4. would the absence of cellular respiration in animals impact the process of photosynthesis?

Yes

Explanation:

The process of cellular respiration would affect the rate of photosynthesis in plants as animals release carbon dioxide as a by product which is used by plants. Though there are many other sources of carbon dioxide but animals are major source of carbon dioxide.

Plants use this carbon dioxide, water and sunlight to make food by the help of the process known as photosynthesis.

Hence, cellular respiration in animals is necessary for the photosynthesis in plants.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.