Reproductive Health

Q.No.1 According to which of the following organisation reproductive health means a total well being in all aspects of reproduction?

a.WHL b.UNESCO c.WHO d.WWW

Ans. c.WHO

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Q.No.2 Which one amongst the following is the first country in the world to initiate action plans and programmes at a national level to attain total reproductive health as social goal?

a.China b.India c.Japan d.USA

Ans. b.India

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Q.No.3 The family planning programmed in India were initiated in 

a.1951 b.1961 c.1971 d.1981

Ans. a.1951

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Q.No.4 RCH stands for

a.Routine Check up of Health b.Reproductive cum Hygine c.Reversible Contraceptive Hazards

d.Reproductive and Child Health Care

Ans. d.Reproductive and Child Health Care

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Q.No.5 The technique which makes use of amniotic fluid for the detection of prenatal disorder is called as 

a.leproscopy b.amniocentesis c.endoscopy d.ultrasound

Ans. b.amniocentesis

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Q.No.6 Saheli a new oral contraceptive developed by

a. AIIMS b.Central Drug Research Institute c.Health care pvt ltd d.Bharat Immunologicals & Biologicals corp. ltd.

Ans. b.Central Drug Research Institute 

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Q.No.7 What is the marriageable age for the females and males respectively in India?

a.18, 18 b.18, 25 c.21,18 d.18, 21

Ans. d.18,21

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Q.No.8 which of the following is traditional method of contraception?

a. Implantation b.Lactational amenorrhoea c.Condoms d.Sterilisation 

Ans. b.Lactational amenorrhoea

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Q.No.9 Which of the following contraceptive also provides protection from contacting STDs and AIDS?

a.Diaphragms b.Spermicidal foams c.Condoms d.Lactational Amenorrhoea

Ans. c.Condoms

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Q.No.10 The diaphragm, cervical cap and vaults are 

a.disposable contraceptive devices b.reusable contraceptives c.non-medicated IUDs d.Cu-releasing IUDs

Ans. b.reusable contraceptives

Chapter 5 : Principles of Inheritance and variation

(a)3 genotypes; 4 phenotypes

(b)4 genotypes; 3 phenotypes

(c)4 genotypes; 4 phenotypes

(d)3 genotypes; 3 phenotypes

Ans. (b)4 genotypes; 3 phenotypes

Explanation: If the genotypes of husband and wife are IAIB and IAi respectively, then the probabilities of genotypes and phenotypes among their children can be worked out as:

                         IA           IB                     and       IA                            i

                       IAIA           IAi             IAIB               IB i

Genotype         IAIA                   IAi            IAIB           IB i

Phenotype        A              A              AB        B

Thus, there are four possible genotypes viz. IAIA     IAi    IAIB        IB i and three possible phenotypes viz. A, AB and B among the children.

14. A tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant. When the F1 plants were selfed the resulting genotypes were in the ratio of

(a)3 : 1 : : Tall : Dwarf

(b)3 : 1 : : Dwarf : Tall

(c)1 : 2 : 1 : : Tall homozygous : Tall heterozygous :Dwarf

(d)1 : 2 : 1 : : Tall heterozygous : Tall homozygous: Dwarf.

Ans. (c)1 : 2 : 1 : : Tall homozygous : Tall heterozygous :Dwarf

Explanation: When a tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant and the F1 plants were selfed the resulting genotypes were in the ratio of 1 : 2 : 1, i.e., Tall homozygous : Tall heterozygous : Dwarf It can be illustrated as given below:

      Tall                   Dwarf

        TT                   tt                parent generation

         T                     t                Gametes

                 Tt                             F1 Generation

           Tall heterozygous

      Tt          x       Tt

TT       Tt                 Tt          tt                  F2 Generation

Tall     Tall              Tall       Dwarf

Phenotypic ratio:  3:1   Tall : Dwarf

Genotypic Ratio: 1:2:1   TT:Tt:tt

15. A gene showing co-dominance has

(a) alleles that are recessive to each other

(b) both alleles independently expressed in the heterozygote

(c) one allele dominant on the other

(d) alleles tightly linked on the same chromosome

Ans. (b) both alleles independently expressed in the heterozygote

Explanation: The phenomenon of expression of both the alleles in a heterozygote is called co-dominance. The alleles which do not show dominance-recessive relationship and are able to express themselves independently when present together are called co-dominant alleles. As a result the heterozygous condition has a phenotype different from either of homozygous genotypes, e.g., alleles for blood group A (IA) and for blood group B (IB) are codominant so that when they come together in an individual, they produce blood group AB.

16. Alleles are

(a) different molecular forms of a gene

(b) heterozygotes

(c) different phenotype

(d) true breeding homozygotes.

Ans. (a) different molecular forms of a gene

Explanation: Genes are the units of inheritance and contain the information that is required to express a particular trait in an organism. Alternating forms of a single gene which code for a pair of contrasting traits are known as alleles. For example, two alleles determine the height of pea plant (tall and dwarf).

17. Multiple alleles are present

(a) at the same locus of the chromosome

(b) on non-sister chromatids

(c) on different chromosomes

(d) at different loci on the same chromosome.

Ans. (a) at the same locus of the chromosome

Explanation: 

18. A man with blood group ‘A’ marries a woman with blood group ‘B’. What are all the possible blood groups of their offspring?

(a)A, B, AB and O

(b) O only

(c) A and B only

(d) A, B and AB only

Ans. (a) A, B, AB and O

Explanation: The man has blood group A, thus its genotype can either be  IAIA or  IAIo. Similarly, woman can either have IBIB, or IBIO genotype. Thus, their offspring can have any of the blood groups A (IAIA or  IAIo), B (IBIB or  IBIo), AB (IAIB) or O (IoIo). 

