8 Photosynthesis Flashcards

Question 1

Q

Where does the Calvin cycle take place?

Answer

A

stroma of the chloroplast

Question 2

Q

When oxygen is released as a result of photosynthesis, it is a direct by-product of

Answer

A

splitting water molecules.

Question 3

Q

Which statement describes the functioning of photosystem II?

Answer

A

The electron vacancies in P680+ are filled by electrons derived from water.

Question 4

Q

Which of the following are directly associated with photosystem I?

Answer

A

receiving electrons from the thylakoid membrane electron transport chain

Question 5

Q

What are the products of linear photophosphorylation?

Answer

A

ATP and NADPH

Question 6

Q

Where does the Calvin cycle occur?

Answer

A

E

The Calvin cycle occurs in the stroma.

Question 7

Q

The light reactions of photosynthesis use _____ and produce _____. water … NADPH

Answer

A

water … NADPH

NADPH is a reactant in the Calvin cycle.

Question 8

Q

Identify a thylakoid.

Question 9

Q

The photosynthetic membranes are found in the _____ in plant cells.

Answer

A

chloroplasts

Question 10

Q

Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle.

Answer

A

oxidized…reduced

During the light reactions of photosynthesis, water is oxidized, and during the Calvin cycle, carbon is reduced.

Question 11

Q

Plants are photoautotrophs. What does this mean?

Answer

A

They use light energy to drive the synthesis of organic molecules from inorganic materials.

Question 12

Q

When oxygen is released as a result of photosynthesis, it is a direct by-product of

Answer

A

splitting water molecules.

Question 13

Q

Which term describes ATP production resulting from the capture of light energy by chlorophyll?

Answer

A

Photophosphorylation

The excitation of chlorophyll by light energy initiates a chain of events that leads to ATP production.

Question 14

Q

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?

Answer

A

Proton gradient

A proton gradient across chloroplast and mitochondrial membranes drives ATP synthesis by the enzyme ATP synthase.

Question 15

Q

Which of these phosphorylates ADP to make ATP?

Question 16

Q

_____ releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment.

Answer

A

B

The energy released as electrons are passed along the electron transport chain is used to pump protons into the thylakoid compartment.

Question 17

Q

_____ splits water into 1/2 O₂, H⁺, and e^- .

Answer

A

Photosystem II splits water into 1/2 O², H⁺, and e^- .

Question 18

Q

Energized electrons from ____ enter an electron transport chain and are then used to reduce NADP⁺.

Answer

A

C

Energized electrons from photosystem I are used to reduce NADP⁺.

Question 19

Q

Chlorophyll can be found in _____.

Answer

A

A and C

The photosystems contain chlorophyll.

Question 20

Q

Which of the following is a product of the light reactions of photosynthesis?

Answer

A

oxygen, ATP, and NADPH

Question 21

Q

When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by _____.

Answer

A

splitting water

The electrons removed from water are transferred to P680.

Question 22

Q

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?

Answer

A

The light-independent reactions turn CO₂, a gas, into usable carbon in the form of sugars.

CO₂ is unusable until plants have “fixed” this carbon into sugar.

Question 23

Q

Which of the following molecules is the primary product of photosystem I?

Answer

A

NADPH

The NADPH produced by photosystem I is used to supply energy for the production of sugars during photosynthesis.

Question 24

Q

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?

Answer

A

The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.

Question 25

Q

Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose?

Answer

A

Regneration of RuBP

The regeneration of RuBP ensures that the Calvin cycle can proceed indefinitely, since RuBP fixes carbon dioxide into an organic molecule that is used to produce sugar.

Question 26

Q

After 3-PGA is phosphorylated, it is reduced by _____

Question 27

Q

How many carbon dioxide molecules must be added to RuBP to make a single molecule of glucose?

Answer

A

6

Six carbon dioxide molecules are required to produce two G3P molecules, which can be combined to make one glucose molecule.

Question 28

Q

In the Calvin cycle, how many ATP molecules are required to regenerate RuBP from five G3P molecules?

Question 29

Q

Which of the following products of the light reactions of photosynthesis is consumed during the Calvin cycle?

Question 30

Q

The overall function of the Calvin cycle is _____.

Answer

A

making sugar

Using the ATP and NADPH made during the light reactions, carbon is reduced in the Calvin cycle and sugar is made.

Question 31

Q

C₄ plants occur more commonly in desert conditions because _____.

Answer

A

they can fix carbon at the lower CO₂ concentrations that develop when the stomata are closed

Question 32

Q

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?

Answer

A

blue and violet

Question 33

Q

How does carbon dioxide enter the leaf?

Answer

A

through the stomata

Question 34

Q

When chloroplast pigments absorb light, _____.

Answer

A

their electrons become excited

Question 35

Q

Rubisco is _____.

Answer

A

the enzyme in plants that first captures CO₂ to begin the Calvin cycle

Rubisco catalyzes the first step of the Calvin cycle—the incorporation of a molecule of carbon dioxide with a 5-carbon sugar. The 6-carbon product is so unstable that it decomposes immediately into two 3-carbon phosphoglycerates.

Question 36

Q

What is the role of NADP⁺ in photosynthesis?

Answer

A

It is the primary electron acceptor.

Question 37

Q

In photosynthesis, what is the fate of the oxygen atoms present in CO₂? They end up _____.

Answer

A

in sugar molecules and in water

Question 38

Q

The Calvin cycle occurs in the _____.

Question 39

Q

During photosynthesis, an electron transport chain is used to _____.

Answer

A

transport electrons from photosystem II to photosystem I

Question 40

Q

During photosynthesis in a eukaryotic cell, an electrochemical gradient is formed across the ______.

Answer

A

thylakoid membrane

Question 41

Q

The light reactions of photosynthesis generate high-energy electrons, which end up in _____. The light reactions also produce _____ and _____.

Answer

A

NADPH … ATP … oxygen

Question 42

Q

What is the role of NADP⁺ in photosynthesis?

Answer

A

It forms NADPH to be used in the Calvin cycle.

Question 43

Q

Photorespiration occurs when rubisco reacts RuBP with

Question 44

Q

Why are C4 plants more suited to hot climates than C3 plants?

Answer

A

Unlike C₃ plants, they keep fixing carbon dioxide even when the concentration of carbon dioxide in the leaf is low.

Question 45

Q

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

Answer

A

fix CO2 into organic acids during the night.