Ch. 7 Photosynthesis

Question 1

Autotrophs

Answer 1

Make own energy through process of photosynthesis and sustain themselves

Question 2

Photoautotrophs

Answer 2

Use energy of light to produce organic molecules

Question 3

Chemoautotrophs

Answer 3

Use inorganic chemicals as their energy source

Question 4

Heterotrophs

Answer 4

Consumers that feed on plants or animals

Question 5

Chloroplasts

Answer 5

Light absorbing organelles; site of photosynthesis

Question 6

Chlorophyll

Answer 6

Light absorbing molecule that makes plants green and plays a role in converting solar energy to chemical energy; concentrated in cells of mesophyll

Question 7

Stomata

Answer 7

Tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit

Question 8

Stroma

Answer 8

Thick fluid enclosed by the inner membrane of a chloroplast

Question 9

Thylakoids

Answer 9

Interconnected membranous sacs suspended in the stroma; house much of the machinery that converts light energy to chemical energy

Question 10

Where are thylakoids concentrated?

Answer 10

In stacks called grana

Question 11

How does the structure of a chloroplast aid in its function?

Answer 11

The stacks and disks provide a large surface area for the reactions of photosynthesis

Question 12

What is the function of the internal compartment of thylakoids?

Answer 12

Thylakoid space, works in similar function to the intermembrane space of a mitochondrian

Question 13

Chlorophyll molecules (pigments)

Answer 13

Built into thylakoid membrane and capture light energy

Question 14

Light Reactions

Answer 14

Chlorophyll absorbs light energy and converts it to ATP and NADH; water is split and given off as oxygen

Question 15

NADH

Answer 15

Electron carrier

Question 16

Calvin Cycle

Answer 16

Uses products of light reactions to synthesize carbon dioxide to sugar

Question 17

What happens to the enzymes that drive the Calvin Cycle?

Answer 17

They are dissolved in the stroma

Question 18

What drives the energy needed for sugar synthesis?

Answer 18

The ATP generated by the light reactions

Question 19

How does the NADH produced in light reactions aid in the Calvin Cycle?

Answer 19

Provides the high energy electrons that drive the synthesis of glucose from carbon dioxide

Question 20

Does the Calvin Cycle require light?

Answer 20

Not directly. Often referred to as dark reactions or light independent.

Question 21

Carbon Fixation

Answer 21

Initial incorporation of carbon from CO2 into organic compounds (removal of carbon from air)

Question 22

What type of energy does sunlight contain?

Answer 22

Electromagnetic energy

Question 23

Electromagnetic Spectrum

Answer 23

Visible light

Question 24

Photons

Answer 24

Fixed quantity of light energy; shorter wavelengths=more energy

Question 25

Chlorophyll a

Answer 25

Absorbs blue-violet and red light. Reflects green; participates directly in light reactions

Question 26

Chlorophyll b

Answer 26

Absorbs blue and orange. Reflects yellow-green; Does not participate directly in light reactions

Question 27

Carotenoids

Answer 27

Family of yellow-orange pigments. Absorb mainly blue-green light

Question 28

What is the function of carotenoids?

Answer 28

Provide photoprotection: dissipate excess light energy that would otherwise damage chlorophyll. Also interact with oxygen to form reactive oxidative molecules

Question 29

What happens when chloroplasts absorb photons (light energy)?

Answer 29

Increases the potential energy of the pigment’s electrons and sends the electrons into an unstable state

Question 30

What happens to the unstable electrons after photons are absorbed?

Answer 30

Drop back down to their “ground state” and release their excess energy as heat

Question 31

Photosystem

Answer 31

Cluster of a few hundred pigment molecules that functions as a light gathering antenna

Question 32

What happens when a photon strikes one of the pigment molecules?

Answer 32

The light energy jumps from molecules to molecule until it arrives at the reaction center of the photostem

Question 33

What happens when the light energy reaches the reaction center?

Answer 33

A primary electron acceptor accepts these electrons and becomes reduced = 1st stage of converting light energy to chemical energy

Question 34

How do light reactions generate ATP and NADH?

Answer 34

Electrons are removed from water and passed from photosystem II to I, then accepted by NADP+ and reduced to NADH. Between the two photosystem, electrons move down the ETC and provide energy for the synthesis of ATP

Question 35

Electron Transport Chain

Answer 35

Provides energy for the synthesis of ATP by chemosis

Question 36

Chemosis

Answer 36

Powers ATP in light reactions because the ETC produces a concentration gradient of hydrogen ions across a membrane

Question 37

How does the calvin cycle make sugar from carbon dioxide?

Answer 37

With the energy of ATP and the electrons from NADPH, the carbons from CO2