respiration (topic 4)

Question 1

Answer 1

• constant speed
• constant temperature
• constant effort

Question 2

name two substances needed in larger amounts by the muscles during vigorous exercise than when resting

Answer 2

• glucose
• oxygen

Question 3

give one other way to increase the blood flow other than - the heart to pump out a larger volume of blood each beat

Answer 3

increased heart rate

Question 4

compare after training programme to before training programme (2)

Answer 4

• lower resting rate
• lower rate during exercise
• recovers faster after exercise

Question 5

Answer 5

a higher concentration would be difficult to stir

Question 6

Answer 6

aerobic respiration

Question 7

energy is released in respiration, give two uses of this energy

Answer 7

• movement
• keeping warm
• active transport
• building larger molecules
• cell division

Question 8

what are the two products of anaerobic respiration in plants

Answer 8

• carbon dioxide
• ethanol

Question 9

(2)

Answer 9

• atmospheric air contains less carbon dioxide than exhaled air
• flask 3 contains more carbon dioxide, produced during (aerobic) respiration

Question 10

why do scientists use controls (2)

Answer 10

• for comparison
• to check that no other variable is influencing the results

Question 11

the student repeated the investigation with dead boiled peas, predict what will happen to the limewater in flasks 1 and 3 after 10 minutes (2)

Answer 11

• flask 1 would remain colourless
• flask 3 would remain colourless

Question 12

Answer 12

Question 13

why is more lactic acid made in the muscles when running at 18 km per hour than when running at lower speeds (3)

Answer 13

• more energy is needed
• not enough oxygen can be supplied to muscles
• oxygen debt
• more anaerobic respiration to supply the extra energy (or more glucose changed to lactic acid)
• not enough aerobic respiration

Question 14

why cant we sustain exercise when this reaction (glucose -> lactic acid) happens in our muscle cells (2)

Answer 14

• build-up of lactic acid causes cramps/pain
• muscles become fatigued
• muscles stop contracting
• not enough energy is transferred

Question 15

Answer 15

• electron microscope
• higher magnification
• higher resolution

Question 16

suggest how the student could modify his method to ensure his results are reproducible (2)

Answer 16

• collect the carbon dioxide with a measuring cylinder
• measure the volume collected in a certain time using a timer

Question 17

how does anaerobic respiration in yeast differ from anaerobic respiration in muscle cells (3)

Answer 17

• yeast produces ethanol but muscles produce lactic acid
• yeast produces carbon dioxide but muscles do not
• both release small amounts of energy

Question 18

a group of students planned an investigation to determine the effects of running on breathing rate, the students measured their breathing rates before running and immediately after running for 5 minutes, write a hypothesis for their investigation (2)

Answer 18

• running will increase the breathing rate compared to the resting breathing rate
• followed by a gradual return to the resting breathing rate after exercise

Question 19

describe how the students could measure their breathing rates (2)

Answer 19

• count the number of breaths in one minute
• use a spirometer

Question 20

suggest why running has an effect on the students breathing rate (3)

Answer 20

• breathing rate increases
• provides more oxygen for respiration
• more oxygen is needed to pay off any subsequent oxygen debt

Question 21

a group of scientists conducted an identical experiment, but instead of measuring the volunteers breathing rate, the scientists analysed the composition of the air exhaled before and after running for 5 minutes, describe how you would expect the concentration of carbon dioxide to vary, give reasons for your prediction (6)

Answer 21

prediction (max 3 marks):
- carbon dioxide concentration is constant before exercise
- carbon dioxide concentration is highest immediately after exercise
- carbon dioxide concentration starts decreasing after exercise
explanation of variation in CO2 (max 3 marks):
- more energy used during exercise means higher rates of respiration
- aerobic respiration releases carbon dioxide
- oxygen is not supplied fast enough OR more oxygen required by muscles
- leads to oxygen debt
- anaerobic respiration happens in muscles
- which produces lactic acid
- lactic acid is broken down to glucose

Question 22

compare the heart rates of the two friends (3)

Answer 22

• the heart rate of friend B is higher than the heart rate of friend A
• the heart rate of friend B increases more during exercise
• the heart rate of friend A is level during exercise whereas the heart rate of friend B keeps increasing
• friend A returns to their resting heart rate faster than friend B

Question 23

why do the friends heart and breathing rates increase during exercise (2)

Answer 23

• oxygen and glucose are needed for respiration
• breathing rate increases to bring oxygen into the body more quickly
• and to remove carbon dioxide from the body more quickly
• heart rate increases to deliver oxygen and glucose to the muscles
• and to take the waste products from respiration away from the muscles

Question 24

one of the friends leads a sedentary lifestyle, whilst the other exercises several times a week, which friend exercises regularly, explain your answer (2)

Answer 24

• friend A
• friend A has a lower resting heart rate