Principles of Inheritance and Variation

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

1. Both of the characters are controlled by more than one gene
2. The two genes are linked and present on the same chromosome
3. The two genes are located on two different chromosomes
4. Chromosomes failed to separate during meiosis

Which of the following most appropriately describes haemophilia ?

1. Chromosomal disorder
2. X-linked recessive gene disorder
3. Dominant gene disorder
4. Recessive gene disorder

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

1. crossing-over
2. translocation
3. duplication
4. inversion

If a colour-blind man marries a woman who is homozygous for normal colour vision, the probability of their son being colour-blind is

1. 0.75
2. 0.5
3. 0
4. 1

A true breeding plant is -

1. produced due to cross-pollination among unrelated plants
2. one that is able to breed on its own
3. near homozygous and produces offspring of its own kind
4. always homozygous recessive in its genetic constitution

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

1. inversion
2. translocation
3. duplication
4. crossing over

Alleles are

1. true breeding homozygotes
2. different phenotype
3. heterozygotes
4. different molecular forms of a gene

Multiple alleles are present

1. on different chromosomes
2. at the same locus of the chromosome
3. at different loci on the same chromosome.
4. on non-sister chromatids

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

1. A and B only
2. A, B, AB and O
3. A, B and AB only
4. O only

How many pairs of contrasting characters in pea plants were studied by Mendel in his experiments?

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

An abnormal human baby with ‘XXX’ sex chromosomes was born due to

1. formation of abnormal sperms in the father
2. fusion of two ova and one sperm
3. formation of abnormal ova in the mother
4. fusion of two sperms and one ovum

Select the incorrect statement with regard to Haemophilia :

1. It is a dominant disease
2. A single protein involved in the clotting of blood is affected
3. It is a recessive disease
4. It is a sex-linked disease

If both parents are carriers for thalassemia, which is an autosomal recessive disorder, what are the chances of pregnancy resulting in an affected child ?

1. 100%
2. 25%
3. no chance
4. 50%

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 is an example of :

1. Codominance
2. Partial dominance
3. Incomplete dominance
4. Complete dominance

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

1. law of dominance
2. co-dominance
3. incomplete dominance
4. inheritance of one gene

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

1. The genes are tightly linked
2. The genes show independent assortment
3. If the genes are present on the same chromosome, they undergo more than one crossovers in every meiosis.
4. The genes may be on different chromosomes

In our society women are blamed for producing female children. Choose the correct answer for the sex-determination in humans.

1. Due to some defect like aspermia in man
2. Due to the genetic make up of the particular sperm which fertilizes the egg
3. Due to the genetic make up of the egg
4. Due to some defect in the women

Which one is the incorrect statement with regards to the importance of pedigree analysis?

1. It confirms that DNA is the carrier of genetic information
2. It helps to trace the inheritance of a specific trait
3. It confirms that the trait is linked to one of the autosome
4. It helps to understand whether the trait in question is dominant or recessive

Down's syndrome in humans is due to :

1. Three 'X' chromosomes
2. Monosomy
3. Three copies of chromosome 21
4. Two 'Y' chromosomes

Represented below is the inheritance pattern of a certain type of traits in humans. Which one of the following conditions could be an example of this pattern ? [figure]

1. Haemophilia
2. Sickle cell anaemia
3. Thalassemia
4. Phenylketonuria

A test cross is carried out to :

1. Determine whether two species or varieties will breed successfully
2. Determine the genotype of a plant at F2
3. Predict whether two traits are linked
4. Assess the number of alleles of a gene

Which one of the following is a wrong statement regarding mutations ?

1. UV and gamma rays are mutagens
2. Deletion and insertion of base pairs cause frame-shift mutations
3. Cancer cells commonly show chromosomal aberrations
4. Change in a single base pair of DNA does not cause mutation

A normal-visioned man whose father was colour-blind, marries a woman whose father was also colour-blind. They have their first child as a daughter. What are the chances that this child would be colour-blind ?

1. 50%
2. 25%
3. 100%
4. Zero percent

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

1. Monohybrid cross with incomplete dominance
2. Co-dominance
3. Monohybrid cross with complete dominance
4. Dihybrid cross

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

1. only one Y chromosome
2. only one X chromosome
3. one X and one Y chromosome
4. two X chromosomes

Test cross in plants or in Drosophila involves crossing:

1. the F1 hybrid with a double recessive genotype
2. between two genotypes with dominant trait
3. between two F1 hybrids
4. between two genotypes with recessive trait

Which one of the following conditions correctly describes the manner of determining the sex ?

1. XO condition in humans as found in Turner Syndrome, determines female sex
2. XO type of sex chromosomes determine male sex in grasshopper
3. Homozygous sex chromosomes (ZZ) determine female sex in Birds
4. Homozygous sex chromosomes (XX) produce male in Drosophila

Mutations can be induced with :

1. Gamma radiation
2. Infra Red radiations
3. IAA
4. Ethylene

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

1. five
2. four
3. three
4. six

Study the pedigree chart of a certain family given below and select the correct conclusion which can be drawn for the character – [figure]

1. The trait under study could not be colourblindness
2. The female parent is heterozygous
3. The parents could not have had a normal daughter for this character
4. The male parent is homozygous dominant