Biology 5090/32 — October/November 2020

Cambridge O-Level · Practical Test · worked solutions for every part, with the mark scheme

questions

marks

minutes

Topics Experimental Contexts · Observations and Measurements · Analysis, Conclusions and Evaluation · Planning Experiments and Investigations · Use of Techniques, Apparatus and Materials · Microscopy and Biological Drawing

Q121MExperimental ContextsObservations and MeasurementsAnalysis, Conclusions and EvaluationPlanning Experiments and InvestigationsFree sample

When a seed germinates, the stem of the seedling grows upwards.

You are going to investigate differences between seedlings grown in the light and seedlings grown in the dark.

You are provided with approximately 15 seedlings grown in the light and 15 grown in the dark.

(a)

(i)

Examine the seedlings that have been provided. Complete the table to compare the leaf colour, leaf size and stem length of seedlings grown in the light and in the dark.

feature	seedlings grown in light	seedlings grown in dark
leaf colour
leaf size
stem length

(ii)

Select five seedlings grown in the light and five grown in the dark.

Measure the length of each stem to the height of the lowest leaf.

Record your measurements in the table below and calculate the mean lengths.

seedling	stem length in light / $\text{mm}$	stem length in dark / $\text{mm}$
1
2
3
4
5
mean length / $\text{mm}$

(b)

Suggest why the growth observed in the dark might be an advantage to a plant in a shady, forest environment.

______

(c)

Some scientists wanted to investigate the effect of fertiliser on the growth of wheat. Wheat seeds were planted in soil to which nitrogen fertiliser had been added. After the seedlings had grown to a height of $8\,\text{cm}$ , they were measured at regular intervals.

The mean heights of the plants are shown in the table.

time / days	mean height of plants / $\text{cm}$
0	8
10	10
30	29
60	58
90	73
110	73

(i)

Construct a line graph of the data on the grid below. Join your points with ruled, straight lines.

Fig. 1.1

(ii)

Use your graph to find the mean height of the plants at 50 days. Show your working on the graph.

mean height = ______

(iii)

Describe how the rate of growth of these plants changed between days 0 and 110.

______

(iv)

Describe how to complete this investigation to find whether fertiliser does have an effect on the rate of growth of wheat.

______

(v)

Increase in height was used as a measure of growth. Suggest two other plant features that could have been used to measure growth.

______

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