GCSE Biology Exam Doctor

1. GCSE Biology Exam Doctor How plants respond to their surroundings Question 2 Question 3 Question 4 Question 1 Question 5 Question 6

2. GCSE Biology Exam Doctor How plants respond to their surroundings Question 1

3. Plants respond to certain stimuli in their environment by growing towards or away from the stimulus. • (a) (i) Name three factors in a plant’s environment which influence the direction of plant growth. • 1. ………………………. 2. …………………..…. 3. ……..……………….....(3) • (ii) Name the growth responses of the plant to the factors you have listed. • ………………………. 2. ……………………. 3. ………………………..(3) • (iii) Name the plant growth hormone that regulates these growth responses. • ………………………………………………………………………………….(1)

4. (b) (i) How do the growth responses of shoots differ from the growth responses of roots? Refer to the responses you have listed above, in your answer. …………………………………………………………………………………….. …….………………………………………………………………………………. …….………………………………………………………………………………. …………………………………………………………………………………. (3) (ii) Suggest why growth responses of stems and roots are important to the life of plants. …………………………………………………………………………………….. …….………………………………………………………………………………. …………………………………………………………………………………. (2)

5. Plants respond to certain stimuli in their environment by growing towards or away from the stimulus. • (a) (i) Name three factors in a plant’s environment which influence the direction of plant growth. • 1. ………………………. 2. …………………..…. 3. ……..……………….....(3) • (ii) Name the growth responses of the plant to the factors you have listed. • ………………………. 2. ……………………. 3. ………………………..(3) • (iii) Name the plant growth hormone that regulates these growth responses. • ………………………………………………………………………………….(1) Gravity. Light. Moisture. Geotrophism. Phototaxism. Hydrotropism. Auxin, also ethene.

6. (b) (i) How do the growth responses of shoots differ from the growth responses of roots? Refer to the responses you have listed above, in your answer. …………………………………………………………………………………….. …….………………………………………………………………………………. …….………………………………………………………………………………. …………………………………………………………………………………. (3) (ii) Suggest why growth responses of stems and roots are important to the life of plants. …………………………………………………………………………………….. …….………………………………………………………………………………. …………………………………………………………………………………. (2) Roots grow towards gravity and water but away from light. Shoots grow towards light. So roots anchor into the soil and can get their water and salt supplies. Shoots grow to the best source of light for photosynthesis.

7. Mark scheme Plants respond to certain stimuli in their environment by growing towards or away from the stimulus. • (a) (i) Name three factors in a plant’s environment which influence the direction of plant growth. • 1. ………………………. 2. …………………..…. 3. ……..……………….....(3) • (ii) Name the growth responses of the plant to the factors you have listed. • ………………………. 2. ……………………. 3. ………………………..(3) • (iii) Name the plant growth hormone that regulates these growth responses. • ………………………………………………………………………………….(1) light; gravity; water; ref unilateral/concentration gradient; max 3 phototropism; geotropism; hydrotropism; auxin;

8. Mark scheme (b) (i) How do the growth responses of shoots differ from the growth responses of roots? Refer to the responses you have listed above, in your answer. …………………………………………………………………………………….. …….………………………………………………………………………………. …….………………………………………………………………………………. …………………………………………………………………………………. (3) (ii) Suggest why growth responses of stems and roots are important to the life of plants. …………………………………………………………………………………….. …….………………………………………………………………………………. …………………………………………………………………………………. (2) shoot tips grow towards light but root tips grow away from light; root tips grow towards gravity but shoot tips grow away from gravity; root tips grow towards water but shoot tips do not grow to or away from water; response to light makes shoot/leaves find the best light intensity for photosynthesis; response to gravity makes roots anchor plants in soil to get water/salts; response to water makes roots grow to the best water source;

9. Plants respond to certain stimuli in their environment by growing towards or away from the stimulus. • (a) (i) Name three factors in a plant’s environment which influence the direction of plant growth. • 1. ………………………. 2. …………………..…. 3. ……..……………….....(3) • (ii) Name the growth responses of the plant to the factors you have listed. • ………………………. 2. ……………………. 3. ………………………..(3) • (iii) Name the plant growth hormone that regulates these growth responses. • ………………………………………………………………………………….(1) Gravity. Light. Moisture. Geotrophism. Phototaxism. Hydrotropism. Spelling error –’trophism’ is related to feeding. ‘Tropism’ is related to growth. Some exam boards would mark ‘geotrophism’ wrong. 5 7 ‘Phototropism’ was correct. ‘Phototaxism’ is when the complete organism moves to the light. Auxin, also ethene. ‘Auxin’ was correct. ‘Ethene’ was incorrect and so the mark was lost. Never give two names when only one was asked for.

