Deck 19: The Light Reactions of Photosynthesis

Question 1

Which of the following,when in the correct protein environment,is a very strong oxidant capable of extracting electrons from water?

A) calcium
B) copper
C) manganese
D) magnesium
E) iron

Answer 1

C

Question 2

Which of the following is an accessory pigment found in plants?

A) plastocyanin
B) $\beta$ -carotene
C) chlorophyll a
D) cytochrome b
E) None of the answers is correct.

Answer 2

$\beta$ -carotene

Question 3

What structure within the chloroplast resembles a flattened disk?

A) photosystem I
B) photosystem II
C) stroma lamellae
D) thylakoid
E) cytochrome bf complex

Answer 3

D

Question 4

The transfer of excitation energy from one molecule to one nearby through electromagnetic interactions is called ________________________________.

Question 5

The light-induced electron transfer in photosynthesis results in the transfer of ___________ into the thylakoid space.

Question 6

______________________ is the term for a bacteriochlorophyll that has two protons instead of a magnesium ion at its center.

Question 7

What is the principal photoreceptor in chloroplasts of green plants?

A) $\beta$ -carotene
B) chlorophyll a
C) chlorophyll b
D) pheophytin
E) phycocyanin

Question 8

What ion is found at the center of the tetrapyrole in chlorophyll a?

A) calcium
B) manganese
C) iron
D) copper
E) magnesium

Question 9

The process in which a positive charge forms on one molecule by the loss of a electron which has been excited by light,and a negative charge forms on another by the gain of an electron is referred to as _____________________________________.

Question 10

What is another name for the CF₁-CF₀ complex?

A) ATP synthase
B) photosystem I
C) photosystem II
D) ferredoxin- NADP⁺ reductase
E) cytochrome bf complex

Question 11

What cofactor is required by plastocyanin for proper activity?

A) manganese
B) iron
C) copper
D) magnesium
E) zinc

Question 12

The inner membrane of a chloroplast surrounds a compartment called the _____________.

Question 13

In the light reactions of photosynthesis,the cooperation between photosystem II and photosystem I creates a flow of electrons from H₂O to the final acceptor,_____________.

Question 14

Electrons flow from photosystem II to photosystem I through the ________________ complex.

Question 15

What organelle is the site of photosynthesis?

A) chloroplast
B) mitochondria
C) vacuole
D) endoplasmic reticulum
E) None of the answers is correct.

Question 16

The manganese center of photosystem II converts _________ to __________.

Question 17

P680 is the pigment reaction center for ____________________.

Question 18

In _______________,ATP is generated without the concomitant formation of NADPH.

Question 19

What prosthetic group is associated with ferredoxin-NADP⁺ reductase?

A) manganese center
B) plastoquinone
C) quinone A₁
D) FAD
E) iron-sulfur center

Question 20

Photosystem II responds to wavelengths of light shorter than _____ nm.

A) 450
B) 520
C) 580
D) 650
E) 680

Question 21

In bacterial photosynthesis,how would the light energy be used if the reduced bacteriopheophytin (BPh^- returned the electron to the P960⁺ cytochrome?

A) It would follow a separate electron-transport chain.
B) It would be lost as heat.
C) It would stimulate the ejection of a second electron.
D) A proton would be pumped.
E) None of the answers is correct.

Question 22

What is the original source of electrons used to neutralize the special pair in photosystem II?

A) reduced cytochrome bf
B) NADH
C) H₂O
D) membrane lipids
E) ferredoxin

Question 23

Complete the following reaction for photosystem I (be sure to balance the reaction with regard to the electrons):Pc(Cu⁺)+ Fd_ox + light $\rarr$

A) Pc(Cu⁺) + Fd_ox + light $\rarr$ Pc (Cu⁺) + (Cu⁺) Fd_red
B) Pc(Cu⁺) + Fd_ox + light $\rarr$ Pc (Cu²⁺) + Fd_red
C) Pc(Cu⁺) + Fd_ox + light $\rarr$ Pc + Fd_red(Cu²⁺)
D) Pc(Cu⁺) + Fd_ox + light $\rarr$ Pc^- (Cu³⁺) + Fd_red
E) None of the answers is correct.

