CBSE Class 12 Biology Principles Of Inheritance And Variation Worksheet Set 03

a) Is the trait recessive or dominant?

b) Is the trait sex- linked or autosomal? 

c) Give the genotypes of the parents in generation I and of their third and fourth child in generation II.

2 Recently a girl baby has been reported to suffer from haemophilia. How is it possible? Explain with the help of a cross.

3 In one family each of the four children has a different blood group. Their mother is group A and the father is group B. Explain this pattern of inheritance with the help of a cross along with the genotypes.

4 Why are F2 phenotypic and genotypic ratios same in a cross between red-flowered snapdragon and white-flowered snapdragon plants. Explain with the help of a cross.

5 Workout a cross between true breeding red and white flowered dog-flower plants ( Snapdragon) up to F2 progeny. Explain the results of F1 and F2 generations.

Important Questions for NCERT Class 12 Biology Principles of Inheritance and Variation

Question. In monohybrid cross proportion of 3 : 1 explains:
(a) Dominance
(b) Segregation
(c) Both (a) and (b)
(d) Unit factor

Answer : C 

Question. The modified allele is equivalent to the unmodified allele when it produces :
(a) Normal enzyme
(b) A non functional enzyme
(c) No enzyme at all
(d) Inactive enzyme

Answer : A

Question. Dominance of any character generally depends on
(a) Gene or product related informations of any gene
(b) Character choosen by ourself in study
(c) Environmental factors
(d) Both 1 and 2

Answer : D

Question. Mandel published his work in 1865 but it remained unrecognised till 1900. Which of the following reason was not responsible for it
(a) Communication was not easy
(b) His concept of genes (factors) as stable and discrete unit was not accepted by hiscontemporaries as an explanation for apparently continuous variations
(c) Use of mathematics to explain biological phenomenon
(d) Use of emasculation technique

Answer : D

Question. Parallelism between charomosome and behaviour of gene was established by
(a) de Vries, Correns and Tschermark
(b) Sutton and Boveri
(c) Bateson and Punnet
(d) Landsteiner and de Castello

Answer : B

Question. Chromosomal disorders arise due to
(a) Absence of one or more chromosomes
(b) Excess of one or more chromosomes
(c) Abnormal arrangement of one or more chromosomes
(d) All the above

Answer : D

Question. Which of the following symptom is not assocoated with Down's syndrome
(a) Flat back of head
(b) Many loops on finger tips
(c) Big and wrinked tongue
(d) Congenital liver diseases

Answer : D

Question. Who among the following united the knowledge of chromosomal segregation with Mendelian principles and called it chromosomal theory of inheritance
(a) Bateson
(b) Boveri
(c) Sutton
(d) Correns

Answer : C

Question. Segregation of alleles is a random process so what would be the chances of a gamete containing either alleles
(a) 25 %
(b) 50 %
(c) 75 %
(d) 100 %

Answer : B

Question. In a large number of insects the mechanism of sex determination is of :
(a) XO type
(b) XY type
(c) ZW type
(d) All the above

Answer : A

Question. Male heterogamety found in :
(a) Human
(b) Grasshopper
(c) Many birds
(d) 1 and 2 both

Answer : D

Ques. A marriage between normal visioned man and colour blind woman will produce offspring
(a) colour blind sons and 50% carrier daughter
(b) 50% colourblind sons and 50% carrier daughter
(c) normal males and carrier daughters
(d) colour blind sons and carrier daughters.

Answer: D

Ques. Haemophilic man marries a normal woman. Their offspring will be
(a) all haemophilic
(b) all boys haemophilic
(c) all girls haemophilic
(d) all normal. 

Answer: D 

Ques. A woman with two genes for haemophilia and one gene for colour blindness on one of the ‘X’ chromosomes marries a normal man. How will the progeny be?
(a) 50% haemophilic colour-blind sons and 50% normal sons.
(b) 50% haemophilic daughters (carrier) and 50% colour blind daughters (carrier).
(c) All sons and daughters haemophilic and colourblind.
(d) Haemophilic and colour-blind daughters.

