Unit 4 - Hypothesis
No matter how keen we are to start, before we can begin an experiment, we need to do a risk assessment.

Unit 4 - Hypothesis

When planning an investigation, the first stage is to come up with a hypothesis. Many students see a hypothesis as prediction of the outcome of an experiment - but it is a lot more than that. This GCSE Biology quiz will help you get to grips with what exactly a hypothesis is.

A hypothesis is a prediction backed up with a scientific reason saying why you think the prediction is correct. Effectively it is what you expect the outcome of an experiment to be and the reason why you expect it. The experimental part of your investigation is then aimed at testing your hypothesis. Always keep reminding yourself of your hypothesis when planning your experiment as that will help to keep you on track.

An example of a hypothesis would be that 'seedlings growing in a greenhouse will grow faster than seedlings on a window sill because there is more light for photosynthesis'. To improve on this, you could add 'there is more light because it is coming into the greenhouse from all sides and not just from the side where there is the window'.

Variables will affect the outcome of your experiment so they need to be identified. Once you have your hypothesis, you can then begin to identify the independent variable, the dependent variable and the control variables. The dependent variable is the factor that you think will change. In the example above, the dependent variable is therefore the growth rate. The independent variable is the factor that you think will cause the dependent variable to change, in our example it would be the amount of light. The control variables are harder to work out and you may find that you add more control variables to the list when you are designing your experiment. The more detail you add to your hypothesis the more it will help you to make sure that the experiment you design will investigate the right variables. It helps you to control the variables better too.

Before we can start the experiment, we need to do a...
risk assessment
risk measurement
risk statement
risk awareness course
You can only do this when you have decided on your method that you will use to carry out your experiment
After writing a hypothesis, we need to write the...
results table
variables list
Once you have decided on the variables, you can then begin to think about the experiments that you will do to test the hypothesis
The hypothesis that links fossils with prehistoric organisms can only be tested if....
we could clone the organisms
we could go back in time and do the experiments to prove it
we could match them up with organisms alive today
we could speed up the process of fossil formation
Yes! Believe it or not, without actually going back in time, the link between an actual fossil and an actual organism cannot usually be proven. Palaeontologists (scientists who study fossils) are now developing ways of obtaining DNA from certain fossils which can then be used to prove the links
When do we come up with a hypothesis?
After obtaining results
Before we start the experiment
During the experiment
After the conclusion
It is the very first thing that you need to do when planning an investigation
Another phrase to describe a hypothesis is...
a sheer fluke
an educated guess
a red herring
a shot in the dark
A hypothesis is a prediction based on what you know, so it is an educated guess that can be tested
Which of these is a hypothesis?
As the temperature increased, the rate of reaction increased
As the temperature increases, I think that the rate will also increase due to the increased kinetic energy of the particles
As the temperature increases, things will start to happen
As the temperature increased, the reactants fizzed and caused a massive explosion
The first and the last options must be wrong as they are written in the past tense. The third is not precise enough but the second option offers a prediction and a scientific reason
Which of these is a hypothesis?
As the concentration of acid increases, I think the rate will also increase because there are more particles
The results show that more acid increases the rate
There is one odd result at an acid concentration of 10%
I think that Leeds United are the best team in the world because they have the best players
Option 2 is a conclusion, option 3 is an evaluation and option 4 does not indicate the dependent and independent variables precisely enough - what is meant by best team ... the one that scores the most goals? The one that wins the most matches? A hypothesis should be very precise
Which is the correct order for an investigation?
Conclusion, results, method, hypothesis
Hypothesis, results, conclusion, method
Hypothesis, method, results, conclusion
Results, conclusion, hypothesis, method
We always start an investigation with a hypothesis
What is a scientific hypothesis?
A fact supported by a prediction
An outcome supported by experimental results
A measurement made very accurately using complex equipment
A prediction supported by scientific reasoning
It doesn't matter if either the prediction or the reasoning is wrong - that will be decided by the experimental work you do to test the hypothesis
"I think that X will happen because of Y" is an example of...
This is probably the simplest way of describing a hypothesis
You can find more about this topic by visiting BBC Bitesize - Practical skills

Author:  Donna Maria Davidson

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