The osmoregulatory/excretory system of a freshwater flatworm is based on the operation of _____.

A) protonephridia

B) metanephridia

C) Malpighian tubules

D) nephrons

Answer: A

Materials are returned to the blood from the filtrate by which of the following processes?

A) filtration

B) selective reabsorption

C) secretion

D) excretion

Answer: B

Excretory organs known as Malpighian tubules are present in _____.

A) flatworms

B) insects

C) jellyfish

D) sea stars

Answer: B

The production of antibodies

a. occurs in B cells and is referred to as the humoral immunity response

b. occurs in T cells and is referred to as cellular immunity.

c. occurs in B cells and is referred to as cellular immunity.

d. occurs in T cells and is referred to as humoral immunity.

e. None of the above are correct.

Answer: a. occurs in B cells and is referred to as the humoral immunity response

The end product of thymine degradation is _______.

a. urea

b. NH4+

c. allantoate

d. b-alanine.

e. b-aminoisobutyrate

Answer: e. b-aminoisobutyrate

All of the following are directly involved in protein turnover except _______.

a. hsp

b. calpains

c. cathepsin

d. proteosome

e. None of the above are correct.

Answer: e. None of the above are correct.

Components of the transulfuration pathway include all of the following except _____.

a. SAM

b. cysteine

c. homocysteine

d. ATP

e. BH4

Answer: e. BH4