Figure 19 shows a diagram of a red blood cell from a turtle and a diagram of a red blood cell from a human - Edexcel - GCSE Biology - Question 8 - 2018 - Paper 1
Question 8
Figure 19 shows a diagram of a red blood cell from a turtle and a diagram of a red blood cell from a human.
(a)(i) These cells are animal cells.
Animal cells do no... show full transcript
Worked Solution & Example Answer:Figure 19 shows a diagram of a red blood cell from a turtle and a diagram of a red blood cell from a human - Edexcel - GCSE Biology - Question 8 - 2018 - Paper 1
Step 1
a(i) Animal cells do not have
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Answer
Animal cells do not have a cell wall. This is an essential distinction as plant cells possess a cell wall that provides structural support, while animal cells are encased by a cell membrane.
Step 2
a(ii) Calculate the length of the magnified image
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Answer
To find the length of the magnified image, multiply the actual length of the turtle's red blood cell by the magnification factor:
20.5extμmimes400=8200extμm.
Thus, the length of the magnified image of the red blood cell is 8200 μm.
Step 3
a(iii) Calculate the actual width of the human red blood cell
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First, convert the magnified width from mm to μm:
3.08extmm=3080extμm.
Next, divide by the magnification factor:
4003080extμm=7.7extμm.
Therefore, the actual width of the human red blood cell is 7.7 μm.
Step 4
b(i) Describe a method to measure elasticity
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To determine how much the ring of tissue stretches, first measure the initial length of the tissue. Then, incrementally add 10 g masses to the hook until the tissue no longer returns to its original length. After each addition, record the new length of the tissue. Continue this process until the maximum extent of stretching is observed.
Step 5
b(ii) Give one safety precaution
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One safety precaution to take when handling animal tissue is to wash hands thoroughly after completing the experiment to prevent contamination.
Step 6
c Explain why the circulatory system of a frog is less efficient
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The circulatory system of a frog is less efficient because:
Frogs have a three-chambered heart compared to the four-chambered heart of humans, which results in mixing of oxygenated and deoxygenated blood.
This mixing means less efficient oxygen delivery to tissues, since some deoxygenated blood enters the systemic circulation.
In addition, the single ventricle of frogs cannot separate blood flows effectively, leading to reduced oxygenation compared to the dual ventricle system in humans.
