Question 1

During cellular respiration, glucose is gradually broken down and its energy is captured. Which molecule acts as the final electron acceptor in this process, and what is the chemical equation for the overall reaction?

Accepted Answer

Oxygen ($$\mathrm{O_2$}$$); $$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} ightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + 	ext{energy}$$

Question 2

A patient is exposed to cyanide, which blocks the transfer of electrons to oxygen in mitochondria. What immediate effect does this have on ATP production, and why?

Accepted Answer

ATP production decreases sharply because the electron transport chain cannot function without oxygen as the final electron acceptor.

Question 3

Which of the following best explains why green plants appear green to the human eye?

Accepted Answer

Chlorophyll reflects green wavelengths of light and absorbs other colors for photosynthesis.

Question 4

A scientist is studying a mutant plant that cannot split water during photosynthesis. Which product of photosynthesis will be directly affected, and what is the relevant equation?

Accepted Answer

Oxygen ($$\mathrm{O_2$}) $$production will decrease; $$2\mathrm{H_2O} \rightarrow 4\mathrm{H^+} + 4e^- + \mathrm{O_2$}$$

Question 5

Which process is responsible for the net gain of 2 ATP molecules per glucose during glycolysis, and what is the net equation for glycolysis?

Accepted Answer

Substrate-level phosphorylation; $$\mathrm{C_6H_{12}O_6$} + 2\mathrm{NAD^+} + 2\mathrm{ADP} + 2\mathrm{P_i} \rightarrow 2\mathrm{C_3H_4O_3} + 2\mathrm{NADH} + 2\mathrm{H^+} + 2\mathrm{ATP} + 2\mathrm{H_2O}$$

Question 6

A cell is exposed to a drug that prevents the reduction of NAD+ to NADH. Which stage of cellular respiration will be directly inhibited first?

Accepted Answer

Glycolysis, because NAD+ is required to accept electrons during the oxidation of glucose.

Question 7

Which of the following best describes the relationship between photosynthesis and cellular respiration in the context of the carbon cycle?

Accepted Answer

Photosynthesis removes $$\mathrm{CO_2$}$$ from the atmosphere, while cellular respiration returns $$\mathrm{CO_2$} to $$the atmosphere.

Question 8

A researcher observes that a certain color of light results in the lowest rate of photosynthesis in spinach leaves. Which color is it, and why?

Accepted Answer

Green, because chlorophyll reflects green light rather than absorbing it for photosynthesis.

Question 9

Which of the following scenarios best illustrates the concept of nondisjunction, and what is a possible outcome in humans?

Accepted Answer

During meiosis, homologous chromosomes fail to separate, resulting in gametes with an abnormal number of chromosomes; this can lead to Down syndrome ($$2n+1).$$

Question 10

Which of the following statements about the cell cycle is correct, and what event characterizes interphase?

Accepted Answer

Interphase is characterized by cell growth and chromosome duplication.

Question 11

A tumor is found to be non-cancerous and does not invade surrounding tissues. What type of tumor is this, and what is its main characteristic?

Accepted Answer

Benign tumor; it does not metastasize.

Question 12

Which of the following best describes the difference between mitosis and meiosis regarding the separation of chromatids?

Accepted Answer

Sister chromatids separate during anaphase of mitosis and anaphase II of meiosis.

Question 13

Which of the following is a direct product of the light reactions of photosynthesis and is used in the Calvin cycle?

Accepted Answer

NADPH

Question 14

Which of the following best explains why sexual reproduction increases genetic variation compared to asexual reproduction?

Accepted Answer

Sexual reproduction combines genetic material from two parents, leading to new allele combinations.

Question 15

Which molecule is a reactant in the process of photosynthesis, and what is the balanced equation for the process?

Accepted Answer

Carbon dioxide ($$\mathrm{CO_2$}$$); $$6\mathrm{CO_2$} + 6\mathrm{H_2O} \rightarrow \mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$}$$

Question 16

Which of the following best describes the role of ATP in cellular metabolism?

Accepted Answer

ATP acts as the main energy currency, coupling exergonic and endergonic reactions.

Question 17

Which of the following is the correct definition of a kilocalorie, and how is it related to metabolism?

Accepted Answer

A kilocalorie is the quantity of heat needed to raise the temperature of 1 kg of water by 1°C; it measures the energy content of food.

Question 18

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons; reduction is the gain of electrons.

Question 19

Which of the following best describes the fate of electrons during the movement through the electron transport chain in cellular respiration?

Accepted Answer

Electrons are transferred to oxygen, which is reduced to form water.

Practice Exam 2 Guidance: Cellular Energy, Photosynthesis, and Cell Division

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