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 |
The sex of the fetus is determined:
1. | at the time of fertilization by the type of sperm fertilizing the ovum. |
2. | at the time of fertilization by the female parent as she always produces an egg with an X chromosome. |
3. | at the time of implantation due to the secretion of TDF by the fetal testes. |
4. | at the time of implantation due to the secretion of ODF by the fetal testes. |
The number of recessive traits in a garden pea in the list given in the box below is:
dwarf stem height, wrinkled seed shape, yellow seed color; yellow pod color, inflated pod shape, terminal flower position, violet flower color |
1. | 2 | 2. | 3 |
3. | 4 | 4. | 5 |
A cross that involves the breeding of a phenotypically dominant individual with a phenotypically recessive individual, in order to determine the zygosity of the former by analyzing proportions of offspring phenotypes is termed as a:
1. | Monohybrid cross | 2. | Test cross |
3. | Back cross | 4. | Reciprocal cross |
Which of the following observations regarding a monohybrid cross cannot be explained with the Law of Dominance?
1. | Expression of only one of the parental characters in F1 |
2. | Expression of both parental characters in F2 |
3. | 3:1 phenotypic ratio in F2 |
4. | A gamete receives only one of the two-unit factors present in the parent |
The rediscovery of Mendel’s Laws is credited independently to:
1. | de Vries, Correns and von Tschermak |
2. | Sutton and Boveri |
3. | Garrod |
4. | Beadle and Tatum |
Drosophila melanogaster is a model organism for the study of genetics. The advantages of this organism include all the following except:
1. | A long life cycle |
2. | A large number of progeny produced by a single mating |
3. | Clear differentiation between sexes |
4. | Hereditary variation is easily seen with low-power microscopes |
Half of the male and half of the female offspring were red-eyed, and half of the male and half of the female offspring were white-eyed when a female Drosophila of unknown genotype was crossed with a white-eyed male fly, of genotype XwY. What was the genotype of the female fly?
1. | Xw+ Xw+ | 2. | Xw Xw |
3. | Xw+ Xw | 4. | Xw+ Y |
Identify the incorrect statement regarding the various methods of sex determination in living organisms:
1. | A male grasshopper has an odd number of chromosomes in its somatic cells. |
2. | A person with Klinefelter syndrome will be genotypically female. |
3. | In butterflies the female flies are diploid while the male flies are haploid. |
4. | A fruit fly with two X chromosomes and two sets of autosomes will be a fertile female. |
Identify the incorrectly matched pair regarding the Mendelian disorders:
1. | Sickle cell anemia: a single base substitution at the sixth codon of the beta-globin gene |
2. | Phenylketonuria: an inborn error of metabolism due to the lack of an enzyme that converts tyrosine to phenylalanine |
3. | Beta thalassemia: the gene involved is a single gene located on chromosome 11 |
4. | Hemophilia: a sex-linked recessive trait extremely rare in females |