen in:
a. Platypus
b. Snails
c. Cockroach
d. Peacock
8. A cross between two tall plants resulted in offspring having few dwarf
plants. What would be the genotypes of both the parents?
a. TT and Tt
b. Tt and Tt
c. TT and TT
d. Tt and tt
9. In a dihybrid cross, if you get 9:3:3:1 ratio it denotes that:
a. The alleles of two genes are interacting with each other
b. It is a multigenic inheritance
c. It is a case of multiple allelism
d. The alleles of two genes are segregating independently.
10. Which of the following will not result in variations among siblings?
a. Independent assortment of genes
b. Crossing over
c. Linkage
d. Mutation
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PRINCIPLE OF INHERITANCE
NIT II: STRUCTURAL AND VARIATION
ORGANISATION IN PLANTS AND 31
ANIMALSUNIT II: STRUCTURAL ORGANISATION IN PLANTS AND
11. Mendel’s Law of independent assortment holds good for genes situated
on the:
a. non-homologous chromosomes
b. homologous chromosomes
c. extra nuclear genetic element
d. same chromosome
12. Occasionally, a single gene may express more than one effect. The
phenomenon is called:
a. multiple allelism
b. mosaicism
c. pleiotropy
d. polygeny
13. In a certain taxon of insects some have 17 chromosomes and the others
have 18 chromosomes. The 17 and 18 chromosome-bearing organisms
are:
a. males and females, respectively
b. females and males, respectively
c. all males
d. all females
14. The inheritance pattern of a gene over generations among humans is
studied by the pedigree analysis. Character studied in the pedigree
analysis is equivalent to:
a. quantitative trait
b. Mendelian trait
c. polygenic trait
d. maternal trait
15. It is said that Mendel proposed that the factor controlling any character
is discrete and independent. His proposition was based on the
a. results of F3 generation of a cross.
b. observations that the offspring of a cross made between the
plants having two contrasting characters shows only one
character without any blending.
c. self pollination of F1 offsprings
d. cross pollination of F1 generation with recessive parent
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32 BIOLOGY, EXEMPLAR PROBLEMS
16. Two genes ‘A’ and ‘B’ are linked. In a dihybrid cross involving these two
genes, the F1 heterozygote is crossed with homozygous recessive
parental type (aa bb). What would be the ratio of offspring in the next
generation?
a. 1 : 1 : 1: 1
b. 9:3:3:1
c. 3:1
d. 1:1
17. In the F2 generation of a Mendelian dihybrid cross the number of
phenotypes and genotypes are:
a. phenotypes - 4; genotypes - 16
b. phenotypes - 9; genotypes - 4
c. phenotypes - 4; genotypes - 8
d. phenotypes - 4; genotypes - 9
18. Mother and father of a person with ‘O’ blood group have ‘A’ and ‘B’
blood group, respectively. What would be the genotype of both mother
and father?
a. Mother is homozygous for ‘A’ blood group and father is
heterozygous for ‘B’
b. Mother is heterozygous for ‘A’ blood group and father is
homozygous for ‘B’
c. Both mother and father are heterozygous for ‘A’ and ‘B’ blood
group, respectively
d. Both mother and father are homozygous for ‘A’ and ‘B’ blood
group, respectively
VERY SHORT ANSWER TYPE QUESTIONS
1. What is the cross between the progeny of F1 and the homozygous
recessive parent called? How is it useful?
2. Do you think Mendel’s laws of inheritance would have been different if
the characters that he chose were located on the same chromosome.
3. Enlist the steps of controlled cross pollination. Would emasculation
be needed in a cucurbit plant? Give reasons for your answer.
4. A person has to perform crosses for the purpose of studying inheritance
of a few traits / characters. What should be the criteria for selecting
the organisms?
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PRINCIPLE OF INHERITANCE
NIT II: STRUCTURAL AND VARIATION
ORGANISATION IN PLANTS AND 33
ANIMALSUNIT II: STRUCTURAL ORGANISATION IN PLANTS AND
5. The pedigree chart given below shows a particular trait which is absent
in parents but present in the next generatoin irrespective of sexes.
Draw your conclusion on the basis of the pedigree.
