3.5.2 Respiration

Question 1

ATP hydrolysis releases energy in small manageable amounts

Answer 1

so little energy is wasted when used in the cell

Question 2

ATP can be rapidly re-synthesised after hydrolysis

Answer 2

so a continual supply is available in the cell

Question 3

ATP can transfer energy to other molecules by adding one of its phosphate groups

Answer 3

so it can make molecules more reactive

Question 4

ATP cannot cross the cell surface membrane

Answer 4

so it ensures that it is always available inside the cell for chemical processes

Question 5

ATP is small and soluble

Answer 5

so it can easily diffuse through the cytoplasm and provide energy for different chemical reactions

Question 6

Only one bond is broken to release energy during ATP hydrolysis to ADP

Answer 6

so it releases energy immediately

Question 7

ATP function and properties

Answer 7

ATP hydrolysis releases energy in small manageable amounts
so little energy is wasted when used in the cell

ATP can be rapidly re-synthesised after hydrolysis
so a continual supply is available in the cell

ATP can transfer energy to other molecules by adding one of its phosphate groups
so it can make molecules more reactive

ATP cannot cross the cell surface membrane
so it ensures that it is always available inside the cell for chemical processes

ATP is small and soluble
so it can easily diffuse through the cytoplasm and provide energy for different chemical reactions

Only one bond is broken to release energy during ATP hydrolysis to ADP
so it releases energy immediately

Question 8

What is the first stage of anaerobic and aerobic respiration?

Answer 8

Glycolysis

Question 9

Equation for aerobic, aerobic respiration

Answer 9

Aerobic - requires the presence of oxygen (glucose) and produces carbon dioxide, water and a lot of ATP
● Anaerobic - takes place in the absence of oxygen (glucose) and produces lactic acid (in animals) or ethanol and carbon dioxide (in plants and fungi) and only produces a little ATP

Question 10

ATP cycle

Answer 10

ATP hydrolase
hydrolysis
Exergonic reaction

ATP synthase
Condensation
Endergonic reaction

Question 11

2 coenzyme in respiration process

Answer 11

NAD
FAD

Question 12

Glycolysis process

Answer 12

Glucose is phosphorylated using 2ATP
The glucose phosphate is split into two triose phosphate molecules - LYSIS
The 2 triose phosphates are oxidised forming 2 NADH (reduced NAD), coupled to the addition of phosphate. This process is catalysed by dehydrogenase enzymes.
Substrate level phosphorylation occurs forming 4 ATP, with a net of 2ATP,
producing 2 pyruvate molecules are formed for every glucose oxidised

Question 13

What substance and how they are transport into mitochondria during respiration

Answer 13

Pyruvate active transport
Oxygen diffusion
ADP and PI active transport

Question 14

Link reaction

Answer 14

Pyruvate is actively transported from the cytoplasm into the mitochondrial matrix by carrier proteins on the mitochondrial membrane
The pyruvate loses a carbon atom (decarboxylation), which forms a carbon dioxide molecule The 2C compound is oxidised to acetate, losing hydrogen atoms (NAD is reduced to NADH) Acetate combines with coenzyme A to form acetyl coenzyme A.

Question 15

Kerb cycle

Answer 15

2C Acetyl CoA combines with a 4C organic compound to produce a 6C molecule (citrate)
The 6C molecule is oxidised, with H atoms transferred to form reduced NAD and it loses a carbon as CO2 forming a 5C molecule.
The 5C molecule is oxidised, with H atoms transferred to form reduced NAD and it loses a carbon as CO2 forming a 4C molecule.
The 4C molecule is further oxidised producing reduced NAD and reduced FAD. ATP is also formed. The original 4C molecule that reacts with acetyl CoA is regenerated and the cycle continues.

Question 16

Oxidative pgosphorylation

Answer 16

High energy electrons carried by the reduced coenzymes (NADH and FADH2) are passed to electron carriers (the coenzymes are oxidised again)
As the electrons flow down the electron transport chain (ETC), they lose energy and the energy is transferred to pump hydrogen ions out of the matrix into the intermembrane space.
Electrons are transferred onto oxygen which combines with hydrogen ions to form water (the oxygen is reduced).
Oxygen is the final electron acceptor.

Chemiosmosis
ATP synthase is located in the inner mitochondrial membrane
There is a concentration of hydrogen ions (protons) in the intermembrane space due to the movement of electrons through the ETC.
Hydrogen ions flow down their concentration gradient through the ATP synthase protein and the energy is transferred to make ATP from ADP and Pi.

Question 17

Other respiratory substrate

Answer 17

Glycerol , fatty acid
Amino acid

Question 18

Where does anaerobic respiration happen?

Answer 18

Cytoplasm

Question 19

Can you explain how anaerobic respiration in animal works after production of pyruvate in glycolysis

Answer 19

The conversion of pyruvate to lactate in animals (and some bacteria) regenerates NAD (from NADH), allowing glycolysis to keep going

Question 20

Can you explain how anaerobic respiration in plant and fungi works after production of pyruvate in glycolysis

Answer 20

Ethanol fermentation occurs in plants and some microorganisms such as yeast.
It allows NAD to be regenerated to keep glycolysis going. To produce ATP

Question 21

Apparatus to measure rate of respiration

Answer 21

Respirometer

Question 22

Limitation and solution of using methylene blue to measure the rate of respiration of organism

Answer 22

End point is subjective even using colour chart
Use colour perimeter which provides quantitative data as objective

Difficulty in seeing colour change in water bath
Required taking it out to see the colour lead to temperature drop
Use see thermostatic water bath, use a beaker to create mobile water bath

Question 23

In practical of the methylene blue testing rate of respiration, why must both solution be left into water bath for five minute before reaction?

Answer 23

So the yeast and the methylene blue solution equilibrate to the test temperature in the water bath

Question 24

In practical of the methylene blue testing rate of respiration, why did methylene blue solution turn colourless

Answer 24

deHydrogenase remove hydrogen from NADH and methylene pick up this hydrogen and reduce it to form colourless solution

Question 25

In respirometer experiment why the liquid would move towards the left when the organism is in the left test tube

Answer 25

The respiring organism took in oxygen from the air in the experimental tube on the left. The carbon dioxide produce in the respiration is absorbed by the alkaline therefore the volume of gas decrease in the experimental tube causing a decrease in pressure and is comparatively lower than the tip, therefore the coloured liquid moved to the experimental tube on the left.

Question 26

What is the purpose of soda line/ sodium hydroxide in respirometer experiment

Answer 26

To absorb carbon dioxide produce in respiration so the volume of oxygen absorbed by the organism can be measured

Question 27

Explain why the apparatus in the respirometer experiments must be airtight

Answer 27

To prevent air entering or leaving as this would change the volume and therefore the pressure affecting the movement of the colour liquid and the validity off the result

Question 28

Why there’s a blue rain on top of the yeast In practical of the methylene blue testing rate of respiration

Answer 28

Because that part of the methylene blue meets the air so it oxidised
When they mix the solution, it will reset to the starting point

Question 29

suggest one explaination for higher glycerol and fatty acid concentration in blood plasma of athletes after they were given caffeine

Answer 29

breakdown of fat
at increased rate / by mobilisation of fat store