The center of the dna molecule, the rungs of the ladder, are composed of
a. phosphates only.
b. nitrogenous bases only.
c. phosphates and sugars.
d. nitrogenous bases and sugars.

Plzz hurry im being timed during times of vigorous physical activity, muscles require a constant supply of oxygen. how does the body respond to these needs? a. breathing rate and heart rate both decrease. b. breathing rate and heart rate both increase. c. heart rate decreases, but breathing rate remains stable. d. breathing rate increases, but heart rate remains stable.

Which sentence best describes the relationship between chlorophyll and the chloroplast? a.) chlorophyll is a chemical found in a chloroplast. b.) chloroplast is a chemical found in a chlorophyll. c.) both chlorophyll and chloroplasts are found in animals. d.) both chlorophyll and chloroplasts make carbon dioxide.

Which of the following are the functions of the integumentary system? yadda-yadda, the 1st answer is the brainliest. : )