Topic 4 - Bioenergetics (respiration)

Question 1

What is the definition of respiration?

Answer 1

the process of transferring energy fro glucose (this happens in every living cell continuously)

Question 2

What happens in respiration?

Answer 2

Energy is transferred from the breakdown of glucose

Question 3

Is respiration exothermic or endothermic?

Answer 3

Exothermic (energy is transferred to the surroundings)

Question 4

Why do plants and animals need to respire?

Answer 4

to transfer energy from their food to their cells

Question 5

Give 3 ways of how organisms use the energy transferred by respiration?

Answer 5

1) to build up larger molecules from smaller ones (proteins fro amino acids)
2) In animals, it is used to allow the muscles to contract
3) In mammals and birds, energy is used to keep body temperature steady in cooler surroundings

Question 6

What is the metabolism of a cell or body?

Answer 6

The sum of all the reactions that happen in a cell or body

Question 7

What controls chemical reactions in cells?

Answer 7

enzymes
- these reactions are linked to form bigger reactions

Question 8

What two things can happen in reactions in cells?

Answer 8

• larger molecules are made from smaller ones
• larger molecules are broken into smaller ones

Question 9

Give two examples of larger molecules breaking into smaller ones

Answer 9

• glucose is broken down in respiration (energy transferred powers the reactions in the body that make molecules)
• excess protein is broken down to produce urea - this is excreted in urine

Question 10

Give 3 examples of larger molecules being made from smaller ones?

Answer 10

• small glucose molecules are joined to form starch, glycogen and cellulose
• lipid molecules are each made from one molecule of glycerol + 3 fatty acids
• glucose is combined with nitrate ions to make amino acids (these then make proteins)

Question 11

What is starch?

Answer 11

a storage molecule in plant cells

Question 12

What is glycogen?

Answer 12

a storage molecule in animal cells

Question 13

What is cellulose?

Answer 13

a component of plant cell walls

Question 14

What is aerobic respiration?

Answer 14

respiration using oxygen (this is the most efficient way to transfer energy from glucose) - this happens all the time in animals and plants

Question 15

Where does aerobic respiration take place?

Answer 15

in the mitochondria

Question 16

What is the word equation for aerobic respiration?

Answer 16

glucose + oxygen –> carbon dioxide + water

Question 17

What is the symbol equation for aerobic respiration?

Answer 17

C6 H12 O6 + 6O2–> 6CO2 + 6H20

Question 18

When does anaerobic respiration happen?

Answer 18

When you do vigorous exercise and your body can’t supply enough oxygen to your muscles (you start doing anaerobic respiration as well as aerobic respiration)

Question 19

What is anaerobic respiration?

Answer 19

the incomplete breakdown of glucose which makes lactic acid

Question 20

What is the word equation for anaerobic respiration in muscle cells?

Answer 20

glucose –> lactic acid

Question 21

What is the symbol equation for anaerobic respiration?

Answer 21

C6H12O6 –> 2C3H6O3

Question 21

What are two disadvantages of anaerobic respiration?

Answer 21

-Does not transfer nearly as much energy as aerobic respiration because the glucose isn’t fully oxidised
- it is only useful in emergencies (allows you to keep using your muscles for a while longer)

Question 22

What do plant and yeast cells produce when they respire anaerobically

Answer 22

ethanol (alcohol) and carbon dioxide

Question 23

What is anaerobic respiration in yeast cells called?

Answer 23

fermentation

Question 24

What is the word equation for anaerobic respiration in plant and yeast cells?

Answer 24

glucose --> ethanol + carbon dioxide

Question 25

State 2 uses of yeast fermentation

Answer 25

Bread making- the carbon dioxide from fermentation makes the bread rise Beer and wine making- it's the fermentation that produces alcohol

Question 26

Why do your cells respire more when you exercise?

Answer 26

- increased muscle contraction requires more energy -the energy comes from increased respiration

Question 27

What are the effects of increased respiration?

Answer 27

- you need to get more oxygen to your cells - breathing rate and volume increase to get more oxygen into the blood - heart rate increases to get blood around the body quicker (also removes CO2 more quickly)

Question 28

Why can't you sustain long periods of exercise?

Answer 28

-lactic acid builds up in the muscles, which gets painful - long periods of exercise can cause muscle fatigue (the muscles get tired and stop contracting efficiently)

Question 28

When does an oxygen debt happen?

Answer 28

After respiring anaerobically

Question 29

What is an oxygen debt

Answer 29

the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it fro, the cells

Question 30

How does your body get rid of lactic acid?

Answer 30

oxygen reacts with the lactic acid to form carbon dioxide and water

Question 31

What do you continue to do after you stop exercising and why?

Answer 31

- you continue to breathe heavily to get more oxygen into the blood and muscle cells - pulse and breathing rate stay high whilst there are high levels of lactic acid and carbon dioxide

Question 32

Name another way your body copes with high levels of lactic acid

Answer 32

-Blood that enter your muscles can transfer lactic acid to the liver - In the liver, lactic acid is converted back to glucose