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2.1 Supplying the cell

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Question 26

A researcher investigates the water potential of sweet potato (Ipomoea batatas\textit{Ipomoea batatas}Ipomoea batatas) tissue using sucrose solutions of varying concentrations.

This is the method that they use:

  • Step 1: Use a cork borer to cut six cylinders of sweet potato tissue.
  • Step 2: Place each cylinder into a separate boiling tube containing a different concentration of sucrose solution.
  • Step 3: Leave the boiling tubes in a water bath at 25∘C25 ^\circ\text{C}25∘C for 3 hours.
  • Step 4: Remove the sweet potato cylinders from the tubes.
a.

The researcher wants to calculate the percentage change in mass for each sweet potato cylinder. Describe the additional steps needed in the method to obtain the necessary data.

[3]
b.

State two variables, other than temperature, that the researcher should control in this investigation.

[2]
c.

Describe how the researcher could determine if their findings are both repeatable and reproducible.

[3]
d.

Some of the sweet potato cylinders decreased in mass. Explain, in terms of water potential, why some of the cylinders decreased in mass.

[2]
Markscheme

2.1 Supplying the cell Questions

  1. GCSE
  2. /Biology
  3. /2.1 Supplying the cell

82 exam-style questions on OCR GCSE Biology 2.1 Supplying the cell, covering 2.1.1 Transport across cell membranes, 2.1.2 Mitosis and the cell cycle, 2.1.3 Importance of cell differentiation, and 2.1.4 Stem cells. Each one has a worked solution and a mark scheme showing where the marks go.

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