19. If two persons with ‘AB’ blood group marry and have sufficiently large number of children, these children could be classified as ‘A’ blood group: ‘AB’ blood group : ‘B’ blood group in 1 : 2 : 1 ratio. Modern technique of protein electrophoresis reveals presence of both ‘A’ and ‘B’ type proteins in ‘AB’ blood group individuals. This in an example of

(a) partial dominance

(b) complete dominance

(c) codominance

(d) incomplete dominance.

Ans. (c) codominance

Explanation: The phenomenon of expression of both the alleles in a heterozygote is called co-dominance. The alleles which do not show dominance-recessive relationship and are able to express themselves independently when present together are called co-dominant alleles. As a result the heterozygous condition has a phenotype different from either of homozygous genotypes, e.g., alleles for blood group A (IA) and for blood group B (IB) are codominant so that when they come together in an individual, they produce blood group AB.

20. Which idea is depicted by a cross in which the F1 generation resembles both the parents?

(a) Inheritance of one gene

(b) Co-dominance

(c) Incomplete dominance

(d) Complete dominance

Ans. (b) Co-dominance

Explanation: In co-dominance, both the alleles are able to express themselves independently when present together resulting in a phenotype that is intermediate between both the parental homozygous phenotypes, thereby resembling both of them. E.g., roan coat colour in cattle is a result of co-dominance of alleles for white and red coat colour.

Q21. F2 generation in a Mendelian cross showed that both genotypic and phenotypic ratios are same as 1 : 2 : 1.

It represents a case of

(a) co-dominance

(b) dihybrid cross

(c) monohybrid cross with complete dominance

(d) monohybrid cross with incomplete dominance.

Ans. (d) monohybrid cross with incomplete dominance.

Explanation: The inheritance of flower colour in the dog flower (snapdragon or Antirrhinum sp.) is a an example of incomplete dominance. In a cross between true- breeding red-flowered (RR) and true-breeding white- flowered plants (rr), the F1 (Rr) was pink. When the F1 was self-pollinated the F2 resulted in the following ratio, 1 (RR) Red : 2 (Rr) Pink : 1 (rr) White. Here, the genotype ratios were 1 : 2 : 1 as in any Mendelian monohybrid cross, but the phenotype ratios had changed from the 3 : 1 dominant : recessive ratio to 1 : 2 : 1. 

Q22. A test cross is carried out to

(a) determine the genotype of a plant at F2

(b) predict whether two traits are linked

(c) assess the number of alleles of a gene

(d) determine whether two species or varieties will breed successfully. (Mains 2012)

Ans. (a) determine the genotype of a plant at F2

Explanation: Test cross is performed to determine the genotype of F2 plant. In a typical test cross, an organism showing dominant phenotype and whose genotype is to be determined is crossed with one that is homozygous recessive for the allele being investigated, instead of self- crossing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism. Given below is an illustration of test cross:

F2 Plant Purple Flower

                                              Dominant phenotype

                                               Unknown phenotype

                                                two possibilities 

Test                   White flower                              White flower

cross              pp         x      PP                                   Pp      x       PP 

               homozygous     homozygous                heterozygous      homozygous

                recessive            dominant                    dominant             recessive

Gametes    p   p              P    P                              P  p               p    p 

                Pp Pp     Pp        Pp                                Pp  Pp           PP    pp 

                All flowers purple                                 half purple       half white

Q23. Test cross in plants or in Drosophila involves crossing

(a) between two genotypes with recessive trait

(b) between two F1 hybrids

(c) the F1 hybrid with a double recessive genotype

(d) between two genotypes with dominant trait.

Ans. c) the F1 hybrid with a double recessive genotype

Explanation: the F1 hybrid with a double recessive genotype

Q24. 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

Ans. (c) Four

Explanation:

The three alleles IA, IB and i of gene I in ABO blood group system can produce six different genotypes and four different phenotypes as shown below :

Genotypes                   Phenotypes

IA,IA                        Blood group A

IAi

IB,IB                        Blood group B

IB i  

IAIB    Blood group AB

ii         Blood group O

25. The genotype of a plant showing the dominant phenotype can be determined by

(a) test cross

(b) dihybrid cross

(c) pedigree analysis

(d) back cross.   

Ans. a. Test cross

Explanation: Test cross is performed to determine the genotype of F2 plant. In a typical test cross, an organism showing dominant phenotype and whose genotype is to be determined is crossed with one that is homozygous recessive for the allele being investigated, instead of self- crossing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism. Given below is an illustration of test cross:

F2 Plant Purple Flower

                                              Dominant phenotype

                                               Unknown phenotype

                                                two possibilities 

Test                   White flower                              White flower

cross              pp         x      PP                                   Pp      x       PP 

               homozygous     homozygous                heterozygous      homozygous

                recessive            dominant                    dominant             recessive

Gametes    p   p              P    P                              P  p               p    p 

                Pp Pp     Pp        Pp                                Pp  Pp           PP    pp 

                All flowers purple                                 half purple       half white

26. 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 of 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. (2010)

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

Explanation: According to Mendel’s law of dominance, in heterozygous individuals a character is represented by two contrasting factors called alleles or allelomorphs which occur in pairs. Out of the two contrasting alleles, only one is able to express its effect in the individual. It is called dominant factor or dominant allele. The other allele which does not show its effect in the heterozygous individual is called recessive factor or recessive allele. The option (c) in the given question cannot be explained on the basis of law of dominance. It can only be explained on the basis of Mendel’s law of independent assortment, according to which in a dihybrid cross, the two alleles of each character assort independently (do not show any blending) of the alleles of other character and separate at the time of gamete formation. Both the characters are recovered as such in F2 generation producing both parental and new combinations of traits.

