How many membranes does the mitochondria have?
a. 1
b. 2
c. 3
d. 4

b. 2

Explanation:

The mitochondria has 2 membranes namely the outer membrane and the inner membrane , which are separated by an inter membrane space. The outer membrane is selectively permeable to ions and molecules and also holds the whole mitochondria structure .in contrast ,the inner membrane is less permeable and  it is where electron transport occurs , between  protein complexes found within the structure.

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.

trachea, alveoli, lung capillaries, arteries