5A - photosynthesis and respiration

Question 1

what are the 4 stages of aerobic respiration and where do they occur?

Answer 1

Glycolysis - cytoplasm
link reaction - mitochondrial matrix
krebs cycle - mitochondrial matrix
oxidative phosphorylation - inner membrane / cristae

Question 2

describe gylcolysis

Answer 2

glucose (6C) is phosphorylated due to the hydrolysis of 2ATP into 2ADP +2Pi forming glucose phosphate (6C) . this molecules splits into triose phosphate ( 3C X 2). this molecule is oxidised, losing a hydrogen which is picked up by the co - enzyme, 2NAD being reduced into 2NADH. 4ADP and 4Pi forms 4ATP in a condensation reaction. 2 3C pyruvates are formed.

Question 3

what is the gain of molecules at the end of glycolysis

Answer 3

2ATP, 2NADH and 2 3C pyruvate molecules.

Question 4

describe the link reaction

Answer 4

pyruvate molecule is oxidised and NAD is reduced forming NADH. the pyruvate is decarboxylated releasing CO2 and producing an acetate molecule. acetate reacts with co-enzyme A forming acetyl coenzyme A

Question 5

describe the krebs cycle

Answer 5

acetyl CoA reacts with a 4C molecule producing a 6C moleucle. the 6C molecule is decarboxylated releasing 2 carbons and producing 2 CO2 molecules. it is oxidised releasing hydrogens which are taken up by by 3 NAD enzymes and 1 FAD enzyme, producing 3NADH and 1FADH2. an ATP molecule is produced via substrate level phosphorylation. this will reproduce a 4C molecule.

Question 6

what are the products of the krebs cycle

Answer 6

2CO2, 3NADH,1FADH2 and 1ATP

Question 7

describe oxidative phosphorylation

Answer 7

NADH and FADH2 are oxidised releasing the H. the H splits into an electron and a proton. the electron moves across the etc through cattier proteins, releasing energy which is used in the active transport of protons across the inner membrane space, this forms an electro-chemical gradient. protons move back to the matrix through ATP synthase via facilitated diffusion. this causes rotation- for every 1 proton there is 1 rotation, and 1 ATP molecule is made every 3 rotations-
oxygen acts as the final electron acceptor, joining with 2 electrons and 2 protons to produce 1 water molecule.

Question 8

what happens to lipids before they are used as products

Answer 8

they are hydrolysed by lipase into fatty acids and glycerol. the glycerol is phosphorylated and then converted into triose phosphate, entering glycolyis

Question 9

what happens to the glycerol before entering the process of respiration

Answer 9

the glycerol is phosphorylated and then converted into triose phosphate, entering glycolyis

Question 10

what happens to the fatty acids before entering the process of respiration

Answer 10

the fatty acids are converted into acetyl conenzyeme A, entering the krebs cycle

Question 11

when is protein used at respiratory substrate

Answer 11

severe starvation

Question 12

what happens to proteins inorder to be used as a respiratory substrate

Answer 12

proteins are hydrolysed into amino acids. 3 carbon compounds are converted into pyruvates. 4 and 5 carbon compounds are used directly in the krebs cycle

Question 13

what is deamination

Answer 13

removal of the amine group NH2

Question 14

steps of alcohol fermentation in anaerobic respiration

Answer 14

occurs in yeast and some plants.
pyruvate will lose a molecule of CO2 and accepts a hydrogen from NADH. this produces ethanol and regenerates NAD

Question 15

pathway of lactate fermentation in anaerobic respiration

Answer 15

occurs in animals and bacteria.
pyruvate accepts a hydrogen from NADH.
this produces lactate and regenerates NAD

Question 16

negatives of respiring anaerobically in animals

Answer 16

accumulation of lactate causes cramp and muscle fatigue. as lactate is acidic it will reduce the pH affecting enzymes

Question 17

what is anerobic respiration and where does it occur

Answer 17

respiration in the absence of oxygen. occuring in the cytoplasm of the cell

Question 18

what is the efficiency of aerobic respiration

Answer 18

38 molecules of ATP produced = 32% efficiency

Question 19

what is the net production of ATP in anaerobic respiration

Answer 19

2 molecules

Question 20

word equation for photosynthesis

Answer 20

carbon dioxide + water -> glucose + oxygen

Question 21

why do plants need energy

Answer 21

photosynthesis
active transport
DNA replication
protein synthesis
mitosis + meiosis

Question 22

structure of an ATP molecule

Answer 22

adenine, ribose sugar and 3 phosphate groups

Question 23

why is ATP a good energy source

Answer 23

1. releases energy in small and manageable amounts so no energy is wasted
2. ATP is easily broken down so energy is easily released
3. cant leave the cell so there is always an energy source

Question 24

location of the dependent and independent reactions

Answer 24

dependent - thylakoid membrane of the chloroplasts
independent - stroma of the chloroplast

Question 25

Describe the structure of a thylakoid membrane, and proteins it contains?

