Chapter 5

Question 1

What are the inputs and outputs of photosynthesis?

Answer 1

Input: CO₂ + H₂O | Output: Glucose (C₆H₁₂O₆), O₂, H₂O

Question 2

What is the chemical equation for photosynthesis?

Answer 2

6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

Question 3

What happens to glucose after it is made?

Answer 3

Used in respiration, stored as starch, or converted into cellulose

Question 4

Where does photosynthesis mainly occur?

Answer 4

In the leaves, specifically in mesophyll cells

Question 5

What organelle is responsible for photosynthesis?

Answer 5

Chloroplasts (contain chlorophyll to capture light)

Question 6

What is the role of stomata in photosynthesis?

Answer 6

Allow CO₂ in and O₂ out through pores in leaves

Question 7

What is the function of the xylem?

Answer 7

Transports water from roots to leaves for photosynthesis

Question 8

Name two key enzymes in the light-dependent stage.

Answer 8

Photosystem and ATP synthase

Question 9

What are the key coenzymes in photosynthesis?

Answer 9

NADPH, ATP, NADP⁺, ADP + Pi

Question 10

Where does the light-dependent stage occur?

Answer 10

Thylakoid membranes in the chloroplast

Question 11

What is the purpose of the light-dependent stage?

Answer 11

Produce ATP and NADPH for the next stage

Question 12

Briefly describe the steps of the light-dependent stage.

Answer 12

Sunlight excites electrons, water splits, ATP & NADPH are formed, O₂ is released

Question 13

What are the inputs and outputs of the light-dependent stage?

Answer 13

Input: H₂O, NADP⁺, ADP + Pi | Output: O₂, NADPH, ATP

Question 14

Where does the light-independent stage occur?

Answer 14

Stroma of the chloroplast

Question 15

What is the purpose of the Calvin Cycle?

Answer 15

Use ATP & NADPH to convert CO₂ into glucose

Question 16

What are the inputs and outputs of the Calvin Cycle?

Answer 16

Input: CO₂, NADPH, ATP | Output: Glucose, NADP⁺, ADP + Pi

Question 17

What is the role of Rubisco in photosynthesis?

Answer 17

Catalyzes the fixation of CO₂ to RuBP to form 3-PGA

Question 18

What happens when Rubisco binds O₂ instead of CO₂?

Answer 18

Photorespiration occurs, wasting energy and reducing efficiency

Question 19

What affects Rubisco’s choice of substrate?

Answer 19

Substrate concentration, temperature, and stomatal openness

Question 20

What are C3 plants?

Answer 20

Plants that do normal photosynthesis in mesophyll cells; adapted to cool, wet climates

Question 21

What are C4 plants?

Answer 21

Plants that separate carbon fixation (mesophyll) and Calvin Cycle (bundle sheath); adapted to hot, sunny climates

Question 22

What is a benefit and cost of C4 photosynthesis?

Answer 22

Benefit: less photorespiration | Cost: uses extra ATP

Question 23

What are CAM plants?

Answer 23

Plants that fix CO₂ at night and close stomata during the day; adapted to arid environments

Question 24

How do CAM plants reduce water loss?

Answer 24

Open stomata only at night and store malate for daytime use

Question 25

How does light intensity affect photosynthesis?

Answer 25

Increases rate up to a plateau due to limiting factors

Question 26

Which light colors maximize photosynthesis?

Answer 26

Red, blue, and violet light (not green, which is reflected)

Question 27

How does temperature affect photosynthesis?

Answer 27

Optimal around 25°C; too high → enzyme denaturation, more photorespiration

Question 28

How does pH affect photosynthesis?

Answer 28

Enzymes have optimal pH; outside this range, enzymes denature and rate drops

Question 29

How does CO₂ concentration affect photosynthesis?

Answer 29

Higher CO₂ increases rate until saturation; low CO₂ limits rate

Question 30

How does water availability affect photosynthesis?

Answer 30

Closed stomata to save water reduce CO₂ intake, lowering photosynthesis

Question 31

What is enzyme inhibition in photosynthesis?

Answer 31

Inhibitors reduce rate; reversible ones can be overcome with more substrate

Question 32

What is a limiting factor in photosynthesis?

Answer 32

A condition that prevents the rate from increasing any further

Question 33

What are current uses of CRISPR in agriculture?

Answer 33

Virus resistance, drought/heat tolerance, slower ripening, improved nutrition

Question 34

How can CRISPR enhance photosynthesis?

Answer 34

Mimic C4/CAM traits, modify Rubisco, chloroplasts, or stomata

Question 35

How might CRISPR affect future crops?

Answer 35

More resilient, productive, and efficient crops for rising global demand