Answer: B 

Ques. Mental retardation in man, associated with sex chromosomal abnormality is usually due to
(a) moderate increase in Y complement
(b) large increase in Y complement
(c) reduction in X complement
(d) increase in X complement. 

Answer: D 

Ques. Albinism is known to be due to an autosomal recessive mutation. The first child of a couple with normal skin pigmentation was an albino. What is the probability that their second child will also be an albino?
(a) 50% (b) 75%
(c) 100% (d) 25% 

Answer: D 

Ques. A person with the sex chromosomes XXY suffers from
(a) gynandromorphism
(b) Klinefelter’s syndrome
(c) Down’s syndrome
(d) Turner’s syndrome. 

Answer: B

Ques. In which of the following diseases, the man has an extra X-chromosome?
(a) Turner’s syndrome
(b) Klinefelter’s syndrome
(c) Down’s syndrome
(d) Haemophilia 

Answer: B

Ques. A person whose father is colour blind marries a lady whose mother is daughter of a colour blind man. Their children will be
(a) all sons colour blind
(b) some sons normal and some colour blind
(c) all colour blind
(d) all daughters normal. 

Answer: D

Ques. A genetically diseased father (male) marries with a normal female and gives birth to 3 carrier girls and 5 normal sons. It may be which type of genetic disease?
(a) Sex-influenced disease
(b) Blood group inheritance disease
(c) Sex-linked disease
(d) Sex-recessive disease 

Answer: C

Ques. An abnormal human male phenotype involving an extra X-chromosome (XXY) is a case of
(a) Edward’s syndrome
(b) Klinefelter’s syndrome
(c) intersex
(d) Down’s syndrome. 

Answer: B

Ques. The genes, which remain confined to differential region of Y-chromosome, are
(a) autosomal genes
(b) holandric genes
(c) completely sex-linked genes
(d) mutant genes. 

Answer: B

Ques. Albinism is a congenital disorder resulting from the lack of which enzyme?
(a) Tyrosinase
(b) Xanthine oxidase
(c) Catalase
(d) Fructokinase 

Answer: A

Ques. The colour blindness is more likely to occur in males than in females because
(a) the Y-chromosome of males have the genes for distinguishing colours
(b) genes for characters are located on the sexchromosomes
(c) the trait is dominant in males and recessive in females
(d) none of these. 

Answer: B

Ques. Of both normal parents, the chances of a male child becoming colour blind are
(a) none
(b) possible only when all the four grand parents had normal vision
(c) possible only when father’s mother was colour blind
(d) possible only when mother’s father was colour blind. 

Answer: D

Ques. Of a normal couple, half the sons are haemophiliac while half the daughters are carriers. The gene is located on
(a) X-chromosome of father
(b) Y-chromosome of father
(c) one X-chromosome of mother
(d) both the X-chromosomes of mother.

Answer: C

Ques. A colour blind mother and normal father would have
(a) colour blind sons and normal/carrier daughters
(b) colour blind sons and daughters
(c) all colour blind
(d) all normal. 

Answer: A

Ques. Down’s syndrome is due to
(a) crossing over
(b) linkage
(c) sex-linked inheritance
(d) non-disjunction of chromosomes. 

Answer: D

Ques. In human beings 45 chromosomes/single X/XO abnormality causes
(a) Down’s syndrome
(b) Kinefelter’s syndrome
(c) Turner’s syndrome
(d) Edward’s syndrome. 

Answer: C

Ques. A colour blind girl is rare because she will be born only when
(a) her mother and maternal grand father were colour blind
(b) her father and maternal grand father were colour blind
(c) her mother is colour blind and father has normal vision
(d) parents have normal vision but grand parents were colour blind. 

Answer: B

Ques. In Down’s syndrome of a male child, the sex complement is
(a) XO
(b) XY
(c) XX
(d) XXY. 

Answer: B

Ques. 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.

Answer: D

Ques. Which one is a hereditary disease?
(a) Cataract
(b) Leprosy
(c) Blindness
(d) Phenylketonuria

Answer: D

Ques. Both husband and wife have normal vision though their fathers were colour blind. The probability of their daughter becoming colour blind is
(a) 0%
(b) 25%
(c) 50%
(d) 75%.

Answer: A

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