Chapter Practice

If a pea plant with round green seed (RRyy) is crossed

PART 1

pea plant with wrinkled yellow seed (rrYY), the seeds

produced in F₁ -generation are

Objective Questions

(a) wrinkled and green

(b) wrinkled and yellow

(d) round and green

●

The genotype of the height of an organism is written

Multiple Choice Questions

as Tt. What conclusion may be drawn?

The process through which characters pass from one

(a) The allele for height has at least two different genes

generation to another is called

(b) There are atleast two different alleles for the gene for

(a) inheritance

(b) heredity

height

(d) evolution

single allele

Which of the following statements is not true with

(d) There is one allele for height with two different forms

respect to variation?

The first generation cross of pure tall and short pea

(a) All variations in a species have equal chance of survival

plant gives tall pea plants. F₂ -generation will give

(b) Change in genetic composition results in variation

(a) dwarf pea plant

(b) tall pea plant

basis of evolutionary processes.

(d) Variation is minimum in asexual reproduction.

10.

A cross between a pure-breed pea plant A and B is

Free earlobes are ...(i)... traits and attached earlobes

shown below.

are ...(ii)... traits.

Parents plants : A × B

(a) (i) recessive, (ii) dominant

F₁-generation : A

(b) (i) dominant, (ii) recessive

F₂-generation : A, A, A, B

Choose the correct option for A and B.

(d) None of the above

(a) A are tall and B are round

A trait in an organism is influenced by

(b) A are tall and B are dwarf

(a) paternal DNA only

(NCERT Exemplar)

(b) maternal DNA only

(d) A are round and B are tall

11.

If pea plants having round green seeds and wrinkled

(d) neither by paternal nor by maternal DNA

yellow seeds are crossed, what phenotypic ratio will

Which amongst the listed tools was used to study the

be obtained in F₂ progeny plants?

law of inheritance in pea plant by Gregor J Mendel?

(a)

1:2:1

(b) 3 : 1

(d) 9 : 3 : 4

(a) Family tree

(b) Pedigree chart

12.

The result of a dihybrid cross between two

(d) Herbarium sheet

individuals is recorded as

A cross between a tall plant (TT) and short pea plant

Phenotypes of Numbers of seeds

(tt) resulted in progeny that were all tall plants

progeny

obtained

because

(NCERT Exemplar)

Round, A

315

(a) tallness is the dominant trait

(b) shortness is the dominant trait

Round, B

108

C, Yellow

101

(d) height of pea plant is not governed by gene ‘T’ or ‘t’

Wrinkled, D

Choose the correct option for A, B, C and D.

15. Choose the correct statement from the following.

I. Variation in plants are much lesser than human

(a) Green

Yellow

Round

Yellow

beings.

(b) Yellow

Green

Wrinkled

Green

II. Each trait in child is influenced by only paternal

Yellow

Wrinkled

Green

DNA.

(d) Green

Green

Round

Yellow

III. An individual having two different alleles for the

13.

Carefully study the cross shown below with labels (i),

same trait is called hybrid.

(ii) and (iii). Identify the option that indicates the

IV. Traits that are passed on from parents to their

correct labellings.

offspring are controlled by genes.

Codes

(a) I, II and III

(b) I, III and IV

(d) I, II and IV

Purple

White

(i)

^● Assertion-Reasoning MCQs

Direction (Q. Nos. 16-20) Each of these questions

contains two statements,Assertion (A) andReason (R).

Purple

Each of these questions also has four alternative

choices, any one of which is the correct answer. You

(ii)

have to select one of the codes (a), (b), (c) and (d) given

below.

(iii)

(a) Both A and R are true and R is the correct explanation

of A

Purple

Purple Purple

White

(b) Both A and R are true, but R is not the correct

(a)

(i) Cross-fertilisation, (ii) Self-fertilisation, (iii) F₁-generation

explanation of A

(b) (i) Self-fertilisation, (ii) Cross-fertilisation, (iii) F₂-generation

(c)

(i) Cross-fertilisation, (ii) Self-fertilisation, (iii) F₂-generation

(d) A is false, but R is true

(d) (i) Self-fertilisation, (ii) F₂-generation (iii) Cross-fertilisation

16.

