Which of the following is the best reason that scientific models are used?
a. they prove scientific theories
b. they visualize things that are very complex, very large, or very small
c. they provide a concrete view of something abstract
d. they precisely mimic something in nature

Explain why phospholipid molecules form a bilayer. (3 marks)

This is a typical grassland food web. it is also a small picture of an important cycle on earth: the carbon cycle. describe how the carbon gets into this food web. a) bacteria and fungi, the decomposers, recycle carbon from dead organisms. b) carbon is found in the grass and is passed from one level to the next in this food web. eliminate c) all living things give off carbon dioxide as a by-product of respiration and it is released into the atmosphere. d) plants use carbon dioxide as a reactant in photosynthesis, to make usable chemical energy in the form of a sugar.

Can a trait be both polygenic and have multiple alleles? explain why or why not.