B9 - Respiration

Question 1

What is respiration, and what is it for?

Answer 1

-an exothermic reaction that continuously occurs in living cells
-the energy released supplies the energy needed for living processes to occur

Question 2

Give 4 things living organisms use energy for:

Answer 2

-chemical reactions to build bigger molecules (or break down)
-muscular contraction to bring about movement
-maintaining stable internal body temperature to stay warm
-active transport

Question 3

Give the 2 equations that represent aerobic and anaerobic respiration:

Answer 3

aerobic
glucose + oxygen → carbon dioxide + water

anaerobic
glucose → lactic acid

Question 4

How is anaerobic respiration different to aerobic respiration?

Answer 4

-anaerobic respiration involves incomplete glucose oxidation, forming lactic acid and thus an oxygen debt
-far less energy released

However, anaerobic respiration is faster as it releases less energy, so more glucose needs to be partially oxidated to meet the body’s energy demands

Question 5

What is the equation for anaerobic respiration in yeast cells? What is the name of this specific process, and why is it important?

Answer 5

glucose → ethanol + carbon dioxide

-fermentation
-used to manufacture bread and alcoholic drinks

Question 6

What is the equation for anaerobic respiration in plant cells?

Answer 6

glucose → ethanol + carbon dioxide

this is the same as yeast cells

Question 7

Compare anaerobic respiration in a yeast cell with anaerobic respiration in a muscle cell:

Answer 7

-yeast produces ethanol but muscles produce lactic acid
-yeast produces CO2 but muscles do not
-both release small amounts of energy

COMPARE

Question 8

How does the body respond to exercise and why?

Answer 8

increased demand for energy from respiration, so HR, breathing rate/volume increases to supply muscles with more oxygenated blood and glucose faster for aerobic respiration

Question 9

What happens if insufficient oxygen is supplied to the muscles during exercise?

Answer 9

-anaerobic respiration takes place
-incomplete oxidation of glucose results in a build-up of lactic acid, creating oxygen debt
-muscles become fatigued and don’t contract efficiently

Question 10

How does the body deal with an excess of lactic acid?

Answer 10

blood flowing through the muscles transports lactic acid to the liver, where it is reacted with oxygen to form glucose

Question 11

What is oxygen debt?

Answer 11

the amount of extra oxygen needed after exercise to react with the accumulated lactic acid to remove it from the muscle cells

Question 12

What is metabolism?

Answer 12

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

Question 13

Name 4 metabolic reactions:

Apart from respiration/photosynthesis

Answer 13

-converting glucose to starch/glycogen/cellulose
-lipid molecule synthesis from 1 glycerol and 3 fatty acids
-reacting glucose and nitrate ions to form amino acids then proteins
-breakdown of excess proteins to form urea for excretion

The process of deamination is covered in B12 and is a paper 2 topic

Question 14

If you one organism (A) has a higher SA:V than the other, why would its metabolic rate be higher than the other (B)?

Answer 14

-A has a larger SA:V and so will lose heat more quickly per unit volume
-it requires a greater rate of respiration to generate more heat to keep itself warm
-respiration is a large part of metabolism, so it’s metabolic rate would be higher than B

Question 15

Explain why a person with a leaky heart valve has difficulty exercising:

Answer 15

-backflow can occur
-some blood stays in the heart (instead of being pumped out)
-less oxygen and glucose supplied to muscle cells so less aero. resp.
-less energy released, so less efficient muscle contraction
-anaerobic respiration takes place so lactic acid builds up
-muscle fatigue