Question 24

In bacterial photosynthesis,what is one way in which the proton gradient is created?

A) reduction of a quinone that causes uptake of two protons from the cytoplasm
B) the reduction of NADPH
C) the transfer of protons from NADH across the membrane via a shuttle system
D) the conversion of H₂O to H⁺
E) None of the answers is correct.

Question 25

After P960 absorbs light,what are the next few steps in bacterial photosynthesis?

Question 26

In green plant photosynthesis,how many protons are transferred into the thylakoid lumen after absorption of four photons to PSII and four photons to PSI?

A) 2
B) 4
C) 8
D) 12
E) 18

Question 27

How is a chloroplast similar to a mitochondria?

Question 28

Why are chlorophylls good candidates for photoreceptors?

Question 29

Light absorption induces electron transfer from P680 to

A) pheophytin.
B) Q.
C) cytochrome c.
D) chlorophyll a.
E) None of the answers is correct.

Question 30

Which of the following is/are light harvesting molecules?

A) vitamin D
B) carotenoids
C) chlorophyll b
D) plastocyanin
E) carotenoids and chlorophyll b

Question 31

Chloroplasts are similar to mitochondria in that they

A) have outer membranes that are highly permeable to small molecules and ions.
B) are double-membrane organelles.
C) contain electron transport chains.
D) contain a stroma.
E) move protons from outside to inside for ATP production.

Question 32

How is light used in photosynthesis?

A) The light is necessary to make the chlorophyll green, so the pigment can transmit electrons.
B) The light is used to generate high-energy electrons with great reducing potential.
C) The light provides heat energy for the chloroplasts.
D) The light is absorbed by oxygen which is converted into water.
E) None of the answers is correct.

Question 33

Light absorbed by a chlorophyll a causes an electron to move

A) from the photon to the chlorophyll.
B) from ground state to an excited state.
C) to a neighboring water molecule.
D) from chlorophyll to ADP.
E) None of the answers is correct.

Question 34

Bacterial reaction centers are analogous to

A) photosystem I.
B) photosystem II.
C) succinate dehydrogenase.
D) photosystem I and photosystem II.
E) All of the answers are correct.

Question 35

The D1 and D2 subunits of photosystem II

A) span the thylakoid membrane.
B) are similar to each other.
C) are homologous to the L and M chains of the bacterial center.
D) are similar to each other and are homologous to the L and M chains of the bacterial center.
E) All the answers are correct.

Question 36

Humans do not produce energy by photosynthesis.Why,then,is this process critical to our survival?

Question 37

What is the immediate source of the electron regained by the oxidized P960 in bacterial photosynthesis?

A) plastoquinone
B) an NADPH molecule from a supporting pathway
C) complex III of the respiratory electron-transport chain
D) reduced cytochrome
E) None of the answers is correct.

Question 38

Write out the general chemical reaction for photosynthetic production of carbohydrates and oxygen.

Question 39

The pathway of electron flow from H₂O to NADP⁺ in photosynthesis is referred to as

A) cooperative special pairs.
B) photorespiration.
C) the Z scheme of photosynthesis.
D) photophosphorylation.
E) None of the answers is correct.

Question 40

How are thylakoid membranes unique?

A) They contain only 10% phospholipids.
B) They contain 40% galactolipids.
C) They have equivalent amounts of protein and lipid.
D) They contain only 10% phospholipids, and they have equivalent amounts of protein and lipid.
E) All the answers are correct.

Question 41

How is it possible to make ATP without generating NADPH?

Question 42

How is charge recombination of BPh^- and P960⁺ suppressed in bacterial photosynthesis?

Question 43

Describe the path of electrons in photosystem I.Provide a diagram if necessary.

Question 44

Write the overall reaction of photosystem II.

Question 45

Give the overall net equation as catalyzed by the "Z scheme" of photosynthesis.

Question 46

What are the likely reasons that manganese evolved as the ion used in photosystem II?

Question 47

How do herbicides such as diuron or atrazine work?

Question 48

What is the role of accessory pigments in photosynthesis?

Question 49

Describe the arrangement of the photosynthetic assemblies in the thylakoid membranes.

Question 50

Describe the process of cyclic photophosphorylation.