Topic 5 - Photosynthesis and Respiration Flashcards

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1
Q

What is the equation for photosynthesis ?

A

6CO2 + 6H2O = C6H12O6 + 6O2

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2
Q

What is photosynthesis ?

A

The process where energy from light is used to make glucose.

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3
Q

What is the equation for respiration ?

A

C6H12O6 + 6O2 = 6CO2 + 6H2O

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4
Q

What is respiration ?

A

The release of energy

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5
Q

What does anaerobic respiration in plants and yeast produce ?

A

ethanol and carbon dioxide

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6
Q

Why is ATP needed ?

A

cells cant get energy directly from glucose, so in respiration the energy released from glucose is used to make ATP which carries energy in cells to where it is needed.

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7
Q

What is a photosystem ?

A

A light absorbing pigment attached to a protein. it contains chlorophyll in the middle

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8
Q

where are the products of photosynthesis stored ?

A

starch grains in the stroma

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9
Q

What is the thick fluid in chloroplast called ?

A

stroma

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10
Q

Where does the light dependent reaction of photosynthesis take place ?

A

The thylakoid membrane of the chloroplast

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11
Q

What is the light dependent reaction of photosynthesis also called ?

A

Photophosphorylation

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12
Q

What occurs during photophosphorylation (LDR) ?

A
  1. Photoionisation: light energy is absorbed by the chlorophyll. The light energy excites electrons and they move to a higher energy level. They move down an electron transport chain and a series of redox reactions occur.
  2. Photolysis: These electrons must be replaced so light energy is used to split water into oxygen, protons and electrons
  3. Chemiosmosis: The electrons loose energy as they move down the electron transfer chain and this energy is used to transport the protons across the membrane into the thylakoid. This forms a proton gradient. Protons move down the concentration gradient by ATP synthase.
  4. The energy from this movement combines ADP and Pi to form ATP.
  5. The electrons and protons are transferred to NADP to form reduced NADP.
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13
Q

What is the light independent reaction also called ?

A

The calvin cycle

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14
Q

Where does the calvin cycle take place ?

A

The stroma of the chloroplast

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15
Q

What is the function of the calvin cycle ?

A

It makes triose phosphate which can be used to make useful compounds such as carbohydrates, lipids and proteins.

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16
Q

What happens during the light independent reaction

A
  1. Carbon dioxide enters the leaf through the stomata and diffuses into the stroma of the chloroplast. It is combined with RuBP ( a five carbon compound), this reaction is catalysed by rubisco. This produces an unstable 6 carbon compound which quickly breaks down into 2 molecules of a 3 carbon compound called GP
  2. GP is reduced into triose phosphate by reduced NADP.
  3. Some triose phosphate is converted into useful compounds, e.g. glucose. Some continue into the calvin cycle to regenerate RuBP which uses ATP from the LDR.
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17
Q

What useful organic substances are triose phosphate converted into ?

A

Carbohydrates
lipids
amino acids.

18
Q

How many turns of the calvin cycle produces 1 hexose sugar?

A

6 turns.
3 turns makes 6 triose phosphate molecules.
5 out of 6 molecules are used to regenerare RuBP.
1 molecule of triose phosphate is left however it only contains 3 carbon atoms, so 3 more turns are needed to result in another triose phosphate molecule. resulting in a hexose sugar.

19
Q

what are the products of the LDR ?

A

ATP
reduced NADP

20
Q

Why do plants look green ?

A

only certain wavelengths of light are used for photosynthesis.
The photosynthetic pigments only absorb red and blue light in sunlight, green light is reflected which is why they look green.

21
Q

What are limiting factors for photosynthesis ?

A

light intensity
temperature
carbon dioxide levels

22
Q

What are the similarities and differences of aerobic and anaerobic respiration ?

A

aerobic requires oxygen, however anaerobic does not
they both produce ATP, although anaerobic produces less
Both start with glycolysis but the stage after differ.
Both take place in the cytoplasm of cells

23
Q

What is glycolysis ?

A

splitting one molecule of glucose into two molecules of pyruvate. it does not require oxygen

24
Q

where does glycolysis happen ?

A

cytoplasm of cells

25
Q

What happens during glycolysis in anaerobic respiration and aerobic respiration ?