27. ABO blood grouping is controlled by gene I which has three alleles and show co-dominance. There are six genotypes. How many phenotypes in all are possible?

(a) Six

(b) Three

(c) Four

(d) Five 

Ans. c) Four

Explanation: The three alleles IA, IB and i of gene I in ABO blood group system can produce six different genotypes and four different phenotypes as shown below :

Genotypes                   Phenotypes

IA,IA                        Blood group A

IAi

IB,IB                        Blood group B

IB i  

IAIB    Blood group AB

ii         Blood group O

28. A cross in which an organism showing a dominant phenotype is crossed with the recessive parent in order to know its genotype is called

(a) monohybrid cross   

(b) back cross

(c) test cross

(d) dihybrid cross.

Ans. c) test cross

Explanation: Test cross is performed to determine the genotype of F2 plant. In a typical test cross, an organism showing dominant phenotype and whose genotype is to be determined is crossed with one that is homozygous recessive for the allele being investigated, instead of self- crossing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism. Given below is an illustration of test cross:

F2 Plant Purple Flower

                                              Dominant phenotype

                                               Unknown phenotype

                                                two possibilities 

Test                   White flower                              White flower

cross              pp         x      PP                                   Pp      x       PP 

               homozygous     homozygous                heterozygous      homozygous

                recessive            dominant                    dominant             recessive

Gametes    p   p              P    P                              P  p               p    p 

                Pp Pp     Pp        Pp                                Pp  Pp           PP    pp 

                All flowers purple                                 half purple       half white

29. In Antirrhinum two plants with pink flowers were hybridized. The F1 plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridisation? Red flower colour is determined by RR and white by rr genes.

(a) rrrr

(b) RR

(c) Rr

(d) rr

Ans. (c) Rr

Explanation: The given situation is an example of incomplete dominance where phenotype found in F1 generation do not resemble either of the two parents. The genotype of the two plants used for cross will be:

Parents genotype                Rr                 x               Rr

Phenotype                         Pink                              Pink

Gametes                         R     r                             R        r

Cross                            RR   Rr

                                    Rr   rr

Genotype ratio;   RR :  Rr  :  rr

                         1    :   2    :   1

Phenotype ratio Red : Pink: White

The incomplete dominance of dominant allele (here‘R’) over recessive allele (here ‘r’) could be due to mutations (insertion, deletion, substitution or inversion of nucleotides). The mutant allele generally produces a faulty or no product. This modification in the product may lead to incomplete dominance of the (unmodified) wild type dominant allele.

30. In pea plants, yellow seeds are dominant to green. If a heterozygous yellow seeded plant is crossed with a green seeded plant, what ratio of yellow and green seeded plants would you expect in F1 generation? 

(a) 9 : 1

(b) 1 : 3

(c) 3 : 1

(d) 50 : 50

Ans. (d) 50 : 50

Explanation: Yellow (Y) seeds are dominant to green (y). So, a heterozygous yellow seeded plant will have the genotype of (Yy) and a green seeded plant will have genotype of (yy). When these two plants are crossed, the F1 generation will have the ratio of yellow : green as 50 : 50. It is shown as:

                    Yy (heterozygous yellow)             x           yy (homozygous green)

gametes          Y      y                                               y            y 

F1 Generation                Yy                                                        yy                       

F1 Generation                 Yellow                        :                      green

                                           50                        :                        50

31. A common test to find the genotype of a hybrid is by

(a) crossing of one F2 progeny with female parent

(b) studying the sexual behaviour of F1 progenies

(c) crossing of one F1 progeny with male parent

(d) crossing of one F2 progeny with male parent

Ans. (c) crossing of one F1 progeny with male parent

Explanation: A common test to find the genotypes of a hybrid is by crossing of one F1 progeny with male parent

32. Test cross involves

(a) crossing between two genotypes with dominant trait

(b) crossing between two genotypes with recessive trait

(c) crossing between two F1 hybrids

(d) crossing the F1 hybrid with a double recessive genotype.

Ans. (d) crossing the F1 hybrid with a double recessive genotype

Explanation: Test cross is performed to determine the genotype of F2 plant. In a typical test cross, an organism showing dominant phenotype and whose genotype is to be determined is crossed with one that is homozygous recessive for the allele being investigated, instead of self- crossing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism. Given below is an illustration of test cross:

F2 Plant Purple Flower

                                              Dominant phenotype

                                               Unknown phenotype

                                                two possibilities 

Test                   White flower                              White flower

cross              pp         x      PP                                   Pp      x       PP 

               homozygous     homozygous                heterozygous      homozygous

                recessive            dominant                    dominant             recessive

Gametes    p   p              P    P                              P  p               p    p 

                Pp Pp     Pp        Pp                                Pp  Pp           PP    pp 

                All flowers purple                                 half purple       half white 

33. Phenotype of an organism is the result of

(a) genotype and environment interactions

(b) mutations and linkages

(c) cytoplasmic effects and nutrition

(d) environmental changes and sexual dimorphism.

Ans. (a) genotype and environment interactions

Explanation: The external manifestation, morphological or physiological expression of an individual with regard to one or more characters is called phenotype. For recessive genes, phenotype and genotype are similar. For dominant genes, the phenotype is same for both homozygous states. Phenotype is influenced by environment as well as age. A child definitely differs from adolescent, the latter from adult and an adult from aged one. Many phenotypes are determined by multiple genes. Thus, the identity of phenotype is determined by genotype and environment

34. A gene is said to be dominant if

(a) it expresses its effect only in homozygous state

(b) it expresses its effect only in heterozygous condition

(c) it expresses its effect both in homozygous and heterozygous condition

(d) it never expresses its effect in any condition.

