MCQs on Polygenic Inheritance

The phenomena of polygenic inheritance takes place when one trait is governed by two or more genes. These genes are typically larger, quantity-wise and smaller in the effect they can possess. Some of the examples of polygenic inheritance in humans are skin color, height, weight, eye color etc.

1. In corolla length of Nicotiana longiflora, polygenic inheritance was studied by

(a) Joseph Kolreuter

(b) E.M. East

(c) Francis Galton

(d) Nilsson-Ehle

Answer: (b)

2. Marriages between close relatives should be avoided as it causes more

(a) Abnormalities in child birth

(b) Mutations

(c) Recessive alleles to come together

(d) Multiple births

Answer: (c)

3. When two or more nonallelic gene pairs affect the same character in the same way, it is called

(a) pleiotropy

(b) polygenic inheritance

(c) additive expressivity

(d) total penetrance

Answer: (b)

4. Polygenes exhibit

(a) Different phenotypes

(b) Different genotypes

(c) Similar genotypes and phenotypes

(d) Both (a) and (b)

Answer: (a)

5. Raju and Rani are planning a family, but sas each has a brother having the sickle-cell disorder, they are worried that their kids might develop the disorder too. Neither Raju, Rani nor their respective parents have the disorder. They decide to consult a genetic counsellor who conveys them this

(a) its is possible that none of their kids will have the disorder, but blood tests on both of

them should be carried out to confirm

(b) all of their children will have sickle-cell disorder

(c) one of four of their children can be expected to have sickle cell

(d) there is no chance of any of their kids having sickle cell

Answer: (a)

6. Traits which exhibit continuous phenotypic variation are typically determined by this inheritance form

(a) incomplete dominance

(b) polygene inheritance

(c) multiple-allele inheritance

(d) sex-linked inheritance

Answer: (b)

7. One of the X chromosomes in females is inactivated by

(a) environmental factors

(b) enzymes coded for by mitochondrial DNA

(c) number of dominant genes found on each X chromosome

(d) epigenetic markers

Answer: (d)

8. Pick the correct statement

(a) Pleiotropic genes exhibit single phenotype

(b) Pleiotropy is caused by a gene that has multiple phenotypic effect

(c) Lethal genes causes the appearance of ancestral characters

(d) Sickle cell anemia is an example of multifactorial inheritance

Answer: (b)

9. Which of these illustrates pleiotropy?

(a) Matings between earless sheep and long eared sheep always result in short eared

offspring

(b) Human cystic fibrosis causes many symptoms from respiratory distress to digestive

problems

(c) Wheat kerneis can range from white to red in color, a trait governed by multiple

genes

(d) The genes for scarlet eyes and hairy body in fruit flies are located on the same

chromosome

Answer: (b)

10. Morphan’s syndrome is as a result of

(a) Polygene

(b) Pseudogene

(c) Modifier gene

(d) Pleiotropic gene

Answer: (d)

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