Answer:
a. only T gametes
b. only t gametes
c. TT
d. tt
Explanation:
This question involves a single gene coding for stem length in pea plant. The allele for tall stem length (T) is dominant to dwarf stem length (t).
- A purebred is an organism that will only transfer one type of phenotype to its offspring or produce only one type of GAMETE. Hence, to do this, a purebred must have a homzygous genotype. According to this question;
a. A purebred tall plant (TT) will produce only 'T' gametes.
b. A purebred dwarf plant (tt) will produce only 't' gametes.
c. The genotype of a purebred tall plant will be 'TT'
d. The genotype of a purebred dwarf plant will be 'tt'
Answer:
The radii of the arterioles constrict by humoral control and by nervous control.
Explanation:
The vascular system regulation is performed by the smooth muscle of the arterioles, which constitute the maximum resistance point. The smooth muscle relaxation provokes vasodilation, increasing its diameter. On the contrary, smooth muscle contraction provokes a decrease in the arteriole´s diameter, reducing the blood flow.
This muscle is under the control of the autonomous nervous system and certain hormones.
Substances such as adrenaline, noradrelanine, angiotensine, vasopresin, and endotelines cause vasoconstriction.
Also, there are many vasoconstrictor fibers of the sympathetic nerves that increase resistance and modify blood flow.