Ans. (c) it expresses its effect both in homozygous and heterozygous condition

Explanation: Dominant factor is an allele or Mendelian factor which expressess itself in the hybrid (heterozygous) as well as in homozygous state. It is denoted by capital letter.

35. When dominant and recessive alleles express itself together it is called

(a) co-dominance

(b) dominance

(c) amphidominance

(d) pseudodominance.

Ans. (a) co-dominance

Explanation: In co-dominance, both the alleles are able to express themselves independently when present together resulting in a phenotype that is intermediate between both the parental homozygous phenotypes, thereby resembling both of them. E.g., roan coat colour in cattle is a result of co-dominance of alleles for white and red coat colour.

36. In hybridisation, Tt × tt gives rise to the progeny of ratio

(a) 2 : 1

(b) 1 : 2 : 1

(c) 1 : 1

(d) 1 : 2.

Ans. (c) 1 : 1

Explanation: Crossing of individuals having dominant phenotype with its homozygous recessive is a test cross, which can be represented as:

F1 hybrid          x           Homozygous recessive

Tt                      x            tt - parent

T  &   t                              t -Gametes

Tt (tall)     tt (Dwarf)       Test cross progeny

Thus, ratio of progeny is = 1:1

37. A child’s blood group is ‘O’. The parent’s blood groups cannot be

(a) A and B

(b) A and A 

(c) AB and O

(d) B and O

Ans. C. AB and O 

Explanation: O blood group of a child cannot be obtained from the parents having blood group O × AB. The parents blood groups may be A × O, A × B, B × O, B × A, O × A and O × B.

38. A child of O-group has B-group father. The genotype of father will be 

(a) IOIO (b) IBIB

(c) IAIB (d) IBIO

Ans. d. IBIO

Explanation: The genotype of the child would be IOIO (recessive). Hence, the genotype of the father can only be IBIO.

39.An allele is dominant if it is expressed in

(a)both homozygous and heterozygous states

(b)second generation

(c)heterozygous combination

(d)homozygous combination.

Ans. (a)both homozygous and heterozygous states

Explanation: 

40.An organism with two identical alleles is 

(a) dominant

(b) hybrid

(c) heterozygous

(d) homozygous.   (1992)

Ans. (d) homozygous.  

Explanation: An organism with two identical alleles is homozygous. Homozygous have identical genes at the same locus on each member of a pair of homologous/ chromosomes.

41.A man of A-blood group marries a woman of AB blood group. Which type of progeny would indicate that man is heterozygous A?

(a)AB

(b) A

(c) O

(d) B

Ans. d. B

Explanation: IAIO × IAIB gives us the following genotypes IAIA, IOIB, IAIB. Hence, when a man of blood group A marries a woman of AB blood group, B progeny would indicate that man is heterozygous A. 

42. Multiple alleles control inheritance of

(a) phenylketonuria

(b) colour blindness

(c) sickle cell anaemia

(d) blood groups. 

Ans. (d) blood groups

Explanation: ABO blood group system is due to multiple allelism. A gene can have more than two alleles or allelomorphs, which can be expressed by mutation in wild form in more than one ways. These alleles or allelomorphs make a series of multiple alleles. The mode of inheritance in case of multiple alleles is called multiple allelism. A well known and simplest example of multiple allelism is the inheritance of ABO blood groups in human beings. In human population, 3 different alleles for this character are found - IA IB and IO. A person is having only two of these three alleles and blood type can be determined. 

43. The contrasting pairs of factors in Mendelian crosses are called

(a) multiple alleles

(b) allelomorphs

(c) alloloci

(d) paramorphs.

Ans. (b) allelomorphs

Explanation: The contrasting pairs of factors in Mendelian crosses are called allelomorphs. Alleles or allelomorphs are the different forms of a gene, having the same locus on homologous chromosomes and are subject to Mendelian (alternative) inheritance.

44. Mendel’s last law is

(a) segregation

(b) dominance

(c) independent assortment

(d) polygenic inheritance. (1991)

Ans. (c) independent assortment

Explanation: Mendel’s last law is independent assortment. The principle of independent assortment states that when two individuals differ from each other in two or more pairs of factors, the inheritance of one pair is quite independent of the inheritance of other

45. Blue eye colour is recessive to brown eye colour. A brown eyed man whose mother was blue eyed marries a blue-eyed woman. The children will be

(a) both blue eyed and brown eyed 1 : 1

(b) all brown eyed

(c) all blue eyed

(d) blue eyed and brown eyed 3 : 1.

Ans. (a) both blue eyed and brown eyed 1 : 1

Explanation: The brown eyed man will have the genotype Bb and his wife bb. Hence, Bb × bb = Bb : bb. Therefore, the children shall be both blue eyed and brown eyed the ratio is 1 : 1.

46. RR (Red) Antirrhinum is crossed with white (WW) one. Offspring RW are pink. This is an example of

(a) dominant-recessive

(b) incomplete dominance

(c) hybrid

(d) supplementary genes.

Ans. (b) incomplete dominance

Explanation: : The inheritance of flower colour in the dog

flower (snapdragon or Antirrhinum sp.) is a an example of incomplete dominance. In a cross between true- breeding red-flowered (RR) and true-breeding white- flowered plants (rr), the F1 (Rr) was pink. When the F1 was self-pollinated the F2 resulted in the following ratio, 1 (RR) Red : 2 (Rr) Pink : 1 (rr) White. Here, the genotype ratios were 1 : 2 : 1 as in any Mendelian monohybrid cross, but the phenotype ratios had changed from the 3 : 1 dominant : recessive ratio to 1 : 2 : 1.

