OAT General Biology 3

Question 1

A cell with a water potential of -0.4 MPa is placed in a solution with a water potential of -0.2 MPa. Water will:

Accepted Answer

Move out of the cell

Answer

Water moves by osmosis from higher (less negative) to lower (more negative) water potential, so water exits the cell toward the -0.2 MPa solution.

Question 2

Which stage of cellular respiration produces the most ATP per glucose molecule?

Accepted Answer

Oxidative phosphorylation

Answer

Oxidative phosphorylation (electron transport chain + chemiosmosis) generates approximately 32-34 ATP per glucose, far more than the other stages.

Question 3

What is the function of the sinoatrial (SA) node in the heart?

Accepted Answer

Initiates the electrical impulse for each heartbeat

Answer

The SA node is the heart's natural pacemaker, spontaneously generating electrical impulses that trigger each cardiac contraction.

Question 4

Which of the following is a characteristic feature of prokaryotic cells?

Accepted Answer

70S ribosomes

Answer

Prokaryotes have 70S ribosomes (composed of 50S and 30S subunits), while eukaryotes have 80S ribosomes in the cytoplasm.

Question 5

Hardy-Weinberg equilibrium requires which of the following conditions?

Accepted Answer

Random mating among individuals

Answer

One of the five Hardy-Weinberg assumptions is random mating; violations of this or other assumptions cause allele frequencies to change over time.

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