The photograph shows a magnified image of bacterial cells from a human intestine - Edexcel - GCSE Biology - Question 3 - 2017 - Paper 1
Question 3
The photograph shows a magnified image of bacterial cells from a human intestine.
(a) Which of the statements about cells are true?
1. Bacterial cells and plant c... show full transcript
Worked Solution & Example Answer:The photograph shows a magnified image of bacterial cells from a human intestine - Edexcel - GCSE Biology - Question 3 - 2017 - Paper 1
Step 1
Which of the statements about cells are true?
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Answer
The only correct answer is A.
Statement 1 is correct because bacterial cells and plant cells do have a cell wall. Statement 2 is incorrect since bacterial cells do not have a nucleus.
Step 2
Compare the mass of prebiotic chemical A with that of prebiotic chemical B in these foods.
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Answer
In the table, the following comparisons can be made:
Onions: A (17.3 g) > B (16.9 g)
Dandelion leaves: A (15.8 g) > B (11.8 g)
Garlic: A (12.5 g) > B (5.0 g)
Artichokes: A (18.0 g) > B (11.5 g)
Overall, the mass of prebiotic chemical A is greater than that of prebiotic chemical B for each food listed.
Step 3
Which food shown in the table would cause the greatest increase in the number of beneficial bacteria in the intestines?
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Answer
Onions would cause the greatest increase in beneficial bacteria, as they contain the highest mass of prebiotic chemical A.
Step 4
How much time will it take for 10 g of beneficial bacteria to increase to 80 g?
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Answer
To calculate the time:
We know that the bacteria double every hour. Starting with 10 g, we can illustrate the doubling sequence:
After 1 hour: 20 g
After 2 hours: 40 g
After 3 hours: 80 g
Thus, it will take 3 hours.
Step 5
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The only correct answer is C.
Prebiotic chemicals are oligosaccharides. Hormones and beta carotenes do not qualify, and stanol esters are also incorrect.
Step 6
Describe how scientists would investigate this claim.
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Answer
To investigate the positive effects of probiotic yoghurt, scientists can conduct controlled clinical trials where one group consumes the yoghurt while a control group refrains. Researchers would measure health parameters such as gut microbiota composition, digestive health, and immune response over time, using statistical analysis to determine any significant differences between groups.
