4.4.2.1 Aerobic and Anaerobic Respiration

Question 1

Where does energy come from?

Answer 1

• energy for life comes from the sun via food chains
• food is broken down to release energy to be used by cells
• the process which cells release energy is called cellular respiration - occurs in the mitochondria of the cell

Question 2

Cell respiration:

Answer 2

• an exothermic reaction which is continuously occurring in living cells where cells break down glucose and which releases energy (+byproducts) to fuel cells’ living processes (can use oxygen)
• the energy transferred supplies all the energy needed for all the cells living processes
• respiration is a vital process that is speeded up and controlled by enzymes

Question 3

How can respiration take place in cells?

Answer 3

aerobically (using oxygen) or anaerobically (without oxygen) to release energy

Question 4

What is respiration needed for?

Answer 4

To release energy for:

• for chemical reactions to keep them alive and to build larger molecules
• for movement e.g. muscle contraction
• for keeping warm (body warmth
• for transmitting nerve impulses
• for cell division
• for maintaining a constant environment within our bodies
• active transport of substances

Question 5

How is the cytoplasm involved in respiration?

Answer 5

• where enzymes are made
• location of reactions in anaerobic respiration

Question 6

How is the nucleus involved in respiration?

Answer 6

holds genetic code for enzymes involved in respiration

Question 7

How is the mitochondria involved in respiration?

Answer 7

contains enzymes for aerobic respiration

Question 8

How is the cell membrane involved in respiration?

Answer 8

• allows gases and water to pass freely into and out of the cell
• controls the passage of other molecules

Question 9

Aerobic respiration:

Answer 9

• A form of respiration that uses oxygen to release energy from molecules like glucose
• It yields the most energy
• Most of the reactions that make up aerobic respiration take place in the mitochondria

Question 10

Word equation and formula for aerobic respiration in muscles:

Answer 10

Question 11

Function of mitochondria:

Answer 11

site of aerobic respiration which releases energy for the cells processes (function)

Question 12

Adaptations of mitochondria:

Answer 12

folded inner membranes to increase the surface area for a higher rate of aerobic respiration

Question 13

Is the number of mitochondria related to the energy produced by the cell?

Answer 13

the cells that release the most energy have the most mitochondria because they are very active cells e.g. retinal eye cells

Question 14

Which cells have very few mitochondria and why?

Answer 14

hair cells, bacterial cells and red blood cells as they would be the least active and therefore need the least energy

Question 15

Anaerobic respiration:

Answer 15

• A form of respiration that releases energy from molecules like glucose without using oxygen
• Used to obtain if insufficient oxygen is reaching the muscles for aerobic respiration
• Less energy is transferred compared to aerobic respiration as the oxidation of glucose is incomplete
• It is only used as a last resort (e.g. during hard exercise) for example during a sprint where it is difficult to breathe in enough oxygen

Question 16

Word equation and formula for anaerobic respiration in animals:

Answer 16

Question 17

Word equation and formula for anaerobic respiration in organisms like yeast:

Answer 17

Question 18

What is anaerobic respiration in yeast called?

Answer 18

anaerobic respiration in yeast is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks

Question 19

Why will anaerobic respiration eventually kill yeast?

Answer 19

because the ethanol will become toxic to the yeast

Question 20

What are products of anaerobic respiration in yeast for?

Answer 20

CO2 is used to make bread rise

Question 21

What food products utilise anaerobic respiration?

Answer 21

• bread
• alcohol
• vinegar
• cheese
• yoghurt

Question 22

What are the stages of anaerobic respiration?

Answer 22

• vigorous exercise
• aerobic respiration provides less and less energy
• heart and lungs cannot supply oxygen to muscle cells fast enough to satisfy demand
• anaerobic respiration provides energy
• glucose is broken down into lactic acid
• lactic acid accumulates in muscles causing fatigue
• forced to stop the exercise
• lactic acid transported from the muscles to the liver by the blood
• lactic acid oxidised to O2 and CO2
• oxygen debt has been repaid

Question 23

Oxygen debt:

Answer 23

the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells (as although lactic acid is energy it is also toxic)

Question 24

Metabolism:

Answer 24

the sum of all the reactions in a cell or the body

Question 25

What sort of a molecule is glycogen?

Answer 25

Carbohydrate used as an energy store

Question 26

What is glycogen made of?

Answer 26

Glucose molecules joined in chains

Question 27

Where is glycogen found?

Answer 27

In animals, in liver (mainly) and muscles

Question 28

When is glycogen made?

Answer 28

When blood glucose levels are high (after meals and when resting)

Question 29

Which hormone promotes glycogen formation?

Answer 29

Insulin

Question 30

When is glycogen used?

Answer 30

When blood glucose levels are low (when fasting and exercising)

Question 31

How is glycogen used?

Answer 31

Broken down into glucose molecules which are then respired

Question 32

Exothermic reactions:

Answer 32

reactions which transfer energy to the surroundings

Question 33

What does the energy transferred by aerobic and anaerobic respiration supply?

Answer 33

the energy transferred supplies all the energy needed for living processes