Nails are made of a protein called ____
a) collagen
b) vinculin
c) keratin
d) elastin
Ans: c) keratin
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Molecular oxygen (O2), which is required for the production of ATP by mitochondria, must pass through at least three membranes to get to the enzymes where it is used
O2 is also produced in chloroplasts and must pass through at least four membranes to be released from the plant. How does O2 move across biological membranes? A. There are numerous protein transporters that allow O2 to travel across membranes. B. O2 is nonpolar, and very small, so it can diffuse across the membrane. C. O2 undergoes a chemical reaction that binds it to other substances that are transported across the membranes. D. O2 is hydrophilic and travels with water across the membranes.
What are the modified stems of cacti called?
a. bulbs b. corms c. rhizomes d. tubers
e. cladodesWhich endocrine gland receives signals from the hypothalamus via the sympathetic nervous system?
a. adrenal medulla b. adrenal cortex c. thyroid gland d. pancreas e. anterior pituitary
Which is the correct pathway of a protein through a cell as it is being made?
A) Nucleus, ribosome, Golgi apparatus B) Golgi apparatus, ribosome, rough endoplasmic reticulum C) Nucleus, smooth endoplasmic reticulum, Golgi apparatus D) Golgi apparatus, ribosome, mitochondria