A

phosphorylation: in the cytoplasm of a cell, glucose is phosphorylated using 2 phosphate fmolecules from 2 atp. This creates once molecule of glucose phosphate and 2 molecules of adp. Glucose phosphate is split into 2 molecules of triose phosphate
Oxidation: Triose phosphate is oxidised by 2NAD to form 2NADH. This results in 2 molecules of pyruvate (3C) . 4 ATP molecules are produced but 2 are used up, so there is a net gain of 2.

26
Q

What happens at the end of glycolysis in anaerobic respiration ?

A

Pyruvate is converted into ethanal then ethanol (in plants and yeast) or lactate ( in animals and bacteria), using the oxidation of NADH.
The production of ethanol or lactate regenerates NAD so that glycolysis can continue.

27
Q

What happens during the link reaction of aerobic respiration ?

A

in the mitochondrial MATRIX, 2 molecules of Pyruvate is decarboxylated as one carbon atom is removed from each pyruvate in the form of (2) carbon dioxide molecules.
Pyruvate is oxidised to form 2 molecules of acetate and NAD is reduced into NADH.
Acetate is combined with co enzyme A to form 2 molecules of acetyl coenzyme A.
No ATP is produced.

28
Q

Where does the link reaction and the krebs cycle take place ?

A

mitochondrial matrix.

29
Q

what happens during the krebs cycle ?

A

Acetyl coenzyme A combines with a 4 carbon molecule to form citrate a 6 carbon molecule. Coenzyme A returns to the link reaction.
Citrate is converted into a 5C molecule and a carbon dioxide molecule is removed. NAD is reduced into NADH
The 5C molecule is converted into a 4c molecule (oxaloacetate) by removing carbon dioxide.
NAD is reduced into NADH and 2 FAD is reduced into 2 FADH.
ATP is produced by the transfer of pi to adp. this is called substrate level phosphorylation.
Citrate is converted into oxaloacetate

30
Q

What happens during oxidative phosphorylation ?

A

Energy carried by electrons from NADH AND FADH is used to make ATP.
Hydrogen atoms released by NADH and FADH dissociate into protons and electrons. electrons move down the electron transport chain loosing energy.
The energy pumps protons from the mitochondrial matrix to the intermembrane space. the concentration of protons is now higher in the intermembrane space forming an electrochemical gradient.
Protons move down the gradient into the matrix by atp synthase. This drives the synthesis of ATP from ADP and Pi. This is called chemiosmosis.
In the matrix, protons, electrons and oxygen form water. Oxygen is the final electron acceptor.

31
Q

Where does oxidative phosphorylation occur ?

A

intermembrane of the mitochondria

32
Q

what are the stages of aerobic respiration ?

A

glycolysis
link reaction
krebs cycle
oxidative phosphorylation

33
Q

how many molecules of ATP are made by NADH

A

2.5 per molecule of NADH

34
Q

How many molecules of ATP are made by FADH

A

1.5 molecules of ATP per FADH

35
Q

how many ATP molecules are made during aerobic respiration

A

32

36
Q

how can mitochondrial disease affect ATP production

A

it affects how proteins function in the krebs cycle or oxidative phosphorylation, reducing ATP production.
This may cause anaerobic respiration to occur more to make up for ATP shortage
This results in lots of lactate production which can cause muscle fatigue and weakness.
Some lactate will diffuse into the bloodstream leading to high lactate concentration in the blood

37
Q

What is the net gain of ATP during oxidative phosphorylation ?

A

28

38
Q

why is the theoretical yield of atp rarely achieved ?

A

some ATP is used up transporting pyruvate into the mitochondria
Not all H+ ions will move through ATP synthase
Some energy released in the electron transport chain is lost as heat.

39
Q

why is glucose not the only respiratory substrate ?

A

other respiratory substrates include the breakdown products of lipids and amino acids, which enter the krebs cycle.

40
Q

Describe the properties and functions of chloroplasts.

Cell Structure

A

A small, flattened structure found in plant and agal cells. It’s surrounded by a double membrane and also had membranes inside called thylakoid membranes, these are stacked in some parts of the chloroplast to form grana. Grana are linked together by lamellae - thin flat peices of thylakoid membrane).