Humans and other animals cannot digest wood because they a. cannot digest any carbohydrates. b. cannot chew it fine enough. c. lack the enzyme needed to break down cellulose. d. get no nutrients from it. 9. Explain how it could be possible

c. lack the enzyme needed to break down cellulose

Explanation:

Starch is the form of carbohydrate which is taken through food by humans and animals and digested by them. Amylase is the enzyme that is used to digest starch in them.  

Wood is made up of cellulose and the enzyme which is used to digest cellulose is cellulase. Humans and animals do not have cellulase enzymes therefore they are not able to digest and breakdown cellulose.

Therefore as humans and animals lack enzymes needed to digest cellulose they can not digest wood.

when it is at an intermediate population density