After analysis of results drawn from his experiments with pea plants, Mendel concluded:
1. | There is considerable genetic variation in garden peas. |
2. | Traits are inherited in discrete units, and are not the results of "blending." |
3. | Recessive genes occur more frequently in the F1 than do dominant ones. |
4. | Genes are composed of DNA. |
A dihybrid test cross leads to a frequency of recombinants of 50% in progeny. The most obvious conclusion will be:
1. | The two genes likely are located on different chromosomes. |
2. | All of the offspring have combinations of traits that match one of the two parents. |
3. | Abnormal meiosis has occurred. |
4. | Independent assortment is hindered. |
In a family, father and son express a sex-linked recessive trait. The mother is phenotypically normal. What is the probability that she might be a carrier for the trait?
1. | 0 | 2. | 0.25 |
3. | 0.5 | 4. | 1.0 |
The father and the mother of a child, with blood group O, have the blood groups A and B respectively. If these parents then have non-identical twins, what is the probability that both twins will have blood group B?
1. | ¼ | 2. | 1/8 |
3. | ¾ | 4. | 1/16 |
Identify the correct statement regarding phenylketonuria:
1. | The affected individual is unable to convert tyrosine to phenylalanine |
2. | It is inherited as an X-linked recessive trait |
3. | Phenylalanine accumulates in the brain and is excreted in urine |
4. | It is an inborn error of metabolism |
Assuming independent assortment, the ratio of progeny with the genotypes AaBb : Aabb : aaBb : aabb from a dihybrid cross AabB X AaBb will respectively be:
1. | 4 : 3 : 2 : 1 | 2. | 4 : 4 : 2 : 1 |
3. | 4 : 2 : 2 : 1 | 4. | 4 : 2 : 1 : 1 |
Total number of autosomes will be the same in:
I. | Male and female humans |
II. | Male and female birds |
III. | Male and female Drosophila |
IV. | Male and female grasshopper |
1. | Only I, II, and III | 2. | Only I, II, and IV |
3. | Only II, III, and IV | 4. | I, II, III, and IV |
The genetic change shown in the given figure shows the pathogenesis of:
1. | Phenylketonuria | 2. | Cystic fibrosis |
3. | Sickle cell anemia | 4. | Thalassemia |
In some Camellia cultivars, a cross between a red homozygous flower and a white homozygous flower will produce offspring that have red and white spots as shown in the given diagram. This can best be explained by:
1. | Incomplete dominance | 2. | Co-dominance |
3. | Pleiotropy | 4. | Variable expressivity |
The inheritance pattern of the trait shown in the given pedigree is most likely:
1. | Autosomal recessive | 2. | Sex-linked recessive |
3. | Autosomal dominant | 4. | Sex-linked dominant |