The graph shows the blood glucose concentrations of two people, over an eight-hour period, after eating a meal - Edexcel - GCSE Biology - Question 5 - 2013 - Paper 1
Question 5
The graph shows the blood glucose concentrations of two people, over an eight-hour period, after eating a meal.
(a) (i) Describe the changes in blood glucose concen... show full transcript
Worked Solution & Example Answer:The graph shows the blood glucose concentrations of two people, over an eight-hour period, after eating a meal - Edexcel - GCSE Biology - Question 5 - 2013 - Paper 1
Step 1
Describe the changes in blood glucose concentration for the person with diabetes.
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Answer
The blood glucose concentration for the person with diabetes initially increases sharply after the meal, reaching a peak of approximately 350 mg per dm³. Following this peak, the concentration decreases gradually, though it remains elevated compared to the person without diabetes, eventually stabilizing at around 250 mg per dm³.
Step 2
Calculate the difference in blood glucose concentration between the person with diabetes and the person without diabetes two hours after eating a meal.
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Answer
Two hours after eating, the blood glucose concentration for the person with diabetes is 350 mg per dm³, while for the person without diabetes, it is 100 mg per dm³. Therefore, the difference is:
350−100=250
Thus, the answer is 250 mg per dm³.
Step 3
In which two-hour period did the blood glucose concentration change the most for the person with diabetes?
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Answer
The blood glucose concentration changed the most in the period from 0 – 2 hours, as this is where the steep increase occurs.
Step 4
Name the organ that releases insulin to regulate blood glucose concentrations.
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Answer
The pancreas is the organ that releases insulin to regulate blood glucose concentrations.
Step 5
Explain how growth hormones cause phototropism and gravitropism in plants.
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Answer
Growth hormones, such as auxins, play a crucial role in plant responses to light and gravity.
Phototropism
Phototropism refers to the plant's growth in response to light. When a plant detects light, auxins are produced in the shoot tip.
These auxins migrate to the shaded side of the shoot, promoting cell elongation in that area.
As a result, the shoot bends toward the light, facilitating more efficient photosynthesis.
Gravitropism
Gravitropism (or geotropism) refers to how plants respond to gravity. Auxins are also involved in this response, directing growth in roots and shoots differently.
In roots, auxins are concentrated on the lower side, causing those cells to elongate less than the upper side, leading the root to bend downwards toward gravity.
In shoots, auxins have the opposite effect, promoting growth on the downside, which makes the shoot bend upwards, away from gravity.
This coordinated action enables plants to orient themselves optimally in their environment.