One parent has a dominant gene for a
straight thumb and a recessive gene for a
bent thumb. The other parent has two
recessive genes for a bent thumb. Let T
represent straight thumbs and t represent
bent thumbs. What is the probability, or
possibility, that one of their children will
have a bent thumb?
The probability of a child with a bent thumb
is out of 4, or
%.

The probability of a child with a bent thumb  is out of 4 is 50%.

Explanation:

Information given:

dominant gene = straight thumb (genotype TT, Tt)

recessive trait = bent thumb (genotype  tt)

from the question genotype of parents can be deduced:

Parent 1 = Tt

parent 2 = tt

from the Punnet square:

  T     t

t  Tt    tt  

t   Tt    tt  

From the results of Punnet square it is seen that 50% of progeny will be straight thumb and 50% of progeny will be bent thump.

phenotype ratio and genotype ratio = 1:1

There will be 50 % probability that one of their offspring will be with bent thumb.

progeny with bend thump percent = x100

                                        = 50%.

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