CBSE Class 12 Biology 2024-25: Chapter 4 Principles Of Inheritance And Variation Competency-Based Questions with Answers; Download Free PDF

Get ready for your CBSE Class 12 Biology exams with our easy guide on Chapter 4: Principles Of Inheritance And Variation. This chapter is very important, especially with the new exam pattern starting in the 2024-25 school year. The CBSE will include 50% more competency-based questions. These questions ask you to use what you've learned in real-life situations.

In this article, we focus on key questions from Chapter 4: Principles Of Inheritance And Variation. These questions help you think and solve problems. You’ll find different types of questions, such as multiple-choice, true-false, gap-filling, and short-answer questions. Each question has clear answers to help you understand the concepts better.

To help you study, you can download a free PDF that has all the competency-based questions from Chapter 4: Principles Of Inheritance And Variation along with their answer keys.

CBSE 10 Biology Chapter 4 : Principles Of Inheritance And Variation Competency-Based Questions

Q.1 In mice, brown fur is dominant and white fur is recessive. A biologist crossed a brown fur male with a white fur female and obtained two brown fur and two white fur offspring. Which of the following statementsis MOST likely to be true?

A. Both parents are heterozygous.
B. Only the male parent is homozygous.
C. Only the male parent is heterozygous.
D. Only the female parent is heterozygous.

Answer. C. Only the male parent is heterozygous.

Q.2 In which of the following process would genetic variation occur? P) mutation in liver cells Q) development of a zygote to an embryo R) gene flow from one population to another

A. only P
B. only Q
C. only P and Q
D. only P and R

Answer. D. only P and R

Q.3 What will be the kernel colour of offspring in the F1 generation?

A. white
B. dark red
C. medium red
D. intermediate red

Answer. D. intermediate red

Q.4 What would be the ratio of kernel colours in the F2 generation?

A. 1:2:1
B. 9:3:3:1
C. 1:4:6:4:1
D. 1:6:15:20:15:6:1

Answer. C. 1:4:6:4:1

Q.5 In a cross between pea plants having round green seeds (RRGG) and wrinkled yellow seeds(rrgg), what percentage of eggs will carry both the round and green alleles for the F2 generation?

A. 9%
B. 93%
C. 64% D.
D. 25%

Answer. D. 25%

Download PDF
CBSE Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants: Important Competency-Based Questions 2024-25	Click Here
CBSE Class 12 Biology Chapter 2 Human Reproduction: Important Competency-Based Questions 2024-25	Click Here
CBSE Class 12 Biology Chapter 3 Reproductive Health: Important Competency-Based Questions 2024-25	Click Here
CBSE Class 12 Biology Chapter 4 Principles Of Inheritance And Variation: Important Competency-Based Questions 2024-25	Click Here

Q.6 Marfan syndrome is a connective tissue disorder in humans caused due to the mutation of the FBN1 gene coding for fibrillin-1. Some symptoms of this disease are abnormally long limbs, heart murmurs, and extreme nearsightedness. Marfan syndrome is an example of .

A. a chromosomal disorder
B. polygenic inheritance
C. codominance
D. pleiotropy

Answer. D. pleiotropy

Q.7 State two ways in which sex determination in humans is different from that in honeybees.

Answer. 1 mark each for any two differences such as:

- Sex determination in humans is of the XY type i.e the male has 2 different sex chromosomes (X and Y) and females have 2 copies of X chromosome whereas it is of the haplodiploid type in bees i.e, females are diploid and males are haploid (only one set of chromosomes)

- Males in bees are produced by parthenogenesis and females by fertilization, whereas both male and female offspring in humans are produced by fertilization.

- Sperm production by mitosis in bees and by meiosis in humans.

[Accept any other point of difference]

Q.8 The pea plant is a self-pollinating plant.

(a) Why was this fact about the pea plant a concern in Mendel's experiments?
(b) How did Mendel ensure that self-pollination was avoided in his experiments?

Answer. (a) In Mendel's experiment, self-pollination would have led to unknown and undesirable results as the experiment would not have been controlled.

(b) by the removal of stamen or anther from the flower bud

Q.9 State TWO points of difference and TWO points of similarity between Klinefelter's syndrome and Turner's syndrome.

