Assertion (A): | If a couple have a female child from the first pregnancy, they will have a male child from the next pregnancy. |
Reason (R): | In each pregnancy, there is always 50 per cent probability of either a male or a female child. |
1. | (A) is False but (R) is True. |
2. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
3. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
4. | (A) is True but (R) is False. |
Assertion (A): | Pedigree analysis is used for the analysis of inheritance of genetic traits in human families. |
Reason (R): | Choice matings are not possible in humans and the number of progeny are also limited, usually. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |
Assertion (A): | The son of a woman who carries the gene for colour blindness has a 50 percent chance of being colour blind. |
Reason (R): | Colour blindness is inherited as an autosomal recessive condition in humans. |
1. | (A) is False but (R) is True |
2. | (A) is True but (R) is False |
3. | Both (A) and (R) are True and (R) is the correct explanation of (A) |
4. | Both (A) and (R) are True but (R) is not the correct explanation of (A) |
Assertion (A): | Regarding Down's syndrome, parents of the affected individual are usually genetically normal. |
Reason (R): | The probability increases from low in 20-year-old mothers to higher in those of age 45. |
1. | (A) is True but (R) is False |
2. | Both (A) and (R) are True and (R) is the correct explanation of (A) |
3. | Both (A) and (R) are True but (R) is not the correct explanation of (A) |
4. | (A) is False but (R) is True |
I: | artificial hybridisation experiments were carried out. |
II: | statistical analysis and mathematical logic were applied to problems in biology. |
1. | Only I | 2. | Only II |
3. | Both I and II | 4. | Neither I nor II |
Statement I: | Genes are the units of inheritance and contain the information that is required to express a particular trait in an organism. |
Statement II: | Genes which code for a pair of contrasting traits are known as alleles, i.e., they are slightly different forms of the same gene |
1. | Statement I is correct; Statement II is incorrect |
2. | Statement I is correct; Statement II is correct |
3. | Statement I is incorrect; Statement II is correct |
4. | Statement I is incorrect; Statement II is incorrect |
I: | Homozygous dominant progeny |
II: | Homozygous recessive progeny |
III: | Heterozygous progeny |
Assertion (A): | Mendel self-pollinated the F2 plants and found that dwarf F2 plants continued to generate dwarf plants in F3 and F4 generations. |
Reason (R): | The genotype of the dwarfs was homozygous. |
1. | Both (A) and (R) are True but (R) does not correctly explain (A). |
2. | Both (A) and (R) are True and (R) correctly explains Assertion. |
3. | Both (A) and (R) are False. |
4. | (A) is True but (R) is False. |
I: | \(Rr \times Rr\) | II: | \(Rr \times rr\) |
III: | \(RR \times rr\) | IV: | \(Rr \times RR\) |
1. | Communication was not easy in those days. |
2. | His concept of genes (or factors, in Mendel’s words) as stable and discrete units that controlled the expression of traits and, of the pair of alleles which did not ‘blend’ with each other, was not accepted by his contemporaries as an explanation for the apparently continuous variation seen in nature. |
3. | Mendel’s approach of using mathematics to explain biological phenomena was totally new and unacceptable to many of the biologists of his time. |
4. | Although Mendel’s provided correct physical proof for the existence of unit factors as discrete entities, his explanations could mot convince others. |