47. ABO blood group system is due to

(a) multifactor inheritance

(b) incomplete dominance

(c) multiple allelism

(d) epistasis. (1990)

Ans. c. multiple allelism

Explanation: ABO blood group system is due to multiple allelism. A gene can have more than two alleles or allelomorphs, which can be expressed by mutation in wild form in more than one ways. These alleles or allelomorphs make a series of multiple alleles. The mode of inheritance in case of multiple alleles is called multiple allelism. A well known and simplest example of multiple allelism is the inheritance of ABO blood groups in human beings. In human population, 3 different alleles for this character are found - IA IB and IO. A person is having only two of these three alleles and blood type can be determined.

48. tt mates with Tt. What will be characteristic of offspring?

(a) 75% recessive (b) 50% recessive

(c) 25% recessive (d) All dominant

Ans. b.50% recessive

Explanation: 

Crossing of individuals having dominant phenotype with its homozygous recessive is a test cross, which can be represented as:

F1 hybrid          x           Homozygous recessive

Tt                      x            tt - parent

T  &   t                              t -Gametes

Tt (tall)     tt (Dwarf)       Test cross progeny

Thus, ratio of progeny is = 1:1

49. Haploids are able to express both recessive and dominant alleles/mutations because there are

(a) many alleles for each gene

(b) two alleles for each gene

(c) only one allele for each gene in the individual

(d) only one allele in a gene.

Ans. c. only one allele for each gene in the individual

Explanation: Haploids are able to express both recessive and dominant alleles/ mutations because there are only one allele for each gene in the individual. Diploid is an organism containing two different alleles or individual containing both dominant and recessive genes of an allelic pairs.

50. Experimental verification of the chromosomal theory of inheritance was done by

(a) Mendel (b) Sutton

(c) Boveri (d) Morgan. 

Ans. d. Sutton and Boveri

Explanation: Sutton and Boveri proposed the chromosomal theory of inheritance but its experimental verification was done by Thomas Hunt Morgan.

51. What map unit (centimorgan) is adopted in the construction of genetic maps?

(a) A unit of distance between genes on chromosomes, representing 50% cross over.

(b) A unit of distance between two expressed genes, representing 10% cross over.

(c) A unit of distance between two expressed genes, representing 100% cross over.

(d) A unit of distance between genes on chromosomes, representing 1% cross over.

Ans. d. A unit of distance between genes on chromosomes, representing 1% cross over

Explanation: Genetic map is a linear graphic representation of the sequence and relative distance of various genes present in a chromosome. 1% crossing over between two linked genes is known as 1 map unit or centiMorgan (cM).

52. The frequency of recombination between gene present on the same chromosome as a measure of the distance between genes was explained by

(a) Sutton Boveri (b) T.H. Morgan

(c) Gregor J.Mendel     (d) Alfred Sturtevant.

Ans. d. Alfred Sturtevant

Explanation: T.H. Morgan coined the term linkage to describe the physical association of genes on chromosome and term recombination to describe the generation of non- parental gene combinations. Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes.

Q53. The mechanism that causes a gene to move from one linkage group to another is called

(a) inversion (b) duplication

(c) translocation (d) crossing-over.

Ans. c. translocation

Explanation: Translocation is a chromosomal abnormality caused by rearrangement of parts between non- homologous chromosomes. It may cause a gene to move from one linkage group to another.

Q54. In a test cross involving F1 dihybrid flies, more parental-type offspring were produced than the recombinant-type offspring. This indicates

(a) the two genes are linked and present on the same chromosome

(b) both of the characters are controlled by more than one gene

(c) the two genes are located on two different chromosomes

(d) chromosomes failed to separate during meiosis.

Ans.  (a) the two genes are linked and present on the same chromosome

Explanation: If in a dihybrid test cross more parental combinations appear as compared to the recombinants in F2 generation, then it is indicative of involvement of linkage. Linkage is the tendency of two different genes on the same chromosome to remain together during the separation of homologous chromosomes at meiosis. During complete linkage no recombinants are formed whereas in incomplete linkage few recombinants are produced along with parental combinations

55. The term “linkage” was coined by

(a) G. Mendel (b) W. Sutton

(c) T.H. Morgan (d) T. Boveri. (2015)

Ans. (c) T.H. Morgan

Explanation: Linkage is the phenomenon of certain genes staying together during inheritance through generations without any change or separation due to their being present on the same chromosome. Linkage was first suggested by Sutton and Boveri (1902-1903) when they propounded the famous “chromosomal theory of inheritance.” Bateson and Punnett (1906) while working on sweet pea found that the factors for certain characters do not show independent assortment. However, it was Morgan (1910) who clearly proved and defined linkage on the basis of his breeding experiments in fruit fly (Drosophila melanogaster).

56. The movement of a gene from one linkage group to another is called

(a) translocation (b) crossing over

(c) inversion (d) duplication.

Ans. (a) translocation

Explanation:  Translocation is a chromosomal abnormality caused by rearrangement of parts between non- homologous chromosomes. It may cause a gene to move from one linkage group to another.

57. Fruit colour in squash is an example of

(a) recessive epistasis

(b) dominant epistasis

(c) complementary genes

(d) inhibitory genes.

Ans. (b) dominant epistasis

Explanation: A dominant epistatic allele suppresses the expression of a non-allelic gene whether the latter is dominant or recessive. The gene which suppresses the expression of a non-allelic gene is known as epistatic gene. The gene or locus which is suppressed by the presence of non-allelic gene is termed as hypostatic gene. In summer squash or Cucurbita pepo, there are three types of fruit colour— yellow, green and white. White colour is dominant over other colours while yellow is dominant over green. Yellow colour is formed only when the dominant epistatic gene is represented by its recessive allele (w). When the hypostatic gene is also recessive (y), the colour of the fruit is green, i.e.,

W_ Yy, W_ yy = White 

wwY_     = Yellow

 wwyy           =  Green

58. Which of the following statements is not true of two genes that show 50% recombination frequency?

(a) The gene show independent assortment.

