2019HSCShort answer

Q27 (b)

4 marks

Question

Yeast is a single-celled fungus that can reproduce by budding.
Outline a procedure that could be used to test the effect of temperature on reproduction in yeast.

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Solution

Criteria	Marks
Provides a suitable procedure which includes:<br>– How the independent variable is changed<br>– How the dependent variable is measured<br>– Variables kept constant<br>– Repetition<br>– Logical sequence	4
Outlines how the independent variable is changed<br>Outlines how the dependent variable is measured<br>AND<br>Includes variables kept constant OR includes repetition	3
Provides features of a relevant investigation	2
Provides some relevant information	1

Sample answer:

Prepare a suspension of yeast cells.
Prepare water baths at three temperatures (15°C, 25°C and 35°C).
Mix the suspension.
Measure and place 5 mL of suspension into 9 test tubes.
Place three test tubes in each water bath.
Incubate for 2 hours and mix.
Take a drop from each test tube and place on a microscope slide with a coverslip.
Count the yeast cells using a mm grid on low power at each temperature and record the data.
Compare the number of cells recorded at each temperature.

Supplied marking guidance · human reviewed

Compare this with your working, not only your final sentence.

Syllabus alignment

Module 5 · Heredity

ReproductionCompare sexual and asexual reproduction across animals, plants, fungi, bacteria and protists.

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