Class 12 Biology - Principles of Inheritance and Variation - Multiple Choice Questions (MCQs)
Q1. In Mendel’s experiments with the garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), and yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the F2 generation of the cross RRYY × rryy?
(a) Round seeds with yellow cotyledons, and wrinkled seeds with yellow cotyledons.
(b) Only round seeds with green cotyledons.
(c) Only wrinkled seeds with yellow cotyledons.
(d) Only wrinkled seeds with green cotyledons.
Q2. Human blood grouping is ABO instead of ABC because O in it refers to
(a) no antigen A or B on RBCs.
(b) other antigens besides A and B.
(c) overdominance of its gene over A and B.
(d) one antibody only either anti-A or anti-B.
Q3. Mendel’s law of segregation as applied to the chromosomes during meiosis means that
(a) the pairing of homologs will take place leading to segregation of the types
(b) alleles of a gene separate from each other when homologs separate in meiosis-I
(c) genes on the same chromosome will show 50% crossing over
(d) different alleles of a gene will be passed on together through mitosis
Q4. Mendel’s Law of independent assortment holds good for genes situated on the
(a) non-homologous chromosomes
(b) homologous chromosomes
(c) extranuclear genetic element
(d) same chromosome
Q5. Occasionally, a single gene may express more than one effect. The phenomenon is called
(a) multiple allelism
(b) mosaicism
(c) pleiotropy
(d) polygeny
Q6. Who introduced the idea of spontaneous generation?
(a) Anaximander
(b) Oparin
(c) Pasteur
(d) Redus
Q7. A gene is said to be dominant if
(a) it expresses its effect only in the homozygous state
(b) it expresses its effect only in heterozygous condition
(c) it expresses its effect both in homozygous and heterozygous conditions
(d) it never expresses its effect in any conditions
Q8. If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is
(a) autosomal dominant
(b) autosomal recessive
(c) sex-linked dominant
(d) sex-linked recessive
Q9. A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the parents?
(a) TT and Tt
(b) Tt and Tt
(c) TT and TT
(d) Tt and tt
Q10. Which one of the following traits of garden pea studied by Mendel was a recessive feature?
(a) Round seed shape
(b) Axial flower position
(c) Green seed colour
(d) Green pod colour
Answers:
1. (a) Round seeds with yellow cotyledons, and wrinkled seeds with yellow cotyledons.
2. (a) no antigen A or B on RBCs.
3. (b) alleles of a gene separate from each other when homologs separate in meiosis-I
4. (b) homologous chromosomes
5. (c) pleiotropy
6. (a) Anaximander
7. (c) it expresses its effect both in homozygous and heterozygous condition
8. (d) sex-linked recessive
9. (b) Tt and Tt
10. (c) Green seed colour
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