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Biology A Level > Photosynthesis, Respiration and ATP > Flashcards

Photosynthesis, Respiration and ATP Flashcards

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1
Q

What is energy needed for in plants and animals?

A

Plants - photosynthesis, active transport, DNA replication, cell division and protein synthesis
Animal - muscle contraction, maintain body temperature, active transport, DNA replication, cell division and protein synthesis

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2
Q

Equation for photosynthesis.

A

6CO2 + 6H2O + energy = C6H12O6 + 6O2

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3
Q

Equation for respiration.

A

C6H12O6 + 6O2 = 6CO2 + 6H2O + energy

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4
Q

Why is ATP a good energy source?

A
  • Only releases a small (manageable) amount of energy so none is wasted as heat
  • It is small and solvable making it easy to transport
  • It is easily broken down in a one step reaction
  • Can’t pass out of the cell so is always an immediate energy source
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5
Q

What is phosphorylation and photophosphorylation?

A

Adding phosphate to a molecule and adding phosphate to a molecule using light.

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6
Q

What is photolysis?

A

Splitting a molecule using light energy.

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7
Q

What is photoionisation not?

A

Light energy excites electrons in a molecule/atom giving them more energy, making them a positively charged ion - they are released.

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8
Q

What is decarboxylation?

A

Removal of carbon dioxide from a molecule.

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9
Q

What is dehydrogenation?

A

Removal of hydrogen from a molecule.

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10
Q

What is a redox reaction?

A

Reactions that include oxidation (lost electrons and gain oxygen/lost hydrogen) and reduction (gained electrons and lost oxygen/gained hydrogen).

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11
Q

What is a coenzyme?

A

Molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another.

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12
Q

Where does photosynthesis occur?

A

In the chloroplasts thylakoids are stacked into grana which are linked by lamellae.

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13
Q

What photosynthetic pigments do chloroplasts contain and what do they do?

A

Chlorophyll a and b, and carotene. They absorb light energy needed for photosynthesis and are found in the thylakoid membrane.

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14
Q

What are the main difference between the LIR and the LDR?

A
  • LDR needs light energy, LIR doesn’t

- LDR happens in thylakoid membranes, LIR happens in the stroma

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15
Q

In the LDR what is the energy from photoionising chlorophyll used for?

A
  • Making ATP
  • Reducing NADP
  • Photolysis of water (splitting into protons, electrons and oxygen)
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16
Q

In the first stage of the LDR light energy excites electrons in chlorophyll, how?

A

Light energy absorbed by PSII which excited electrons in chlorophyll, moving them to a higher energy level which releases them from the chlorophyll and they nice down the electron transfer chain to the PSI, in photoionisation.

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17
Q

In the second stage of the LDR photolysis of water produces protons, electrons and O2, describe how.

A

Excited electrons leaving PSII must be replaces, so light energy splits water in photolysis, releasing electrons.

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18
Q

In stage three of the LDR, energy from the excited electrons makes ATP, describe how.

A

Electrons lose energy as they move down the transfer chain, the energy is used to transport protons into the thylakoid, creating a proton gradient across the membrane which allows protons to move along their concentration gradient into the stroma via ATP synthase, the energy from this combines ADP and Pi in phosphorylation.

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19
Q

In the fourth stage of LDR reduced NADP is formed, how?

A

Light energy is absorbed by PSI which excites electrons to an even higher energy level, these sell trona are transferee to NADP along with a proton from the stroma forming NADPH.

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20
Q

What is chemiosmosis?

A

The process of electrons flowing down the electron transfer chain and creating a proton gradient or drive ATP synthesis.

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21
Q

What does the LDR produce?

A

ATP, NADPH, O2.

22
Q

What does the LIR produce?

A

TP and RuBP (ribulose bisphosphate).

23
Q

What happens in the first stage of the Calvin cycle?

A
  • CO2 enters leaf through stomata an diffuses into chloroplasts stroma where is is combined with RuBP (5C) catalysed with rubisco
  • This creates a 6C compound which is broken down into two 3C GP molecules
24
Q

What happens in the second stage of the Calvin cycle?

A
  • ATP from LDR provides energy to reduce GP into 3C TP, this requires H ions which come from the NADPH in LDR
  • 1/6 TP turned into organic compounds, 5/6 continues in cycle to regenerate RuBP which uses remaining ATP
25
Q

Why is the Calvin cycle important?

A

Carbohydrates with 6 sugars (hexose sugars) are made by joining two TP molecules.
Lipids a made using glycerol which is synthesised from TP and fatty acids which are synthesised from GP.
Some amino acids made from GP.

26
Q

How many times must the Calvin cycle occur to produce one hexose sugar?

