MCQ’s Based on Heterosis for ICAR (SRF or JRF) /ASRB /CSIR NET/BET Exams #1

 

1. One of the consequences of inbreeding is increase in the relative frequency of
   A) Recessive homozygotes only
   B) Dominant homozygotes only
   C) Heterozygotes
   D) Both homozygotes
   Ans: D

2. The decrease in size and vigour in early generations of inbreeding is due to
   A) Loss of superior genes
   B) Reduction in the frequency of superior genes
   C) Expression of many lethal and sub-vital recessive alleles
   D) Loss of hybrid vigour
   Ans: C

3. One of the objections against dominance hypothesis was that
   A) Homozygotes comparable to F1 hybrids could never be obtained
   B) Dominant genes are known to be linked
   C) Dominant genes at different loci were found in parents of hybrids
   D) Not many dominant lethal known
   Ans: A

4. Overdominance hypothesis for heterosis could not be accepted because
   A) It assumes presence of multiple alleles
   B) Overdominance at individual loci could never be demonstrated
   C) Partial dominance between alleles is known at many loci
   D) Epistatic interactions at different dominant loci is known
   Ans: B

5. Heterozygous offsprings have superior fitness than their homozygous parents due to
   A) Heterosis
   B) Incomplete dominance
   C) Codominance
   D) Linkage
   Ans: A

6. What fraction of the offspring of the cross AaBb × AaBb would show the dominant phenotypes for both genes?
   A) 3/16
   B) 6/16
   C) 9/16
   D) 12/16
   Ans: C

7. Heterosis is
   A) Appearance of spontaneous mutations
   B) Induction of mutations
   C) Mixture of two or more traits
   D) Superiority of hybrids over their parents
   Ans: D

8. First successful hybrid through artificial crosses was produced by
   A) Camerarius
   B) Fairchild
   C) Koelreuter
   D) Johnson
   Ans: C

9. The term heterosis was coined by
   A) Shull
   B) Johanssen
   C) Correns
   D) Bateson
   Ans: A

10. Very good heterosis in maize crop can be obtained by crossing
    A) Cross pollinating varieties
    B) Inbred lines
    C) Varieties which have shown self-sterility
    D) Varieties which give a very high yield as a result of outbreeding
    Ans: B

11. Epistatic interaction will lead to the maximum heterosis if
    A) Epistasis is of complementary type predominantly
    B) Interacting pairs of genes are dispersed in both the parents
    C) Both of the above
    D) None of the above
    Ans: C

12. According to additive-dominance model, better parent heterosis results when
    A) Σh is positive and greater than Σd
    B) Σh is negative and greater than Σd
    C) Σh is positive and less than Σd
    D) Σh is negative and less than Σd
    Ans: A

13. In plants heterosis can be fixed by
    A) Vegetative propagation
    B) Apomixes
    C) Balanced lethal system
    D) All above
    Ans: D

14. Dominance of linked gene hypothesis was proposed by
    A) Shull
    B) Jones
    C) East
    D) Dobzhansky
    Ans: B

15. The term overdominance was coined by

1. Jones

2. East

3. Shull

4. Hull
   Ans: 1) Jones

16. The term heterozygosis was coined by
    A) East and Hays (1912)
    B) East and Shull (1908)
    C) Devenport (1908)
    D) Shull (1945)
    Ans: B

17. Phenotypic appearance in F2 generation in complementary gene action
    A) 12:3:1
    B) 9:3:4
    C) 9:7
    D) 13:3
    Ans: C