(b) If the genes are present on the same chromo- some, they undergo more than one cross-overs in every meiosis.

(c) The genes may be on different chromosomes.

(d) The genes are tightly linked.      

Ans. (d) The genes are tightly linked.   

Explanation

59. When two unrelated individuals or lines are crossed, the performance of F1 hybrid is often superior to both its parents. This phenomenon is called

(a) heterosis (b) transformation

(c) splicing (d) metamorphosis.

Ans. (a) heterosis

Explanation: The increased vigour displayed by the offspring from a cross between genetically different parents is called heterosis. Hybrids from crosses between different crop varieties (F1 hybrids) are often stronger and produce better yields than the original varieties.

60. Select the correct statement from the ones given below with respect to dihybrid cross.

(a) Tightly linked genes on the same chromosomes show higher recombinations.

(b) Genes far apart on the same chromosome show very few recombinations.

(c) Genes loosely linked on the same chromosome show similar recombinations.

(d) Tightly linked genes on the same chromosome show very few recombinations.

Ans. (d) Tightly linked genes on the same chromosome show very few recombinations.

Explanation: Linkage is the phenomenon of certain genes staying together during inheritance through generations without any change or separation due to their being present on the same chromosome. Linked genes occur in the same chromosome. Strength of the linkage between two genes is inversely proportional to the distance between the two, i.e., two linked genes show higher frequency of crossing over (recombination) if the distance between them is higher and lower frequency if the distance is small.

61. A human male produces sperms with the genotypes AB, Ab, aB and ab pertaining to two diallelic characters in equal proportions. What is the corresponding genotype of this person?

(a) AaBB (b) AABb

(c) AABB (d) AaBb

Ans. d) AaBb

Explanation As sperms produced are with genotypes AB, Ab, aB, ab (two diallelic character) the person must be heterozygous for both genes. So, his genotype will be AaBb.

62. In Mendel’s experiments with garden pea, round seed shape (RR) was dominant over wrinkled seeds (rr), yellow cotyledon (YY) was dominant over green cotyledon (yy). What are the expected phenotypes in the F2 generation of the cross RRYY × rryy?

(a) Round seeds with yellow cotyledons, and wrinkled seeds with yellow cotyledons

(b) Only round seeds with green cotyledons

(c) Only wrinkled seeds with yellow cotyledons

(d) Only wrinkled seeds with green cotyledons

Ans. (a) Round seeds with yellow cotyledons, and wrinkled seeds with yellow cotyledons

Explanation: Since round seed shape is dominant over wrinkled seed shape and yellow cotyledon is dominant over green cotyledon so RRYY individuals is round yellow and rryy is wrinkled green.

Round yellow seeds × Wrinkled green seeds 

               RRYY           rryy

F1 generation    RrYy

F2 generation is obtained by selfing  F1.

RRYY RRYy RrYY RrYy

RRYy RRyy RrYy Rryy

RrYY RrYy         rrYY rrYy

RrYy         Rryy           rrYy rryy

Expected phenotypes in F2 generation 

Round yellow seed - Wrinkled yellow seed - Round green seed - Wrinkled green seed 

        9                               3                              3                         1

63. In order to find out the different types of gametes produced by a pea plant having the genotype AaBb it should be crossed to a plant with the genotype

(a) AABB

(b) AaBb  

(c) aabb

(d) aaBB.

Ans. (c) aabb

Explanation: A test cross involving the crossing of F1 individual with the homozygous recessive parent. It is done to find out homozygous and heterozygous individuals. So, AaBb should be crossed with aabb.

64. In a plant, red fruit (R) is dominant over yellow fruit

(r) and tallness (T) is dominant over shortness (t). If a plant with RRTt genotype is crossed with a plant that is rrtt,

(a) 25% will be tall with red fruit

(b) 50% will be tall with red fruit

(c) 75% will be tall with red fruit

(d) all the offspring will be tall with red fruit.

Ans. 

Explanation

65. Lack of independent assortment of two genes A and B in fruit fly Drosophila is due to

(a) repulsion (b) recombination

(c) linkage (d) crossing over.

Ans. 

Explanation

66. Two crosses between the same pair of genotypes or phenotypes in which the sources of the gametes are reversed in one cross, is known as

(a) test cross (b) reciprocal cross

(c) dihybrid cross (d) reverse cross.   

Ans. 

Explanation

67. There are three genes a, b, c. Percentage of crossing over between a and b is 20%, b and c is 28% and a and c is 8%. What is the sequence of genes on chromosome?

(a) b, a, c (b) a, b, c

(c) a, c, b (d) None of these   

Ans. 

Explanation

68. Two non-allelic genes produces the new phenotype when present together but fail to do so independently then it is called

(a) epistasis

(b) polygene

(c) non complementary gene

(d) complementary gene.

Ans. 

Explanation

69. A and B genes are linked. What shall be genotype of progeny in a cross between AB/ab and ab/ab?

(a) AAbb and aabb (b) AaBb and aabb

(c) AABB and aabb (d) None of these

Ans. 

Explanation

70. Ratio of complementary genes is

(a) 9 : 3 : 4

(b) 12 : 3 : 1

(c) 9 : 3 : 3 : 4

(d) 9 : 7.

Ans. (d) 9 : 7.

Explanation: If two genes present on different loci produce the same effect when present alone but interact to form a new trait when present together, they are called complementary genes. The F2 ratio is modified to 9 : 7 instead of 9 : 3 : 3 : 1.