10. (b) (i) How do the growth responses of shoots differ from the growth responses of roots? Refer to the responses you have listed above, in your answer. …………………………………………………………………………………….. …….………………………………………………………………………………. …….………………………………………………………………………………. …………………………………………………………………………………. (3) (ii) Suggest why growth responses of stems and roots are important to the life of plants. …………………………………………………………………………………….. …….………………………………………………………………………………. …………………………………………………………………………………. (2) Roots grow towards gravity and water but away from light. Shoots grow towards light. The responses of shoots to gravity and water were not referred to, so the comparisons to roots were not made. So roots anchor into the soil and can get their water and salt supplies. Shoots grow to the best source of light for photosynthesis. 3 5

11. GCSE Biology Exam Doctor How plants respond to their surroundings Question 2

12. The table below shows various plant activities. (a) Complete the table by selecting words from the following list. gravity salts auxin light ethene glucose insects wind water humidity dark (7)

13. The table below shows various plant activities. (a) Complete the table by selecting words from the following list. gravity salts auxin light ethene glucose insects wind water humidity dark Light. Auxin. Water. Gravity. Light. Water. Glucose. (7)

14. Mark scheme The table below shows various plant activities. (a) Complete the table by selecting words from the following list. gravity salts auxin light ethene glucose insects wind water humidity dark light; ethene; auxin; gravity; dark; water; water; (7)

15. The table below shows various plant activities. (a) Complete the table by selecting words from the following list. gravity salts auxin light ethene glucose insects wind water humidity dark Light. Auxin. ‘Ethene’ does this. Water. ‘Auxin’ does this. Gravity. Light. This happens in prolonged dark 3 7 Water. Glucose. They store water. (7)

16. GCSE Biology Exam Doctor How plants respond to their surroundings Question 3

17. Two sets of cress seedlings were grown. Set A received all round light. Set B received light from one side only. Set B Set A • (i) Describe the appearance of each set of seedlings after two days in these conditions. • ……………………………………………………………...………………………. • …………………………………………………………………………………………………………………………………………………………………………...(2)

18. (b) Describe the role of auxin in the responses of the set A and set B seedlings. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………...………………………………………………………………………………………………………………………………………………………………………………………………………………………………… (5)

19. Two sets of cress seedlings were grown. Set A received all round light. Set B received light from one side only. Set B Set A • (i) Describe the appearance of each set of seedlings after two days in these conditions. • ……………………………………………………………...………………………. • …………………………………………………………………………………………………………………………………………………………………………...(2) Seedlings in A had grown upwards but were not as tall as in B where the seedling had grown towards the light.

20. (b) Describe the role of auxin in the responses of the set A and set B seedlings. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………...………………………………………………………………………………………………………………………………………………………………………………………………………………………………… (5) In A auxin is inactivated by light so the seedlings do not elongate much. In set B in darkness the auxin is not inactivated and so causes much elongation so the seedlings become very tall. In B with one sided light the auxin is destroyed on the light side so the other side grows faster so the shoot turns to the light.

21. Mark scheme Two sets of cress seedlings were grown. Set A received all round light. Set B received light from one side only. Set B Set A • (i) Describe the appearance of each set of seedlings after two days in these conditions. • ……………………………………………………………...………………………. • …………………………………………………………………………………………………………………………………………………………………………...(2) seedlings in set A had grown vertically; seedlings in set B had bent/grown towards the light and were taller than A;

22. Mark scheme (b) Describe the role of auxin in the responses of the set A and set B seedlings. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………...………………………………………………………………………………………………………………………………………………………………………………………………………………………………… (5) auxin produced in shoot tip; diffuses down stem and stimulates cell elongation; auxin inhibited by light/destroyed by light/moves away from light; in set A auxin inactivated by light so less upward growth; when set B is etiolated auxin is not inactivated so great upward growth; in B auxin inactivated on light side so less growth on light side more on dark side (allow alternative auxin explanations);

23. Two sets of cress seedlings were grown. Set A received all round light. Set B received light from one side only. Set B Set A 2 2 • (i) Describe the appearance of each set of seedlings after two days in these conditions. • ……………………………………………………………...………………………. • …………………………………………………………………………………………………………………………………………………………………………...(2) Seedlings in A had grown upwards but were not as tall as in B where the seedling had grown towards the light. A good, concise answer.

