Photosynthesis Module 5

Question 1

Biological processes which require energy in plants?

Answer 1

Photosynthesis
active transport
DNA replication
Cell division
Protein synthesis

Question 2

Biological processes which require energy in animals?

Answer 2

Everyone in plants except photosynthesis+ maintenance of body temp

Question 3

Respiration definition?

Answer 3

Living cells release energy from glucose, and used to power all biological processes in the cell

Question 4

Metabolic pathway?

Answer 4

A series of small reactions controlled by enzymes ( respiration or photosynthesis)

Question 5

Phosphorylation?

Answer 5

Adding Phosphate to a molecule using light

Question 6

Photolysis?

Answer 6

Splitting of a molecule using light energy

Question 7

Hydrolysis?

Answer 7

Splitting of a molecule using water

Question 8

Decarboxylation?

Answer 8

Removal of CO2 from a molecule

Question 9

Dehydrogenation?

Answer 9

Removal of hydrogen from a molecule

Question 10

Coenzyme?

Answer 10

Molecules which aids the function of an enzyme, by moving chemical groups from one molecule to another

In photosynthesis it’s NADP, transfer hydrogen from one molecule to another

Question 11

Features of chloroplasts?

Answer 11

Small flattened organelles, location of photosynthesis
Have double membrane called chloroplast envelope
Thylakoids are stacked up to from Grana in the chloroplast, and are linked together by lamellae
Contain photosynthetic pigments

Question 12

What are photosynthetic pigments?

Answer 12

Examples are chlorophyll a, b and carotene

Absorb light energy and found in thylakoid membrane, and are attached to proteins = photosystem

Question 13

Where are primary pigments found?

Answer 13

Reaction centre, where electrons are excited during LDR

Chlorophyll a

Question 14

Where are accessory pigments found?

Answer 14

Make up harvesting system, surround each reaction centre and transfer light energy
Chlorophyll b and carotene

Question 15

PS1 wavelength absorbed?

Answer 15

700nm

Question 16

PS11 wavelength absorbed?

Answer 16

680nm

Question 17

Stroma?

Answer 17

Gel like substance surrounding thylakoid membranes, contains enzymes and organic sugars
Chlorplasts have their own circular DNA found in it
Carbohydrates can be stored as starch granules in it

Question 18

What’s the mobile phase?

Answer 18

Liquid solvent

Question 19

What’s the stationary phase?

Answer 19

Gel it’s transferring through

Question 20

How do you find Rr value?

Answer 20

Distance travelled by spot / distance travelled by solvent

Question 21

Non cyclic photophosphorylation ( LDR)?

Answer 21

Light energy absorbed by PS11 (680nm), exciting electrons in chlorophyll
Electrons move to a higher energy level to an electron carrier, and then move down a transport chain to PS1

As excited electrons leave PS11, they need to be replaced so light energy splits water into H+ ions, electrons and oxygen (goes into atmosphere)

(chemiosmosis)
The excited electrons lose energy as they move down the electron transport chain
This energy is used to transport protons into the thylakoid, via protein pumps, so thylakoid has higher conc of protons than stroma, forming a gradient across the membrane
Protons move down conc gradient into stroma via enzyme ATP synthase, the energy from this movement combines ADP and inorganic phosphate, forming ATP

Light energy absorbed by PS1 (700nm), which excites the electrons to an even higher energy level
Finally electrons are transferred to NADP, along with a H+ ion to form reduced NADP

Question 22

Cyclic photophosphorylation?

Answer 22

Only uses PS1
Cyclic as electrons aren’t passed onto NADP, but passed back to PS1 via electron carriers
Therefore electrons recycled and repeatedly flow through
No Reduced NADP or O2 formed, little bit of ATP made

Question 23

Calvin cycle explained (LIR)?

Answer 23

CO2 enters leaf through stomata, diffuses into stroma of chloroplast
Combines with RuBp, making an unstable 6C compound which splits into 2 3C compounds called GP
Rubsico enzyme catalyses reaction between CO2 and RuBp

ATP from LDR turns GP into TP, this reaction also requires H+ ions from reduced NADP in the LDR, reduced NADP is recycled back to form NADP
TP converted into many useful compounds

5 out of every 6 TP molecules aren’t used to make Hexose sugars, but are regenerated to form RuBp
Regenerating RuBP uses rest of ATP produced in LDR

Question 24

What are the useful substances made by the Calvin Cycle?

Answer 24

Carbs- 2 TP molecules
Lipids, using glycerol synthesised from TP and fatty acids from GP
Amino acids from GP

Question 25

How many turns of Calvin cycle to produce 1 hexose sugar?

Answer 25

6

Question 26

Ideal conditions for photosynthesis?

Answer 26

High light intensity of a certain wavelength

Temperature around 25 degrees
If temps too low enzymes become inactive
If temp too high:
enzymes denatured
Stomata close to reduce water loss, so less CO2 enters reducing photosynthesis
Thylakoid membranes damaged, LDR stage slowed as reduced sites for e- transfer

Carbon dioxide levels at 0.4%, any higher stomata start to close

Question 27

Saturation point?

Answer 27

Where increasing factor anymore doesn’t make a difference

Question 28

Why does when a plant have low water levels photosynthesis decreases?

Answer 28

Stomata close to reduce water loss, less CO2 enters

Question 29

How does low light energy affect concentration of different compounds?

Answer 29

Reduced NADP and ATP concs will be low, as slow LDR
Conversion of Gp to Tp and RuBp slow
So Gp levels rise, but Tp and RuBp fall

Question 30

How does low temperature affect concentrations of compounds?

Answer 30

Enzymes rate will be slower, levels of RuBp Tp and Gp slower

Question 31

How does low CO2 conc affect concentrations of compounds?

Answer 31

Conversion of RuBp to GP is slow, so RuBp increases and Gp and Tp fall