Bio Exam 2 chapter 5 photosynthesis

Question 1

What is the name given to organisms that can make their own food and thus sustain themselves without consuming organic molecules derived from other organisms?
A) chemotrophs
B) heterotrophs
C) synthesizers
D) autotrophs

Answer 1

D. Autotrophs.
Note: Autotroph means “self-feeders.” It means using CO2 as the carbon source and making its own organic carbon molecules.

Question 2

Photoautotrophs:
A) make sugar by using organic raw materials.
B) produce organic molecules from inorganic molecules.
C) use energy from the sun.
D) eat other organisms that use light energy to make food molecules.
E) include only the green plants.

Answer 2

E. Include only the green plants.
Note: Photo means using energy from the sun. Photoautotroph would mean self-feeders powered by sunlight.

Question 3

Which of the following is an example of a photoautotroph?
A) cyanobacteria in freshwater and marine ecosystems
B) grizzly bears in Alaska
C) bacteria in our mouth
D) mushrooms growing on the side of a dead tree

Answer 3

A. Cyanobacteria in freshwater and marine ecosystems.
Note: Land plants only account for 30% of photosynthetic capacity of the Earth. Ocean cyanobacteria and algae account for about 70% of photosynthetic capacity.

Question 4

Autotrophs that utilize light as their energy source are:
A) chemosynthetic autotrophs.
B) photoautotrophs.
C) fungi.
D) heterotrophs.

Answer 4

B. Photoautotrophs.

Question 5

What is the likely origin of chloroplasts?
A) mitochondria that had a mutation for photosynthesis
B) photosynthetic prokaryotes that lived inside eukaryotic cells
C) prokaryotes with photosynthetic mitochondria
D) eukaryotes that engulfed photosynthetic fungi

Answer 5

B. Photosynthetic prokaryotes that lived inside eukaryotic cells.

Question 6

In most green plants, chloroplasts are:
A) concentrated in a zone of leaf tissue called the mesophyll.
B) concentrated in a portion of the leaf called the stroma.
C) evenly distributed throughout the leaf tissue.
D) evenly distributed throughout the entire plant.

Answer 6

A. Concentrated in a zone of leaf tissue called the mesophyll.

Question 7

________ cells in leaves are specialized for photosynthesis.
A) Companion
B) Mesophyll
C) Sclerenchyma
D) Tracheid

Answer 7

B. Mesophyll.

Question 8

CO2 enters and O2 escapes from a leaf via:
A) stomata.
B) thylakoids.
C) grana.
D) stroma.

Answer 8

A. Stomata.
Note: The singular word for stomata is stoma. Don’t confuse that with stroma, which means the space inside a chloroplast.

Question 9

In the chloroplast, sugars are made in a compartment that is filled with a thick fluid called the:
A) stomata.
B) thylakoid.
C) matrix.
D) stroma.

Answer 9

D. Stroma.

Question 10

Chloroplasts contain disklike membranous sacs arranged in stacks called:
A) cristae.
B) thylakoids.
C) grana.
D) vacuoles.

Answer 10

C. Grana.

Question 11

Where is chlorophyll found in a plant cell?
A) stroma
B) thylakoid membranes
C) cytoplasm
D) cristae

Answer 11

B. Thylakoid membranes.

Question 12

The oxygen released into the air as a product of photosynthesis comes from:
A) water.
B) glucose.
C) carbon dioxide.
D) chlorophyll.

Answer 12

A. Water.
Note: The oxygen is taken from H2O. O2 is released as a waste product, and the hydrogen is used to combine with CO2 to form sugars.

Question 13

If you expose a photosynthesizing plant to water that contains both radioactive H and radioactive O, in which of the products of photosynthesis will the radioactive H and O show up?
A) H and O both in glucose
B) H in glucose; O in water
C) H in water; O in glucose
D) H in glucose and water; O in O2

Answer 13

D. H in glucose and water; O in O2.

Question 14

A redox reaction involves the transfer of:
A) oxygen.
B) water.
C) an electron.
D) carbon dioxide.

Answer 14

C. An electron.
Note: You absolutely need to remember oxidation is losing electrons and reduction is gaining electrons. You may see variations of this question.

