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Question 1
Organisms increase their chance of survival by responding to stimuli. |
a) | What are stimuli?
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b) | Woodlice move away from light sources. What type of behavioural response is this? Explain your answer.
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c) | When woodlice are placed in dry conditions, they move faster and change direction more often. What type of behavioural response is this? Explain your answer.
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d) | Suggest and explain the advantage of woodlice moving away from light sources and moving faster in dry conditions.
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Question 2
A group of students investigated how fruit fly larvae, Drosophila melanogaster, responded to light. They divided a circular piece of material into 12 sectors and placed a lamp at a fixed distance. Their equipment is shown in the diagram below. The larvae were placed in the centre of the material and left for 10 minutes. After 10 minutes, the students recorded the number of larvae in each sector. Their results are shown in the table below. |
a) | What conclusion can be made based on these data?
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b) | Describe the evidence for the conclusion you wrote in part a.
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c) | Suggest an improvement the students could have made to their method to ensure that the larvae were responding to light only.
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d) | Explain why larvae were present in sectors ranging from 2 to 12.
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Question 3
A scientist investigated simple behaviour displayed by woodlice. He cultured a sample of woodlice in a tray containing food at 18°C. He then transferred the woodlice onto the centre of a glass surface without food. The glass surface has a temperature gradient across it ranging from 18°C to 22°C. He recorded the position of each woodlouse 30 minutes after being transferred to the glass surface. The diagram below shows the glass surface after 30 minutes. |
a) | What type of behavioural response was shown by the woodlice?
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b) | How do the results support this?
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c) | It was important that the scientist made sure the level of light was dim and even across the glass surface. Suggest two reasons why.
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d) | Suggest why the woodlice were concentrated at the 18°C side of the glass plate.
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Question 4
A student investigated how the human body louse responds to temperature. The human body louse is a parasitic insect that lives on clothing and feeds on the skin surface. The student placed a human body louse in a chamber, half of which was kept at 32°C and half at 36°C. The student recorded the number of turns the louse made in each half of the chamber. Their results are shown in the table below.
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a) | State a null hypothesis for this investigation.
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b) | Name the type of behavioural response shown by the body louse. Give evidence for your answer.
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c) | Suggest and explain one advantage of the body louse behaving in this way.
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d) | Suggest two factors that should be kept constant in the chamber so that the body louse displays normal behaviour.
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Question 5
A group of students investigated the effect of humidity on the behaviour of woodlice. They used petri dishes with different amounts of silica gel at the bottom to change the relative humidity of each dish. They then placed a mesh over the silica gel and placed the woodlice on top of the mesh. They left each dish for 20 minutes before recording the number of woodlice that were still moving. They repeated their experiment until they had used 100 woodlice for each humidity. Their results are shown in the graph below.
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a) | Suggest why the students left each dish for 20 minutes before recording their results.
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b) | Some of the points on the graph above do not fall on the curve. Suggest why.
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c) | One of the students concluded that the change in woodlice behaviour is caused by the change in humidity. Suggest two reasons why this conclusion may not be true.
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d) | Explain how the movement of woodlice in low humidity conditions is an advantage to their survival.
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Question 6
A scientist investigated how worms respond to different colours. She used a circular piece of cardboard divided into four coloured segments. She placed 40 worms in the centre of the cardboard and recorded their positions after 45 minutes. She repeated this experiment another two times. Her results are shown in the table below.
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a) | Give one conclusion you can make from the results table above.
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b) | Give the evidence for your conclusion in part a.
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c) | Another scientist thought that the movement of the worms may be affected by the Earth’s magnetic field. Suggest one way the investigation could be improved to remove this possibility.
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d) | The scientist wanted to use a statistical test to analyse her results. Name the statistical test she should use and suggest a null hypothesis.
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Question 7
A student investigated how an insect responds to humidity. They used a choice chamber divided into 2 sections. In one section they placed silica gel beads to absorb any water and in the other they placed a damp paper towel. They recorded the path taken by the insect on a piece of paper. The diagram below shows their results.
