Together, respiration and photosynthesis keep the levels of carbon dioxide and oxygen in the atmosphere

a. fairly constant

b. always changing

c. decreasing

d. increasing

A. fairly constant

Explanation:

In photosynthesis plants used carbon dioxide and produced oxygen while in respiration oxygen is taken and carbon dioxide is released thus level of both gases remain constant.

Aerobic respiration

It is the breakdown of glucose molecule in the presence of oxygen to yield large amount of energy. Water and carbon dioxide are also produced as a byproduct.

Glucose + oxygen → carbon dioxide + water + 38ATP

Photosynthesis:

It is the process in which in the presence of sun light and chlorophyll by using carbon dioxide and water plants produce the oxygen and glucose.

Carbon dioxide + water + energy →   glucose + oxygen

water is supplied through the roots, carbon dioxide collected through stomata and sun light is capture  by chloroplast.

Chemical equation:

6H₂O + 6CO₂ + energy  →   C₆H₁₂O₆ + 6O₂

i'm not sure

explanation:

i'll try whatever you got