a. Complete the following Punnett squares of a dihybrid cross between two rats. One has black fur (BB) and short tail (tt), the other has brown fur (bb) and long tail (TT).
| X | Bt | • | • | • |
| • | • | • | • | • |
| bT | • | • | • | • |
| • | • | • | • | • |
| • | • | • | • | • |
(b)i.How many of the offspring will have black fur and short tail?
ii. How many of the offspring will have brown fur and long tail?
iii. How many of the offspring will have black fur and long tail?
iv. How many of the offspring will have brown fur and short tail?
(c)
i.If there were twenty (20) chromosomes in the leaf cell of a plant, how many chromosomes would be in each of the following cells of the plant?pollen grain.
ii. If there were twenty (20) chromosomes in the leaf cell of a plant, how many chromosomes would be in each of the following cells of the plant? guard cell.
iii. If there were twenty (20) chromosomes in the leaf cell of a plant, how many chromosomes would be in each of the following cells of the plant? ovule.
iv. If there were twenty (20) chromosomes in the leaf cell of a plant, how many chromosomes would be in each of the following cells of the plant? root cell
Explanation
a.
| X | Bt | Bt | Bt | Bt |
| bT | BbtT | BbtT | BbtT | BbtT |
| bT | BtbT | BbtT | BbtT | BbtT |
| bT | BbtT | BbtT | BbtT | BbtT |
| bT | BbtT | BbtT | BbtT | BbtT |
(b)
i.black fur and short tail-0
ii. brown fur and long tail-0
iii. black fur and long tail-16
iv. brown fur and short tail-0
(c)
i.Pollen grain: 10
ii. Guard cell: 20
iii. Ovule: 10
iv. Root cell: 20