biology chapter 5

The Calvin cycle cannot proceed without the molecules _____ and ____ which are produced by the light reactions of photosynthesis

ATP NADPH

What is produced in the light reactions which provides energy and reducing power for the carbon reactions?

ATP and NADPH

protons diffusing through the enzyme complex called _______ _______ provide energy that the enzyme uses to generate ATP in the light reactions.

ATP synthase

Photorespiration Rubisco binds oxygen and eventually releases carbon dioxide (reverse of carbon fixation). Takes place in C3 plants when stomata are closed and O2 concentration in leaves rises.

C3 pathway CO2 binds to rubisco to form PGA the first step in a pathway that fixes carbon as glucose. takes place in C3 plants when stomata are open and O2 concentrations in leaves are low.

1. Carbon dioxide diffuses into the leaf when stomata are open at night. 2. Carbon dioxide is stored as a four-carbon molecule in vacuoles within mesophyll cells. 3. The stored four-carbon molecule is moved from vacuoles to chloroplasts of mesophyll cells and carbon dioxide is released. 4. Carbon dioxide enters the Calvin cycle when the stomata are closed during the day.

CAM pathway

1. The enzyme rubisco combines carbon dioxide with RuBP to form a six-carbon unstable molecule. 2. The 6-carbon molecule splits to form PGA 3. PGA is converted into PGAL 4. Some PGAL is converted into glucose and other sugars, and some PGAL is converted back to RuBP

Calvin cycle

CAM photosynthesis

Carbon dioxide is incorporated into a 4-carbon molecule at night, and the Calvin cycle takes place during the day in mesophyll cells.

C3 pathway

Carbon dioxide is used by the enzyme rubisco to produce PGA

C4 photosynthesis

Carbon dioxide is used to produce oxaloacetate, and the Calvin cycle takes place in bundle-sheath cells.

products of the Calvin cycle

NADP+ glucose (from PGAL) ADP

The second electron transport chain of the light reactions uses electrons to reduce NADP+ and form

NADPH

photorespiration

Oxygen is used by the enzyme rubisco in an energetically wasteful reaction

When carbon dioxide enters the Calvin cycle, it combines with _________, which is a 5-carbon sugar with two phosphate groups

RuBP

Within the chloroplast, the gelatinous fluid containing DNA, ribosomes, and enzymes is called the

STROMA

In the light reactions of photosynthesis, what drives the synthesis of ATP by ATP synthase?

a proton gradient across the thylakoid membrane

Compared to a plant with accessory pigments, a plant without accessory pigments would

absorb less light

chlorophyll b

accessory pigment that reflects green wavelengths of light

carotenoids

accessory pigment that relect red, orange, and yellow wavelengths of light

Heterotrophs

animals, humans, fungi

The _______ pigments of photosystems pass the captured photon energy to the reaction center.

antenna

Within a photosystem, what pigments capture photon energy and funnel the energy to the reaction center chlorophyll?

antenna pigments

What type of organism has the ability to make its own food?

autotroph

________ use inorganic molecules to make organic compounds in processes including photosynthesis.

autotrophs

____________ use inorganic molecules to make organic compounds in processes including photosynthesis

autotrophs

_____________ use inorganic molecules to make organic compounds in processes including photosynthesis.

autotrophs

peanuts most trees spinach

c3 plants

sugarcane corn crabgrass

c4 plants

pineapple cacti

cam plants

The second stage of photosynthesis is called the _____ reactions, which use ATP and NADPH to reduce carbon dioxide to glucose molecules

carbon

NADPH and carbon dioxide are reactants in the

carbon reaction

two stages of photosynthesis

carbon reactions light reaction

The green, photosynthetic pigment found in plants, algae, and cyanobacteria is called _______ a.

chorophyll

What happens to the glucose produced in photosynthesis?

combined with other molecules to form larger compounds used to build cellulose of cell walls used as energy for cellular respiration

During the light reactions, energized _____________ from a reaction center chlorophyll a molecule are eventually donated to form the molecule NADPH

electron

A group of proteins in the thylakoid membrane that shuttles electrons between proteins is called ____ ___ chain

electron transpot

Photosynthesis is considered an oxidation-reduction process because

electrons are transferred between molecules

ATP is a nucleotide that stores potential __________ between phosphate groups

energy

Electron transport chains release __________ through shuttling of electrons in the light reactions.

