Chapter 5: Photosynthesis

Chlorophyll's absorption spectrum

explains why chlorophyll is green.

The light-dependent reactions in plants occur in the

thylakoid membrane.

An electron from Photosystem II is lost when it is excited by a photon of light. Photosystem II is supplied with another electron from

water.

In photolysis, energy from light is used to split

water.

Johann Baptista van Helmont concluded that the willow tree gained its weight from

water.

In the Calvin cycle, _______ ATP's and ________ NADPH's are required for a net output of two molecules of glyceraldehyde 3-phosphate.

18; 12

The six-carbon molecule that results from carbon fixation in the Calvin cycle immediately breaks down into

3-phosphoglycerate

Visible light ranges between

380-750 nm.

In the regeneration phase of the Calvin cycle 10 glyceraldehyde 3-phosphates will be regenerated into __________ RuBP.

6

A photon with a wavelength of __________ is optimal to move an electron from ground state to an excited state in Photosystem I.

700 nm

Which of the following takes place as a result of photosynthetic electron transport?

A proton gradient is established across the thylakoid membrane.

Which of the following molecules are both produced by reactions in the thylakoids and consumed by reactions in the stroma?

ATP and NADPH

Which statement about the Calvin cycle is incorrect?

ATP and NADPH form during the reduction phase.

Which statement is true regarding cyclic electron flow in photosynthesis?

ATP is produced without increasing the amount of NADPH.

The end products of the light-dependent reactions of photosynthesis include

ATP, NADPH, and O2

How is photosystem II linked to photosystem I?

An electron from photosystem II is passed to photosystem I.

The most likely candidate for the first photosynthetic organisms are the

Archaea.

How are C4 and CAM plants similar?

Both cases employ an enzyme other than rubisco to initially fix carbon.

In what way do CAM plants and C4 plants differ?

Carbon fixation is not separated from the Calvin cycle in CAM plants, while it is in C4 plants.

Which of the following statements regarding chlorophyll is false?

Chlorophyll a has one major absorption peak at approximately 550 nm.

Which statement is not true?

Chlorophyll a is green because it absorbs green wavelengths.

Which statement about rubisco is true?

It uses carbon dioxide as a substrate.

Who found that plants give off oxygen in the presence of light and give off some carbon dioxide in the dark?

Jan Ingenhousz

Chlorophyll contains a porphyrin ring that has a hydrocarbon tail attached. Which of the following atoms is found in the center of the porphyrin ring?

Mg

Why is it difficult for most plants to carry out photosynthesis during hot, dry conditions?

Oxygen builds up and carbon dioxide levels get too low because of the closing of the stomata.

Which takes place when a C4 plant first fixes carbon dioxide?

PEP carboxylase is required.

Which of the following is the major difference between cyclic and noncyclic photophosphorylation?

Photosystem II is not involved in cyclic photophosphorylation.

Which statment regarding stomata is false?

Stomata allow for uptake of water vapor from the atmosphere.

The reactions of the Calvin cycles are referred to as light-independent reactions, yet in most plants they occur during daylight hours. Why?

The Calvin cycle depends on ATP and NADPH from the light-dependent reactions.

The Calvin cycle is light independent but typically occurs during the day. Why?

The Calvin cycle depends on products of the light reactions.

Which of the following statements is correct?

The Calvin cycle is an example of light independent metabolism.

Which of these conversions in the Calvin cycle uses the NADPH and ATP from the light-dependent reactions?

The conversion of 3-phosphoglycerate to glyceraldehyde 3-phosphate.

Which of these statements concerning the light-dependent reactions of photosynthesis is not true?

The energy lost from the excited electrons can be used to split carbon dioxide if it is present in large quantities.

Regarding the light-dependent reactions, which statement is correct?

The light-dependent reactions take in water and release oxygen to produce ATP and NADPH.

What happens when water containing an oxygen isotope is supplied to a plant?

The oxygen isotope is released into the air.

__________ is the source of energy for life on Earth.

The sun

Which statement about light is incorrect?

The wavelength of a photon is directly proportional to its energy.

Which of the following statements regarding water's role in photosynthesis is the most accurate?

Water is split during photosynthesis.

Which of the following does not take place during cyclic photophosphorylation?

Water provides electrons to photosystem I.

Which structure is found within the thylakoid membrane?

a light-harvesting antenna

During photorespiration

a two-carbon molecule leaves the chloroplast for every oxygen molecule that binds to RuBP.

An action spectrum for a plant has less extreme peaks and valleys than an absorption spectrum for chlorophyll a of the same plant because

an action spectrum reflects the presence of other pigments in the plant.

The relative effectiveness of different wavelengths of light on the rate of photosynthesis is shown by

an action spectrum.

The light harvesting antennae

are groups of pigments that help capture energy from light in a photosystem.

The extant Archaean group known as the extreme halophiles use a pigment called ___________________ to harness light energy.

bacteriorhodopsin

The main source of carbon in photosynthesis is from

carbon dioxide.

Which of the following is not a stage in the Calvin cycle?

carbon regeneration

During photosynthesis, photophosphorylation and photolysis both occur in the

chloroplasts.