71. Independent assortment of genes does not take place when

(a) genes are located on homologous chromosomes

(b) genes are linked and located on same chromosome

(c) genes are located on non-homogenous chromosome

(d) all of these. (2001)

72. Due to the cross between TTRr × ttrr the resultant progenies show what percent of tall, red flowered plants?

(a) 50% (b) 75%

(c) 25% (d) 100% (2000)

73. A gene pair hides the effect of another gene. The phenomenon is called

(a) dominance (b) segregation

(c) epistasis (d) mutation.         (1999)

74. If Mendel had studied the seven traits using a plant with 12 chromosomes instead of 14, in what way would his interpretation have been different?

(a) He would not have discovered the law of independent assortment.

(b) He would have discovered sex linkage.

(c) He could have mapped the chromosome.

(d) He would have discovered blending or incomplete dominance. (1998)

75. Crossing over in diploid organism is responsible for

(a) segregation of alleles

(b) recombination of linked alleles

(c) dominance of genes

(d) linkage between genes. (1998)

76. A fruit fly is heterozygous for sex-linked genes, when mated with normal female fruit fly, the males specific chromosome will enter egg cell in the proportion

(a) 3 : 1 (b) 7 : 1

(c) 1 : 1 (d) 2 : 1.

77. When two dominant independently assorting genes react with each other, they are called

(a) collaborative genes (b) complementary genes

(c) duplicate genes (d) supplementary genes.

(1996)

78. When two genetic loci produce identical phenotypes in cis and trans position, they are considered to be

(a) multiple alleles (b) the parts of same gene

(c) pseudoalleles (d) different genes. (1995)

79. The phenomenon, in which an allele of one gene suppresses the activity of an allele of another gene, is known as

(a) epistasis (b) dominance

(c) suppression (d) inactivation.     (1995)

80. Which of the following is suitable for experiment on linkage?

(a) aaBB × aaBB (b) AABB × aabb

(c) AaBb × AaBb (d) AAbb × AaBB

(1993)

81. Two dominant nonallelic genes are 50 map units apart. The linkage is

(a) cis type (b) trans type

(c) complete (d) absent/incomplete.

(1993)

82. Mendel studied inheritance of seven pairs of traits in pea which can have 21 possible combinations. If you are told that in one of these combinations, independent assortment is not observed in later studies, your reaction will be

(a) independent assortment principle may be wrong

(b) Mendel might not have studied all the combinations

(c) it is impossible

(d) later studies may be wrong. (1993)

83. In a cross between AABB × aabb, the ratio of F2 genotypes between AABB, AaBB, Aabb and aabb would be

(a) 9 : 3 : 3 : 1 (b) 2 : 1 : 1 : 2

(c) 1 : 2 : 2 : 1 (d) 7 : 5 : 3 : 1.       (1992)

84. Segregation of Mendelian factors (no linkage, no crossing over) occurs during

(a) anaphase I (b) anaphase II

(c) diplotene (d) metaphase I.     (1992)

85. The allele which is unable to express its effect in the presence of another is called

(a) codominant (b) supplementary

(c) complementary        (d) recessive. (1991)

86. Cross between AaBB and aaBB will form

(a) 1AaBB : 1aaBB (b) all AaBB

(c) 3AaBB : 1aaBB (d) 1AaBB : 3aaBB.

(1990)

45

87. In a genetic cross having recessive epistasis, F2 phenotypic ratio would be

(a) 9 : 6 : 1 (b) 15 : 1

(c) 9 : 3 : 4 (d) 12 : 3 : 1. (1990)

88. Bateson used the terms coupling and repulsion for linkage and crossing over. Name the correct parental of coupling type alongwith its cross over or repulsion.

(a) Coupling AABB, aabb; Repulsion AABB, aabb

(b) Coupling AAbb, aaBB; Repulsion AaBb, aabb

(c) Coupling aaBB, aabb; Repulsion AABB, aabb

(d) Coupling AABB, aabb; Repulsion AAbb, aaBB

(1990)

89. Segregation of Mendelian factor (Aa) occurs during

(a) diplotene (b) anaphase I

(c) zygotene/pachytene (d) anaphase II.     (1990)

90. Two linked genes a and b show 20% recombination. the individuals of a dihybrid cross between ++/++ × ab/ab shall show gametes

(a) ++ : 80 : : ab : 20

(b) ++ : 50 : : ab : 50

(c) ++ : 40 : : ab : 40 : : + a : 10 : : + b : 10

(d) ++ : 30 : : ab : 30 : : + a : 20 : : + b : 20. (1989)

Polygenic Inheritance

91. Which of the following characteristics represent ‘inheritance of blood groups’ in humans?

(i) Dominance

(ii) Co-dominance

(iii) Multiple allele

(iv) Incomplete dominance

(v) Polygenic inheritance

(a) (ii), (iii) and (v) (b) (i), (ii) and (iii)

(c) (ii), (iv) and (v) (d) (i), (iii) and (v)

(NEET 2018)

92. Inheritance of skin colour in humans is an example of

(a) point mutation

(b) polygenic inheritance

(c) codominance

(d) chromosomal aberration. (2007)

93. How many different kinds of gametes will be produced by a plant having the genotype AABbCC?

(a) Two (b) Three

(c) Four (d) Nine (2006)

94. Which one of the following is an example of polygenic inheritance?

(a) Skin colour in humans

(b) Flower colour in Mirabilis jalapa

(c) Production of male honeybee

(d) Pod shape in garden pea (2006)

46 NEET-AIPMT Chapterwise Topicwise Solutions Biology

95. On selfing a plant of F1-generation with genotype “AABbCC”, the genotypic ratio in F2-generation will be

(a) 3 : 1

(b) 1 : 1

(c) 9 : 3 : 3 : 1

(d) 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1. (2002)

96. In human beings, multiple genes are involved in the inheritance of

(a) sickle-cell anaemia (b) skin colour

(c) colour blindness (d) phenylketonuria.

