5 - Energy Transfers

Question 1

Photoionisation

Answer 1

when light energy ‘excites’ electrons in an atom or molecule, giving them more energy and causing them to be released.

The release of electrons causes the atom or molecule to become a positively charged ion

Question 2

Coenzyme used in photosynthesis

Answer 2

NADP

Question 3

How is NADP reduced?

Answer 3

Using the H+ ion released from the photolysis of water

Question 4

Photosynthetic pigments

Answer 4

Coloured substances that absorb the light energy needed for photosyntesis

Question 5

What happens to carbohydrates produced from photosynthesis?

Answer 5

Stored as starch grains in the stroma

Question 6

Where does the light-dependent reaction take place?

Answer 6

Thylakoid membrane of the chloroplasts

Question 7

Uses of energy released from photoionisation of chlorophyll

Answer 7

Some is used to reform ATP - transfers energy to the light independent reaction

Some is used to reduce NADP to form NADPH - transfers hydrogen to the light independent reaction

Some is used to split water into H+, e- and O2

Question 8

Where does the Calvin cycle take place?

Answer 8

Stroma of the chloroplast

Question 9

Use of energy lost as electrons move down the electron transport chain

Answer 9

Transport protons into the thylakoid, so the thylakoid has a higher concentration of protons than the stroma, forming a proton gradient across the thylakoid membrane

Question 10

Thylakoid

Answer 10

Fluid-filled sacs that are stacked up inside the chloroplasts

Question 11

Lammella

Answer 11

Contain photosynthetic pigments

Each pigment has evolved to absorb different wavelengths of light

Question 12

Examples of photosynthetic pigments

Answer 12

Chlorophyll a

Chlorophyll b

Carotene

Question 13

Photosystem

Answer 13

Within the thylakoid membrane, photosynthetic pigments are attached to proteins

Question 14

Photophosphorylation

Answer 14

Production of ATP from ADP and Pi

Question 15

Where are electron carrier proteins located?

Answer 15

Thylakoid membrane

Question 16

Energy released from the electron transport chain

Answer 16

Pumps protons from the stroma into the thylakoids. The protons are being transported against their concentration gradient and this requires energy

Question 17

What happens as protons build up in the thylakoid?

Answer 17

A proton gradient forms across the thylakoid membrane because the concentration of protons inside the thylakoid is greater than in the stroma

Question 18

Chemiosmosis

Answer 18

As protons diffuse down the concentration gradient across the thylakoid membrane, ATP synthase is activated by energy and converts ADP and Pi into ATP

Question 19

Products of cyclic vs non-cyclic photophosphorylation

Answer 19

Cyclic - ATP, no NADP

Non-cyclic - ATP and NADP

Question 20

When is NADPH produced?

Answer 20

When light is absorbed by PSI

Question 21

Which photosystem uses cyclic photophosphorylation?

Answer 21

PSI

Question 22

Which photsystem uses non-cyclic photophosphorylation?

Answer 22

PSII

Question 23

What happens when CO2 diffuses into the leaves through the stomata?

Answer 23

It combines with RuBP to give an unstable 6C compund

Question 24

What happens to the unstable 6C compund produced in the 1st step of the Calvin Cycle?

Answer 24

Rapidly splits into 2 molecules of glycerate-3-phosphate

Question 25

Carbon fixation

Answer 25

The combination of CO2 with RuBP

Question 26

Reduction of glycerate-3-phosphate

Answer 26

Reduced to triose phosphates Driven by 2ATP + 2H+ from NADPH

Question 27

1/6 Triose phosphate

Answer 27

Converted into hexose sugars

Question 28

5/6 Triose Phosphate

Answer 28

Used to regenerate RuBP Driven by 1ATP

Question 29

Catalyst of carbon fixation

Answer 29

Rubisco

Question 30

Components of lipids formed in the Calvin Cycle

Answer 30

Triose phosphates are used in the synthesis of glycerol Fatty acids are formed from glycerate 3-phosphate

Question 31

Why does the light-dependent reaction take place in the thylakoid?

Answer 31

Light energy is absorbed by the thylakoid membrane

Question 32

Ethanol Fermentation

Answer 32

Convertion of pyravete to ethanol under anaerobic conditions Takes place in plants and yeast

Question 33

How is pyravate converted to ethanol?

Answer 33

Pyruvate is first converted to ethanal by pyruvate decarboxylase (CO2 byproduct) Ethanal is then reduced to ethanol, using ethanol dehydrogenase and NADH

Question 34

Lactate Fermentation

Answer 34

Conversion of pyruvate to lactate Takes place in animals and some bacteria, when there is an insufficient oxygen supply

Question 35

How is pyruvate reduced to lactate?

Answer 35

Catalysed by lactate dehydrogenase NADH oxidised to NAD

Question 36

Net gain of link

Answer 36

CO2 NADH

Question 37

Acetyl CoA

Answer 37

Acts as a carrier for the 2C acetyl group It reacts with oxaloacetate (4C) to produce citrate (6C)

Question 38

Net gain of Krebs

Answer 38

2CO2 3NADH ATP FADH2

Question 39

Where does oxidative phosphorylation take place?

Answer 39

Inner mitochondrial membrane

Question 40

Features of the inner mitochondrial membrane that allows production of ATP on a large scale

Answer 40

3 electron carrier proteins ATP synthase

Question 41

Methylene blue

Answer 41

Blue in its oxidised state Colourless in its reduced state

Question 42

Enzyme which catalyses the reaction in which pyruvate is reduced to lactate

Answer 42

Lactate dehydrogenase

Question 43

2 uses of organic molecules produced by plants

Answer 43

Respiratory substrates Make other biological molecules, forming new biomass

Question 44

Biomass

Answer 44

The chemical energy store for an organism

Question 45

Dry mass

Answer 45

The mass of an organism after its water has been removed

Question 46

Mass of C

Answer 46

Usually about half the drymass

Question 47

Calorimeter

Answer 47

Measures energy contained within dry biomass Burns biomass and calculats the chemical energy released per gram

Question 48

2 methods for measuring biomass

Answer 48

Dry mass of tissue per unit area Mass of carbon

Question 49

Gross primary production

Answer 49

The chemical energy stored in plant biomass, in a given area or volume