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

Question: Following pedigree chart shows
a) character carried by Y-chromosome
b) character is sex-linked recessive
c) character is sex-linked dominant
d) character is recessive autosomal
Answer: a

Question: In honeybees, male and female gametes are produced through
a) mitosis
b) mitosis and meiosis, respectively
c) meiosis
d) meiosis and mitosis, respectively
Answer: b

Question: Which one of the following pairs is wrongly matched?
a) XO type – Grasshopper
b) ABO blood grouping – Codominance
c) Starch synthesis in pea – Multiple allele
d) TH Morgan – Linkage
Answer: c

Question: The number of chromosomes in female and male honeybees are
a) 32
b) 16
c) 32 and 16, respectively
d) 16 and 32, respectively
Answer: c

Question: The chromosomal denotation for heterogametic females and homogametic males are
a) ZW and ZZ
b) ZO and ZZ
c) XX and XO
d) Both (a) and (b)
Answer: d

Question: Sex determination is controlled by A and others are B
a) Allosomes, Autosomes
b) Allosomes, Sex-chromosomes
c) Sex-chromosomes, Allosomes
d) Autosomes, Sex-chromosomes
Answer: a

Question: Male heterogamety is seen in
a) Humans
b) Grasshopper
c) Drosophila
d) All of these
Answer: d

Question: Identify the type of inheritance in the diagram
a) Dominant X-linked
b) Recessive X-linked
c) Dominant Y-linked
d) Cytoplasmic/Mitochondrial
Answer: d

Question: Choose the incorrect pair amongst the following
a) Male bird – Homogametic
b) Female bird – Heterogametic
c) Male Drosophila – Heterogametic
d) None of the above
Answer: d

Question: A human male contains karyotype A, and a human female has B
a) 44+XX, 44+XY
b) 44+XY, 44+XX
c) 44+XO, 44+XX
d) 44+XX, 44+XO
Answer: b

Question: Identify the symbols given below and the correct option with respect to A, B, C and D.
a) A–Male, B–Female, C–Sex unspecified, D–Affected male
b) A–Male, B–Female, C–Sterile, D–Carrier male
c) A–Male, B–Female, C–Fertile, D–Affected female
d) A–Female, B–Male, C–Sex unspecified, D–Carrier female
Answer: a

Question: A pleiotropic gene
a) is not found in humans
b) is a single gene which exhibits multiple phenotypic expressions
c) shows effect on metabolic pathways to produce various phenotypes
d) Both (b) and (c)
Answer: d

Question: In human skin colour, the genotype with three dominant and three recessive alleles will produce
a) darkest skin colour
b) lightest skin colour
c) intermediate skin colour
d) patches of black and white
Answer: c

Question: The polygenic traits
a) are influenced by environment
b) phenotype reflects the contribution of each allele
c) effect of each allele is additive
d) All of the above
Answer: d

Question: Linked genes observed by Morgan were present on
a) X-chromosome
b) different chromosome
c) heterologous chromosome
d) paired chromosome
Answer: a

Question: Sickle-cell anaemia is a classical example of
a) frame-shift mutation
b) point mutation
c) Both (a) and (b)
d) None of the above
Answer: b

Question: Choose the incorrect pairing among the following.
a) Sutton and Boveri – Chromosome theory
b) Walter and Boveri – Behaviour of chromosome during cell division
c) T.H. Morgan – Mutation
d) Henking – Barr bodies
Answer: c

Question: In human skin colour which is a polygenic trait, all dominant and all recessive alleles show
a) Darkest and lightest skin colour, respectively
b) Lightest and darkest skin colour, respectively
c) Only darkest skin colour
d) Only lightest skin colour
Answer: a

Question: The diagram shows inheritance of haemophilia in a family. What is the genotype of individual M?
a) M – XY
b) M – XX
c) M – XhXh
d) M – XhX
Answer: d

Question: A normal woman whose father was colourblind marries a normal man. Expected children?
a) All daughters normal, 50% sons colourblind
b) All daughters normal, all sons colourblind
c) 50% daughters colourblind, all sons normal
d) All daughters colourblind, all sons normal
Answer: a

Question: If there are four nitrogenous bases (A, T, G, C), how many transitions and transversions are possible?
a) Transition = 8, Transversion = 4
b) Transition = 4, Transversion = 4
c) Transition = 8, Transversion = 4
d) Transition = 4, Transversion = 8
Answer: d

Question: In the pedigree below, filled symbols represent affected individuals. Identify the type.
a) X-linked dominant
b) Autosomal recessive
c) Autosomal dominant
d) X-linked recessive
Answer: b

Question: Observe the pedigree chart. The cause of trait is due to
a) Incompletely dominant allele
b) Dominant allele
c) Either dominant or recessive allele
d) Recessive allele
Answer: c

Question: A woman has an X-linked condition on one of her X-chromosomes. This chromosome can be inherited by
a) Only grandchildren
b) Only sons
c) Only daughters
d) Both (b) and (c)
Answer: d

Question: Colour blindness in humans
a) results from defects in red or green cones
b) is caused by mutation in a gene on X-chromosome
c) affects males more frequently
d) All of the above
Answer: d

Question: Which of the following most appropriately describes haemophilia?
a) X-linked recessive gene disorder
b) Chromosomal disorder
c) Dominant gene disorder
d) Recessive gene disorder
Answer: a

Question: In haemophilia, the affected protein is involved in
a) formation of RBCs
b) formation of WBCs and platelets
c) coagulation of blood
d) anticoagulation
Answer: c

Question: The pedigree shows inheritance of attached ear lobes. Which condition is correct?
a) Parents are heterozygous
b) Parents are homozygous recessive
c) Parents are homozygous dominant
d) All are incorrect
Answer: a

Question: Sickle-cell anaemia is caused by mutation in the gene controlled by HbA and HbS. Identify X, Y, Z.
a) GTG – CAC – Val (GUG)
b) CAC – CTC – Val (GUG)
c) GTA – GAG – Val (GUG)
d) GTC – GAC – Val (GUG)
Answer: a

Question: Failure of segregation of chromatids during cell division results in gain or loss of chromosomes. This condition is called
a) aneuploidy
b) hypopolyploidy
c) hyperpolyploidy
d) polyploidy
Answer: a

Question: In sickle-cell anaemia
a) both parents are heterozygous carriers but unaffected
b) a single pair of alleles controls the disease
c) only HbS HbS individuals show the diseased phenotype
d) all of the above
Answer: d

Question: A cell in telophase shows no cell plate formation and contains more chromosomes than other dividing cells. This results in
a) polyploidy
b) somaclonal variation
c) polyteny
d) aneuploidy
Answer: a

Question: β-thalassemia in humans is controlled by
a) HBA2 gene on chromosome 16
b) HBB gene on chromosome 11
c) HBA1 gene on chromosome 15
d) HBA1 and HBA2 genes on chromosome 8
Answer: b

Question: In phenylketonuria
a) enzyme phenylalanine hydroxylase is absent
b) phenylalanine does not convert to tyrosine
c) phenylpyruvic acid is formed
d) all of the above
Answer: d

Question: Genes A, B and C are linked; A and B are closer than A and C. Which statements are correct?
I. A might be before B and C
II. B might be between A and C
III. C might be between A and B
IV. More crosses cannot occur between A and C than between A and B
a) I and II
b) II and III
c) III and IV
d) I, II and IV
Answer: a