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Q. No.Mendel published his work on inheritance of characters in 1865 but for several reasons, it remained unrecognised till 1900. These reasons included all the following except:
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.
Subtopic: Chromosomal Basis of Inheritance: Introduction |
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Identify the incorrectly matched pair:
| 1. | de Vries, Correns and von Tschermak | Independently rediscovered Mendel’s laws |
| 2. | Walter Sutton and Theodore Boveri | Gave chromosomal theory of inheritance |
| 3. | Sturtevant | Discovered the mechanism of sex determination in fruit flies |
| 4. | T. H. Morgan | Demonstrated that genes are carried on chromosomes |
Subtopic: Chromosomal Basis of Inheritance: Introduction |
83%
From NCERT
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Consider the given two statements:
1. Statement I is correct; Statement II is correct
2. Statement I is correct; Statement II is incorrect
3. Statement I is incorrect; Statement II is incorrect
4. Statement I is incorrect; Statement II is correct
| Statement I: | The two alleles of a gene pair are located on homologous sites on homologous chromosomes. |
| Statement II: | The pairing and separation of a pair of chromosomes would lead to the segregation of a pair of factors they carried. |
2. Statement I is correct; Statement II is incorrect
3. Statement I is incorrect; Statement II is incorrect
4. Statement I is incorrect; Statement II is correct
Subtopic: Chromosomal Basis of Inheritance: Introduction |
87%
From NCERT
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Consider the given two statements:
| Assertion (A): | X-linked recessive disorders are always expressed in males. |
| Reason (R): | Males have only one X chromosome. |
| 1. | Both (A) and (R) are True but the (R) does not correctly explain the (A). |
| 2. | Both (A) and (R) are True and the (R) correctly explains the (A). |
| 3. | (A) is False but (R) is True. |
| 4. | (A) is True but (R) is False. |
Subtopic: Pedigree Analysis: Problem Solving |
From NCERT
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When preparing genetic map using recombination data, it is assumed that 1% of crossing over equals:
1. one map unit.
2. two map units.
3. five two map units.
4. ten map units.
1. one map unit.
2. two map units.
3. five two map units.
4. ten map units.
Subtopic: Recombination & Gene Mapping |
83%
From NCERT
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If the strength of linkage between y and w is higher than w and m [y, w and m are three linked genes located on a chromosome]:
| 1. |
the number of recombinants between y and w will be higher than the number of recombinants between w and m.
|
| 2. |
the number of recombinants between y and w will be lower than the number of recombinants between w and m.
|
| 3. |
the number of recombinants between y and w will be equal to the number of recombinants between w and m.
|
| 4. |
no recombinants between y and w and between w and m will be formed as they are linked.
|
Subtopic: Understanding Linkage |
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Consider the two statements:
| Statement I: | The dominant phenotype can be produced only by an organism with a homozygous dominant genotype. |
| Statement II: | The results of a test cross indicate whether an individual with the dominant phenotype is heterozygous or homozygous dominant. |
| 1. | Statement I is correct; Statement II is correct |
| 2. | Statement I is correct; Statement II is incorrect |
| 3. | Statement I is incorrect; Statement II is incorrect |
| 4. | Statement I is incorrect; Statement II is correct |
Subtopic: Monohybrid Cross: Further Understanding |
72%
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Both parents are carriers for an autosomal recessive trait. What proportion of their progeny are expected to be affected by this disorder?
1. 0
2. ¼
3. ½
4. ¾
1. 0
2. ¼
3. ½
4. ¾
Subtopic: Pedigree Analysis: More Examples |
68%
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Identify the incorrectly matched pair:
| Organism | Mechanism of sex determination | |
| 1. | Honey bees | Haplo-diploidy |
| 2. | Grasshoppers | XX-XO female heterogamety |
| 3. | Birds | ZZ-ZW female heterogamety |
| 4. | Fruit fly | Genic balance |
Subtopic: Sex Determination: Further Considerations |
69%
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Consider the given two statements:
| Assertion (A): | Human skin colour trait is spread over a gradient rather than having distinct alternate forms. |
| Reason (R): | Human skin colour is a polygenic trait. |
| 1. | Both (A) and (R) are True but the (R) does not correctly explain the (A). |
| 2. | Both (A) and (R) are True and the (R) correctly explains the (A). |
| 3. | (A) is False but (R) is True. |
| 4. | (A) is True but (R) is False. |
Subtopic: Polygenic Inheritance & Pleiotropy |
68%
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