24. (b) Describe the role of auxin in the responses of the set A and set B seedlings. ……………………………………………………………………………………. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………...………………………………………………………………………………………………………………………………………………………………………………………………………………………………… (5) In A auxin is inactivated by light so the seedlings do not elongate much. In set B in darkness the auxin is not inactivated and so causes much elongation so the seedlings become very tall. In B with one sided light the auxin is destroyed on the light side so the other side grows faster so the shoot turns to the light. For a complete answer also refer to auxin synthesis in the tip and its diffusion down the stem to the zone of elongation. 4 5

25. GCSE Biology Exam Doctor How plants respond to their surroundings Question 4

26. The drawing shows a corn seedling at various stages of germination. A shows the seedling soon after the emergence of the radicle, which was marked with an ink dot. B shows the same seedling 8 hours later. A B Plumule (a) (i) State why the radicle is growing vertically downwards. ………………………………………………………………………………………(2) Ink dot Radicle

27. (ii) Explain why the radicle only grows down below the ink dot. ………………………………………………..……………..………………………………… …………………..…………………………………………………………………………….. …………………..…………………………………………………………………………….. ………………..……………………………………………………………………………..(4) (iii) What would happen to the growth of the radicle if the soil was dry on one side and damp on the other? ……………………………………………………………………………...……………...(2) A B Plumule Ink dot Radicle

28. The drawing shows a corn seedling at various stages of germination. A shows the seedling soon after the emergence of the radicle, which was marked with an ink dot. B shows the same seedling 8 hours later. A B Plumule (a) (i) State why the radicle is growing vertically downwards. ………………………………………………………………………………………(2) Ink dot Because it is positively geotropic. Radicle

29. (ii) Explain why the radicle only grows down below the ink dot. ………………………………………………..……………..………………………………… …………………..…………………………………………………………………………….. …………………..…………………………………………………………………………….. ………………..……………………………………………………………………………..(4) (iii) What would happen to the growth of the radicle if the soil was dry on one side and damp on the other? ……………………………………………………………………………...……………...(2) A B Plumule Above the tip the cells are fully formed so do not grow any more. The growth is from the tip where the auxin is produced. This diffuses up to cause cells to elongate just behind the tip. Ink dot Radicle The root would grow towards the water and so would bend.

30. Mark scheme The drawing shows a corn seedling at various stages of germination. A shows the seedling soon after the emergence of the radicle, which was marked with an ink dot. B shows the same seedling 8 hours later. A B Plumule (a) (i) State why the radicle is growing vertically downwards. ………………………………………………………………………………………(2) Ink dot it grows towards gravity; positive geotropism; Radicle

31. Mark scheme (ii) Explain why the radicle only grows down below the ink dot. ………………………………………………..……………..………………………………… …………………..…………………………………………………………………………….. …………………..…………………………………………………………………………….. ………………..……………………………………………………………………………..(4) (iii) What would happen to the growth of the radicle if the soil was dry on one side and damp on the other? ……………………………………………………………………………...……………...(2) A B Plumule above the dot cells are differentiated so do not elongate; auxin produced in tip; diffuses upward to cause elongation just above tip; auxin distributed evenly; so elongation is even on every side of radicle; max 4 Ink dot Radicle the root/radicle would grow towards the water (and so would bend); positive hydrotropism; hydrotropic response is stronger than the geotropic response; max 2

32. The drawing shows a corn seedling at various stages of germination. A shows the seedling soon after the emergence of the radicle, which was marked with an ink dot. B shows the same seedling 8 hours later. A B Plumule (a) (i) State why the radicle is growing vertically downwards. ………………………………………………………………………………………(2) Ink dot Because it is positively geotropic. Radicle Refer to ‘positive geotropism’ – 2 marks were available. 1 2

33. (ii) Explain why the radicle only grows down below the ink dot. ………………………………………………..……………..………………………………… …………………..…………………………………………………………………………….. …………………..…………………………………………………………………………….. ………………..……………………………………………………………………………..(4) (iii) What would happen to the growth of the radicle if the soil was dry on one side and damp on the other? ……………………………………………………………………………...……………...(2) A B Plumule Above the tip the cells are fully formed so do not grow any more. The growth is from the tip where the auxin is produced. This diffuses up to cause cells to elongate just behind the tip. Also refer to ‘even distribution of auxin so cells elongate equally on all sides (grows down)’. Ink dot Radicle 4 6 The root would grow towards the water and so would bend. 2 marks available – also refer to ‘positive hydrotropism’ or to the ‘hydrotropic response overriding the geotropic response’.

