Topic 5 - Energy For Biological Processes

Question 1

What is cellular respiration?

Answer 1

Cellular respiration is the process by which energy from food molecules is transferred to ATP.

Question 2

What are the two types of cellular respiration?

Answer 2

Aerobic respiration & Anaerobic respiration.

Question 3

What is Aerobic respiration?

Answer 3

Aerobic respiration is the form of cellular respiration that takes place in the presence of Oxygen.

Question 4

What is the equation for Aerobic Respiration?

Answer 4

Glucose + Oxygen —> Carbon Dioxide
+ Water (+ ATP)

Question 5

What are the 4 main stages in Aerobic Respiration?

Answer 5

• Glycolysis
• Link Reaction
• Krebs Cycle
• Electron Transport Chain

Question 6

Where does glycolysis take place?

Answer 6

In the Cytoplasm.

Question 7

Where does the Link reaction take place?

Answer 7

In the matrix.

Question 8

Where does the Krebs Cycle take place?

Answer 8

In the matrix.

Question 9

Where does the Electron Transport Chain take place?

Answer 9

In the Cristae.

Question 10

What is Reduction?

Answer 10

• Reduction is the addition of electrons (negative charge) to a substance.
• In the cell this is brought about by the addition of Hydrogen or the removal of Oxygen.

Question 11

What is Oxidation?

Answer 11

• Oxidation is the removal of electrons (negative charge) from a substance.
• Any substance that has oxygen added, OR hydrogen or electrons removed, is described as ‘Oxidised’.

Question 12

What are the names of the coenzymes used in cellular respiration?

Answer 12

NAD & FAD

Question 13

What does NAD become when it accepts a hydrogen atom?

Answer 13

Reduced NAD (NADH)

Question 14

What does FAD become when it accepts a hydrogen atom?

Answer 14

Reduced FAD (FADH2)

Question 15

What apparatus can be used to measure the rate of respiration in a school lab?

Answer 15

Respirometer

Question 16

Summarise Glycolysis

Answer 16

• ATP is used to phosphorylate the glucose
• This makes the glucose more reactive
• The phosphorylated glucose is then split to make 2 molecules of Glycerate-3-phosphate (GP)
• Finally via several steps GP is converted to Pyruvate

Question 17

Where does the Pyruvate go after glycolysis if Oxygen is present?

Answer 17

Mitochondria (specifically the matrix).

Question 18

Where does the pyruvate go after glycolysis if little to no oxygen is present?

Answer 18

The pyruvate will remain in the cytoplasm.

Question 19

What is the net ATP produced in aerobic respiration?

Answer 19

31 ATP.

Question 20

What is the net ATP produced in anaerobic respiration?

Answer 20

2 ATP.

Question 21

What are the waste products in aerobic respiration?

Answer 21

Water & Carbon Dioxide.

Question 22

What are the waste products in anaerobic respiration?

Answer 22

• Lactic acid (Mammals)
  OR
• Ethanol & CO2 (Plants)

Question 23

How and where is most the ATP produced during cellular respiration?

Answer 23

Most the ATP produced in cellular respiration is made through a series of OXIDATION and REDUCTION reactions in the ELECTRON TRANSPORT CHAIN.

Question 24

What does a basic Respirometer consist of?

Answer 24

• Sealed chamber containing the living organisms
• A chemical (such as Soda Lime) to absorb the carbon dioxide produced by respiration
• Manometer tube (containing fluid)
• Tap
• syringe

Question 25

What causes the fluid in the manometer to move (when using a respirometer)?

Answer 25

• When the living organisms respire they use oxygen so the pressure in the tubes reduce.
• This causes the fluid in the manometer to move.

Question 26

In what direction does the fluid in the manometer move when organisms are respiring?

Answer 26

The fluid in the manometer moves TOWARDS the living organisms as they respire.

Question 27

What is the purpose of the syringe in the respirometer?

Answer 27

It measures the volume of gas needed to return the Manometer to normal.

Question 28

What are the products of glycolysis?

Answer 28

• 2 NADH
• 2 Pyruvate
• Net of 2 ATP

Question 29

Why is the ATP produced in anaerobic respiration lower?

Answer 29

The ATP produced in anaerobic respiration is lower because some of the NADH is used to reduce pyruvate to lactate, rather than entering the electron transport chain.

Question 30

Why do we breathe heavily after intense exercise?

Answer 30

Oxygen is need to Oxidise the built up lactate (toxic) back in to pyruvate.

Question 31

Why is it called the ‘link reaction’ ?

Answer 31

Because this reaction ‘links’ glycolysis to the next stage, the Krebs cycle.

Question 32

Summarise the Link Reaction.

Answer 32

• Pyruvate (3C) crosses the mitochondrial membrane from the cytoplasm.
• 1C is removed from Pyruvate (decarboxylation)
• This forms 1 CO2 and a 2C compound which joins with coenzyme A to form Acetyl CoA (2C)
• At the same time Pyruvate loses more hydrogen to NAD

Question 33

What are decarboxylases ?

Answer 33

Decarboxylases are enzymes that remove carbon dioxide.

Question 34

What are Dehydrogenases?

Answer 34

Dehydrogenases are enzymes that remove hydrogen.

Question 35

What are the products of the link reaction?

Answer 35

• Acetyl CoA (2C)
• CO2
• NADH

Question 36

Summarise the Krebs cycle.

Answer 36

• Acetyl CoA (2C) combines with 4C compound to form 6C ‘citrate’
• The 6C ‘citrate’ undergoes many reactions until it is broken down to the original 4C compound
• The 4C compound then joins with the next Acetyl CoA and the cycle happens again