energy

In the Calvin cycle, ATP and NADPH are used to convert carbon dioxide into

glucose and other sugars

In each chloroplast, there are between 10 and 100 ________, which are of stacks of thylakoids

grana

Green tires stacked inside the chloroplast

granum

How does life depend on photosynthesis?

incorporates atmospheric CO2 into organic compounds feeds photosynthesizers directly feeds heterotrophs indirectly produces oxygen essential to many forms of life

A long wavelength contains _____ energy compared to the energy contained by a short wavelength.

less

When stomata are closed in C# plants, water loss is __________ and photorespiration is ____________.

low high

chlorophyll a

most abundant pigment in plants; reflects green wavelengths of light

In the CAM pathway, stomata are ___________ at night when water loss is less and are _______________ during the day while maintaining a high concentration of carbon dioxide in the chloroplasts.

open closed

1. The electron transport chain receives energized electrons from photosystem II. 2. Electrons are shuttled through a series of proteins in the thylakoid membrane. 3. The energy lost from the electrons drives the active transport of protons from the stroma into the thylakoid space. 4. The electrons are passed to photosystem I.

order during the first transpot chain of the light reacttions, between photsystem II and photosystem I.

Light consists of ________, which are discrete packets of kinetic energy.

photons

If stomata remain open, carbon dioxide diffuses into the plant and oxygen diffuses out, therefore minimizing __________ but maximizing water loss

photorespiration

In a metabolic pathway called ________, plants algae, and some types of bacteria convert solar energy into chemical energy, such as glucose.

photosynthesis

Plants, algae, and some microorganisms use energy from the sun to make organic molecules in a process called

photosynthesis

A grouping of photosynthetic pigments and associated proteins is called a ________, which is embedded in the thylakoid membrane of chloroplasts.

photosystem

A grouping of photosynthetic pigments and associated proteins is called a _________, which is embedded in the thylakoid membrane of chloroplasts

photosystem

1. Antenna pigments capture a photon of light. 2. Energy is passed to the electrons of the reaction center. 3. Two excited electrons are passed to the second electron transport chain.

photosystem I

1. Antenna pigments capture a photon of light 2. Light energy is transferred to the reaction center. 3. Two electrons carrying potential energy are passed to the electron transport chain.

photosystem II

What part of a plant cell captures light energy?

pigment molecules

reactant carbon dioxide (CO2) water (H2O)

product oxygen (O2) glucose (C6H12O6)

all the components of a photosystem

proteins a reaction canter chlorophyll accessory pigments chlorophyll pigments

In a photosystem, antenna pigments capture photon energy and funnel it to the __________ __________, which consists of a chlorophyll a molecule and its associated proteins

reaction center

The enzyme that combines carbon dioxide and RuBP and is known as

rubisco

Gases enter and exit a plant leaf through openings called

stomata

Plants conduct gas exchange in photosynthesis by bringing in carbon dioxide and releasing oxygen through openings called __________.

stomata

The openings in the epidermis of a leaf or stem for gas exchange are called ______

stomata

plants in dry environments must regulate when ________ open and close to minimize both water loss and a wasteful metabolic pathway called _____________, in which O2 instead of CO2 binds to rubisco.

stomata photorespiration

The carbon reactions of photosynthesis occur in the _____, which is the fluid interior of chloroplasts.

stroma

fluid in the interior of a chloroplast

stroma

How do antenna pigments enhance the efficiency of photosynthesis?

they transfer captured light energy to where photosynthetic reactions occur

The light reactions occur in the

thylakoid membranes

True or false: Accessory pigments extend the range of light that a cell can harness.

true

The portion of the electromagnetic spectrum that plants use for photosynthesis is

visible light

The oxygen by-product of photosynthesis is created by the splitting of _____ molecules to replace the electrons ejected from the reaction center of photosystem II.

water

What molecule donates two electrons to the reaction center chlorophyll a of photosystem II to replace the electrons that were passed to the 1st electron transport chain?

water

events that occur in the C4 pathway

water loss is minimized The light and carbon reactions take place in different locations.