6. In order to obtain the F 1 generation Mendel pollinated a pure-breeding
tall plant with a pure breeding dwarf plant. But for getting the F 2
generation, he simply self-pollinated the tall F1 plants. Why?
7. “Genes contain the information that is required to express a
particular trait.” Explain.
8. How are alleles of particular gene differ from each other? Explain its
significance.
9. In a monohybrid cross of plants with red and white flowered plants,
Mendel got only red flowered plants. On self-pollinating these F1
plants got both red and white flowered plants in 3:1 ratio. Explain
the basis of using RR and rr symbols to represent the genotype of
plants of
parental generation.
10. For the expression of traits genes provide only the potentiality and the
environment provides the opportunity. Comment on the veracity of the
statement.
11. A, B, D are three independently assorting genes with their recessive
alleles a, b, d, respectively. A cross was made between individuals of Aa
bb DD genotype with aa bb dd. Find out the type of genotypes of the
offspring produced.
12. In our society a woman is often blamed for not bearing male child.
Do you think it is right? Justify.
13. Discuss the genetic basis of wrinkled phenotype of pea seed.
14. Even if a character shows multiple allelism, an individual will only
have two alleles for that character. Why?
15. How does a mutagen induce mutation? Explain with example.
SHORT ANSWER TYPE QUESTIONS
1. In a Mendelian monohybrid cross, the F 2 generation shows identical
genotypic and phenotypic ratios. What does it tell us about the
nature of alleles involved? Justify your answer.
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34 BIOLOGY, EXEMPLAR PROBLEMS
2. Can a child have blood group O if his parents have blood group ‘A’
and ‘B’. Explain.
3. What is Down’s syndrome? Give its symptoms and cause. Why is it that
the chances of having a child with Down’s syndrome increases if the age
of the mother exceeds forty years?
4. How was it concluded that genes are located on chromosomes?
5. A plant with red flowers was crossed with another plant with yellow
flowers. If F1 showed all flowers orange in colour, explain the
inheritance.
6. What are the characteristic features of a true-breeding line?
7. In peas, tallness is dominant over dwarfness, and red colour of
flowers is dominant over the white colour. When a tall plant bearing
red flowers was pollinated with a dwarf plant bearing white flowers,
the different phenotypic groups were obtained in the progeny in
numbers mentioned against them:
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White = 128
Mention the genotypes of the two parents and of the four offspring types.
8. Why is the frequency of red-green colour blindness is many times
higher in males than that in the females?
9. If a father and son are both defective in red-green colour vision, is it
likely that the son inherited the trait from his father? Comment.
10. Discuss why Drosophila has been used extensively for genetical studies.
11. How do genes and chromosomes share similarity from the point of view
of genetical studies?
12. What is recombination? Discuss the applications of recombination from
the point of view of genetic engineering.
13. What is artificial selection? Do you think it affects the process of
natural selection? How?
14. With the help of an example differentiate between incomplete dominance
and co-dominance.
15. It is said, that the harmful alleles get eliminated from population over
a period of time, yet sickle cell anaemia is persisting in human
population. Why?
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PRINCIPLE OF INHERITANCE
NIT II: STRUCTURAL AND VARIATION
ORGANISATION IN PLANTS AND 35
ANIMALSUNIT II: STRUCTURAL ORGANISATION IN PLANTS AND
LONG ANSWER TYPE QUESTIONS
1. In a plant tallness is dominant over dwarfness and red flower is
dominant over white. Starting with the parents work out a dihybrid
cross. What is standard dihybrid ratio? Do you think the values would
deviate if the two genes in question are interacting with each other?
2. a. In humans, males are heterogametic and females are
homogametic. Explain. Are there any examples where males are
homogametic and females heterogametic?
b. Also describe as to, who determines the sex of an unborn child?
Mention whether temperature has a role in sex determination.
3. A normal visioned woman, whose father is colour blind, marries a
normal visioned man. What would be probability of her sons and
daughters to be colour blind? Explain with the help of a pedigree
chart.
4. Discuss in detail the contributions of Morgan and Sturvant in the
area of genetics.
5. Define aneuploidy. How is it different from polyploidy? Describe the
individuals having following chromosomal abnormalities.
a. Trisomy of 21st Chromosome
b. XXY
c. XO
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