Question

what do lipids predominantly consist of, besides carbon and hydrogen?
a. oxygen
b. sulfur
c. phosphorus
d. nitrogen
which element forms peptide bonds between amino acids in proteins?
a. sulfur
b. carbon
c. nitrogen
d. oxygen
which hormone is released by the pancreas to lower blood sugar levels?
a. thyroxine
b. adrenaline
c. insulin
d. glucagon

Explanation:

First Question:

Lipids are organic compounds. Their main elements are carbon, hydrogen, and oxygen (in smaller amounts compared to C and H). Sulfur, phosphorus, and nitrogen are not predominant in most lipids. So the correct option is a.

Peptide bonds form between the carboxyl group of one amino acid and the amino group of another. The amino group has nitrogen, and the peptide bond structure (–CO–NH–) involves nitrogen. Carbon, sulfur, and oxygen don't form the peptide bond's key linking part here. So the correct option is c.

The pancreas releases insulin to lower blood sugar (it helps cells take in glucose). Thyroxine is from the thyroid, adrenaline from the adrenal gland, and glucagon (from pancreas) raises blood sugar. So the correct option is c.

Answer:

a. Oxygen

Second Question: