Photosynthesis And LDR

Question 1

What are autotrophs

Answer 1

Produce their own food through photosynthesis/chemosynthesis

Question 2

What are heterotrophs

Answer 2

Must consume autotrophs and absorb its molecules and breaks them down to get the energy

Question 3

Two types of producers

Answer 3

-photoautotrophs: plants which use light energy to produce glucose
-chemoautotrophs: bacteria near deep-sea hydrothermal vents which use energy from chemical reactions to make glucose

Question 4

What type of membrane does chloroplast have

Answer 4

Double membrane

Question 5

Characteristics of the two membranes in chloroplasts

Answer 5

Outer membrane: freely permeable
Inner membrane: contains transporter molecules that allow sugars, amino acids and proteins to move from cytoplasm into chloroplast

Question 6

What is a thylakoid stack called and why

Answer 6

Granum (multiple grana) to increase surface area

Question 7

What do thylakoids contain

Answer 7

The proteins(electron carriers) and pigments needed for the light dependent reaction and enzymes for photolysis of water

Question 8

Why are there DNA loops in the chloroplast

Answer 8

Contain genes to produce some of the enzymes and proteins of chloroplast

Question 9

What is the role of the stroma

Answer 9

Contains enzymes needed for the light independent reaction and is a gel-like substance that surrounds the thylakoid stacks

Question 10

What is an electron transport chain

Answer 10

A chain of proteins through which excited electrons flow

Question 11

Process of the light dependent reaction

Answer 11

-light energy absorbed by photosystem II which excites electrons in chlorophyll
-electrons move to higher energy level and move down the electron transport chain to photosystem I which produces ATP
-these excited electrons from chlorophyll leave PSII so must be replaced
-light energy splits water into protons, electrons and oxygen in photolysis to replace lost electrons
-the electrons lose energy as they move down the electron transport chain, this energy is used to transport protons into thylakoids via carrier proteins so higher concen than stroma(proton gradient)
-protons move down concen gradient into stroma via enzyme ATP synthase and process called chemiosmosis, this movement produces energy which is used to combine ADP and inorganic phosphate(Pi) to form ATP
-light energy is absorbed in PSI which excites the electrons again to a higher energy level
-the electrons are transferred to NADP along with a proton from the stroma to form reduced NADP

Question 12

Three things light energy absorbed in the light dependent reaction is used for

Answer 12

-making ATP from ADP and Pi (inorganic phosphate) in photophosphorylation
-making reduced NADP from NADP
-splitting water into protons, electrons and oxygen in photolysis

Question 13

Where does the LDR occur

Answer 13

Thylakoid membranes of chloroplasts

Question 14

What is chemiosmosis

Answer 14

Diffusion of protons from a region of high to low concen through a partially permeable membrane

Question 15

What are the pigments in plants

Answer 15

Chlorophyll a and b, xanthophylls and carotenoids

Question 16

Where are the different pigments located and their roles

Answer 16

Chlorophyll b, xanthophyll and carotenoids are all embedded in thylakoid membrane in chloroplasts which are light harvesting systems which absorb (harvest) light energy of dif wavelengths
-chlorophyll a in reaction centre where photosynthesis takes place

Question 17

What is cyclic phosphorylation

Answer 17

2 electrons from PSI move back to replace those lost from PSII so no photolysis of water, do not produce reduced NADP

Question 18

What is non-cyclic phosphorylation

Answer 18

Excited electrons in PSI used to reduce NADP so water must undergo photolysis in PSII to replace excited electrons