In humans, the ability to roll up the sides of the tongue into a U-shape is controlled by one gene. Ability to roll the tongue is dominant to the inability to roll it. If two people who can roll their tongues each had one parent who could not, what is the probability that they will have a child who cannot roll his/her tongue

25%

Explanation:

male                                

can roll tongue     -     cannot roll tongue

female

can roll tongue     -     cannot roll tongue

If they have a child, the possible combinations are:

1)

father's gene: can roll tongue

mother's gene: can roll tongue

RESULT = THE CHILD WILL BE ABLE TO ROLL HIS/HER TONGUE

2)

father's gene: can roll tongue

mother's gene: cannot roll tongue

RESULT = THE CHILD WILL BE ABLE TO ROLL HIS/HER TONGUE

3)

father's gene: cannot roll tongue

mother's gene: can roll tongue

RESULT = THE CHILD WILL BE ABLE TO ROLL HIS/HER TONGUE

4)

father's gene: cannot roll tongue

mother's gene: cannot roll tongue

RESULT = THE CHILD WILL NOT BE ABLE TO ROLL HIS/HER TONGUE

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.