Question

question 25
the enzyme catalase is an important chemical in the functioning of the
○ mitochondria
○ proteasomes
○ peroxisomes
○ lysosomes

question 26
the cell extension that contains microfilaments is called:
○ microvilli.
○ flagella.
○ cilia.
○ all cell extensions contain microfilaments.

question 27
in the cell membrane, the hydrophilic part of the phospholipid molecule:
○ faces the exterior of the cell.
○ faces the interior of the cell.
○ is in the center of the phospholipid bilayer.
○ both a and b.

Explanation:

Question 25

Catalase is an enzyme that breaks down hydrogen peroxide. Peroxisomes are organelles that contain catalase to detoxify hydrogen peroxide. Mitochondria are for energy production, proteasomes for protein degradation, and lysosomes for digestion. So catalase functions in peroxisomes.

Microvilli are cell extensions with microfilaments (actin filaments) for structure. Flagella and cilia have microtubules, not microfilaments. Not all cell extensions have microfilaments (e.g., cilia/flagella have microtubules). So microvilli contain microfilaments.

Phospholipids in the cell membrane have a hydrophilic head and hydrophobic tails. The hydrophilic heads face the aqueous environments (exterior and interior of the cell), while hydrophobic tails face the center. So the hydrophilic part faces both exterior (A) and interior (B), so option D (both A and B).

Answer:

C. peroxisomes.

Question 26