The complex mixture of polymers coating the spore that protects the spore from dessication and UV radiation is:

Sporopollenin

Explanation:

Sporopollenin is a biological polymer that is highly cross linked and made up of oxygen, hydrogen and carbon. It is referred to a chemically inert biopolymer because of its toughness and stability in rocks that have been in existence for over 500 million years.  In other words, sporopollenin is chemically stable.

It is an important component of the outer layer or coating of pollen grains and plant spores. This protects spores from UV radiation and dessication.

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.

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.