Principles of Inheritance and Variation PYQ's

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Previous Year Questions:

1. Match the List I with List II                                                                                                       (2024)

 

                      LIST I                                                                                     LIST II

A. Two or more alternative forms of a gene.                                           I. Back cross

B. Cross of F1 progeny with homozygous recessive parent.                  II. Ploidy

C. Cross of F1 progeny with any of the parent.                                     III. Allele

D. Number of chromosome sets in plant.                                               IV. Test cross

Choose the correct answer from the options given below.

1) A-I, B-II, C-III, D-IV

2) A-II, B-I, C-III, D-IV

3) A-III, B-IV, C-I, D-II

4) A-IV, B-III, C-II, D-I

Ans. 3 - A-III, B-IV, C-I, D-II

Explanation: Two or more alternative form of genes are called allele. Cross of F1 progeny with homozygous recessive parent is called a test cross. Cross of F1 progeny with any parent is called a back cross. Number of chromosome sets in plant is called ploidy.

2. In a plant, black seed color (BB/Bb) is dominant over white seed color (bb). In order to find out the genotype of the black seed plant with which of the following genotype will you cross it?  (2024)

1) BB          2) bb

3) Bb          4) BB/Bb

Ans. 2 - bb

Explanation: To determine the genotype we use test cross. In a test cross an organism is crossed with the recessive genotype. The progenies of such a cross can be easily analyzed to predict the genotype of the test organism.

3. Which one of the following can be explained on the basis of Mendel's Law of Dominance? (2024)

A.     Out of one pair of factors one is dominant and the other is recessive.

B.     Alleles do not show any expression and both the characters appear as such in F2 generation.

C.     Factors occur in pair in normal diploid plant.

D.     The discrete unit controlling a particular character is called factor.

E.     The expression of only one of the parental characters is found in a monohybrid cross.

Choose the correct answers from the options given below.

1) A, B and C only

2) A, C, D and E only

3) B, C and D only

4) A, B, C, D and E

Ans. 2 - A, C, D and E only

Explanation: According to the law of dominance, Characters are controlled by discrete units called factors, Factors occur in pairs, In a dissimilar pair of factors on member of the pair dominates (dominant) the other (recessive). In a monohybrid cross, only one of the parental character is expressed, which is in line with Mendel's Law of Dominance. Hence option A, C D and E are correct. 

4. A pink flowered snapdragon plant was crossed with a red flowered snapdragon plant. What type of phenotypes is/are expected in the progeny?                                                                  (2024)

1) Only red flowered plants

2) Red flowered as well as pink flowered plants

3) Only pink flowered plants

4) Red, pink as well as white flowered plants

Ans. 2 - Red flowered as well as pink flowered plants

Explanation: Snapdragon show incomplete dominance. Pink flower have genotype Rr and red flower have genotype RR. The cross is shown below: 

	R	r
R	RR (Red)	Rr (Pink)
R	RR (Red)	Rr (Pink)

From the cross we can see that the progeny contains red and pink flowers.