4.4.2 Respiration

Question 1

Respiration

Answer 1

Is an enzyme-controlled reaction that breaks down glucose to release energy, in the form of a substance called ATP

Exothermic reaction

Question 2

What is respiration for in animals and plants

Answer 2

Animals:
Powering chemical reactions, e.g biosynthesis
Muscle contractions
Regulating body temperature

Plants:
Active transport

Question 3

Aerobic respiration word and symbol equation

Answer 3

Glucose + oxygen -> carbon dioxide + water
C6H12O6 + 6CO2 -> 6CO2 + 6H2O

Question 4

Anaerobic respiration in animals

Answer 4

When insufficient oxygen is present, e.g muscles during vigorous exercise, so glucose cannot be fully oxidised
Produces lactic acid

Question 5

Drawbacks of anaerobic respiration in muscles

Answer 5

Glucose is not fully oxidised, therefore less energy is released
Lactic acid builds up which can be toxic to cells in high concentrations and causes MUSCLE FATIGUE

Question 6

Anaerobic respiration in plants and yeast word equation

Answer 6

Glucose -> carbon dioxide + ethanol
(Fermentation)

Question 7

Effect of exercise

Answer 7

More blood is delivered to the muscles every minute
So more O2 carried by haemoglobin in RBCs and glucose carried through plasma are delivered to the muscles
So the muscles can carry out a faster rate of aerobic respiration
And prevent anaerobic respiration from happening
So more energy is released allowing the muscles to continue contracting
And more carbon dioxide is removed from the muscles

Question 8

How does increased breathing rate help the body in its response to exercise

Answer 8

Increased breathing rate means increased oxygen taken into the lungs, which then diffuses into the bloodstream
Then it can be delivered to cells of the body for increased rate of respiration

Question 9

Oxygen debt

Answer 9

After respiring anaerobically, lactic acid must be transported to the liver where it is converted back into glucose, using oxygen.
The extra oxygen required to react with the lactic acid is oxygen

Question 10

How do muscles have access to glucose during exercise

Answer 10

There may not be a sufficient supply of glucose—cells have a limited supply
So muscle cells store glycogen which can be rapidly converted to glucose during exercise

Question 11

Metabolism definition and examples

Answer 11

All chemical reactions in cells
Food eaten:
Glucose—respiration, makes glycogen, makes starch
Fatty acids and glycerol—lipids
Amino acids—makes protein, makes urea which is then excreted

Other processes:
Photosynthesis
Production of amino acids from glucose and nitrate ions

Question 12

Role of liver in metabolism—substance: poisonous substances, e.g ethanol

Answer 12

Detoxifies substances - makes sure they are removed from blood

Question 13

Role of liver in metabolism—substance: excess amino acids

Answer 13

breaks down excess amino acids into ammonia which gets turned into the less harmful substance urea

Question 14

Role of liver in metabolism—substance: red blood cells

Answer 14

Breaks down old/dead red cells and stores the iron until it is needed to make more RBCs

Question 15

Role of liver in metabolism—substance: lactic acid

Answer 15

Lactic acid produced by muscles travels to the liver which converts it back to glucose (glycogen)