A

6 as only one TP is available out of 6 after 3 times. Two TP’s are required per hexose sugar.

27
Q

What are the optimum conditions for photosynthesis?

A
  1. High light intensity of a certain wavelength, the more intense the more energy, needed for LDR, the photosynthetic pigments only absorb red and blue light in sunlight.
  2. Temperature around 25’C as optimum for enzymes and stomata close at high temps to prevent water loss preventing CO2
  3. CO2 at 0.4%
28
Q

Light intensity limiting factor graph.

A

Up until a point rate increases with intensity, here light intensity is the limiting factor, after this point (saturation point) it plateaus and light intensity makes no difference as something else is the limiting factor.

29
Q

What is a saturation point?

A

The point where another factor begins to limit the reaction.

30
Q

Temperature limiting factor graph.

A

Plateau when temperature is no longer the limiting factor.

31
Q

CO2 concentration limiting factor graph.

A

Levels off when CO2 is no longer limiting factor.

32
Q

Why is CO2 neeed?

A

Used to produce glucose by photosynthesis which allows plant to respire more meaning they have more ATP for growth - DNA replication, cell division and protein synthesis.

33
Q

What is the first stage of respiration?

A

Glycolysis - splitting glucose into two 3C pyruvate, which happens in the cytoplasm of the cell, anaerobic process.

34
Q

What happens in the first stage of glycolysis?(phosphorylation)

A

Glucose is phosphorylated using phosphate from ATP, creating glucose phosphate and ADP, another phosphate is added making hexose bisphosphate which is split into two triose phosphate.

35
Q

What happens in the second stage of glycolysis?(oxidation)

A

Triose phosphate oxidised making two pyruvates, lost hydrogen collected by NAD making NADH.

36
Q

What is produced in glycolysis?

A

4 ATP, two used up in stage one so net gain of 2 ATP.

37
Q

What happens to the NADH in aerobic respiration?

A

Two NADH’s go to oxidative phosphorylation.

38
Q

What happens to the two pyruvates in aerobic respiration?

A

Actively transported into the matrix of the mitochondria for the link reaction.

39
Q

What happens to the two pyruvates in anaerobic respiration?

A

Converted into ethanol (plants and yeast) and lactate (animals) using NADH, in fermentation reactions.

40
Q

What happens in alcoholic fermentation?

A

Pyruvates releases CO2 making ethanal, it takes a hydrogen from NADH producing ethanol and NAD.

41
Q

What happens in lactate fermentation?

A

Pyruvates gains a hydrogen ion producing lactate (lactic acid) and NAD.

42
Q

What happens after the production of either ethanol or lactate?

A

Regenerates oxidised NAD allowing glycolysis to continue even without much oxygen - small amount of ATP produced.

43
Q

What happens in the Link Reaction?

A

Pyruvate is decarboxylated (carbon removed in form of CO2), then oxidised making acetate and NAD is reduced. Acetate and coenzyme A coming to make acetylene coenzyme A.

44
Q

How many pyruvates are made for each glucose molecule? How many times does link reaction and Krebs cycle happen for each glucose molecule?

A

Two.

45
Q

What happens in Krebs cycle?

A

Acetylene CoA combines with 4C molecule to make 6C molecule, coenzyme returns to link reaction. 6C decarboxylated making it 5C, CO2 released, also dehydrogenation which is used o reduce NAD. 5C decarboxylated and dehydrogenated producing 4C molecule and one reduced FAD and two reduced FAD. ATP produced in substrate level phosphorylation - direct transfer of phosphate group.

46
Q

What is produced in Krebs cycle?

A 
1 CoA - back to link reaction 
2 CO2 - waste product 
1 ATP - energy 
3 NADH - oxidative phosphorylation 
1 FADH - oxidative phosphorylation 
1 4C - reused
47
Q

What is oxidative phosphorylation?

A

Energy carried by electrons from reduced coenzymes used to make energy.

48
Q

Describe the process of oxidative phosphorylation.

A

NADH and FADH oxidised, releasing H atoms which split into protons and electrons, electrons move down electron transfer chain and lose energy. Energy used to pump protons from mitochondrial membrane into intermembrane space, increasing concentration creating a electrochemical gradient. Protons move along gradient through ATP synthetase which synthesises ATP from ADP and Pi - chemiosmosis. Protons, electrons and O2 combine to form water.

49
Q

Why is oxygen important in respiration?

A

It is the final electron carrier.

50
Q

How many molecules of ATP can be made from one glucose molecule?

A

32

51
Q

Describe the affects of mitochondrial disease.

A

Affects proteins in oxidative phosphorylation and Krebs cycle, reducing ATP production as anaerobic respiration increases, creating lots of lactate causes muscle fatigue and weakness.

Biology A Level (14 decks)

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