When a cluster of genes shows linkage behaviour they:

1. Do not show a chromosome map

2. Show recombination during meiosis

3. Do not show independent assortment

4. Induce cell division

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. 50% will be tall with red fruit

2. 75% will be tall with red fruit

3. All the offspring will be tall with red fruit

4. 25% will be tall with red fruit

Reason for trisomy in Down's syndrome is:
1.  Non-disjunction during sperm formation
2.  Non-disjunction during egg formation
3.  Non-disjunction at the time of egg or sperm formation
4.  Addition of one extra chromosome during mitosis

Test cross in plants or in Drosophila involves crossing:
1. between two genotypes with dominant trait
2. between two genotypes with recessive trait
3. between two F₁ hybrids
4. the F₁ hybrid with a double recessive genotype

A couple has a son. What is the probability that their next child will be a daughter?
1. ½
2. 1
3. 0
4. ¼

The male honeybees:
1. do not have father and cannot have sons
2. do not have father but can have sons
3. do not have grandfather and cannot have grandsons
4. do not have father and do not have grandfather

The rediscovery of Mendel’s laws is credited to:
1. Morgan and Sturtevant
2. Knight and Goss
3. de Vries, Correns and Tschermak
4. Avery, Macleod and McCarty

A dihybrid test cross results in a 50% frequency of recombinants in progeny. This shows that:
1. The two genes are most likely located on different chromosomes
2. One of the genes must be located on the X chromosome
3. The two genes are closely linked on the same chromosome
4. The two genes must be pleiotropic

Select the correct match:

A primary non-disjunction event involving an autosome may lead to:
1. Down’s Syndrome
2. Klinefelter’s syndrome
3. Turner’s syndrome
4. Cushing’s syndrome