Photosynthesis

Question 1

Define photosynthesis

Answer 1

The process whereby light energy is transformed into chemical energy, and used to synthesise both organic and inorganic molecules

Question 2

Define autotroph

Answer 2

Organisms that use light energy or chemical energy to synthesise complex organic molecules

Question 3

Define heterotroph

Answer 3

Organisms that ingest and digest complex organic molecules, releasing the chemical potential energy stored in them

Question 4

What were the first lifeforms on Earth

Answer 4

Chemoautotrophs

Question 5

What are organisms that can photosynthesise called

Answer 5

Photoautotrophs

Question 6

Why does respiration in autotrophs and heterotrophs depend on photosynthesis

Answer 6

The products of photosynthesis are the reactants of respiration. (and vv)

Question 7

Where does photosynthesis take place

Answer 7

In the chloroplasts

Question 8

What type of membrane does a chloroplast have

Answer 8

Double membrane

Question 9

What is the difference between the two membranes

Answer 9

The outer one is permeable to small ions, the inner one is less permeable and has transport proteins embedded in it.

Question 10

What is the inner membrane folded into

Answer 10

Lamellae, which are stacked up like pancakes. Each stack is a granum

Question 11

What are the two regions of a chloroplast

Answer 11

Stroma and grana

Question 12

What is the stroma

Answer 12

A fluid filled matrix, where the reactions of the light independent stage take place

Question 13

What are photosynthetic pigments

Answer 13

Molecules that absorb light energy. They absorb a range of wavelengths in the visible region

Question 14

What are the photosynthetic pigments organised into

Answer 14

Photosystems

Question 15

Where are the enzymes needed to catalyse light-independent reactions held

Answer 15

The stroma

Question 16

Which membrane are the photosystems held in

Answer 16

The thykaloid membrane

Question 17

What type of chlorophyll is in the PPRC

Answer 17

A

Question 18

What type of chlorophyll is in the accessory pigments

Answer 18

B (and cartenoids)

Question 19

What is an accessory pigment

Answer 19

Light-absorbing compounds, found in photosynthetic organisms. They absorb wavelengths not well absorbed by chlorophylls and pass the energy to the PPRC

Question 20

What is the structure of chlorophyll

Answer 20

Long phytol (hydrocarbon) chain and a porphyrin group

Question 21

What are the two forms of chlorophyll

Answer 21

P680 and P700

Question 22

What is photophosphorylation

Answer 22

The making of ATP from ADP and Pi in the presence of light

Question 23

What are electron carriers

Answer 23

Molecules that transfer electrons

Question 24

What are electron acceptors

Answer 24

Chemicals that accept electrons from another compound. They are reduced whilst acting as oxidising agents

Question 25

Where does the light dependent stage of photosynthesis occur

Answer 25

On the thykaloid membrane

Question 26

PS1 occurs mainly on...

Answer 26

... the intergranal lamellae

Question 27

PS11 occurs mainly on...

Answer 27

... the granal lamellae

Question 28

What is the process of splitting water with light called

Answer 28

Photolysis

Question 29

In which photosystem does photolysis occur

Answer 29

PS11

Question 30

What is the equation for photolysis

Answer 30

2H2O --> 4H+ + 4e- + O2

Question 31

What is the oxygen produced by photolysis used for

Answer 31

Plant aerobic respiration | Human aerobic respiration (leaves through stomata)

Question 32

Where do H+ and e- come from

Answer 32

Water

Question 33

What process uses H ions to produce ATP

Answer 33

Chemiosmosis

Question 34

What is NADPH used for

Answer 34

The reduction of carbon dioxide

Question 35

Why is water needed in plants (other than source of H and e)

Answer 35

It is used to keep plant cells turgid

Question 36

What is the word for light travelling in particles

Answer 36

A photon

Question 37

What is the Endosymbiotic Theory

Answer 37

Photosynthetic bacteria were acquired, by endocytosis, by early eukaryotic cells.

Question 38

Describe the process of non-cyclic photophosphorylation

Answer 38

1. Light strikes PSII 2. 2 electrons become excited and leave the chlorophyll molecule 3. Electrons pass along electron carriers and release energy 4. H+ passes through ATP synthesise and forms ATP 5. These electrons, along with the protons from photolysis of water join NADP 6. NADPH formed

Question 39

Describe the process of cyclic photophosphorylation

Answer 39

1. Light strikes PSI and 2 electrons are excited and pass to an electron acceptor/carrier 2. Electron carrier moves down the ETC 3. Small amounts of ATP are made. 4. Electrons return to the PS1

Question 40

What is a light dependent reaction

Answer 40

Takes place in the thylakoid membrane, use light energy to make ATP and NADPH

Question 41

What is the light independent stage

Answer 41

The photosynthesis is where carbon dioxide is fixed and used to build complex organic molecules

Question 42

What is the Calvin Cycle

Answer 42

The set of chemical reactions that take place in chloroplasts during the light independent stage of photosynthesis

Question 43

Describe the Calvin Cycle

Answer 43

1. CO2 diffuses through the stomata into the stroma 2. CO2 combines with Ribulose Bisphosphate (enxzyme is rubisco) 3. Glycerate-3-phosphate is created 4. GP is reduced and phosphorlyated to Triose Phosphate (TP)- ATP and NADPH are used 5. 5/6 molecules of TP are recycled by phosphorylation using ATP to three molecules of RuBP

Question 44

What is a limiting factor

Answer 44

A factor that is present at the lowest or least favourable value

Question 45

Name three limiting factors

Answer 45

Light Water Temperature Chlorophyll presence

Question 46

What are the three main effects that light has on a plant?

Answer 46

Light causes stomata open to increase carbon dioxide diffusing in. Light is trapped by chlorophyll and excited electrons. Light splits water to produce protons.

Question 47

What stage of photosynthesis does temperature have an effect on?

Answer 47

The enzyme controlled reactions of the Calvin Cycle

Question 48

What is used to measure the rate of photosynthesis

Answer 48

Photosynthometer

Question 49

What are the three methods of measuring photosynthesis

Answer 49

- Volume of oxygen production per minute. - Rate of uptake of carbon dioxide. - Rate of increase in dry mass.