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a) | What type of behaviour is shown in the diagram above?
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b) | Give evidence for your answer to part a.
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c) | Suggest and explain one advantage of this behaviour.
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Question 8
A scientist investigated how IAA concentration affects the growth of young plants. He removed the tip of the shoot from each plant and removed a 5 mm length of shoot. He placed each shoot into a Petri dish with a glucose solution and a different concentration of IAA solution. He left each dish in the dark for a week and then measured the length of each shoot. His results are shown in the diagram below.
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a) | Suggest why the scientist added glucose solution to each Petri dish.
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b) | Explain why the scientist removed the tip of the shoot from each plant.
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c) | Describe and explain the results shown in the table above.
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d) | Another scientist repeated the investigation using plant roots rather than shoots. Predict the results he would obtain. Explain your answer.
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Question 9
A student investigated phototropism in the shoots of plants. She removed the tip and placed it on one side of the cut shoot as shown in the diagram below.
She allowed the shoot to grow in the presence of a light source for two weeks. The resulting plant shoot is shown in the diagram below.
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a) | Explain the growth curvature of the shoot shown in the diagram above.
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b) | Explain how this behaviour helps to maintain the plant in a favourable environment
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c) | A scientist investigated the effect of temperature on the uptake of IAA by leaves. He sprayed a solution containing IAA onto the lower surface of a leaf at different temperatures. His results are shown in the diagram below.
Describe and explain the results shown in the diagram above.
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d) | Another scientist repeated the same experiment instead spraying the solution onto the upper surface of the leaf. They found that the rate of uptake was lower for all temperatures investigated. Suggest and explain why.
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Question 10
IAA is a specific growth factor found in plants. |
a) | Name the process by which IAA is transported from growing regions to other tissues in the plant.
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b) | The diagram below shows areas of the root in which IAA is distributed during growth.
Describe the relative concentrations of IAA in each of the shaded areas shown above.
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c) | Explain how the distribution of IAA causes the root to bend.
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d) | In the root tips of some plants, IAA is transported out of cells via carrier proteins. The diagram below shows two cells, A and B, in the root tip of a plant.
Explain why this root tip would bend towards the left.
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Question 11
A group of students investigated tropisms in some plant shoots. They placed each shoot in light coming from one direction and used black plastic to cover some parts of the shoots. The treatment for each shoot is described below.
The students left the shoots to grow for three days and then removed the plastic to observe the results. The diagram below shows the shoots after three days. |
a) | The students were investigating phototropism in plant shoots. Name one other tropism. Describe the stimulus the plant responds to in your named tropism.
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b) | Describe two variables the students should control in this investigation.
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c) | What conclusion can be made about the detection of the light stimulus?
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d) | Explain how IAA causes the bending of shoot A.
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Question 12
A group of scientists investigated the role of IAA in how plants respond to light. They cut the tip off the shoot from two seedlings and placed each shoot tip on a block of agar jelly. They then used a piece of glass to separate the sides of the shoot as shown in the diagram below. After 1 day, they measured the amount of IAA in the agar blocks. Their results are shown in the table below.
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a) | The scientists did not use a control experiment in their investigation. Describe how they could set up another shoot to ensure that any response by the shoots was due to the presence of light.
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b) | One of the scientists hypothesised that light causes IAA to move from the illuminated side to the shaded side. Describe the evidence from their results that supports this hypothesis.
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c) | Predict the direction of growth by shoots A and B.
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d) | IAA affects growth in the roots and in the shoots of plants. Describe the difference between how IAA affects the growth of plants in these two places.
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Question 13
A group of scientists investigated gravitropism in seedlings. They applied different treatments to three seedlings:
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a) | Give one similarity and one difference between a taxis and a tropism.
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b) | The scientists carried out their experiment in a dark room. Suggest why.
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c) | The scientists placed the seedlings so that their roots were growing horizontally and after a period of time, they recorded the direction of growth of the roots. Their results are shown below.
Explain how IAA may have caused the results for treatments B and C.
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d) | What conclusion can be made from treatment A?
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