PRINCIPLES OF INHERITANCE

 

Principle of Inheritance and Variation

 

1. The fruit fly Drosophila melanogaster was found to be very suitable for experimental verification of chromosomal theory of inheritance by Morgan and his colleagues because

a) It reproduces parthenogenetically

b) A single mating produces two young flies

c) Smaller female is easily recognizable from large male

d) It completes the life cycle in about two weeks

 

2. Which one of the following cannot be explained on the basis of Mendel’s Law of Dominance?

a) The discrete unit controlling a particular character is called a factor

b) Out of one pair factors one is dominant and the other recessive

c) Alleles do not show any blending and both the characters recover as such in F2 generation

d) Factors occur in pairs

 

3. ABO blood groups in humans are controlled by the gene I. It has three alleles – IA, IB and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur?

a) Three

b) One

c) Four

d) Two

 

4. Which one of the following symbols and its representation, used in human pedigree analysis is correct?

a) □=○=Mating between relatives

b) ○=Unaffected male

c) □=Unaffected female

d) ◊=Male affected

 

5. Which one of the following conditions correctly describes the manner of determining the sex in the given example?

a) XO type of sex chromosomes determine male sex in grasshopper

b) XO condition in humans as found in Turner syndrome, determines female sex

c) Homozygous sex chromosomes(XX) produce male in Drosophila

d) Homozygous sex chromosomes(ZZ) determine female sex in birds

 

6. A normal-visioned man whose father was blind, marries a woman whose father was also colour blind. They have their first child as a daughter. What are the chances that this child would be colour blind?

a) 100%

b) 0%

c) 25%

d) 50%

 

7. Which of the following statements is not true of two genes that show 50 per cent recombination frequency

a) The genes may be on different chromosomes

b) The genes are tightly linked

c) The genes show independent assortment

d) If the genes are present on the same chromosome

 

8. A pleiotropic gene:

a) Is a gene evolved during Pliocene

b) Controls a trait only in combination with another gene

c) Controls multiple traits in an individual

d) Is expressed only in primitive plants

 

9. A gene showing codominance has:

a) Alleles tightly linked on the same chromosome

b) Alleles that are recessive to each other

c) Both alleles independently expressed in the heterozygote

d) One allele dominant on the other

 

10. Pick out the correct statements:

a) Haemophilia is a sex-linked recessive disease

b) Down’s syndrome is due to aneuploidy

c) Phenylketonuria is an autosomal recessive gene disorder

d) Sickle cell anaemia is an X-linked recessive gene disorder

a) A and D are correct

b) B and D are correct

c) A,C and D are correct

d) A,B and C are correct

 

11. Haemophilia is more common in males because it is a

a) Recessive character carried by Y-chromosome

b) Dominant character carried by Y-chromosome

c) Dominant trait carried by X-chromosome

d) Recessive trait carried by X-chromosome

 

12. ABO blood group in man is controlled by

a) Multiple alleles

b) Lethal genes

c) Sex linked genes

d) Y-linked genes

 

13. Three children of a family have blood groups A, AB and B. What could be the genotypes of their parents?

a) IA IB and Io Io

b) IA Io and IB Io

c) IB IB and IA IA

d) IA IA and Io Io

 

14. Which of the following is not correct?

a) Three or more alleles of a trait in the population are called multiple alleles.

b) A normal gene undergoes mutations to form many alleles.

c) Multiple alleles map at different loci of a chromosome.

d) A diploid organism has only two alleles out of many in the population.

 

15. Which of the following phenotypes in the progeny are possible from the parental combination A x B?

a) A and B only

b) A,B and AB only

c) AB only

d) A,B,AB and O

 

16. Which of the following phenotypes is not possible in the progeny of the parental genotypic combination IA IO X IA IB?

a) AB

b) O

c) A

d) B

 

17. Which of the following is true about Rh factor in the offspring of a parental combination Dd x Dd (both Rh positive)?

a) All will be Rh positive

b) Half will be Rh positive

c) About ¾ will be Rh negative

d) About one fourth will be Rh negative

 

18. What can be the blood group of offspring when both parents have AB blood group?

a) AB only

b) A, B and AB

c) A, B, AB and O

d) A and B only

 

19. If the childs blood group is ‘O’ and fathers blood group is ‘A’ and mother’s blood group is ‘B’ the genotype of the parents will be

a) IA IA and IB Io

b) IA Io and IB Io

c) IA Io and IoIo

d) IoIo and IB IB

 

20. XO type of sex determination and XY type of sex determination are examples of

a) Male heterogamety

b) Female heterogamety

c) Male homogamety

d) Both (b) and (c)

 

21. In an accident there is great loss of blood and there is no time to analyse the blood group which blood can be safely transferred?

a) O and Rh negative

b) O and Rh positive

c)B and Rh negative

d) AB and Rh positive

 

22. Father of a child is colourblind and mother is carrier for colourblindness, the probability of the child being colourblind is

a) 25%

b) 50%

c) 100%

d) 75%

 

23. A marriage between a colourblind man and a normal woman produces

a) All carrier daughters and normal sons

b) 50% carrier daughters and 50% normal daughters

c) 50% colourblind sons and 50% normal sons

d) All carrier offsprings

 

24. Mangolism is a genetic disorder which is caused by the presence of an extra chromosome number

a) 20

b) 21

c) 4

d) 23

 

25. Klinefelters’ syndrome is characterized by a karyotype of

a) XYY

b) XO

c) XXX

d) XXY

 

26. Females with Turners’ syndrome have

a) Small uterus

b) Rudimentary ovaries

c) Underdeveloped breasts

d) All of these

 

27. Pataus’ syndrome is also referred to as

a) 13-Trisomy

b) 18-Trisomy

c) 21-Trisomy

d) None of these

 

28. “Universal Donor” and “Universal Recipients” blood group are _____ and_______respectively

a) AB, O

b) O, AB

c) A, B

d) B, A

 

29. ZW-ZZ system of sex determination occurs in

a) Fishes

b) Reptiles

c) Birds

d) All of these

 

30. Co-dominant blood group is

a) A

b) AB

c) B

d) O

 

31. Which of the following is incorrect regarding ZW-ZZ type of sex determination?

a) It occurs in birds and some reptiles

b) Females are homogametic and males are heterogametic

c) Males produce one types of gamete

d) It occurs in gypsy moth