Pupil sheet · Respiration
Respiration — final check
Name ______________________ Date ____________
Work alone, with the lesson closed. Answer every question; there are no hints.
1. explain
A caterpillar eats leaves and doubles its mass in a few days. Explain why its cells need a lot of energy, and where the energy comes from.
2. state / determine
The root cells of a sunflower seedling respire aerobically. (a) State the word equation for this respiration. (b) Supplement: state the balanced chemical equation for it. (c) Supplement: use the balanced equation to determine how many oxygen molecules the cells use to break down 3 molecules of glucose.
(a) Word equation
(b) Supplement: balanced equation
(c) Supplement: oxygen molecules
3. explain
An earthworm has no lungs: oxygen diffuses into its blood through its moist skin. A pupil says: "An earthworm does not respire, because it does not breathe with lungs." Explain why this is incorrect.
4. describe
Describe how you would investigate the effect of temperature on the rate of respiration of yeast. Include (a) what you would set up, (b) what you would measure and how you would work out the rate, and (c) what you would keep the same, and the control.
(a) What you would set up
(b) What you would measure, and the rate
(c) Kept the same, and the control
5. state / explain
A brewer keeps yeast in a sealed tank of sugary liquid with no air. (a) State the word equation for the respiration of the yeast in the tank. (b) To grow the same mass of new yeast, the yeast in the sealed tank uses up much more sugar than yeast in a tank with air bubbled through. Explain why. (c) Supplement: state the balanced chemical equation for the respiration in the sealed tank.
(a) Word equation
(b) Why more sugar
(c) Supplement: balanced equation
6. describe / explain
A class repeated the yeast investigation with a different packet of yeast. Use their results: (a) describe the effect of temperature on the rate, (b) explain the results, and (c) suggest how to find the optimum temperature more exactly.
| Temperature (°C) | Mean rate (cm³ per minute) |
|---|---|
| 25 | 1.6 |
| 35 | 3.4 |
| 45 | 2.6 |
| 55 | 0.4 |
(a) Describe
(b) Explain
(c) Finding the optimum more exactly
7. explain / state
During a 50 m swimming sprint, a swimmer's arm muscles respire anaerobically as well as aerobically. (a) Explain why. (b) State the word equation for anaerobic respiration in muscles. (c) Supplement: state what builds up in the muscles and blood, and what this causes.
(a) Why
(b) Word equation
(c) Supplement: what builds up, and what it causes
8. explain
Supplement. A pupil writes: "When you play a hard game of basketball, your heart beats faster so that the blood can carry lactic acid to the lungs, to be breathed out." (a) Explain why this is incorrect. (b) Explain how a hard game of basketball makes the heart rate rise.
(a) Why the statement is incorrect
(b) Why the heart rate rises
9. determine / explain / suggest
Supplement. Two runners, P and Q, ran the same 800 m race. The table shows the lactic acid in their blood after the race. The resting value for both is 1.0 mmol per dm³. (a) Determine how long after the race runner Q's lactic acid was back at the resting value. (b) Explain which runner had the larger oxygen debt at the end of the race. (c) Suggest why runner P went on breathing deeply and quickly for longer than runner Q.
| Time after the race (minutes) | Runner P: lactic acid in the blood (mmol per dm³) | Runner Q: lactic acid in the blood (mmol per dm³) |
|---|---|---|
| 0 | 12.0 | 6.0 |
| 10 | 8.5 | 3.5 |
| 20 | 6.0 | 2.0 |
| 30 | 4.0 | 1.0 |
| 40 | 2.5 | 1.0 |
| 60 | 1.0 | 1.0 |
(a) Runner Q back to resting
(b) The larger oxygen debt
(c) Why P breathed deeply for longer