Assertion Dominant allele is an allele whose

14.

Observe the diagram given below.

phenotype expresses even in the presence of

another allele of that gene.

(A)

(B)

(C)

Reason It is represented by a capital letter, e.g. T.

17.

Assertion Mendel self-crossed F₁ progeny to

obtain F₂ -generation.

Reason F₁ progeny of a tall plant with round seeds

and a dwarf plant with wrinkled seeds are all dwarf

plants having wrinkled seeds.

(D)

Male zygote

18.

Assertion The ratio of F₂ plants when Mendel took

Match the labelling referred in Column I and correlate

pea plants with two contrasting characters was

with Column II.

9 : 3 : 3 : 1.

Column I

Column II

Reason The ratio of F₂ plants when Mendel took

1. Y sperm

pea plants with one contrasting character was 1 : 1.

2. Ovum

19.

Assertion All the human female gemetes will have

3. X sperm

only X-chromosome.

4. Female zygote

Reason Females are homogametic with two

X-chromosomes.

Codes

A B C D

20.

Assertion The sex of a child will be determined by

(a)

chromosome received from the father.

(b)

Reason A human male has one X and one

(c)

Y-chromosome.

(d)

His experiments with garden pea along with the

^● Case Based MCQs

inferences drawn together constitute, the foundation

21. Read the following and answer the questions from (i)

of modern genetics.

to (v) given below

Mendel’s contributions were unique because of the

Mendel’s experiment on sweet pea plants having

use of distinct variables and application of

axial flowers with round seeds (AARR) and

mathematics to the problem. He kept the record of

terminal flowers with wrinkled seeds (aarr) is shown

each generation separately and studied the

below.

inheritance of only one pair of characters at a time.

Axial

(i)

Mendel took

contrasting characteristics of pea

Terminal

Round

wrinkled

plants.

Parents

AARR

aarr

(a) eight

(b) seven

(d) five

Gametes

(ii)

After cross pollination of true-breeding tall and

dwarf plants, the F₁ -generation was self-fertilised.

AaRr

The resultant plants have genotype in the ratio

(a)1 : 2 :1 (homozygous tall : heterozygous tall :

(i)

Phenotype of F₁ progeny

homozygous dwarf)

(a) axial round

(b)1 : 2 :1 (homozygous tall : dwarf : heterozygous tall)

(b) axial wrinkled

(d) 3 :1 (dwarf : tall)

(d) terminal round

(iii)

Which Mendelian law states that inheritance of one

(ii)

Phenotype of F₂ progeny produced upon by the

character is always independent to the inheritance

self-pollination of F₁ progeny

of other character within the same individual?

(a) axial round and axial winkled

(a) Law of dominance

(b) terminal round

(b) Law of segregation

(d) All of the above

(d) Both (b) and (c)

(iii)

The phenotypic ratio of the F₂ -generation will be

(iv)

Which one is the possible progeny in

(a) 3 :1

(b) 9 : 3 : 3 :1

F₂-generation of pure breed tall plant with round

(d)1 : 3

seed and short plant with wrinkled seed?

(iv)

A cross between two individuals results in 9 : 3 : 3 :1

(a) Tall plant with round seed

for four possible phenotypes of progeny. This is an

(b) Tall plant with wrinkled seed

example of a

(a) dihybrid cross

(b) F₁-generation

(d) All of the above

(d) test cross

(v)

Round and yellow seed is

(v)

Which of the following law is mainly explained by

(a) recessive

(b) dominant

the given cross?

(d) incomplete dominance

(a) Law of dominance

(b) Law of segregation

PART 2

(d) None of the above

Subjective Questions

23. Read the following and answer the questions from (i)

to (v) given below

^● Short Answer Type Questions

Gregor Johann Mendel is known as a ‘Father of

Modern Genetics’ for his work in the field of the

1. What do you mean by heredity? Who is its founder?

genetics. He worked out the main rules for

(CBSE 2020)

inheritance patterns. The heredity in most of the

2. If a trait ‘A’ exists in 10% of the population of an

living organisms is found to be regulated by certain

asexually reproducing species and a trait ‘B’ exists in

definite principles.

