CBSE Class 12 Biology Principles of Inheritance and Variation MCQs Set I

Question: Polymerisation of mutant haemoglobin molecule in sickle cell anaemia is due to
a) Sulpha drugs
b) Plasmodium falciparum
c) Low oxygen concentration
d) High oxygen
Answer: c

Question: Graphical representation to calculate the probability of all possible genotypes of offspring in a genetic cross is known as
a) Mendel square
b) Punnett square
c) Crossboard method
d) Emasculation method
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: In monohybrid cross, proportion of 3 : 1 explains
a) Dominance
b) Segregation
c) Both (a) and (b)
d) Unit factor
Answer: c

Question: Female heterogamety can be seen in
a) Human beings
b) Drosophila
c) Hen
d) Honey bees
Answer: c

Question: Genes responsible for ABO blood group determine which biomolecule of RBC plasma membrane
a) Phospholipid
b) Proteins
c) Sugars
d) Cholesterol
Answer: c

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

Question: Mendelian disorders are mainly determined by
a) Alteration or mutation in a single gene
b) Absence of one chromosome
c) Excess of one or more chromosomes
d) All the above
Answer: a

Question: Dominance of any character generally depends on
a) Gene or product related information of any gene
b) Character chosen by ourselves in study
c) Environmental factors
d) Both (a) and (b)
Answer: d

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

Question: Who 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. What is the chance of a gamete containing either allele?
a) 25%
b) 50%
c) 75%
d) 100%
Answer: b

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: In case of codominance
a) F₁ generation resembles both parents
b) F₁ generation is intermediate
c) F₁ generation resembles either parent
d) All the above
Answer: a

Question: Which symptom is NOT associated with Down’s syndrome?
a) Flat back of head
b) Many loops on fingertips
c) Big and wrinkled tongue
d) Congenital liver diseases
Answer: d

Question: Parallelism between chromosomes and behaviour of genes was established by
a) de Vries, Correns and Tschermark
b) Sutton and Boveri
c) Bateson and Punnett
d) Landsteiner and de Castello
Answer: b

Question: Gynaecomastia state can be seen in
a) Down’s syndrome
b) Klinefelter’s syndrome
c) Turner syndrome
d) Edward’s syndrome
Answer: b

Question: In the theoretical explanation of allelic interaction for dominant and recessive forms, the recessive trait is seen due to production of
a) Normal enzyme
b) A non-functional enzyme
c) No enzyme production
d) Either (b) or (c)
Answer: d

Question: Mendel published his work in 1865 but it remained unrecognised till 1900. Which reason was NOT responsible?
a) Communication was not easy
b) His concept of genes as stable units was not accepted
c) Use of mathematics in biology
d) Use of emasculation technique
Answer: d

Question: Experimental verification of chromosomal theory of inheritance was proposed by
a) Tschermark
b) de Vries
c) Sutton
d) Morgan
Answer: d

Statement Type Questions

Question: 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 is recessive.
c) Alleles do not show any blending and both the characters recover as such in F2 generation.
d) Factors occur in pairs.
Answer: c

Question: Which one of the following conditions correctly describes the manner of determining the sex in the given example?
a) Homozygous sex chromosomes (ZZ) determine female sex in birds.
b) XO type of sex chromosomes determine male sex in grasshopper.
c) XO condition in human as found in Turner’s syndrome, determines female sex.
d) Homozygous sex chromosomes (XX) produce male in Drosophila.
Answer: b

Question: Which of the following statement is not correct of two genes that show 50% recombination frequency?
a) The genes are tightly linked.
b) The genes show independent assortment.
c) If the genes are present on the same chromosome, they undergo more than one crossover in every meiosis.
d) The genes may be on different chromosomes.
Answer: a

Question: 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) 1 : 1 sex ratio is produced in the offsprings
d) All of these
Answer: b

Question: Which of the following statements are correct?
(i) Haemophilia is a sex-linked recessive disease.
(ii) Down’s syndrome is due to aneuploidy.
(iii) Phenylketonuria is an autosomal dominant gene disorder.
(iv) Phenylketonuria is an autosomal recessive gene disorder.
(v) Sickle-cell anaemia is an X-linked recessive gene disorder.
a) (i), (iii) and (v)
b) (i) and (iii)
c) (ii) and (v)
d) (i), (ii) and (iv)
Answer: d

Question: Which of the following statements are the correct?
(i) Failure of segregation of chromatids during cell division results in aneuploidy.
(ii) Chromosomal disorders are mainly determined by alteration or mutation in a single gene.
(iii) Thalasemia and cystic fibrosis are Mendelian disorders.
(iv) Sickle cell anemia is an X-linked trait.
(v) Haemophilia is an autosome linked recessive disease.
a) (i) and (iii)
b) (i), (iii) and (iv)
c) (iii) and (iv)
d) (ii) and (iii)
Answer: a

Matching Type Questions

Question: Match column-I with column-II and select the correct answer using the codes given below.

Column-I                         Column-II
A. Turner syndrome        I. Trisomy
B. Linkage                      II. AA + XO
C. Y-chromosome          III. Morgan
D. Down’s syndrome      IV. Testis determining factor

(a) A – II; B – I; C – IV; D – III
(b) A – II; B – I; C – IV; D – III
(c) A – IV; B – II; C – I; D – III
(d) A – II; B – III; C – IV; D – I
Answer: d

Question: Match the column-I with column-II and choose the correct option.

Column -I                                  Column -II
A. Incomplete dominance         I. Drosophila
B. Mendelian disorder              II. Antirrhinum sp.
C. Transforming principle         III. Griffith
D. Dihybrid cross                     IV. Haemophilia

(a) A – I; B – IV; C – III; D – II
(b) A – IV; B – II; C – III; D – I
(c) A – II; B – III; C – IV; D – I
(d) A – II; B – IV; C – III; D – I
Answer: d

Question: Match column-I (Definition) with column-II (Terms) and select the correct option from the codes given below.

Column-I                                    Column-II
(Definition)                                 (Terms)
A. A single trait              I. Pleiotropy controlled by three or more than three alleles
B. A single trait             II. Multiple alleles controlled by three or more than three genes
C. A single gene           III. Polygenic inheritance exhibits multiple phenotypic expression

(a) A – II; B – III; C – I
(b) A – III; B – II; C – I
(c) A – I; B – II; C – III
(d) A – II; B – I; C – III
Answer: a