2. photosynthesis Flashcards Preview

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Flashcards in 2. photosynthesis Deck (29)
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1
Q

where does photosynthesis take place

A

in the chloroplasts of plant cells

2
Q

where does photosynthesis take place

A

in the chloroplasts of plant cells

3
Q

chloroplasts are

A

flattened organelles surrounded by a double membrane

4
Q

thylakoids (fluid-filled sacs) are

A

stacked up in the chloroplast into structures called grana (singular=granum)

5
Q

grana are linked together by

A

bits of thykaloid membrane called lamellae (singular=lamella)

6
Q

e.g. of photosynthetic pigments in chlorplasts

A

Chlorophyll A
chlorophyll B
carotene

7
Q

photosynthetic pigments are

A

coloured substances that absorb light energy needed for photosynthesis

8
Q

photosynthetic pigments are found

A

in thykloid membrane

attached to proteins

9
Q

photosynthetic pigment attached to protein is called a

A

photosystem

10
Q

contained within the membrane of the chloroplast and surrounding the thykloids is a

A

gel-like substance called the stroma

11
Q

what does the stroma contain

A

enzymes, sugars and organic acids

12
Q

carbohydrates produced by photosynthesis are not used straight away. they are

A

stored as starch grains in the stroma

13
Q

non-cyclic photophosphorylation

1. Light energy excites the electrons in the chlorophyll

A
  1. light energy is absorbed by photosystem
  2. excites electrons in chlorophyll
  3. electrons move to higher energy level (they have more energy)
  4. released from chlorophyll and move down electron transport chain
14
Q

non-cyclic photophosphorylation

2. photolysis of water produces protons (H+ ions) , electrons and O2

A
  1. as excited electrons from chlorophyll leave Photosystem and move down electron transport chain must be replaced
  2. light energy splits water into protons (H+ ions), electrons and O2 (photolysis)
  3. the reaction is H2O -> 2H+ + 1/2O2
15
Q

non- cyclic photophosphorylation

3. energy from the excited electrons make ATP

A
  1. excited electrons loose energy as they move down the electron transport chain
  2. energy is used to transport protons into the thylakoid. thylakoid has higher concentration of protons in stroma. = proton gradient across thylakoid membrane
  3. protons move down concentration gradient into stroma via enzyme ATP synthase (in thylakoid membrane) energy from movement combines ADP and inorganic phosphate to from ATP
16
Q

non-cyclic photophosphorylation

4. and generated reduced NADP

A
  1. electrons are transferred to NADP along with a proton (H+ ion) from the stroma to form reduced NADP
17
Q

the light dependent reaction

some of the energy from released electrons is used

A
  1. to add a phosphate group to ADP forming ATP (which transfers energy)
  2. to reduce NADP to form reduced NADP (which transfers hydrogen to the light-independent reaction)
18
Q

the light dependent reaction

during the process, H2O is

A

oxidised to O2

19
Q

the light independent reaction

is also called the

A

Calvin cycle

20
Q

the light independent reaction

it doesn’t use

A

light energy directly

but it relys on the products of the light dependent reaction

21
Q

the light independent reaction

it takes place in the

A

stroma of the chloroplast

22
Q

the light independent reaction

what happens in the stroma of the chloroplast

A

ATP and reduced NADP from light dependent reaction supply energy and hydrogen to make simple sugars from CO2

23
Q

phostosystems in the thylakoid membranes are linked by

A

electron carriers

24
Q

electron carriers are

A

proteins that transfer electrons

25
Q

photosystems and electron carriers form an

A

electron transport chain (a chain of proteins through which excited electrons flow)

26
Q

Chemiosmotic theory/ Chemiosmosis

A

process of eletrons flowing down the electron transport chain and creating a proton gradient across the membrane to drive ATP synthesis

27
Q

non-cyclic photo phosphorylation produces

A

ATP, reduced NADP and O2

28
Q

cyclic photophosphorylation only produces

A

a small amount of ATP (no NADP or O2)

29
Q

cyclic photophosphorylation is called cyclic because

A

electrons from chlorophyll molecule arent passed onto NADP but are passed back to photosystem via electron carriers
(electrons are recycled and can repeatedly flow through Photosystem)