(1999)

97. How many different types of genetically different gametes will be produced by a heterozygous plant having the genotype AABbCc?

(a) Six (b) Nine

(c) Two (d) Four (1998)

98. The polygenic genes show

(a) different karyotypes (b) different genotypes

(c) different phenotypes (d) none of these.   (1996)

99. A polygenic inheritance in human beings is

(a) skin colour (b) phenylketonuria

(c) colour blindness     (d) sickle cell anaemia.

(1993)

Pleiotropy

100. Match the terms in column I with their description in column II and choose the correct option.

Column I Column II

A. Dominance (i) Many genes govern a

single character

B. Co-dominance (ii) In a heterozygous

organism only one allele expresses itself

C. Pleiotropy (iii) In a heterozygous

organism both alleles express themselves fully

D. Polygenic (iv) A single gene inheritance

influences many characters

A B C D

(a) (iv) (i) (ii) (iii)

(b) (iv) (iii) (i) (ii)

(c) (ii) (i) (iv) (iii)

(d) (ii) (iii) (iv) (i) (NEET-I 2016)

101. A pleiotropic gene

(a) controls a trait only in combination with another gene

(b) controls multiple traits in an individual

(c) is expressed only in primitive plants

(d) is a gene evolved during Pliocene. (2015)

102. Which of the following is an example of pleiotropy?

(a) Haemophilia (b) Thalassemia

(c) Sickle cell anaemia (d) Colour blindness

(2002)

103. When a single gene influences more than one trait it is called

(a) pseudodominance (b) pleiotropy

(c) epistasis (d) none of these. (1998)

Sex Determination

104. Select the incorrect statement.

(a) Human males have one of their sex-chromosome much shorter than other.

(b) Male fruit fly is heterogametic.

(c) In male grasshoppers, 50% of sperms have no sex-chromosome.

(d) In domesticated fowls, sex of progeny depends on the type of sperm rather than egg.

(NEET 2019)

105. Which of the following pairs is wrongly matched?

(a) Starch synthesis in pea : Multiple alleles

(b) ABO blood grouping : Co-dominance

(c) XO type sex determination: Grasshopper

(d) T.H. Morgan : Linkage (NEET 2018)

106. Which one of the following conditions of the zygotic cell would lead to the birth of a normal human female child?

(a) Two X chromosomes

(b) Only one Y chromosome

(c) Only one X chromosome

(d) One X and one Y chromosome (Mains 2011)

107. In Drosophila, the sex is determined by

(a) the ratio of number of X-chromosome to the sets of autosomes

(b) X and Y chromosomes

(c) the ratio of pairs of X-chromosomes to the pairs of autosomes

(d) whether the egg is fertilized or develops parthenogenetically. (2003)

108. Number of Barr bodies in XXXX female is

(a) 1 (b) 2

(c) 3 (d) 4. (2001)

109. Male XX and female XY sometime occur due to

(a) deletion

(b) transfer of segments in X and Y chromosome

(c) aneuploidy

(d) hormonal imbalance. (2001)

110. Probability of four sons to a couple is (a) 1/4 (b) 1/8

(c) 1/16 (d) 1/32. (2001)

Principles of Inheritance and Variation

111. Genetic identity of a human male is determined by

(a) sex-chromosome (b) cell organelles

47

(c) Sickle cell anaemia – Autosomal recessive

trait,chromosome -11

(c) autosome (d) nucleolus. (1997)

112. When an animal has both the characters of male and female, it is called

(a) super female

(b) super male

(c) intersex

(d) gynandromorph.

Ans. d. gynandromorph

Explanation: Gynandromorph (hermaphrodite) is an animal that possesses both male and female characteristics. For example, earthworm.

113. Mr. Kapoor has Bb autosomal gene pair and d allele sex-linked. What shall be proportion of Bd in sperms?

(a) Zero

(b) 1/2

(c) 1/4

(d) 1/8

Ans. c. 1/4

114. Sex is determined in human beings

(a) by ovum

(b) at time of fertilisation

(c) 40 days after fertilisation

(d) seventh to eight week when genitals differentiate in fetus.

Ans. (b) at time of fertilisation

Explanation: Sex is determined in human beings at the time of fertilisation. Sex of the baby depends upon the sperm which fertilises the ovum.

115. A normal green male maize is crossed with albino female. The progeny is albino because

(a) trait for a albinism is dominant

(b) the albinos have biochemical to destroy plastids derived from green male

(c) plastids are inherited from female parent

(d) green plastids of male must have mutated.

Ans. (c) plastids are inherited from female parent

Explanation: A normal green male maize is crossed with albino female. The progeny is albino because, plastids are inherited from female parents.

116. A family of five daughter only is expecting sixth issue. The chance of its being a son is

(a) zero

(b) 25%

(c) 50%

(d) 100%.

Ans. (c) 50%

Explanation: A family of five daughter only is expecting sixth issue. The chance of its beings a son is 50%. Human have 22 pairs chromosomes which are XX in females and XY in males. So if we cross the parents there is 1 : 1 chance for boy and girl.

117. One of the parents of a cross has a mutation in its mitochondria. In that cross, that parent is taken as a male. During segregation of F2 progenies that mutation is found in

(a) one-third of the progenies

(b) none of the progenies

(c) all the progenies

(d) fifty percent of the progenies.

Ans. (b) none of the progenies