Question

1. (2005 - 38) amino acids link together by peptide bonds to form proteins. in which cellular organelle would this process occur?

a. mitochondrion
b. ribosome
c. lysosome
d. golgi body

1. (2005 - 19) both lipids and carbohydrates are important in animal cells because both —

a. provide insulation
b. store energy
c. form cell walls
d. contain nitrogen
10 (2003 - 19) this graph shows that —
a more enzymes are present at a higher ph
b pepsin is less sensitive to ph than trypsin
c pepsin is less effective at low ph than trypsin
d ph affects the activity rate of enzymes

Explanation:

Question 8

To determine where amino acids link by peptide bonds to form proteins, we recall the function of each organelle:

• Mitochondrion: Produces energy (ATP), not protein synthesis.
• Ribosome: Site of protein synthesis, where amino acids are linked via peptide bonds.
• Lysosome: Digests waste materials, not protein synthesis.
• Golgi body: Modifies and packages proteins, not the site of peptide bond formation.

So the correct answer is the ribosome.

Analyze the roles of lipids and carbohydrates in animal cells:

• Provide insulation: Mainly a lipid (e.g., fat) function, not carbohydrate.
• Store energy: Both lipids (e.g., fats) and carbohydrates (e.g., glycogen) store energy.
• Form cell walls: Animal cells have no cell walls; plant cells use cellulose (carbohydrate) for cell walls.
• Contain nitrogen: Neither lipids (composed of C, H, O, sometimes P) nor carbohydrates (C, H, O) contain nitrogen.

Thus, the correct answer is that both store energy.

Interpret the graph of enzyme activity (pepsin and trypsin) vs. pH:

• Option a: The graph shows activity, not enzyme quantity. Eliminate.
• Option b: Pepsin's curve is narrower, so it's more sensitive to pH than trypsin. Eliminate.
• Option c: Pepsin has peak activity at low pH (around 3), so it's more effective at low pH than trypsin. Eliminate.
• Option d: The graph shows different pH optima for pepsin (low pH) and trypsin (neutral - high pH), so pH affects enzyme activity rate. This is correct.

Answer:

b. Ribosome

Question 9