Help.. The energy in food is measured in units called Calories.
a. true
b. false
17
If you eat more food than your body uses, you will lose weight.
a. true
b. false
18
Carbohydrates are used primarily to build and repair body parts.
a. true
b. false
19
Ptyalin aids in mechanical digestion.
a. true
b. false
20
Muscles in the walls of the esophagus help bring food from the
mouth to the stomach by peristalsis.
a. true
b. false

16. True

17. False

18. False

19. True

20. True

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.

digestion

it excretes wastes