60% of the same population, which trait is likely to

Mendel opted for garden pea (Pisum sativum) to

have arisen earlier?

conduct his experiments. He performed

self-pollination and cross-pollination to understand

3. How does the creation of variations in a species

the inheritance patterns of traits.

promote survival?

4. In any population, no two individuals are absolutely

Recompile the above observations and explain the

similar. Why?

law of inheritance associated with them.

5. A child questioned his teacher that why do organisms

16. Name the plant Mendel used for his experiments.

resemble their parents more as compared to

What type of progeny was obtained by Mendel in

grandparents. In which way, will the teacher explain

F₁ and F₂-generations when he crossed the tall and

to the child?

(CBSE 2015)

short plants? Write the ratio he obtained in

F₂-generation plants.

(CBSE Delhi 2019)

6. Why did Mendel choose pea plant for his experiments?

17. Study the following cross showing self-pollination in

7. How do Mendel’s experiments show that traits may

F₁ progeny. Fill in the blank and answer the

dominant or recessive?

(CBSE 2016)

questions that follows.

8. What do you mean by dominant and recessive

RRyy

× rrYY

Parents

characteristics?

(Round green)

(Wrinkled yellow)

9. Explain difference between phenotype and genotype.

RrYy

……

F₁-generation

(Round yellow)

10. In a pea plant, find the contrasting trait if

(i) the position of flower is terminal

(i) In above question, what is the combination of

(ii) the flower is white in colour

characters in the F₂ progeny? What are the ratios?

(iii) shape of pod is constricted

(CBSE 2015)

(ii) Give reasons for the appearance of new combination

of characters in the F₁ progeny.

(NCERT Exemplar)

11.

How do Mendel’s experiments show that traits are

inherited independently?

(CBSE 2016)

18. How is the sex of a child determined in human

beings?

12.

In a certain species of animal black fur (B) is dominant

over brown fur (b). Predict a genotype and phenotype

19. Does genetic combination of mother play a

of the offspring when both parents are Bb or have

significant role in determining the sex of a newborn?

heterozygous black fur.

(NCERT Exemplar)

13.

A man with blood group A married a woman with blood

^● Long Answer Type Questions

group O and their daughter has blood group O. Is this

20. ‘A trait may be inherited, but may not be expressed’.

information enough to tell you which of the traits blood

Justify this statement with the help of a suitable

group A or O is dominant? Why or why not?

(NCERT)

example.

14.

Write the phenotypic ratio of progeny of

21. Discuss Mendelian laws with examples.

F₂-generation of a dihybrid cross.

(2018, 15)

22. What do you understand by Mendel’s dihybrid

15.

Consider the cross between two parents with

cross? When pea plants having round and yellow

contrasting characteristics given below.

seeds were crossed with plants having wrinkled and

Parents

green seeds and then all the plants of F₁ -generation

RRyy

rrYY

had round and yellow seeds. Find out the

(Round green)

(Wrinkled yellow)

phenotypic ratio of F₂ -generation.

Gametes

23. After self-pollination in pea plants with round,

yellow seeds, following types of seeds were

-generation

obtained by Mendel

RrYy

(Round yellow)

Seeds

Numbers

Round, yellow

630

F₁

Ratio

Round, green

216

F₂-generation

315 round yellow

Wrinkled, yellow

202

108 round green

101 wrinkled yellow

Wrinkled, green

32 wrinkled green

Analyse the result and describe the mechanism of

556 seeds

inheritance which explains these results. (CBSE 2020)

24. ‘In humans, there is a 50% probability of the birth of a

wrinkled-green seeds, two new varieties A-D and

boy and 50% probability that a girl will be born’. Justify

C-B types of seeds were also obtained.

the statement on the basis of the mechanism of

(i) What are A-B type of seeds?

sex-determination in human beings.

(CBSE 2020)

(ii) State whether A and B are dominant traits or

recessive traits.

^● Case Based Questions

(iii) What are A-D type of seeds?

25.

Read the following and answer the questions from (i)

(iv) What are C-B type of seeds?

to (v) given below

(v) Out of A-B and A-D types of seeds, which one will

Inheritance from the previous generation provides

be produced in (a) minimum number and (b)

both, a common body design and subtle changes in it,

maximum number in the F₂ -generation?

for the next generation. Now, when the new

27.

