Photosynthesis (L9)

Question 1

This is the synthesis of energy/food using light in plants.

Answer 1

Photosynthesis

Question 2

Where does photosynthesis occur in plants?

Answer 2

Chloroplasts

• more specifically, light reactions take place in the thylakoid membrane
• carbon fixation occurs in the stroma

Question 3

These reactions use chlorophyll (pigment) to capture light energy and convert it to chemical energy using protein complexes embedded in the thylakoid membrane.

Answer 3

Light reactions

Remember: these take place in the stroma (which is far more exposed than the thylakoids and thylakoid membrane)

Question 4

What does PETC stand for? What is its function?

Answer 4

Photosynthetic Electron Transport Chain.

A pathway that electrons travel through to produce a concentration gradient.

Like as the electrons go through, protons are pumped into the opposite side of the membrane to establish a concentration gradient.

Question 5

What are the sequence of events in the PETC?
Where does it occur?

Answer 5

Remember: photosystems are protein complexes that produce high energy electrons (green picture LTH - PETC concept)

• in the thylakoid membrane

Photosystem II — Cytochrome Complex — Photosystem I — ATP synthase

(Poodle Crouches to Poop Allday) — essentially the poop is like the energy produced

Question 6

Electrons come in with high energy and leave with low energy in this complex. There’s only one in the PETC (of use at least)

Answer 6

Cytochrome complex

Question 7

What is the name of the high energy electron carrier?

Answer 7

NADPH

• formed from (NADP+) + (H+)

Question 8

How is ATP formed?

Answer 8

By breaking down ADP + Pi (like in cellular respiration) through the ATP synthase.

• just that it occurs in the mitochondria for animal cells and it occurs in the chloroplast for plant cells

Question 9

What is the concentration gradient between stroma and thylakoid space (space within the thylakoid where protons are pumped.

Answer 9

Thylakoid space = High H+ (because thylakoid membrane has more electrons)

Stroma = Low H+

Question 10

This is the process of fixating (splitting) carbon to produce carbohydrates/glucose (which is the plant’s food source)

• fixation is done through the formation of NADPH and ATP

Answer 10

Calvin Cycle *occurs in the stroma

• also known as Dark Reaction as no need for light

Question 11

What are the sequence of events in the Carbon Cycle?

Answer 11

Fixation — Reduction — Regeneration

• poodle becomes FRREe!

Question 12

What are the inputs and outputs of photosynthesis?

Answer 12

Inputs = carbon, light, water
Outputs = glucose, oxygen

Question 13

What protein is responsible for ATP generation in plant and animal cells?

Answer 13

ATP Synthase - which requires a proton gradient across a membrane

Question 14

Origin of Chloroplasts and Mitochondria is linked to what?

Answer 14

Theory of Endosymbiosis. Which states that two key organelles in eukaryotes: the mitochondria and chloroplast actually came from an ancestral eukaryote DERIVED from bacteria.

• mitochondria: proteobacteria
• chloroplast: Cyanobacteria

Question 15

Where do light reactions take place?

Answer 15

In the thylakoid membrane

Question 16

Where does carbon fixation occur?

Answer 16

In the stroma

Question 17

What are the three compartments of the chloroplast?

Answer 17

Thylakoid space, intermembrane space, and stroma

Question 18

These reactions capture light energy and convert it into chemical energy.

Answer 18

Light reactions.

Question 19

What do light reactions use to convert light into chemical energy? (2)

Answer 19

Pigment (chlorophyll) and protein complexes (like cytochromes and enzyme ATP synthase)

Question 20

What are the 3 membranes of the chloroplast?

Answer 20

Outer membrane, inner membrane, thylakoid membrane

Question 21

These are protein complexes that contain chlorophyll to absorb the light energy and produce high energy electrons.

Answer 21

Photosystems

Question 22

High energy electrons travel through?

Answer 22

Photosynthetic Electron Transport Chain

Question 23

High energy electrons in the mitochondria travel through?

Answer 23

Electron Transport Chain

Question 24

What is produced in light reactions?

Answer 24

Oxygen and ATP and NADPH

Question 25

What is produced in the carbon fixation/calvin cycle?

Answer 25

glucose.

Question 26

What are ATP and NADPH used for in the Calvin Cycle?

Answer 26

To fix CO2 and produce glucose.

Question 27

What are the inputs of photosynthesis?

Answer 27

Light water and CO2

Question 28

What are the outputs of photosynthesis

Answer 28

Oxygen and glucose

Question 29

How is the proton gradient established in plants?

Answer 29

Via high energy electrons pumping out H+ into the intermembrane space. It occurs between the stroma and the thylakoid space.