Unit 3.3

Question 1

Respiration is what?

Answer 1

Respiration is the oxidation of organic molecules within the cells of organisms with the release of energy.

Question 2

What type of reaction is respiration?

Answer 2

This is a catabolic reaction, involving a series of enzyme catalysed reactions in cells, where energy rich respiratory substrates (carbohydrate, fat or protein) are broken down to release energy, which is mainly used to synthesis ATP. Some energy is also released as excess heat. There are two main types of respiration: aerobic and anaerobic.

Question 3

Which is more efficient?
Which yields more ATP?
Aerobic or anaerobic?

Answer 3

Aerobic is much more efficient and yields many more ATP

Question 4

What is respiration sometimes called? And why?

Answer 4

A metabolic pathway at it is a series of enzyme catalysed chemical reactions that start with a substrate and finish with an end product. This end product then forms the substrate for the next stage of the pathway.

Question 5

In order to synthesise ATP, two mechanisms occur is respiration, what are they?

Answer 5

Substrate level phosphorylation -
Energy is taken in a metabolic reaction directly
from a substrate to add a phosphate to ADP (ADP + Pi = ATP). This happens
throughout Glycolysis, link reaction and krebs cycle

Oxidative phosphorylation - Energy produced by the movement of electrons along a series of electron carriers is used to make ATP from ADP and Pi. This process completes in the electron transport chain

Question 6

What is oxidation?

Answer 6

Addition of oxygen and removal of hydrogen/loss of electrons

Question 7

What is reduction?

Answer 7

Addition of hydrogen, removal of oxygen/gain of electrons

Question 8

What is aerobic respiration?

Answer 8

When a glucose molecule is completely broken down to form carbon dioxide and water

Question 9

Where does aerobic respiration take place?

Answer 9

The cytosine of cytoplasm and mitochondrion

Question 10

What are the four stages of aerobic respiration?

Answer 10

1. Glycolysis (splitting of sugar) - occurs in the cytosol part of the cytoplasm in a cell
2. Link reaction - occurs in matrix of mitochondria
3. Krebs cycle - also occurs in matrix of mitochondria
4. Electron transport chain - occurs in inner mitochondrial membrane

Question 11

What is glycolysis?

Answer 11

• sugar splitting process
• takes place in cytosol of cytoplasm of cells
• does not involve oxygen
• a molecule of 6C is split into 2 molecules of pyruvic acid (puruvate)
  -only stage that can take place without oxygen as it occurs outside the mitochondria

Question 12

What happens during glycolysis?

Answer 12

6C glucose is phosphorylated by adding 2 phosphate groups, removed from 2 molecules of ATP.
This forms hexose phosphate (fructose bisphosphate)

Hexose phosphate splits into 2 molecules of 3C triose phosphate

Each 3C is converted into pyruvic acid, by dehydrogenation using a dehydrogenase enzyme
(Removes H to add to NAD)

Question 13

Quick summary of products of glycolysis

Answer 13

Yield is 4 ATP by substrate level phosphorylation
Reduction reaction resulting in the synthesis of 2 molecules of reduced coenzyme NAD

Question 14

How many different types of molecules went into glycolysis?

Answer 14

3

• ATP
• NAD
• glucose