Question 15

Which of the following statements concerning the role of redox reactions in photosynthesis and cellular respiration is true?
A) Photosynthesis involves only reductions, while respiration involves only oxidations.
B) Photosynthesis involves only oxidations, while respiration involves only reductions.
C) In photosynthesis, carbon dioxide is oxidized to form sugar, while in respiration, sugar is reduced to form carbon dioxide.
D) In photosynthesis, carbon dioxide is reduced to form sugar, while in respiration, sugar is oxidized to form carbon dioxide.

Answer 15

D. In photosynthesis, carbon dioxide is reduced to form sugar, while in respiration, sugar is oxidized to form carbon dioxide.
Note: A compound that is more reduced usually has energy stored. Therefore, oxidation of sugar releases energy. Reduction of carbon dioxide requires energy.

Question 16

What is the source of energy that provides the boost for electrons during photosynthesis?
A) light
B) electromagnetism
C) cellular respiration
D) ATP

Answer 16

A. Light.

Question 17

Which of the following statements regarding photosynthesis is false?
A) ATP is not produced during photosynthesis, but only during cellular respiration.
B) Photosynthesis is ultimately powered by light energy and respiration by the chemical energy of fuel molecules.
C) Photosynthesis consumes CO2; respiration consumes O2.
D) Photosynthesis produces O2; respiration produces CO2.

Answer 17

A. ATP is not produced during photosynthesis, but only during cellular respiration.
Note: Light reactions in photosynthesis produce ATP by chemiosmosis powered by light.

Question 18

The light reactions occur in the ________, while the Calvin cycle occurs in the ________.
A) stroma . . . thylakoid membranes
B) stroma . . . nucleus
C) cytoplasm . . . thylakoid membrane
D) thylakoid membranes . . . stroma

Answer 18

D. Thylakoid membranes . . . stroma.

Question 19

Which of the following are produced during the light reactions of photosynthesis?
A) glucose, ADP, NADP+
B) glucose, ADP, NADP+, CO2
C) ADP, NADP+, O2
D) ATP, NADPH, O2

Answer 19

D. ATP, NADPH, O2.
Note: Chemiosmosis-powered electron transport produces ATP. Electrons are taken from water when sunlight hits a chlorophyll molecule in PSII, and H2O is oxidized to O2. NADP+ is the final electron acceptor in the light reaction and picks up the electron (reduced) to become NADPH.

Question 20

Which of the following is part of the light reaction?
A) carbon fixation
B) reduction of carbon
C) regeneration of NADP+
D) formation of waste products in the form of O2

Answer 20

D. Formation of waste products in the form of O2.
Note: Yes, oxygen is a waste product. Oxygen is actually toxic to a lot of anaerobic organisms.

Question 21

Which of the following are produced during the Calvin cycle?
A) glucose, ADP, NADP+
B) glucose, ADP, NADP+, CO2
C) ATP, NADPH, O2
D) ATP, NADPH, CO2

Answer 21

A. Glucose, ADP, NADP+.
Note: CO2 is reduced to glucose by energy supplied by hydrolysis of ATP (becomes ADP afterward) and oxidation of NADPH (becomes NADP+ afterward).

Question 22

Carbon fixation:
A) occurs when carbon atoms from CO2 are incorporated into an organic molecule.
B) supplies the cell with ATP.
C) occurs during the light reactions.
D) provides the cell with a supply of NADPH molecules.

Answer 22

A. Occurs when carbon atoms from CO2 are incorporated into an organic molecule.

Question 23

Sunlight is a type of ________ energy.
A) electromagnetic
B) potential
C) kinetic
D) nuclear

Answer 23

A. Electromagnetic.

Question 24

Why are most plants green?
A) Chlorophyll a reflects green light.
B) Chlorophyll a absorbs green light.
C) Chlorophyll b primarily uses green light as the source of energy for photosynthesis.
D) Green helps plants blend into their environment as a sort of camouflage.

