12. Which event occurs in prophase I of meiosis, but not prophase of mitosis?
a. Sister chromatids separate and move to opposite poles.
b. All chromosomes line up in a single row at the center of the cell.
c. Homologous pairs separate and move towards opposite poles of the cell.
d. Homologous chromosomes pair to form a tetrad, and may cross over.

d

Explanation:

The tetrad is formed by synapsis of homologous chromosomes.

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.