34. GCSE Biology Exam Doctor How plants respond to their surroundings Question 5

35. An experiment was done to measure the growth of a plant shoot. A light was shone onto the shoot from the side. The length of the shoot nearest to the light and the length of the shaded side of the shoot were measured for several days. The graph shows the results. shaded side of shoot plant shoot light increase in length side nearest light time light turned on • (i) Compare the growth on each side of the shoot after the light was turned on. • …….…………………………………………………………………………………. • …….…………………………………………………………………………………. • ………..…………………………………………………………………………. (3)

36. (ii) Explain how these changes in growth are brought about. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………………………………………..………………………. (3) (b) Suggest advantages of this type of response to the plant. ………….………………………………………………………………………… …….……………………………………………………………………………… …...…………………………………………………………………………… (3)

37. An experiment was done to measure the growth of a plant shoot. A light was shone onto the shoot from the side. The length of the shoot nearest to the light and the length of the shaded side of the shoot were measured for several days. The graph shows the results. shaded side of shoot plant shoot light increase in length side nearest light time light turned on • (i) Compare the growth on each side of the shoot after the light was turned on. • …….…………………………………………………………………………………. • …….…………………………………………………………………………………. • ………..…………………………………………………………………………. (3) Both sides grow at same speed at first. Then the shaded side has more auxin than the lit side and so grows faster. The lit side eventually speeds up its growth while the shaded side goes on growing at the same speed.

38. (ii) Explain how these changes in growth are brought about. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………………………………………..………………………. (3) (b) Suggest advantages of this type of response to the plant. ………….………………………………………………………………………… …….……………………………………………………………………………… …...…………………………………………………………………………… (3) They are caused by auxin. The shaded side produces more auxin than the lit side and so grows faster. They will get more sun and so can photosynthesise better to make more food.

39. Mark scheme An experiment was done to measure the growth of a plant shoot. A light was shone onto the shoot from the side. The length of the shoot nearest to the light and the length of the shaded side of the shoot were measured for several days. The graph shows the results. shaded side of shoot plant shoot light increase in length side nearest light time light turned on • (i) Compare the growth on each side of the shoot after the light was turned on. • …….…………………………………………………………………………………. • …….…………………………………………………………………………………. • ………..…………………………………………………………………………. (3) at first both sides grow at same rate; then growth of shaded side speeds up but growth of lit side slows down/stops; then growth of lit side speeds up but growth of shaded side stays the same rate;

40. Mark scheme (ii) Explain how these changes in growth are brought about. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………………………………………..………………………. (3) (b) Suggest advantages of this type of response to the plant. ………….………………………………………………………………………… …….……………………………………………………………………………… …...…………………………………………………………………………… (3) ref to auxins; produced in the shoot tip; light on lit side causes more auxin to be sent down the shaded side; causing faster growth/cell elongation on the shaded side; max 3 grows towards light/receives more sunlight; allows more photosynthesis/food synthesis; allows more growth;

41. An experiment was done to measure the growth of a plant shoot. A light was shone onto the shoot from the side. The length of the shoot nearest to the light and the length of the shaded side of the shoot were measured for several days. The graph shows the results. shaded side of shoot plant shoot light increase in length side nearest light time light turned on 2 3 You were simply asked to ‘compare the growth’ not to explain it. Thus reference to auxin is irrelevant here. • (i) Compare the growth on each side of the shoot after the light was turned on. • …….…………………………………………………………………………………. • …….…………………………………………………………………………………. • ………..…………………………………………………………………………. (3) Both sides grow at same speed at first. Then the shaded side has more auxin than the lit side and so grows faster. The lit side eventually speeds up its growth while the shaded side goes on growing at the same speed. No comparison – you need to state that the lit side ‘slows down/stops’ growth.

