A population of laboratory rats in Hardy-Weinberg equilibrium displays a polymorphism for coat color controlled by two alleles at a single locus. The B allele codes for black coat colour and is completely dominant. There are 200 rats in the population: 32 are white and 168 are black. How many of the black rats are heterozygous (Bb) at the coat-color locus?

96

Explanation:

In solving Hardy-Weinberg related question, there are two formulas involved:

p + q = 1   ----------------------------- equation (1)

p² + 2pq + q² = 1 ------------------- equation (2)

where;

p is the frequency of the dominant allele.

q  is the frequency of the recessive allele.

p² is the frequency of individuals with the homozygous dominant genotype.

2pq is the frequency of individuals with the heterozygous genotype.

q² is the frequency of individuals with the homozygous recessive genotype.  

Total population of rats = 200

32 are white (bb)  = q²

168 are black (BB)  = p²

How many of the black rats are heterozygous (Bb) at the coat-color locus?

Frequency of individual (q²) =

Frequency of individual  (q²) =

q² = 0.16

To find q from q²; we take the square root of the both sides

√q² = √0.16

q = 0.4

Using the first equation;

p + q = 1

p + 0.4 = 1

p = 1 - 0.4

p = 0.6

To find how many of the black rats are heterozygous (Bb) at the coat-color locus (i.e 2pq) ; we have

= 2 × p × q

= 2 × 0.6 × 0.4

= 0.48

∴ 0.48 × Total population of rats

= 0.48 × 200

= 96

Hence, there are 96 black rats that are heterozygous (Bb) at the coat-color locus

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.

answer: although many types of viruses can cause a common cold, rhinoviruses are the most common culprit. a cold virus enters your body through your mouth, eyes or nose. the virus can spread through droplets in the air when someone who is sick coughs, sneezes or talks. theres your answer

explanation: