A-Level AQA Biology Nervous Coordination: The crown-of-thorns starfish (CO

Question

The crown-of-thorns starfish (COTS) is one of the main causes of the decline of the world’s coral reefs.

Marine biologists used a choice chamber to investigate the effects of flashing and constant light on the behaviour of COTS.

Table 1 shows their results as they presented them. The P values show results from a statistical test.

**Table 1**  
**Behaviour of COTS**  
**Type of light used in choice chamber**  
Flashing  | Constant  
------------|----------  
COTS moving towards the stimulus  | 22 | 12  
COTS moving away from the stimulus  | 28 | 38  
P value  | 0.69 | 0.02

5.1 State a null hypothesis the marine biologists tested in this investigation.

5.2 The natural habitat of COTS is coral reefs of tropical oceans.  
Suggest two factors that should be kept constant in the choice chambers so that COTS display normal behaviour.

1

2

5.3 A journalist studying Table 1 suggested that either type of light could be used to cause COTS to move away from coral reefs.  
Evaluate the journalist’s suggestion.

5.4 One of the reasons COTS can destroy coral reefs in a short time is because COTS move quickly, allowing them to move from one reef to another.

Table 2 shows the maximum speeds recorded of COTS in constant light.

**Table 2**  
**Response to light**  
**Maximum speed / mm min^-1**  
COTS moving towards constant light | 259  
COTS moving away from constant light | 564

Calculate the shortest time one COTS would take to move up a coral reef from 66 m under water to 18 m under water in hours of daylight.

Give your answer to the nearest hour.

The crown-of-thorns starfish (COTS) is one of the main causes of the decline of the world’s coral reefs - AQA - A-Level Biology - Question 5 - 2019 - Paper 3

Worked Solution & Example Answer:The crown-of-thorns starfish (COTS) is one of the main causes of the decline of the world’s coral reefs - AQA - A-Level Biology - Question 5 - 2019 - Paper 3

State a null hypothesis the marine biologists tested in this investigation.

Suggest two factors that should be kept constant in the choice chambers so that COTS display normal behaviour.

Evaluate the journalist’s suggestion.

Calculate the shortest time one COTS would take to move up a coral reef from 66 m under water to 18 m under water in hours of daylight.

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