The principle difference between where salt marshes and mangrove forests grow is

a.
the salinity of the water
b.
the amount of sunlight the plants receive
c.
the intensity of the waves along the coast
d.
the extent of human development in the area

Pls me i need this ! each cell has genes activated depending on it's job and what kind of cell it is. it is the presence of that causes the repressor protein to fall off and unblock the gene on the lac operon. if a gene is turned on then it is being an additional circular chromosome found in some bacteria that is used in genetic engineering.

The part of the eye that closes and opens to let light in is .

1. which of the following levels of protein organization shows the complete 3-d arrangement of the polypeptide chain? a) primary b) secondary c) tertiary d) quaternary 2. the carboxyl groups on a protein molecule are composed of which of the following elements? a) nitrogen and hydrogen b) carbon, hydrogen, and oxygen c) carbon and hydrogen d) nitrogen, oxygen, and carbon 3. what part of the protein molecule makes it unique from other proteins? a) the carboxyl group b) the amino group c) the peptide group d) the r group 4. which of the following is an example of a protein that plays a direct role in immune function? a) collagen b) antibodies c) enzymes d) hormones 5. which of the following statements correctly describes the composition of proteins? a) most are composed of 20 common amino acids. b) most are composed of 10 common amino acids. c) most are composed of 20 common fatty acids. d) most are composed of 10 common fatty acids.