IAL Biology SB2 Assessment 8B
IAL Biology SB2 Assessment 8B
IAL Biology SB2 Assessment 8B
A 1 and 2 only
B 1 and 3 only
C 3 only
D 1, 2 and 3
Your answer
(Total for Question 1 = 1 mark)
2 Vertebrate sensory and motor neurones are each covered by a myelin sheath.
(a) Describe the structure of the myelin sheath.
(4)
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(Total for Question 2 = 6 marks)
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3 (a) Which of the following statements are true?
(1)
1 Phytochrome is a red pigment found in plants.
2 Phytochrome exists in two forms and both are biologically active.
3 Phytochrome influences seed germination and flowering in adult plants.
A 1 and 2 only
B 1 and 3 only
C 3 only
D 1, 2 and 3
Your answer
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(Total for Question 3 = 9 marks)
© Pearson Education Ltd 2019. Copying permitted for purchasing institution only. This material is not copyright free.
This document may have been altered from the original.
4 Sometimes marathon runners drink too much water. This, together with
inappropriate release of the hormone ADH, may lead to exercise-related
hyponatremia (EAH). This is overhydration leading to a potentially lethal low
concentration of sodium ions in the blood. EAH can also occur when users of
the drug ecstasy (MDMA) feel thirsty and drink too much water.
(a) Explain why having too much water in the blood leads to low concentrations
of sodium ions.
(1)
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(b) Explain why a low concentration of sodium ions in body fluids can disrupt
nerve conduction.
(2)
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(Total for question 4 = 4 marks)
© Pearson Education Ltd 2019. Copying permitted for purchasing institution only. This material is not copyright free.
This document may have been altered from the original.