A. Incorrect! No, while this statement is correct, it is not the best answer to the question.

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1 Biochemistry - Problem Drill 18: Photosynthesis No. 1 of What is photosynthesis? Select the best answer. (A) Photosynthesis happens in the chloroplasts. (B) Light absorption by chlorophyll induces electron transfer. (C) A proton gradient across the thylakoid membrane drives ATP synthesis. (D) Photosynthesis is the conversion of light into chemical energy. (E) All of the above No, while this statement is correct, it is not the best answer to the question. No, while this statement is correct, it is not the best answer to the question. No, while this statement is correct, it is not the best answer to the question. No, while this statement is correct, it is not the best answer to the question. E. Correct! Yes, all of these statements are correct with respect to characteristics of photosynthesis. Photosynthesis happens in the chloroplasts. Light absorption by chlorophyll induces electron transfer. A proton gradient across the thylakoid membrane drives ATP synthesis. Photosynthesis is the conversion of light into chemical energy. The correct answer is (E).

2 No. 2 of Which of the following chemical statements best completes this generalized reaction of photosynthesis: CO 2 + H 2 O (A) (CH 2 O) (B) O 2 + (CH 2 O) (C) O 2 + H 2 O (D) 2O 2 +H 2 O (E) None of the above No, this is not the complete product of photosynthesis. B. Correct Yes, these are the products of photosynthesis. No, this is not the complete product of photosynthesis. No, this is not the complete product of photosynthesis. E. Incorrect! No, one of the statements provided is correct with respect to product formation of photosynthesis. Energy from light is transformed and used to drive synthesis of carbohydrates from carbon dioxide and water. CO 2 + H 2 O O 2 + (CH 2 O) The correct answer is (B).

3 No. 3 of Which of the following statements is incorrect with respect to light or photons? (A) Photons have both wave and particle characteristics. (B) When a photon hits an object it can only be reflected or absorbed. (C) Light wave have characteristic frequencies. (D) The visible spectrum refers to light that can be observed / detected by the eye. (E) A quanta is an indivisible unit of energy e.g. photon. No, this is a correct statement so does not answer the question posed. B. Correct! Yes when a photon hits an object it may be: reflected, scattered, absorbed or refracted. No, this is a correct statement so does not answer the question posed. No, this is a correct statement so does not answer the question posed. E. Incorrect! No, this is a correct statement so does not answer the question posed. When a photon hits an object it may be: reflected, scattered, absorbed or refracted. Remember that light has both particle and wave characteristics and this account for the many types of behaviors it has when an encounter is made between it and another surface. The correct answer is (B).

4 No. 4 of What happens when light, a photon, hits an electron? (A) Absorption of photon energy by an electron can cause it to become excited. (B) Any photon can cause an electron to be raised to the excited state. (C) When a photon hits an electron it causes it to return to its ground state energy. (D) If enough energy is absorbed by the electron it will disintegrate. (E) None of the above A. Correct! Yes, absorption of photon energy by an electron in the ground state results in the electron becoming excited. No, the frequency of the light wave must be at or near the vibration frequency of the electron absorbing the energy. No, when electrons take in photon energy it becomes excited and vibrates. No, this is an incorrect response. E. Incorrect! No, one of the answers is correct. Absorption of photon energy by an electron in the ground state results in the electron becoming excited. The correct answer is (A).

5 No. 5 of Below is the diagram of a chloroplast. Correctly identify components 1, 2, 3, and 4. (A) Outer membrane, intermembrane space, inner membrane (B) Outer membrane, intermembrane space, inner membrane (C) Outer membrane, intermembrane space, stroma, thylakoid lumen (D) Outer membrane, intermembrane space, stroma, inner membrane (E) Outer membrane, intermembrane space, inner membrane, stroma No, the structures are not correctly named. No, the structures are not correctly named. No, the structures are not correctly named. No, the structures are not correctly named. E. Correct! Yes, this is the correct identification of the indicated structures. Structure 1 is the outer membrane. Structure 2 is the intermembrane space. Structure 3 is the inner membrane. Structure 4 is the stroma (aqueous fluid). The correct answer is (E).

