Planning Experiments and Investigations

Plants can be provided with fertiliser to help them grow.

Some students were provided with germinated seeds of the same species in some shallow dishes and a 10% fertiliser solution. One dish is shown in Fig. 3.1.

The students had access to any other common laboratory apparatus.

Plan an investigation the students could carry out to find the effect of different fertiliser concentrations on plant growth.

Identify the independent variable in this investigation.

______

Plants can be provided with fertiliser to help them grow.

Some students were provided with germinated seeds of the same species in some shallow dishes and a 10% fertiliser solution. One dish is shown in Fig. 3.1.

The students had access to any other common laboratory apparatus.

Plan an investigation the students could carry out to find the effect of different fertiliser concentrations on plant growth.

Identify the independent variable in this investigation.

______

Describe an investigation you could do to find out whether caffeine in coffee affects the rate at which the heart beats.

A student suggests that another drink contains even more caffeine than coffee. You want to design an investigation to test whether this is true. State two factors which you should control so that the results can be compared with the results of your coffee investigation in (b).

1. ______
2. ______

Construct a table to record the appearance and volume of juice collected from each mixture.

washing the plastic spoon

stirring the mixtures

adding $5\text{ cm}^3$ of water in the test-tube labelled 'no enzyme'.

On the grid, draw a line graph of the data shown in Table 2.1.

Join the points with ruled, straight lines.

Suggest one other method that the students could use to measure the growth of Lemna.

______

Plan an investigation to determine the effect of different concentrations of a nutrient solution on the growth of Lemna. Use the same method of counting the number of leaves that the students used in their investigation for measuring growth.

Construct a bar chart of the data in Table 3.1.

Suggest one improvement to make this investigation more reliable.

Construct a graph on the grid below, from the figures in Table 2.2.

Design, but do not carry out, a laboratory experiment, to investigate the effect of temperature on the formation of yoghurt from milk.