The atmosphere is 80% nitrogen: why do you think plants and animals can't use nitrogen as it is found in the atmosphere?

Atmospheric Nitrogen is unreactive

Explanation:

The atmosphere is made up of about 80% Nitrogen, 16% oxygen, about 4% carbon dioxide, rare gases etc.

However, the 80% Nitrogen is highly unreactive, and needs to be trapped by competent micro organisms known as nitrogen-fixing bacteria in the root nodules of legumes.

Then, it is converted to several forms like nitrites, nitrates (easily absorbed by plants), ammonia and finally escape to the atmosphere again.

This brief illustration explains the NITROGEN CYCLE, and it is the only means by which plants and animals can use the highly unreactive nitrogen

plants and animal cannot use nitrogen in the arthmosphere because nitrogen is a noble gas, unreactive and it is not available in the form they can use them.

Explanation:

Nitrogen is the most abundant gas in the atmosphere constituting about 80% of total gases available.

Nitrogen is important for plants and animal to build proteins, aminoacid and DNA. Nitrogen in the arthmosphers cannot be use by plants and animals because it is unreactive and not available in the form that it can be use.when organisms die, their bodies decompose and nitrogen is released to the soil, bacteria convert the nitrogen to nitrate in a form that can be absorbed by plants roots and used. The leguminous plants have root nodules that contain nitrogen, nitrogen fixing bacteria in the soil convert nitrogen to nitrate to be use by plants. This is a summary of the entire nitrogen cycle.

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.