Why can't plants and animals use the nitrogen directly from the atmosphere?
answer
a. there is not enough of it in the air.
b. nitrogen gas contains the element in an inert, unusable state.
c. they do use it directly from the atmosphere.
d. plants and animals do not need nitrogen for their life processes.

The serengeti plains are part of the african savanna ecosystem and are home to a variety of different species of plants and animals. the serengeti plains experience a seven-month period of seasonal drought each year, during which the ecosystem receives only four inches of rain and the availability of some resources becomes very scarce. which type of limiting factors does the seasonal drought in the serengeti plains affect?