Answer 24

A. Chlorophyll a reflects green light.
Note: Both chlorophyll a and chlorophyll b reflect green light!

Question 25

Which of the following colors contributes the least energy to photosynthesis? A) blue B) red C) orange D) green

Answer 25

D. Green. Note: Green light is least absorbed (or most reflected) by leaves. That’s why leaves are green.

Question 26

Of the following wavelengths of light, which would you expect to be reflected or transmitted by chlorophyll a? A) blue B) green C) yellow D) red

Answer 26

B. Green. Note: Chlorophyll a and b absorb both red and blue light and reflect green light.

Question 27

Plant cells are protected from the harmful effects of reactive oxidative molecules by: A) mitochondria. B) chlorophyll. C) carotenoids. D) ATP.

Answer 27

C. Carotenoids. Note: It is believed that carotenoid pigment can protect animals from oxidative stress as well. It is a well-known “antioxidant” very abundant in carrots and other vegetables. There are other well-known antioxidants produced by plants such as anthocyanins (e.g., in blueberries), polyphenol (e.g., in green tea), resveratrol (in red grapes and wine), and curcumin (e.g., in turmeric roots and curry powder).

Question 28

A packet of light energy is called a: A) quantum. B) pigment. C) photon. D) phaser.

Answer 28

C. Photon. Note: Please don’t confuse “photons” with “protons.” I’ve actually seen multiple students confused about these two terms. Photon is not a real molecule; it is actually a term that describes the dual particle and wave nature of light. While light is generally considered a wave, it also seems to have particulate behavior because many molecules can change shape or emit electrons when bombarded with a certain discrete frequency of light, independent of the intensity of the light. Photons are massless and travel at the speed of light or could simply be conceived as part of the light wave. Protons are real positively charged molecules inside a nucleus of an atom. Each proton has 1 unit of mass (about 6x10^-23 g). According to Einstein’s principle of relativity, only a massless molecule (e.g., photon) can travel at the speed of light (3x10^8 m/s).

Question 29

The energy that excites P680 and P700 is supplied by: A) electrons passing down the electron transport chain. B) ATP. C) photons. D) NADPH.

Answer 29

C. Photons. Note: The 680 and 700 refer to the wavelength of light in nm.

Question 30

As a result of the cascade of electrons down the electron transport chains of the light reactions: A) NADPH is reduced to NADP+. B) NADPH is oxidized to NADP+. C) NADP+ is reduced to NADPH. D) NADP+ is oxidized to NADPH.

Answer 30

C. NADP+ is reduced to NADPH. Note: NADP+ is the final electron acceptor in the light reaction of photosynthesis. It picks up an electron to become NADPH. Remember again, picking up an electron is considered “reduction.” NADPH is oxidized back to NADP+ during the light-independent reaction (Calvin cycle) and is recycled.

Question 31

The electrons lost from the reaction center of photosystem II are replaced by electrons from: A) CO2. B) ATP. C) H2O. D) photosystem I.

Answer 31

C. H2O. Note: H2O is the initial electron donor of the electron transport chain during the light reaction of photosynthesis.

Question 32

Photosystem II: A) has P700 at its reaction center. B) passes electrons to photosystem I. C) does not have a reaction center. D) releases CO2 as a by-product.

Answer 32

B. Passes electrons to photosystem I.

Question 33

Photophosphorylation during photosynthesis differs from oxidative phosphorylation during cellular respiration in that: A) it involves an electron transport chain. B) energy is stored in the form of a proton concentration difference. C) regeneration of ATP is driven by a flow of protons through an ATP synthase. D) the final electron acceptor is NADP+ and not oxygen.

Answer 33

D. The final electron acceptor is NADP+ and not oxygen. Note: The final electron acceptor during oxidative phosphorylation phase of cellular respiration (also known as the Electron Transport Chain) is oxygen. O2 picks up electrons and reacts with H+ to become H2O.

Question 34

In photophosphorylation, energy from electron flow is used to transport ________ from the ________ to the thylakoid compartment, generating a concentration gradient of ________. A) electrons . . . grana . . . H+ B) H+ . . . grana . . . electrons C) H+ . . . stroma . . . H+ D) H+ . . . stroma . . . ATP

Answer 34

C. H+ . . . stroma . . . H+. Note: H+ gradient is generated during electron transport in the light reaction of photosynthesis and the electron transport chain of cellular respiration. The H+ then pass through an ATP synthase to generate ATP in BOTH cases.

