Mod 5 Respiration

Question 1

What are the main features of the ATP molecule that make it an ideal energy store? (3)

Answer 1

• It traps v. small amounts of energy
• It traps energy quickly and readily and releases it equally readily
• By conversion of ADP + Pi to ATP when energy is available and ATP to ADP + Pi when the stored an when the stored energy is needed
• Energy currency of cells
• ATP can’t be transported between cells, it must be released within each cell as it is needed
• As small amounts of energy are involved there is little energy loss during the conversion

Question 2

Why is the link between photosynthesis and respiration in plants vital?

Answer 2

Photosynthesis is how sunlight energy is trapped and used as chemical energy. This chemical energy is used by plants and other organisms for energy release during respiration

Question 3

What process do microorganisms need energy for>

Answer 3

Protein synthesis
Cell division
Growth
Drive chemical processes

Question 4

Function of Active Transport

Answer 4

Pump mechanisms such as movement of molecules through cell membranes against their concentration gradient

• uptake of many food molecules in gut
• uptake of some ions in kidneys
• Na+/K+ pump mechanism in nerve cells to establish a resting or action potential

Question 5

Exocytosis

Answer 5

When large molecules are secreted or released out of a cell

Question 6

Endocytosis

Answer 6

When large molecules are taken into a cell

Question 7

Protein synthesis

Answer 7

building up polypeptides and proteins from amino acids

Question 8

What feature of glycolysis suggests that it is an anaerobic process?

Answer 8

It does not need or use any oxygen and it occurs in both aerobic and anaerobic conditions
It occurs in cytosol (cytoplasm) so all the enzymes needed to convert glucose to pyruvate are found there

Question 9

Where do link reaction and krebs cycle occur?

Answer 9

Both occur in the matrix of the mitochondria where pyruvate is converted to acetate

Question 10

Oxidative phosphorylation takes place on the inner mitochondrial membranes. What features do they have to make it an ideal site for this reaction?

Answer 10

• They are highly folded so a large SA is provided ( increase rate of reaction)
• They carry all the enzymes and carrier molecules needed for ETC and electron transport itself : these are embedded within the membrane, along with ATP synthase
• ATP synthase is where ATP is synthesised through phosphorylation of ADP.

Question 11

Describe the phosphorylation reaction in glycolysis

Answer 11

1 ATP molecule is hydrolysed for each step:
1. glucose to hexose monophosphate
2. to hexose bisphosphate
( Glucose is activated and energy levels raised by adding phosphate to form hexose phosphate and then a second phosphate is added to for hexose bisphosphate - energy and Pi are released for each of these steps)

Question 12

Describe the oxidation stage of glycolysis

Answer 12

TP is oxidised and red NAD formed

2 H atoms are removed to oxidase TP, dehydrogenase enzyme are used with coenzyme NAD acting as H acceptor

Question 13

Describe substrate level phosphorylation in glycolysis

Answer 13

2 red NAD are formed and enough energy to reform 2 ATP molecule
(when substrate - TP is modified by enzyme controlled reaction, enough energy is released to produce ATP)

Question 14

Products of glycolysis for 1 glucose molecule

Answer 14

2 red NAD
2 ATP
2 pyruvate