Answer. 0.5 marks each for any TWO points of difference such as:

- Klinefelter's syndrome is caused due to the presence of an additional copy of the X chromosome whereas Turner's syndrome is caused due to the absence of an X chromosome.

- Klinefelter's syndrome occurs in both genders whereas Turner's syndrome is found in females.

[Accept any other valid point]

0.5 marks each for any TWO similarities such as:

- Both are chromosomal disorders related to the sex chromosomes

- In both disorders, the individuals are sterile.

[Accept any other valid point]

Q.10 Using a Punnettsquare, determine the genotype of the parentsif their child can have any of the four blood groups.

Answer. 1 mark for drawing the Punnett square and 1 mark for identifying both the parental genotypes correctly.

- Child can have any of the four blood groups - IAi, IBi, IAIB, ii

Q.11 State THREE advantages of using Drosophila asthe model organism forstudying genetics as compared to Mendel's pea plant.

Answer. 1 mark each for the following:

Drosophila can be grown on a simple synthetic medium making growth faster and more controlled whereas pea plants were grown naturally, making growth slower and unpredictable.

Drosophila complete theirlife cycle in about two weeks whereas pea plantstake 10-12 weeks.

In Drosophila, there is a clear differentiation of the sexes whereas pea plants are bisexual.

Q.12 Given below is a pedigree chart for an autosomal dominant disorder characterised by trait 'A'.

What evidence in the pedigree chart helps establish that the condition is caused by a dominant allele?

What are the genotypes of the affected and unaffected individuals?

Answer. 1 mark for any one reason such as:

In every generation, there is an affected individual. OR

An affected offspring has an affected parent.

0.5 marks each for the following:

Affected individual - heterozygous dominant OR Aa

Q.13 Given below is the pedigree of a family for a trait

Identify the mode of inheritance of the trait. Give a reason(s) to support your answer.

Choose the correct answer to complete the following sentence:

Colour blindness is a sex-linked condition. However, a
(heterozygous/homozygous) (male/female) will always have normal vision.

Answer. (a) 1 mark for each correct answer:

X-linked recessive disorder

The affected mother has all affected male children but female children are not affected.

(b) 0.5 marks each for the following:

heterozygous

female

Q.14 Cystic fibrosis is a condition in which a defective cf gene (consider allele c) produces faulty transport channels that causes mucus to build up in the ducts of different organs leading to vitamin deficiency diseases, respiratory infections and excessive loss of salt through sweat.

Given below is a pedigree chart for a family. The great-grandmother, represented as I- 1, suffers from cystic fibrosis.

Identify the type of expression of the cystic fibrosis gene. Give a reason to support your answer.

From the pedigree, deduce the pattern of inheritance exhibited by the gene. Justify your answer.

Identify the genotypes of II-2 and III-2.

Answer. (a) 0.5 marks each for the following:

pleiotropy

One gene is affecting multiple organs and therefore contributing to multiple phenotypes.

[Accept any other valid answer]

(b) 0.5 marks each for the following:

recessive disorder

Expression of the trait is skipping generations so it cannot be dominant.

[Accept any other valid answer]

(c) 0.5 marks each for the following:

II-2 - Cc III-2 - Cc

Q.15 Given below is the karyotype of an individual.

What are the characteristic reproductive and physical features of such an individual?

What is the category of such disorders called? How is it caused?

Answer. (a) 0.5 marks for each of the following:

may or may not have an impact on reproductive features

short stature with a small round head

[Accept any other valid answer]

(b) 0.5 marks each for the following:

category: chromosomal disorders/aneuploidy

cause: failure of segregation of chromatids during cell division

-

👉 Read Also - CBSE Class 12 Half-Yearly/Mid Term 2024-25 : Most Important Questions with Answers; PDF Download (All Subjects)

👉 Read Also - How CBSE’s New Exam Pattern Will Impact Class 11 and 12 Students

👉 CBSE Class 12 Study Materials

CBSE Class 12 Syllabus 2024-25	CBSE Class 12 Previous Year Papers
NCERT Books For Class 12 Books	NCERT Class 12 Solutions
CBSE Class 12 Full Study Material	CBSE Class 12 Sample Paper 2024-25