Electrons are excited and leave Photosystem I where they are then taken up by an electron acceptor. The electron acceptor passes them down an electron transport chain of proteins and eventually they are passed back to Photosystem I. What is the name of this pathway?

cyclic electron flow

A major difference between cyclic and noncyclic photophosphorylation is

cyclic photophosphorylation produces no NADPH.

Protons in the lumen of the thylakoid

diffuse out of the lumen to make ATP.

A reaction center of a chloroplast is

embedded in the thylakoid.

Chlorophyll glows red when it is hit with UV light because

energy is released from an electron that falls to its ground state.

True or false? Electrons in the chlorophyll molecule become so excited that they escape to a lower energy level.

false

True or false? Leaves appear green to us because green light is mostly absorbed by chlorophyll a.

false

True or false? NADP is an electron donor during photosynthesis.

false

True or false? Plants are heterotrophs, because they rely on water, light, and carbon dioxide for food.

false

True or false? The C4 and C3 pathways differ in that they take place at different times, whereas CAM and C3 pathways differ in that they occur at different locations within the leaf.

false

True or false? The cuticle is also referred to as the upper epidermis.

false

A proton gradient is formed in both mitochondria and chloroplasts. The chloroplasts differ from the mitochondria in that their proton gradient

flows outward from a lumen rather than inward.

Which of the following molecules represents the end-product of the Calvin cycle?

glyceraldehyde 3-phosphate

Stacks of membranous compartments in chlorplasts are referred to as

grana.

The energy content for visible light is greatest for

green light.

In a hypothetical scenario, the first photosynthetic unit used bacteriorhodopsin as an antennae to capture light and generate a gradient of ____________________ drove the synthesis of ATP.

hydrogen ions

Where would you expect to find the lowest pH in a chloroplast of an actively photosynthesizing cell?

in the lumen of the thylakoid

Where is ATP produced in the light reactions?

in the stroma.

The mesophyll of the leaf

is a tissue composed of cells separated by numerous air spaces.

Ribulose bisphosphate plays an important role in

light independent reactions of photosynthesis.

Chloroplasts are mostly located in the __________.

mesophyll

When an electron from Photosystem I is excited and transferred to a primary electron acceptor, the chlorophyll a in the reaction center will be __________.

oxidized

The waste byproduct produced by photosynthesis in cyanobacteria is

oxygen gas

Light is composed of particles of energy called

photons.

Water's role in photosynthesis is to

provide electrons to the light-dependent reactions.

The Calvin cycle begins when carbon dioxide reacts with what five carbon molecule?

ribulose bisphosphate

Cornelius van Niel discovered that

some bacteria are able to combine the hydrogen from hydrogen sulfide with carbon dioxide to produce carbohydrates.

Carbon dioxide is taken in and water vapor and oxygen are released through the

stoma

The fluid outside of the granum in a chloroplast is called the ___________.

stroma

Based on his findings, Cornelius van Niel was able to conclude

that it was possible that plants split water to release oxygen and make carbohydrates.

Joseph Priestly discovered that

the gas that a mouse removes from the air is produced by plants.

The major site of photosynthesis in plants occurs in the

the leaf.

The addition of carbon dioxide to a five-carbon intermediate followed by a reduction of the product of that reaction is called __________ and occurs in the __________.

the light-independent reactions; the stroma of the chloroplast

Chlorophyll is a green pigment found embedded in

the membrane that makes up the grana.

During the general process of photosynthesis, the energy from light is used to accomplish which process?

the oxidation of water

In the light-dependent reactions __________ takes place, while in the light-independent reactions __________ takes place.

the splitting of water; carbon fixation

In eukaryotic photosynthesis, the transfer of electrons through membrane proteins provides energy to pump protons across

the thylakoid membrane.

Aerobic respiration and the light dependent phases of photosynthesis have all of the following characteristics in common except

they both consume oxygen.

The first photosynthetic organisms were likely archaeans because

they evolved later than bacteria, the first heterotrophs.

The purpose of cyclic electron flow is

to increase the ATP/ NADPH ratio.

True or false? An electron in chlorophyll a is excited to a higher energy level by light and is passed to a nearby electron acceptor molecule in the thylakoid.

true

True or false? Chlorophyll b and carotenoids are pigments used by plants to increase the wavelengths of light that can be used for photosynthesis.

true

True or false? Chlorophyll is able to act as a reducing agent.

true

True or false? Chloroplasts are organelles that are composed of three membranes.

true

True or false? During the C4 pathway, carbon dioxide is fixed in the mesophyll cells and enters the Calvin cycle in the bundle-sheath cells.

true

True or false? Rubisco binds to both oxygen and carbon dioxide.

true

True or false? Water provides the source of electrons in the formation of carbohydrate from CO2 during photosynthesis.

true

True or false? When a chlorophyll molecule becomes excited by light, it becomes a reducing agent.

true

Which of the following sequences correctly represents the flow of electrons in the light-dependent reactions of photosynthesis?

water, Photosystem II, Photosystem I, NADP

During photosynthesis __________ is oxidized and __________ is reduced.

water; carbon dioxide