Question

why do muscle cells require increased oxygen during exercise? *
a) to decrease water concentration in the blood
b) to maintain higher glucose levels in red blood cells
c) to fuel increased cellular respiration for atp production
d) to reduce muscle temperature through fluid absorption

which of the following is the main function of the cell membrane? *
a) generate energy
b) store dna
c) regulate substances in/out of the cell
d) make proteins

what is the shape of the dna molecule? *
a) triple helix

Explanation:

First Question (Why do muscle cells require increased oxygen during exercise?)

• Option A: Oxygen intake during exercise is not related to decreasing water concentration in blood.
• Option B: Muscle cells’ oxygen need isn’t for maintaining glucose in red blood cells (red blood cells don’t use glucose for energy in the same way muscle cells do, and oxygen isn’t for that purpose).
• Option C: During exercise, muscle cells need more energy (ATP). Cellular respiration (which requires oxygen) breaks down glucose to make ATP, so more oxygen is needed to fuel this increased respiration for more ATP.
• Option D: Oxygen doesn’t reduce muscle temperature via fluid absorption; cooling is mainly through sweating and blood flow, not oxygen’s role.

Second Question (Which of the following is the main function of the cell membrane?)

• Option A: Energy generation occurs in mitochondria (for cellular respiration) or chloroplasts (in plants), not the cell membrane.
• Option B: DNA is stored in the nucleus (eukaryotes) or nucleoid (prokaryotes), not the cell membrane.
• Option C: The cell membrane is selectively permeable, controlling what enters and exits the cell (e.g., allowing nutrients in and waste out), which is its main function.
• Option D: Protein synthesis happens at ribosomes, not the cell membrane.

Third Question (What is the shape of the DNA molecule? - Note: Assuming the option "A) Triple helix" is a typo or error, the correct shape is a double helix. If we proceed with the given options (assuming maybe a typo and the intended correct option related to double helix, but based on typical questions, the standard answer is double helix. If the options had "Double helix" as an option, that would be correct. Since the visible option starts with "A) Triple helix" (likely a typo or error), but for the sake of answering based on standard knowledge: )

DNA is composed of two strands of nucleotides that wind around each other to form a structure called a double helix. A triple helix is not the normal structure of DNA (some specialized molecules or artificial constructs might have triple helices, but not the main DNA molecule).

Answer:

C) To fuel increased cellular respiration for ATP production