bio 110 ch 8

the end product of phase 2 of the calvin cycle is G3P. this molecule is used to synthesize ______ and to regenerate the starting material ______ biphosphate

1. carbohydrates 2. RuBP

in photosynthesis, light energy is converted to ______ energy, which in turn is converted to _______ energy in a sugar molecule

1. electrochemical energy 2. chemical energy

PSI and PSII have two main components: a(n) _______ harvesting complex and a(n) ______ center

1. light-harvesting complex 2. reaction center

According to the Z scheme, how many photoactivation events occur during photosynthesis?

2

in some plants, carbon fixation yields a four-carbon molecule instead of 3GP as the first product. such plants are known as ______ plants

C4 plants

_____ plants avoid water loss by closing their stomata during the day and opening them at night.

CAM

how do CAM plants avoid water loss?

CAM plants close their stomata during the day and open them at night

how is NADPH formed in PSI

NADP+ reductase adds two electrons and a H+ to NADP+

the key role of PSI is to produce high-energy electrons that are used to make

NADPH

what are products of the light reactions that are used by the calvin cycle to make carbohydrates?

NADPH and ATP

during photosynthesis, NADPH is synthesized by

Photosystem I

what happens during photorespiration?

Rubisco attaches to O2 to RuBP, and CO2 is produced

the model for photosynthesis that incorporates two photoactivation events and shows the series of energy changes during the light reactions of photosynthesis is called the ______ scheme

Z scheme

in C4 plants, the first product of carbon fixation is

a four-carbon molecule

a pigment is a molecule that can

absorb light

summarize the events of the first phase of the calvin cycle

atmospheric carbon dioxide is fixed into a five carbon sugar

why is light considered a form of electromagnetic radiation?

because it consists of both electric and magnetic energy

plants appear green because they contain

chlorophyll

the green color of plants is due primarily to the absorptive properties of the pigment _______ found in the chloroplasts

chlorophyll

green plants utilize ______ a and b to absorb light energy in photosynthesis

chlorophyll a and b

light is a type of ______ radiation because it consists of energy in the form of electric and magnetic fields

electromagnetic radiation

after a pair of _____ reach the QB, each enters a transport chain in the thylakoid membrane.

electrons

sunlight provides the ______ that is necessary for the synthesis of glucose from carbon dioxide

energy

true or false: glucose is the primary output of the calvin cycle

false

what is the primary output of the calvin cycle?

glyceraldehyde 3-phosphate

________ genes are similar to each other because they are derived from the same ancestral gene

homologous genes

the energy that is released as electrons pass from one electron carrier to the next is used to pump ______ ions into the thylakoid lumen

hydrogen ions

what is the function of chlorophyll during photosynthesis?

it absorbs light energy

what happens to a pair of electrons after it reaches QB?

it enters an electron transport chain in the thylakoid membrane

_______ excite(s) electrons in pigment molecules in photosystems 1 and 2

light

what energy conversion occurs in photosynthesis?

light energy is converted to electrochemical energy, which is converted to chemical energy

how does an electron present in the pigment of the light-harvesting complexes become excited?

light excites an electron in a pigment found in the light-harvesting complexes of the photosystems

the flow of electrons from PSII to PSI is considered to be

linear electron flow (noncyclic electron flow)

Heterotroph definition

must consume food to obtain organic molecules

what molecule is produced by photosystem 2?

oxygen

in hot, dry conditions, rubisco can attach O2 to RuBP in a process called ______. which ultimately produces CO2

photorespiration

the process by which plants capture light energy and use it to synthesize glucose and other organic molecules is called

photosynthesis

a molecule that can absorb light energy is called a

pigment

the light-harvesting complex is composed of several dozen ______ molecules that are anchored to transmembrane proteins

pigment

what happens during photosynthesis?

plants capture energy from sunlight and use it to synthesize organic molecules

Autotroph definition

produces organic molecules from inorganic molecules

what are components of both PSI and PSII?

reaction center and light harvesting complex

in the calvin cycle, CO2 is

reduced

In the last phase of the Calvin cycle, what molecule is regenerated so that the next cycle can occur?

ribulose bisphosphate

the reactions of the calvin cycle occur in the

stroma

the energy required for the synthesis of glucose from carbon dioxide ultimately comes from

sunlight/the sun

Photosystems 1 and 2 are found in the

thylakoid membrane

Where do light reactions occur?

thylakoid membrane

the ______ membrane of the chloroplast contains two independent, light capturing complexes of proteins and pigments called photosystems 1 and 2

thylakoid membrane

purpose of phase 3 of the calvin cycle?

to create a new 5 carbon sugar for the next calvin cycle

photoautotroph definition

uses light energy to drive the synthesis of organic molecules from inorganic molecules

the electrons that exit PSII (photosystem 2) are replenished by electrons from oxidized ______. which yields oxygen gas that can be used by plant cells or released to the environment

water

What is carbon fixation?

It is the initial incorporation of CO2 into organic material.

the energy released as electrons pass from an electron carrier to another in the electron transport chain between photosystem II and photosystem I is used to

- pump H+ - establish an electromagnetic gradient

the G3P produced at the end of the second phase of the calvin cycle is directly used for which of the following?

- regenerate ribulose biphosphate - make glucose or other carbohydrates

what conditions affect the way the calvin cycle operates in photosynthetic organisms?

- water availability - temperature - light intensity

NADP+ reductase transfers two _______ and one _______ to NADP+ to generate NADPH

1. 2 electrons 2. 1 Hydrogen Ion (H+)

sequence of the phases of the calvin cycle from first (one top) to last

1. Carbon fixation 2. reduction and carbohydrate production 3. regeneration of ribulose biphosphate

A(n) _______ can synthesize organic molecules from inorganic molecules, while a(n) ______ must consume food to obtain organic molecules

1. autotroph 2. heterotroph

in the first phase of the ______ ______ atmospheric carbon dioxide is fixed into a 5 carbon sugat

calvin cycle

the incorporation of carbon from CO2 in the atmosphere into an organic molecule is called carbon ________

carbon fixation

in the light reactions, ATP is generated via:

chemiosmosis

similar to ATP synthesis in the mitochondria, ATP synthesis in chloroplasts is achieved by a(n) _______ mechanism called photo phosphorylation

chemiosmotic mechanism