Hemophilia is an X-linked recessive trait. If a non-hemophiliac man mates with a non-hemophiliac woman and they have a hemophiliac son, (a) what is the probability that their next son will have hemophilia? (b) What phenotypes and genotypes are possible for their daughters?

(a) 1/2

(b) Possible Genotype =

    Possible phenotype = non-haemophilic

Explanation:

Let the allele for haemophilia be h, the alternate form would be H.

Genotype of non-haemophilic man would be

Genotype of non haemophilic woman could be either

If they have an haemophilic son, it means the genotype of the woman is

Crossing the two:

  x    =

(a) One out of the two sons is affected. Hence the probability of their next son having haemophilia is 1/2.

(b) the possible genotypes for their daughters are and both of them have no haemophilia.

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c

layer 3 is younger than layer 6.