Chapter 8 Photosynthesis

Question 1

Photosynthesis

Answer 1

Energy from light that is captured and used to synthesize glucose and other organic molecules

Question 2

Glucose Synthase

Answer 2

6 CO2 + 12 H2O + light energy –> C6H12O6 + O2 + 6H2O

Redox reaction
CO2 is reduced
And water is oxidized during the formation of O2

Question 3

Heterotrophs

Answer 3

Must consume organic molecules from their environment to sustain life

Question 4

Autotroph

Answer 4

Sustain themselves by making organic molecules from in organic sources

Question 5

Photoautotroph

Answer 5

Uses light as a source of energy

Ex green plants, algae, Cyanobacteria

Question 6

Cellular respiration

Answer 6

Produces ATP energy using glucose

Question 7

Chloroplast

Answer 7

Organelles in plants and algae that carry out photosynthesis
Contains large quantities of chlorophyll
Contains inner and outer membrane

Question 8

Stomata

Answer 8

Pores through which carbon dioxide enters and oxygen exits the leaf

Question 9

Where is chlorophyll located?

Answer 9

Thylakoid membrane

Question 10

Stages of Photosynthesis: Light reaction

Answer 10

Captures light energy
Produces ATP, NADPH and O2
Takes place in thylakoid membranes

Question 11

Stages of Photosynthesis: Calvin Cycle

Answer 11

Uses ATP and NADPH. To incorporate CO2 into organic molecules
Occurs in stroma

Question 12

Light energy

Answer 12

Light is a type of electromagnetic radiation

Travels through waves caused by the oscillation of the electric and magnetic fields

Question 13

Chlorophyll A

Answer 13

The most important photosynthetic pigment and is found in all photosynthetic organisms

Question 14

Carotenoids

Answer 14

Are yellow to red pigments found in leaves, flowers and fruits

Question 15

Absorption Soectrum

Answer 15

Depicts the wavelengths of light absorbed by different pigments
Wavelengths that are not reflected and give the plant its colour

Question 16

Photo systems

Photosystem 2

Answer 16

Connected by an electron transport chain to photosystem 1

Question 17

(PHII) light harvesting complex

Answer 17

Contains pigments that directly absorb protons of light

Absorption boosts an electron to a higher energy level

Question 18

(PHII) reaction centre

Answer 18

Energy is transferred to a form of chlorophyll A called P680, converting to P680* (unstable)
P680* has an electron transferred to primary electron acceptor, yielding P680+
A low energy electron from water is transferred to P680+ to convert it to P680. O2 is produced

Question 19

In photosynthesis, oxygen gas is produced by

Answer 19

Oxidation of water

Question 20

Electron Transport Chain

Answer 20

Electrons transfer from PSII to an electron transport chain in the thylakoid membrane
Electron transfers release some energy that is used to pump H+ into thylakoid lumen
Plastocyanin of electron transport chain transfers electrons to PSI

Question 21

PSI

Answer 21

Key role is to make NADPH
Light strikes light harvesting complex and energy is transferred to reaction centre
An electron is transferred from chlorophyll A P700 to ferredoxin ( Fd, primary electron accepter), producing P700+
Fd transfers two electrons to the enzyme NADP+ reductase

Question 22

ATP synthase

Answer 22

ATP is produced by a chemiosmotic mechanism called photophorylation ( ADP to ATP using energy from light
H+ flows from the thylakoid lumen into the stroma via ATP synthase

Question 23

Summary so far…

Answer 23

O2 is produced in the thylakoid lumen by oxidation of water by PSII
NADPH is produced in the stroma from electrons that originate in PSII and are boosted in PSI
ATP is produced in the stroma by ATP synthase, using an H+ electrochemical gradient

Question 24

Noncyclic Flow

Answer 24

Electrons move linearly from PSII to PSI and eventually reduce NADP+ to NADPH
Produces ATP and NADPH in roughly equal amounts

Question 25

Cyclic Flow

Answer 25

PSI electrons are excited and follow a cyclical pathway from PSI, to the electron transport chain and back to PSI
H+ electrochemical gradient is generated to make ATP but not NADPH.
Favoured when NADPH levels are high, and ATP levels are low

Question 26

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

Answer 26

D

Question 27

Calvin Cycle

Answer 27

Uses ATP and NADPH from the light reactions stage, combined with CO2 from the atmosphere, to make carbohydrates
For every 6 CO2 molecules, 18ATP are hydrolyzed and 12 NADPH are oxidized
Product: (G3P)

Question 28

Carbon fixation

Answer 28

CO2 is incorporated into ribulose bisphosphate (5C) using the enzyme rubisco
Forms 6 Carbon intermediate that immediately splits into two molecules of 3PG 3 phosphoglycerate

Question 29

Reduction

Answer 29

ATP is used as a source of energy, and NADPH donates high energy electrons

Question 30

Regeneration of RuBP

Answer 30

Two G3P are used to make glucose and other sugars; the remaining 10 G3P are needed to regenerate RuBP via several enzymes. ATP is required for RuBP regeneration

Question 31

What is the function of the enzyme Rubisco

Answer 31

Incorporates CO2 into RuBP