Principles of Inheritance and Variation

Phenotype of an organism is the result of-

1. Environmental changes and sexual dimorphism
2. Cytoplasmic effects and nutrition
3. Genotype and environment interactions
4. Mutations and linkages

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

1. Skin colour in humans
2. Pod shape in garden pea
3. Production of male honey bee
4. Flower colour in Mirabilis jalapa

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 -

1. aaBB
2. aabb
3. AaBb
4. AABB

G-6-P dehydrogenase deficiency is associated with haemolysis of -

1. RBCs
2. Lymphocytes
3. Platelets
4. Leucocytes

A man and a woman, who do not show any apparent signs of a certain inherited disease, have seven children (2 daughters and 5 sons). Three of the sons suffer from the given disease but none of the daughters are affected. Which of the following mode of inheritance do you suggest for this disease?

1. Autosomal dominant
2. Sex-linked recessive
3. Sex-linked dominant
4. Sex-limited recessive

A woman with 47 chromosomes due to three copies of chromosome 21 is characterized by -

1. Superfemaleness
2. Turner's syndrome
3. Triploidy
4. Down's syndrome

Haemophilia is more commonly seen in human males than in human females because -

1. This disease is due to an X-linked dominant mutation
2. This disease is due to a Y-linked recessive mutation
3. This disease is due to an X-linked recessive mutation
4. A greater proportion of girls die in infancy

Which of the following is not a hereditary disease?

1. Cretinism
2. Cystic fibrosis
3. Haemophilia
4. Thalassemia

A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy -

1. May be colour blind or may have normal vision
2. Must have normal colour vision
3. Must be colour blind
4. Will be partially colour blind since he is heterozygous for the colour blind mutant allele.

A woman with 47 chromosomes due to three copies of chromosome 21 is characterized by

1. triploidy
2. Down’s syndrome
3. superfemaleness
4. Turner’s syndrome

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

1. 75% will be tall with red fruit
2. 25% will be tall with red fruit
3. 50% will be tall with red fruit
4. All the offspring will be tall with red fruit

A male human is heterozygous for autosomal genes A and B and is also hemizygous for hemophilic gene h. What proportion of his sperms will be abh?

1. 1/16
2. 1/32
3. 1/8
4. 1/4

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

1. Linkage
2. Recombination
3. Repulsion
4. Crossing over

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 -

1. 50% of the progenies
2. 1/3 of the progenies
3. None of the progenies
4. All the progenies

A normal woman, whose father was colour-blind is married to a normal man. The sons would be :-

1. All colour-blind
2. 75% colour-blind
3. All normal
4. 50% colour-blind

The recessive genes located on X-chromosomes in humans are always -

1. Expressed in females
2. Sub-lethal
3. Expressed in males
4. Lethal

After a mutation at a genetic locus the character of an organism changes due to the change in :-

1. Protein synthesis pattern
2. RNA transcription pattern
3. DNA replication
4. Protein structure

In a mutational event, when adenine is replaced by guanine, it is a case of -

1. Frameshift mutation
2. Transition
3. Transversion
4. Transcription

Which one of the following traits of garden pea studied by Mendel was a recessive feature?

1. Green seed colour
2. Green pod colour
3. Axial flower position
4. Round seed shape

The genes controlling the seven pea characters studied by Mendel are now known to be located on how many different chromosomes?

1. Six
2. Seven
3. Five
4. Four

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:

1. Reciprocal cross
2. Reverse cross
3. Test cross
4. Dihybrid cross

Pattern baldness, moustaches and beard in human males are examples of:

1. Sex limited traits
2. Sex influenced traits
3. Sex determining traits
4. Sex linked traits

Which one of the following conditions though harmful in itself, is also a potential saviour from a mosquito borne infectious disease?

1. Pernicious anaemia
2. Thalassaemia
3. Leukemia
4. Sickle cell anaemia

Down's syndrome is caused by an extra copy of chromosome number 21. What percentage of offspring produced by an affected mother and a normal father would be affected by this disorder?

1. 50%
2. 100%
3. 75%
4. 25%

In Drosophila, the sex is determined by:

1. X and Y chromosomes
2. Whether the egg is fertilized or develops parthenogenetically
3. The ratio of number of X-chromosomes to the sets of autosomes
4. The ratio of pairs of X-chromosomes to the pairs of autosomes

Christmas disease is another name for :-

1. Hepatitis B
2. Sleeping sickness
3. Haemophilia B
4. Down's syndrome

Which of the following is the example of pleiotropy ?

1. Thalassemia
2. Haemophilia
3. Sickle cell anaemia
4. Colour blindness

There are three genes a, b and c. The 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?

1. a, b, c
2. b, a, c
3. a, c, b
4. None

On selfing a plant of F1 generation with genotype “AABbCC”, the phenotypic ratio in F2 generation will be

1. 1 : 1
2. 3 : 1
3. 9 : 3 : 3 : 1
4. 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1

A gene is said to be dominant if : -

1. It is expressed only in heterozygous condition
2. It expresses its effect only in homozygous stage
3. It is never expressed in any condition
4. It is expressed both in homozygous and heterozygous condition