Answer 25

folded membrane containing chlorophyll embedded with transmembrane electron carrier proteins

Question 26

Describe the location of chlorophyll and what is its role?

Answer 26

located on the thylakoid membrane different proteins that absorb light

Question 27

Summary of the light-dependent reaction

Answer 27

first stage of photosynthesis occurs in the thylakoid membrane uses light energy and water to produce ATP and NADPH for the light-independent reaction involves photoionisation of chlorophyll, photolysis and chemiosmosis

Question 28

What happens during photoionisation of chlorophyll

Answer 28

light energy absorbed by the chlorophyll excites electrons so they move to a higher energy level, leaving the chlorophyll some of the energy released is used to make ATP and NADPH

Question 29

What happens during photolysis

Answer 29

light energy absorbed by chlorophyll, splitting water into oxygen, H+ and e-

Question 30

products of photolysis and what are they used for

Answer 30

oxygen - used in respiration or diffuses out the stomata H+ - picked up by NADP to form NADPH, after passing through ATPsynthase, also form ATP e- - join with the magnesium ion found in chlorophyll

Question 31

How is the chemiosmotic gradient formed

Answer 31

electrons gain energy and move across the electron carrier proteins in the thylakoid membrane they release energy which pumps protons across the thylakoid membrane into the stroma an electrochemical gradient made protons pass back across to the thylakoid via ATP synthase producing ATP

Question 32

what happens to the protons after chemiosmosis

Answer 32

combine with NADP to become NADPH

Question 33

products of the light dependent reaction

Answer 33

ATP NADPH oxygen

Question 34

Summary of the light independent reaction

Answer 34

calvin cycle uses CO2, NADPH and ATP to form glucose occurs in the stroma which contains the enzyme rubisco

Question 35

1st step of the calvin cycle

Answer 35

CO2 combines with ribulose bisphosphate (5c) to form an unstable 6c molecule. catalysed by rubisco

Question 36

2nd step of the calvin cycle

Answer 36

the 6c molecule is broken down into 2 glycerate - 3- phosphate (3c) molecules.

Question 37

3rd step of the calvin cycle

Answer 37

GP is reduced to form triose phosphate the energy is provided by the hydrolysis of 2 ATP molecules NADPH is also oxidised for the H+

Question 38

4th step of the calvin cycle

Answer 38

5/6 turns of the calvin cycle produce RuBP from triose phosphate this also uses energy from the hydrolysis of ATP. 1/6 turns of the calvin cycle produce organic compounds e.g. glucose

Question 39

requirements/conditions for photosynthesis

Answer 39

photosynthetic pigments e.g. chlorophyll carbon dioxide water light optimum temperature

Question 40

3 limiting reactants of photosynthesis

Answer 40

light intensity CO2 concentration temperature

Question 41

how does light intensity affect rate of photosynthesis

Answer 41

low light intensity limits the light dependent reaction, this decreases the ATP and NADPH produced, so less is transferred to the light in dependent reaction, decreasing rate of photosynthesis. when there is a high light intensity, something else will be the limiting factor

Question 42

how does CO2 concentration affect rate of photosynthesis

Answer 42

low CO2 concentration limits the light independent reaction, less CO2 can bind with RuBP, less GP and TP made. high CO2 conc means something else is the limiting factor

Question 43

how does temperature affect rate of photosynthesis

Answer 43

low temp, low kinetic energy, low rate of photosynthesis , due to enzyme - catalysed reactions requiring Ke. optimum temp, the optimum rate of photosynthesis high temp, enzymes begin to denature, rate of photosynthesis stops.

Question 44

what is the saturation point

Answer 44

the point on a graph where a different factor become the limiting factor, when the graph begins to plateaux.