When proteins are broken down they also provide A. Oxygen
B. Carbohydrates
C. Energy
D. Amino-acids
E. Carbon dioxide

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Once an egg cell is fertilized by sperm, the cell then, as the embryo develops, it receives nourishment and eliminates wastes by transferring substances from its blood to its mother's blood. a. becomes a fetus immediately and exits the womb b. begins to divide and implants itself in the wall of the uterus c. remains in the uterus without dividing for several months d. travels back to the ovaries until the fetus is developed

What kinds of molecules can pass through the cell membrane without any problem?