Read the following and answer the questions from

generation reproduces, the second generation

(i) to (v) given below

produced will have variations that they inherit from

Mendel selected garden pea for his experiments

the first generation, as well as newly created

because he discovered for the first time the

differences.]

occurrence of two types of seeds in pea plants

For example, if one bacterium divides and gives rise

growing in the garden of his monastery. Mendel then

to two individuals each of them will divided again

used a number of contrasting visible characters of

and give rise to two other individuals in the next

garden peas like.

generation.

Characters

Dominant

Recessive

The four individual bacteria generated would be very

similar with minor differences that occurred due to

1. Plant height

Tall

Dwarf

small inaccuracies to copying of DNA.

2. Flower position

Axial

Terminal

However, in sexual reproduction, even greater

3. Pod colour

Green

Yellow

diversity will be generated. Depending upon the

4. Pod shape

Full

Constricted

nature of variations, different individuals would

have different advantages, the most important

5. Flower colour

Violet

White

advantage of variation to a species is that it

6. Seed shape

Round

Wrinkled

increases the chance of its survival in a changing

environment.

7. Seed colour

Yellow

Green

(i) What do you understand by the term ‘gene’ ?

Mendel’s experiments were performed in three

(ii) In which type of reproduction exchange of genetic

stages in selection of pure or true breeding

material takes place ?

parents, hybridisation and obtaining of

(iii) What is the cause of variation in asexual reproducing

F₁-generation of plants and self-pollination of

organisms ?

hybrid plants and raising of subsequent generations

(iv) Differentiate between genotype and phenotype of an

like F₂, F₃, F₄ , etc.

organism.

(i) How many contrasting traits were taken by

(v) What is the chemical composition of chromosome ?

Mendel in his monohybrid crosses?

(ii) Give a monohybrid cross to explain the

26. Read the following and answer the questions from (i)

F₁-generation formed by a plant with green pod

to (v) given below

colour and yellow pod colour.

A person first crossed pure-breed pea plants having

(iii) State the first law of Mendel.

round-yellow seeds with pure-breed pea plants having

(iv) What do understand by homozygous tall plant and

wrinkled-green seeds and found that only A-B type of

heterozygous tall plant?

seeds were produced in the F₁ -generation.

(v) A Mendelian experiment consisted of breeding

When F₁ -generation pea plants having A-B type

pea plant bearing violet flowers with pea plants

of seeds were cross-breed by self-pollination,

bearing while flowers. What will be the results in

then in addition to the original round yellow and

F₁ progeny?

28. Read the following and answer the questions from

29. Read the following and answer the questions from (i) to

(i) to (v) given below

(v) given below

Observe the following cross between tall plants

A person crossed pure-breed tall pea plants with

having round seeds and dwarf plants having

pure-breed dwarf pea plants and obtained pea plants of

wrinkled seeds.

F₁-generation. He then performed two types of

The individuals obtained in the F₁-generation were

experiments.

thereafter self-crossed.

In the first, he self-crossed the plants of F₁-generation

TTRR

ttrr

(experiment A) and in the second, he crossed the plants of

F₁-generation with the pure-breed dwarf parent plants

(Tall, Round)

(Dwarf, Wrinkled)

(experiment B).

TtRr

× TtRr (F₁-generation self-crossed)

Experiment A : F₁ progeny×F₁ progeny

(Tall, Round)

Experiment B : F₁ progeny×Homozygous dwarf plant

(i) What would be the phenotypes of the individuals

obtained in the F₂ -generation? Give their ratios.

(i) What would be the phenotype of plants in the

F₁-generation?

(ii) Why do you think all the individuals of the

F₁-generation were tall with round seeds?

(ii) What would be the phenotype and genotype ratio of

F₂-generation in experiment ‘A’?

(iii) What will be the number of progeny obtained in

F₂-generation in a dihybrid cross with pure

(iii) How would the genotypic ratio in F₂ generation

dominant traits?

different in experiment ‘B’?

(iv) What would be the phenotype of the individual

(iv) How do we describe the phenotypic character that is

experssed in F₁ -generation? What is the term given to

obtained in F₁ -generation?

the contrasting character?

(v) According to you, what is responsible for the

(v) Name the type of cross shown in experiment B.

inheritance of traits?