A student placed three different sized cubes of agar jelly into separate beakers containing the same concentration of hydrochloric acid - Edexcel - GCSE Biology - Question 4 - 2020 - Paper 1
Question 4
A student placed three different sized cubes of agar jelly into separate beakers containing the same concentration of hydrochloric acid.
The cubes contained a pink i... show full transcript
Worked Solution & Example Answer:A student placed three different sized cubes of agar jelly into separate beakers containing the same concentration of hydrochloric acid - Edexcel - GCSE Biology - Question 4 - 2020 - Paper 1
Step 1
Calculate the distance diffused by hydrochloric acid in one second.
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Answer
To find the distance diffused by hydrochloric acid in one second, divide the distance from the outside of cube B to the pink area by the time taken. The distance is 3 mm and the time is 120 seconds:
Distance per second=120 s3 mm=0.025 mm/s
Step 2
Give one improvement the student should make to this investigation to confirm their results.
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Answer
One improvement the student could make is to repeat the experiment multiple times to ensure consistent results. This could help verify the accuracy of the measurements observed.
Step 3
Devise a method, using cubes of agar jelly, to investigate how temperature affects the rate of diffusion.
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Answer
To investigate how temperature affects the rate of diffusion using agar jelly, follow these steps:
Prepare agar jelly cubes that contain a pink indicator.
Place the cubes in different water baths set at varying temperatures (e.g., 0°C, 20°C, 40°C, and 60°C).
Start a timer as soon as the cubes are placed in the baths.
After a set period (e.g., 5 minutes), remove the cubes and measure the distance from the surface to the clear jelly.
Record the results and analyze how temperature affects the rate of diffusion based on the distance measured.
Step 4
Which is the correct description of the movement of a substance by active transport?
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Answer
The correct description of the movement of a substance by active transport is: A) against a concentration gradient using energy.
Step 5
What is the percentage of preventable cases of cancer that are caused by tobacco?
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Answer
The percentage of preventable cases of cancer caused by tobacco is B) 37%.
Step 6
Give your answer to the nearest whole number.
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Answer
To calculate the number of preventable cases of cancer caused by alcohol, use the total number of preventable cases (163440) and the percentage caused by alcohol (7%):
Preventable cases by alcohol=0.07×163440=11441.8≈11442
Thus, the number of preventable cases of cancer caused by alcohol is 11442.
