Planning Experiments and Investigations
99 questions· page 1 of 10
Plan an investigation to find out the effect of varying light intensity on the increase in height of mustard plant seedlings provided in Petri dishes, as shown in Fig. 3.1.
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.
Suggest why the student waited for 15 minutes before introducing the beetles into the apparatus.
______
The dry part of the container had been treated with a chemical drying agent.
Suggest one advantage and one disadvantage of doing this.
advantage = ______
disadvantage = ______
Suggest one variable in this investigation, apart from humidity, that may affect the distribution of the beetles.
______
After 20 minutes, the student observed that all the beetles had settled on the moist paper.
Design an investigation, using similar apparatus, to show the effect of light on beetle distribution.
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).
- ______
- ______
Describe two variables that the students would need to keep constant during this investigation.
- ______
- ______
Design an investigation using similar apparatus to find out whether thicker bones are stronger than thin bones.
You should consider the need to obtain reliable results when designing your investigation.
The pH of urine in healthy humans is normally 6.5. The pH of urine can be measured using universal indicator paper strips.
A scientist wants to determine whether the pH of human urine is affected by the volume of water drunk. For her investigation she selects 20 healthy female volunteers of similar age and weight.
Plan a method the scientist could use for her investigation.
A student carried out an investigation into the effect of temperature on the rate of starch production. She used phosphorylase from potato tissue and a solution of glucose.
State three factors that the student should have kept constant during this investigation.
- ______
- ______
- ______
Design an investigation to show how temperature affects the germination of cress seeds.
Explain how you will control variables to ensure that this investigation is valid.
______
Suggest two reasons why a number of seeds, rather than just one seed, were placed in each Petri dish at the beginning of the investigation.
- ______
- ______
The students selected three seedlings from each dish to measure. Suggest a method the students could have used for choosing the three seedlings and state an advantage of this method.
method = ______
advantage = ______
On the grid construct a line graph to show the relationship between time and mean height for these seedlings. Join your points with ruled lines.
State two variables that need to be controlled whilst growing these seedlings and explain why they need to be controlled.
variable 1 ______
variable 2 ______
explanation ______
The seeds needed water to germinate and for the seedlings to grow.
Design an investigation to determine the effect of the pH of water on the growth (mean height) of seedlings. You should use seedlings grown in Petri dishes in a laboratory.