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Q. No.Identify the number of correct statements:
I:
Polygenic inheritance takes into account the influence of the environment.
II:
In a polygenic trait, the phenotype reflects the contribution of each allele, i.e., the effect of each allele is additive.
III:
The normal distribution curve is bell-shaped in polygenic inheritance.
IV:
It is also known as quantitative inheritance.
1.
0
2.
1
3.
3
4.
4
Subtopic: Polygenic Inheritance & Pleiotropy |
72%
Level 2: 60%+
Hints
Consider the given statements:
| I: | Where a single gene can exhibit multiple phenotypic expressions, such a gene is called a pleiotropic gene. |
| II: | The underlying mechanism of pleiotropy in most cases is the effect of a gene on metabolic pathways which contribute towards different phenotypes. |
| III: | Phenylketonuria is caused by a defect in the gene that codes for the enzyme phenylalanine hydroxylase and manifests itself through phenotypic expression characterised by mental retardation and a reduction in hair and skin pigmentation. |
| 1. | Statement I is correct, Statement II is correct, Statement III is incorrect. |
| 2. | Statement I is incorrect, Statement II is correct, Statement III is incorrect. |
| 3. | Statement I is correct, Statement II is incorrect, Statement III is correct. |
| 4. | Statement I is correct, Statement II is correct, Statement III is correct. |
Subtopic: Polygenic Inheritance & Pleiotropy |
86%
Level 1: 80%+
Hints
The following figure shows the determination of sex by chromosomal differences. Which of the following is/are correctly matched?
| A |  |
 |
| B |  |
 |
| 1. | Only A | 2. | Only B |
| 3. | Both A and B | 4. | Neither A nor B |
Subtopic: Sex Determination |
Level 3: 35%-60%
Hints
The figure shows the mechanism of sex determination in a honey bee. How many of the given statements will be true for the mechanism of sex determination in honey bees?
| I. | The sex determination in honey bee is based on the number of sets of chromosomes an individual receives. |
| II. | An offspring formed from the union of a sperm and an egg develops as a female (queen or worker), and an unfertilised egg develops as a male (drone) by means of parthenogenesis. |
| III. | The males have double the number of chromosomes than that of a female, therefore, the females are haploid having 16 chromosomes and the males are diploid, i.e., having 32 chromosomes. |
| IV. | This is called a haplodiploid sex-determination system. |
| V. | The males produce sperms by mitosis, they do not have a father and thus cannot have sons, but have a grandfather and can have grandsons. |
| 1. | 2 | 2. | 3 |
| 3. | 4 | 4. | 5 |
Subtopic: Sex Determination |
80%
Level 1: 80%+
Hints
Identify the incorrectly matched pair:
| Pedigree Symbol | Meaning | |
| 1. |  |
Mating between relatives (consanguineous mating) |
| 2. |  |
Parents above and children below(in order of birth – left to right) |
| 3. |  |
Parents with a male child affected with the disease |
| 4. |  |
Five affected offspring |
Subtopic: Pedigree Analysis: Basics |
85%
Level 1: 80%+
Hints
The mode of inheritance of the Mendelian disorder shown in the given pedigree chart is most likely:
1. Autosomal recessive
2. Autosomal dominant
3. Sex-linked recessive
4. Sex-linked dominant
1. Autosomal recessive
2. Autosomal dominant
3. Sex-linked recessive
4. Sex-linked dominant
Subtopic: Pedigree Analysis: Problem Solving | Pedigree Analysis: More Examples |
64%
Level 2: 60%+
Hints
The mode of inheritance of the Mendelian disorder shown in the given pedigree chart is most likely:
| 1. | Autosomal recessive | 2. | Autosomal dominant |
| 3. | Sex-linked recessive | 4. | Sex-linked dominant |
Subtopic: Pedigree Analysis: Problem Solving | Pedigree Analysis: More Examples |
83%
Level 1: 80%+
Hints
The figure shows the point mutation responsible for the pathogenesis of sickle cell anaemia. Identify the correct statements.
1. Only Statement I
2. Only Statement II
3. Both Statement I and Statement II
4. Neither Statement I nor Statement II
| Statement I: | The peptide chain of the haemoglobin molecule that gets mutated leading to the disease is the alpha chain. |
| Statement II: | The mRNA codon X can be GAG and the mRNA codon Y can be GUG. |
2. Only Statement II
3. Both Statement I and Statement II
4. Neither Statement I nor Statement II
Subtopic: Mendelian Disorders: Sickle Cell Anemia |
73%
Level 2: 60%+
Hints
Regarding thalassemia:
1. Statement I is correct, Statement II is correct.
2. Statement I is incorrect, Statement II is correct.
3. Statement I is correct, Statement II is incorrect.
4. Statement I is incorrect, Statement II is incorrect.
| Statement I: | It is an autosome-linked recessive blood disease transmitted from parents to the offspring when both partners are the unaffected carriers for the gene (or heterozygous). |
| Statement II: | The defect could be due to either mutation or deletion which ultimately results in a reduced rate of synthesis of one of the globin chains (α and β chains) that make up haemoglobin. |
2. Statement I is incorrect, Statement II is correct.
3. Statement I is correct, Statement II is incorrect.
4. Statement I is incorrect, Statement II is incorrect.
Subtopic: Mendelian Disorders: Thalassemia |
83%
Level 1: 80%+
Hints
Thalassemia can be classified according to which chain of the haemoglobin molecule is affected.
1. Statement I is correct, Statement II is correct.
2. Statement I is incorrect, Statement II is correct.
3. Statement I is correct, Statement II is incorrect.
4. Statement I is incorrect, Statement II is incorrect.
| Statement I: | α Thalassemia is controlled by a single gene HBB on chromosome 11 of each parent and occurs due to mutation of one or both the genes. |
| Statement II: | β Thalassemia is controlled by two closely linked genes HBA1 and HBA2 on chromosome 16 of each parent. |
2. Statement I is incorrect, Statement II is correct.
3. Statement I is correct, Statement II is incorrect.
4. Statement I is incorrect, Statement II is incorrect.
Subtopic: Mendelian Disorders: Thalassemia |
65%
Level 2: 60%+
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