Photosynthesis

Question 1

Photosynthesis

Answer 1

Process of sunlight, H2O, and CO2 to chemical energy in glucose, water in from roots, CO2 in from stomata

Question 2

Where is photosynthesis done?

Answer 2

Chloroplast

Question 3

Grana

Answer 3

Pancake like stacks of thylakoid membrane

Question 4

Stroma

Answer 4

Fluidlike substance that fills gaps between grana

Question 5

Chlorophyll

Answer 5

Pigment that makes green, chlorophyll A and B and carotenoids (pigments), green is left over and reflected into eyes, in thylakoid membrane

Question 6

What are the two stages of photosynthesis?

Answer 6

Light dependent reaction, electron transport
Light independent reaction, Calvin cycle

Question 7

Light dependent reactions

Answer 7

In the chloroplasts in thylakoid membranes
Captures and converts light energy into chemical energy in the form of ATP and NADPH while splitting water molecules to release oxygen
Light absorption: chlorophyll absorbs light energy, exciting electrons
Water splitting (photolysis): light energy splits water molecules into oxygen, protons (H+), and electrons
Electron transport chain (ETC): excited electrons move through the ETC, creating a proton gradient
ATP formation (photophosphorylation): protons flow back into the stroma through ATP synthase due to the proton gradient; ATP is synthesized from ADP and inorganic phosphate (Pi)
NAPH formation: electrons that have passed through the ETC are transferred to NADP+ along with protons, forming NADPH; NADPH carries high energy electrons to the Calvin cycle for use in synthesizing glucose

Question 8

Calvin cycle (light independent reactions)

Answer 8

In stroma of the chloroplasts
Utilizes ATP and NADPH produced in the light dependent reactions to fix carbon dioxide into glucose
Carbon fixation: CO2 molecules are attached to a 5-C sugar called RuBP by the enzyme RuBisCO; this reaction produces an unstable 6-C compound that immediately splits into two molecules of 3-PGA
Reduction phase: ATP and NADPH from the light dependent reactions are used to convert 3-PGA into G3P, a 3-C sugar; half of the G3P molecules exit the cycle to be used in synthesizing glucose and other carbohydrates
Regeneration of RuBP: the remaining G3P molecules are used to regenerate RuBP with the help of additional ATP; RuBP is regenerated, allowing the Calvin cycle to continue
Glucose synthesis: G3P molecules are used to form glucose and other carbohydrates

Question 9

Electron carriers

Answer 9

Molecules that carry electrons to transfer energy, ATP and NADPH carry energy from light dependent to light independent reaction

Question 10

Chemosynthesis

Answer 10

Organism making food with chemicals, how producers that can’t photosynthesize get energy

Question 11

What affects the rate of photosyntheis?

Answer 11

Light intensity: excites more electrons so reactions happen faster
Amount of CO2: more ingredients to work with and process through cycle
Temperature: increased temperature = accelerated chemical reactions to a degree

Question 12

Why don’t roots need chloroplasts?

Answer 12

They are underground and see no sun, so they don’t need chloroplasts that catch sunlight and do photosynthesis

Question 13

Stomata

Answer 13

Pores on underside of leaf, where waters lost, CO2 enters, O2 exits, if too hot/dry closes to prevent dehydration, also eliminates gas exchange

Question 14

Photorespiration

Answer 14

CO2 drops, O2 increases, adds O2 to Calvin cycle instead of CO2, no sugar or ATP made, wastes resources

Question 15

What are the 2 alternate pathways to avoid photorespiration?

Answer 15

CAM and C4

Question 16

CAM

Answer 16

Done by succulents and pineapples, open stomata at night, closed during day, opposite of normal plants, makes grow slowly

Question 17

C4

Answer 17

Done by corn and sugar cane, partially close stomata during hottest part of day, only lose 1/2 as much water as normal plants