This set of Class 12 Biology Chapter 5 Multiple Choice Questions & Answers (MCQs) focuses on “Inheritance of One Gene-1”.
1. What is the process of removal of anthers termed?
Explanation: Emasculation is the process of removal of anthers. This is carried out to carry out pollination in a controlled manner and avoid self-pollination.
2. What process needs to be avoided for carrying of efficient crosses?
c) Development of embryo
d) Pollen tube development
Explanation: Self-pollination leads to fertilization by the pollen from the same flower. A cross desires pollination and fertilization by pollen from a different plant. Hence self-pollination needs to be avoided.
3. What is the generation of plants produced by the crossing of true-breeding plants called?
Explanation: True-breeding plants are taken as parental plants in crosses. Hence offsprings produced by the crossing of these true-breeding plants are F1 progeny.
4. What does F in “F1 progeny” stand for?
Explanation: F1 progeny refers to the first generation of offsprings. This is also termed as the first Filial generation, thereby stating their filial relationship with the true-breeding plants.
5. What should be the phenotype of the F1 progeny produced by a cross between tall and dwarf true-breeding garden pea plants?
a) Tall plants
b) Dwarf plants
c) Intermediate plants
d) Mixed population of tall and dwarf plants
Explanation: Tall plants are dominant over dwarf plants. Being true-breeding parents, the offsprings will all be heterozygous. Moreover, hence phenotypically, all of them will be tall.
6. I = Inflated, i = constricted. Given that the phenotype of F1 progeny is inflated pods and that the parents are true-breeding, which of the following is not a possible genotype of parents?
a) Parent 1: II; Parent 2: ii
b) Parent 1: II; Parent 2: II
c) Parent 1: ii; Parent 2: ii
d) Parent 1: ii; Parent 2: II
Explanation: Inflated is the dominant phenotype. Hence it can be expressed in two genotypes: II and Ii. The F1 progeny can have it in all the mentioned cases except when both parents are recessive ii.
7. What should be the phenotype of a cross between violet and white-flowered true-breeding garden pea plants?
Explanation: Violet is the dominant factor over white in pea flowers. Hence violet can express even in the presence of white. The cross of violet true-breeding and white true-breeding pea plants will produce all heterozygous offsprings. Thus, all of them will have violet flowers.
8. With green pods as a dominant trait over yellow, which of the following crosses will result in all progeny having yellow pods?
a) Homozygous green and homozygous yellow
b) Heterozygous green and heterozygous green
c) Homozygous yellow and homozygous yellow
d) Homozygous green and homozygous green
Explanation: Yellow being recessive will express only when both alleles are present. That occurs only when both parents can contribute an allele encoding for the yellow pod. For all progeny to have yellow pods, both parents have to be homozygous for yellow pods.
9. The cross of true-breeding yellow and green seeded pea plants can only produce yellow seeded progeny.
Explanation: Being homozygous, these parents will produce all heterozygous individuals. Since yellow is dominant over green seed, the phenotype can be seen in the heterozygous state too. Thus, all progeny will be yellow seeded.
10. If VV produces violet flowers and vv produces white flowers, what will be the phenotype and genotype of the F1 progeny?
a) All violet; Tt
b) All white; tt
c) All violet; TT and Tt
d) All violet; TT, Tt, and tt
Explanation: The VV and vv upon crossing will produce all progeny with genotype Vv. This is the heterozygous state. Violet being dominant over white, all the progeny will have violet flowers.
11. The factor which expresses in homozygous and heterozygous states is called _______
Explanation: A dominant factor masks the expression of its recessive counterpart. Thus, it can express in both homozygous and heterozygous states.
12. A plant that exhibits two alleles for only one trait is called ________
Explanation: Monohybrid refers to a hybrid that differs at only one gene. Thus, a plant that exhibits two alleles for one trait is a monohybrid.
13. During meiosis, what happens to the parental alleles?
a) They segregate
b) They undergo repair
c) They undergo breakage
d) They replicate
Explanation: Based on his studies on pea plants, he observed that the parental recessive traits were observed again only in the F2 progeny without any form of blending in F1 generation. This points out that the factors segregate or separate during the process of meiosis.
14. The presence of two different alleles at a particular locus results in _________
Explanation: Heterozygosity refers to different alleles present at a given locus. This is the condition that is of interest to the study of genetics. It can be used to test the nature of an allele.
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