01. Introduction to Biology

Scientific Investigation
Objective : State the aim of experiment
Problem statement : Pose questions about the observations made
Hypothesis: Formulate a possible explanation based on observations
Variables : Identify and controll the manipulated, responding and fixed variables
Materials and apparatus: List the materials and apparatus which will be used during the experiment
Technicque : State the technique involved in obtaining the results
Procedure: Write the instructions to carry out the experiemnt
Results: Present the results in the form of tables, charts or diagrams. Includecalculations when necessay
Discussions: Discuss, analyse and interprete the data obtained. Determine the relationship between the manipulated variable and the responding variable
Conclusion: Draw a conclusion based on the hypothesis given earlier

Bread is made from a mixture of flour, yeast, sugar and water. The dough is kneaded and left to rise before baking. The time taken for the dough to double its size depends on the amount of yeast used.

Plan and design a laboratory experiment to study the relationship between the amount of yeast used and the time taken for the dough to double its size. The planning of the experiment should include the following aspects:

· Aim of investigation

· Problem statement

· Hypothesis

· Variables

· List of apparatus and materials

· Technique used

· Experimental procedures or methods

· Presentation of data

· Conclusion

ANSWERS

Aim of investigation

To study the relationship between the amount of yeast used and the time taken for the dough to double its size.

Problem statement

What is the effect of the amount of amount of yeast used on the time taken for the dough to double its size?

//How does the amount of yeast used affect the time taken for the dough to double its size?

Hypothesis

The more the amount of yeast used, the faster the time taken for the dough to double its size.

Variables

Manipulated variables: Amount of yeast used

Responding variables: Time taken for the dough to double its size

Fixed variables: Amount of flour// sugar// water (write only one)

Materials

3 g of yeast, 15 g of sugar, 150 g of flour, 150 g of water

Apparatus:

Weighing machine, beakers, mixing bowls, stopwatch

Technique used

Measure and record the time taken for the dough to double its size using a stopwatch.

Procedure

1. Mix 50 g of flour and 5 g of sugar thoroughly in a mixing bowl. Labeled as P. Repeat for mixing bowls Q and R.

2. Mix 0.5 g, 1.0 g and 1.5 g of yeast to mixing bowls P, Q and R respectively.

3. Add 50 ml of water to each mixing bowl and knead for 5 minutes.

4. Place each of the kneaded dough in a beaker and press down the dough. Note the initial level of the dough.

5. Each beaker is covered with a clean cloth and placed in a warm spot.

6. Start the stopwatch and record the time taken for the dough to double its size.

7. The time taken for the dough to double its size for P, Q and R is recorded in a table.

Presentation of data

Mixing bowl	Amount of yeast (g)	The time taken for the dough to double its size (minutes)
P	0.5
Q	1.0
R	1.5

Conclusion

The hypothesis is accepted. The more the amount of yeast used, the faster the time taken for the dough to double its size

BIOLOGY PAPER 3 FORMAT

PAPER 3 (4551/3) This paper consists of 2 compulsory questions. a) Question 1 – Structured item about Scientific Process (33 marks) b) Question 2 – Essay question on Experimental Design (17 marks)

Question 1 – Structured items are evaluated based on the following aspects: a) Observing b) Classifying c) Measuring and using numbers d) Making inferences e) Predicting f) Communicating g) Using spatial time relationship h) Analysing data i) Defining operationally j) Controlling variables k) Forming a hypothesis Total = 33 marks

Question 2 – Planning/designing an experiment which must include the following aspects: a) Problem statement (3marks) b) Hypothesis (3marks) c) Variables (3marks) d) List of apparatus and materials (3marks) e) Experimental procedure or method (3marks) f) Presentation of data (2 marks) Total = 17 marks