42. (ii) Explain how these changes in growth are brought about. ……………………………………………………………………………………. ……………………………………………………………………………………. ………………………………………………………..………………………. (3) (b) Suggest advantages of this type of response to the plant. ………….………………………………………………………………………… …….……………………………………………………………………………… …...…………………………………………………………………………… (3) They are caused by auxin. The shaded side produces more auxin than the lit side and so grows faster. Auxin is produced in the shoot tip. More passes from the tip down the shaded side of the shoot. They will get more sun and so can photosynthesise better to make more food. ‘Sun’ is not accepted by examiners because it is too imprecise. The sun gives off many types of radiation. ‘Light’ or ‘sunlight’ should be used. A reference to ‘more growth’ is also needed here. 3 6

43. GCSE Biology Exam Doctor How plants respond to their surroundings Question 6

44. The diagram shows a clinostat which is used to study tropic movements in plants. When the motor is on the drum slowly rotates. The drum can be put in a vertical or horizontal position. Transparent shield Motor Germinating seed Cork base Rotating drum (a) Describe how you would use the clinostat to show the responses of germinating bean seeds to gravity ………….………………………………...……………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………...………………………………………………………….. (5)

45. (b) How would you modify your experiment to show the responses of germinating bean seeds to one-sided light? ……..………………………..…………………………………………………………..…………………………………………………………………………….. ……..…………………………………………………………………………….. ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………(4)

46. The diagram shows a clinostat which is used to study tropic movements in plants. When the motor is on the drum slowly rotates. The drum can be put in a vertical or horizontal position. Transparent shield Motor Germinating seed Cork base Rotating drum (a) Describe how you would use the clinostat to show the responses of germinating bean seeds to gravity ………….………………………………...……………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………...………………………………………………………….. (5) The clinostat would be horizontal and set to rotate slowly for a couple of hours. After this the root and shoot should show no bending. The clinostat would then be turned off and in time the root would bend downwards towards gravity.

47. (b) How would you modify your experiment to show the responses of germinating bean seeds to one-sided light? ……..………………………..…………………………………………………………..…………………………………………………………………………….. ……..…………………………………………………………………………….. ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………(4) The clinostat would be put in a vertical position and allowed to rotate slowly for several hours. I would have the apparatus in a dark room with a light in one corner of the room. While the clinostat rotated the seedling would show no growth response. When the clinostat was stopped the shoot started to grow towards the light source but the root grew away from it.

48. Mark scheme The diagram shows a clinostat which is used to study tropic movements in plants. When the motor is on the drum slowly rotates. The drum can be put in a vertical or horizontal position. Transparent shield Motor Germinating seed Cork base Rotating drum (a) Describe how you would use the clinostat to show the responses of germinating bean seeds to gravity ………….………………………………...…… …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………...……………………………………………………………...………………………………………………………………………………… (5) use the clinostat in horizontal position; with motor on/rotating the drum slowly; leave for several hours/at least 5 hours; radicle/root (and plumule/stem) would show no curvature; turn motor off and leave for several hours at least 5 hours; radicle would bend/grow downwards towards gravity and plumule would bend/grow upwards away from gravity; stationary clinostat is the control; max 5

49. Mark scheme (b) How would you modify your experiment to show the responses of germinating bean seeds to one-sided light? ……..………………………..…………………………………………………………..…………………………………………………………………………….………………………………………………………………………………………………………………………………………………………………………… ……..…………………………………………………………………………….. ……………………………………………………………………………….. (4) surround shield/drum with black paper except for one slit on side (to admit light); have drum vertical and allow to rotate slowly for several hours; radicle and plumule show no growth curvatures; leave drum stationary for several hours, radicle grows towards slit/light/ plumule grows away from slit/light; stationary clinostat is the control;

50. The diagram shows a clinostat which is used to study tropic movements in plants. When the motor is on the drum slowly rotates. The drum can be put in a vertical or horizontal position. Transparent shield Motor Germinating seed 3 5 Cork base Rotating drum How long? At least 5 hours. Too short – at least 5 hours. (a) Describe how you would use the clinostat to show the responses of germinating bean seeds to gravity ………….………………………………...……………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. ……………………...………………………………………………………….. (5) The clinostat would be horizontal and set to rotate slowly for a couple of hours. After this the root and shoot should show no bending. The clinostat would then be turned off and in time the root would bend downwards towards gravity. Also need to state what the shoot would do + control? If a ‘use of English’ quality mark was attached to this question you would lose it. The question asked ‘how would you ….’ so you should have written ‘I would…’ , rather than used an impersonal description.