Question 35

The chloroplast ATP synthase: A) is a nucleic acid complex. B) couples the flow of H+ to the phosphorylation of ADP. C) is found in the stroma. D) helps transport H+ against the concentration gradient.

Answer 35

B. couples the flow of H+ to the phosphorylation of ADP. Note: Both the chloroplast ATP synthase and mitochondrial ATP synthase are bacterial in origin. They are structurally similar and function in a similar way, and both are known as F-type ATPase.

Question 36

In photosynthesis, the chemiosmotic production of ATP: A) requires oxygen. B) is analogous to the production of ATP in mitochondria. C) is done by the Calvin cycle. D) is a result of the oxidation of glucose.

Answer 36

B. Is analogous to the production of ATP in mitochondria. Note: The F1 ATPase used for producing ATP in chloroplast is very similar to the one found in mitochondria. They produce ATP with the identical principle.

Question 37

Mitochondria transfer ________ energy from ________ to ATP; chloroplasts transform ________ energy into the chemical energy of ATP. A) chemical . . . food . . . light B) food . . . light . . . chemical C) light . . . food . . . kinetic D) food . . . light . . . nuclear

Answer 37

A. Chemical . . . food . . . light.

Question 38

Photosynthetic organisms derive their carbon from A) carbon monoxide. B) carbon dioxide. C) hydrocarbons. D) methane.

Answer 38

B. Carbon dioxide is the main source of carbon for photoautotrophs. In the ocean CO2 dissolves in water to become HCO3- (bicarbonate ion) and that’s the main source of carbon for marine photosynthetic organisms.

Question 39

ATP and NADPH: A) power sugar synthesis during the Calvin cycle. B) are products of the Calvin cycle. C) provide energy to Photosystem I and Photosystem II. D) are used in the electron transport chain to pump H+ into the thylakoid space.

Answer 39

A. Power sugar synthesis during the Calvin cycle.

Question 40

To produce one glucose, the Calvin cycle needs to be run through ________ time(s). A) two B) four C) six D) eight

Answer 40

A. two Note: The immediate product from the Calvin cycle is called G3P. It is a 3-carbon compound. 2 G3P are needed to form 1 glucose. You produce 1 G3P after running a cycle once (3 CO2 is absorbed each time).

Question 41

The Calvin cycle constructs ________, an energy-rich molecule that a plant cell can then use to make glucose or other organic molecules. A) G3P B) ATP C) NADH D) carbon dioxide

Answer 41

A. G3P.

Question 42

The addition of oxygen instead of carbon dioxide to RuBP results in: A) cellular respiration. B) photorespiration. C) photophosphorylation. D) aerobic respiration.

Answer 42

B. Photorespiration. Note: The enzyme Rubisco that attaches CO2 to RuBP makes a mistake 1/4 times and puts oxygen on RuBP instead. This “mistake” phenomenon is known as photorespiration. This actually reduces photosynthetic yield output by 25%.

Question 43

Photorespiration: A) may be an evolutionary relic from when atmospheric O2 levels were low. B) is of benefit to the plant since it breaks down rubisco. C) is attributable to high CO2 levels. D) produces glucose.

Answer 43

A. May be an evolutionary relic from when atmospheric O2 levels were low.

Question 44

What is the main adaptive advantage of the C4 and CAM photosynthesis strategies over the C3 strategy? A) They help the plant conserve water and synthesize glucose efficiently under hot, dry conditions. B) They allow the plant to fix carbon more efficiently under conditions of low atmospheric CO2. C) They allow the plant to fix carbon more efficiently in dim or cool conditions. D) They make it possible for the plant to use the Calvin cycle at night. E) Both A and B

Answer 44

E. Both A and B. Note: Both CAM plants and C4 plants utilize the C4 pathway for carbon fixation (using phosphoenolpyruvate as the carbon acceptor and forming a 4-carbon product called malate) and are both C4 plants. CAM plants only open the stomata at night as a water conservation measure. A is true of CAM plants, and B is true of any C4 plants.

Question 45

The ultimate source of all the food we eat and the oxygen we breathe is: A) cellular respiration. B) photosynthesis. C) glycolysis. D) anaerobic metabolism.

Answer 45

B. Photosynthesis. Note: Specifically, the light reaction of photosynthesis produces oxygen (by splitting water), and the Calvin cycle fixes carbon dioxide into sugars.

