Assertion (A): | A recessive character that is not expressed in heterozygous condition can express when it becomes homozygous. |
Reason (R): | Characters segregate during the formation of gametes. |
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. | Both (A) and (R) are false. |
Assertion (A): | Externally it is not possible to distinguish between the pea plants with the genotypes TT or Tt regarding their heights. |
Reason (R): | Due to the dominance of one trait over the other, 3/4th of the F2 plants in Mendelian monohybrid cross were tall. |
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. | Both (A) and (R) are false. |
Assertion (A): | In each pregnancy there is always 50 percent probability of either a male or a female child. |
Reason (R): | Genetic makeup of the sperm determines the sex of a child. |
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. | Both (A) and (R) are false. |
Assertion (A): | In Mendel's dihybrid cross, the F1 hybrid produces gametes of four different genotypes, each with a frequency of 25% of the total gametes produced. |
Reason (R): | Genes for the characters considered in Mendelian dihybrid cross are not linked and thus there segregation is independent of each other. |
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. | Both (A) and (R) are false. |
Assertion (A): | Regarding sickle-cell anaemia, heterozygous (HbAHbS) individuals appear unaffected but are carrier of the disorder. |
Reason (R): | (HbAHbS) individual has sickle cell trait as there is 50% probability of transmission of the mutant gene to the progeny. |
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. | Both (A) and (R) are false. |
1. | Genes for both the characters are located on the same chromosomes and follow the law of dominance |
2. | Alleles of seed shape and seed colour are present on the same locus of a pair of homologous chromosomes |
3. | Genes for both the characters are present on different chromosomes and follow law of dominance |
4. | Genes for seed shape and seed colour are present on the different loci of the same chromosome and follow the law of codominance |
1. | Arise due to failure of segregation of chromatids during cell cycle |
2. | There is increase in whole set of chromosomes |
3. | Exemplified by Down's syndrome |
4. | Involves gain or loss of one or a few chromosomes |