6 No. 6 of Below is the diagram of a chloroplast. Correctly identify components 5, 6, 7, and 8. (A) Thylakoid membrane, granum, thylakoid, stroma (B) Thylakoid lumen, thylakoid membrane, granum, thylakoid (C) Thylakoid, thylakoid lumen, thylakoid membrane, granum (D) Thylakoid lumen, thylakoid membrane, granum, thylakoid (E) Thylakoid lumen, granum, thylakoid, thylakoid membrane No, this is an incorrect response. B. Correct! Yes, you have correctly identified the structures of the chloroplast. No, this is an incorrect response. No, this is an incorrect response. E. Incorrect! No, this is an incorrect response. Structure 5 is the thylakoid lumen. Structure 6 is the thylakoid membrane. Structure 7 is the granum. Structure 8 is the thylakoid. The correct answer is (B).

7 No. 7 of Below is the diagram of a chloroplast. Correctly identify components 9, 10, 11, and 12. (A) Starch, plastidial DNA, ribosome, drops of lipids (B) Starch,, drops of lipids, ribosome, plastidial DNA (C) Ribosome, starch, plastidial DNA, drops of lipids (D) Starch, plastidial DNA, drops of lipids, ribosome (E) Starch, ribosome, plastidial DNA, drops of lipids No, this is not the correct answer. No, this is not the correct answer. No, this is not the correct answer. No, this is not the correct answer. E. Correct! Yes, this is the correct answer. Structure 5 is starch. Structure 6 is ribosome. Structure 7 is plastidial DNA. Structure 8 are drops of lipids. The correct answer is (E).

8 No. 8 of Which of the following statements is incorrect with respect to the structure shown below? (A) This molecule is responsible for the green pigment of plants. (B) This molecule is located in the thylakoid membrane of chloroplasts. (C) This molecule absorbs green wavelengths of light. (D) This molecule is posses for pyrrole rings. (E) This molecule is chlorophyll. No. This is a correct statement so is not the answer to the question. No. This is a correct statement so is not the answer to the question. C. Correct! Yes, this is chlorophyll and absorbs mostly blue and red wavelengths. It reflects green and hence gives green plants their color. No. This is a correct statement so is not the answer to the question. E. Incorrect! No. This is a correct statement so is not the answer to the question. This is the structure of chlorophyll a (although b and d have similar structures). The characteristics of chlorophyll include: This molecule is responsible for the green pigment of plants. This molecule is located in the thylakoid membrane of chloroplasts. This molecule absorbs deep blue and red wavelengths of light. This molecule is posses for pyrrole rings. The correct answer is (C).

9 No. 9 of Which of the following statements is incorrect with respect to Photosystem II of photosynthesis? (A) It is the process or steps in light dependent photosynthesis. (B) It is located in the thylakoid membrane of plants. (C) Enzymes use photons to energize electrons. (D) Electrons are transferred via a system of coenzymes and cofactors. (E) Ultimately plastoquinol is reduced to plastoquinone. E. Correct! Yes, this statement is incorrect so is the right selection. Plastoquinone is reduced to plastoquinol not the other way around as stated. Plastoquinone is reduced to plastoquinol not the other way around as stated. The correct answer is (E).

10 No. 10 of Which of the following statements is incorrect with respect to Photosystem I of photosynthesis? (A) Photosystem I is the first photosystem in the photosynthetic light reactions of plants. (B) Photosystem 1 consists of several transmembrane proteins. (C) Photosystem I has pigment molecules. (D) The antenna complex of PS I receives the photons. (E) Electrons of PS I can be recycled to increase proton concentration. A. Correct! Yes, this is an incorrect statement so the best response to this question. PS I is actually the second photosystem. It is named PSI because it was discovered prior to PSII not because it comes first in the process. E. Incorrect PS I is actually the second photosystem. It is named PSI because it was discovered prior to PSII not because it comes first in the process. The correct answer is (A).