Question 46

Plants use sugars as: A) a fuel for photosynthesis. B) a starting material for the Calvin cycle. C) a source of electrons for chemiosmosis. D) a fuel for cellular respiration and a starting material for making other organic molecules.

Answer 46

D. A fuel for cellular respiration and a starting material for making other organic molecules. Note: Plants carry out cellular respiration ALL THE TIME, just like animals too! Only the leaves can produce energy (ATP) when exposed to light. The rest of the plants have to get energy by metabolizing sugars in cellular respiration. During the day, photosynthesis usually dominates, and there is net absorption of CO2 and emission of O2. When there is no light, plants will emit CO2 and take in O2, just like animals and other living organisms!

Question 47

Plant cells: A) lack mitochondria and chloroplasts. B) lack mitochondria but have chloroplasts. C) have mitochondria but do not have chloroplasts. D) have mitochondria and chloroplasts.

Answer 47

D. Have mitochondria and chloroplasts.

Question 48

Global warming due to the greenhouse effect may be: A) moderated by photosynthesis, which removes carbon dioxide from the atmosphere. B) made worse by photosynthesis, which adds carbon dioxide to the atmosphere. C) reduced by the burning of fossil fuels, which removes oxygen from the atmosphere. D) of little concern, since it is part of the normal cycle for the planet.

Answer 48

A. Moderated by photosynthesis, which removes carbon dioxide from the atmosphere.

Question 49

Which of the following statements about the greenhouse effect is true? A) The greenhouse effect is reduced by deforestation. B) The greenhouse effect is exacerbated by the use of fossil fuels. C) The greenhouse effect will decrease the average temperature of the planet. D) The greenhouse effect has no direct relationship with the Industrial Revolution of the 1800s.

Answer 49

B. The greenhouse effect is exacerbated by the use of fossil fuels. Note: I have nothing to say if you don’t believe that’s true, except for, I feel really sorry for you…lol..

Question 50

Which of the following has been a major source of ozone destruction over the past 50 years? A) chlorofluorocarbons B) ethylene glycol C) carbon dioxide D) chemiosmosis

Answer 50

A. Chlorofluorocarbons. Note: CFC was very common in aerosol spray before the 1990s but was found to damage the ozone layer. The chemical was finally banned in the 1990s, and the ozone layer has recovered since then.

Question 51

In this drawing of a chloroplast, which structure represents the thylakoid membrane? A) structure A B) structure B C) structure C D) structure D

Answer 51

C. Structure C.

Question 52

According to this figure, how do H+ ions make their way from the stroma to the thylakoid interior? A) through photosystem I B) through an electron transport chain molecule C) through the ATP synthase D) directly through the phospholipids of the thylakoid membrane

Answer 52

B. Through an electron transport chain molecule.

Question 53

Scenario Questions: After reading the paragraph, answer the question(s) that follow. You're conducting an experiment to determine the effect of different wavelengths of light on the absorption of carbon dioxide as an indicator of the rate of photosynthesis in aquatic ecosystems. If the rate of photosynthesis increases, the amount of carbon dioxide in the environment will decrease and vice versa. You've added an indicator to each solution. When the carbon dioxide concentration decreases, the color of the indicator solution also changes. Small aquatic plants are placed into three containers of water mixed with carbon dioxide and indicator solution. Container A is placed under normal sunlight, B under green light, and C under red light. The containers are observed for a 24-hour period. 1) Based on your knowledge of the process of photosynthesis, the plant in the container placed under red light would probably: A) absorb no CO2. B) absorb the same amount of CO2 as the plants under both the green light and normal sunlight. C) absorb less CO2 than the plants under green light. D) absorb more CO2 than the plants under the green light.

Answer 53

D. Absorb more CO2 than the plants under the green light.

Question 54

2) Carbon dioxide absorption is an appropriate indicator of photosynthesis because: A) CO2 is needed to produce sugars in the Calvin cycle. B) CO2 is needed to complete the light reactions. C) plants produce oxygen gas by splitting CO2. D) the energy in CO2 is used to produce ATP and NADPH.

Answer 54

A. CO2 is needed to produce sugars in the Calvin cycle.