Questions Flashcards
What does compare and contrast mean
Compare - similarity
Contrast - differences
What does evaluate / evaluation mean
Say why
What does describe mean
Say what you see
What does suggest ways mean
Use scientific knowledge to work out what it might be
Why do you use a control/ baseline?
To allow comparisons
Which do you always need to remember when drawing graphs?
To include units!!!!!
With ratio questions what should you always make one of them into
Make one of the numbers a one
( Interpolate from ration of 1)
Eg .
4.8 : 2.4
= 2:1
How do you calculate percentage error?
Percentage error = uncertainty divided by reading (measured value) times by 100
What should you always mention when you say ATP
It provides energy
What should you mention when talking about cancer or abnormal methylation
Results in Rapid / Uncontrollable cell division
No control by mitosis
Which forms tumours
How should you approach if you got a importance of something question
Consider the role of what it does first and then explain what would happen without it
———-
Example:
Explain why it is important for acetylcholine to be broken down. [1 mark]
- To prevent sodium channels in the postsynaptic membrane from staying permanently open;
• 2. To stop permanent depolarisation of the postsynaptic membrane;
To explain why it is important for acetylcholine to be broken down, consider the role of acetylcholine:
Role of acetylchloine
- combines with receptor protein on postsynaptic membrane
- causes sodium channels in postsynaptic membrane to stay open
What do you need to ensure you do in application questions
Use the context of the question
——
E.g
Synapses: drugs
Drug binds to receptors
In question it said opioid receptors
Eg.
Muscle contraction
pulls the Actin Filement along
In question it asked how does the myosin molecule move the mitochondria toward the pre synaptic mb
So you need to say pulls the mitochondria along the actin
Give 4 marking points that you should say in evaluation questions
1) Was it tested on a different species? E.g. Mice vs human
2) Was it conducted long enough to see long term effects
3) Did they do a statistic to see if the difference / correlation was significant
4) Did they test a large sample
to ensure results were representative?
increases validity/reliability
——
Other:
. Is there anything you could have done to make your results more precise or accurate?
. Were there any limitations in your method, e.g. should you have taken measurements more frequently?
. Were there any sources of error in your experiment?
. Could you have used more sensitive apparatus or equipment?
How would you structure the answer to this question / how would you get the marks
One environmental issue arising from the use of fertilisers is eutrophication.
Eutrophication can cause water to become cloudy.
You are given samples of water from three different rivers.
Describe how you would obtain a quantitative measurement of their cloudiness. 3 marks
Principle is:
1) Named apparatus
2) What is measured
3) Standardisation of method
———
Answer
Accept any valid method, for example
1) Use of colorimeter;
Reject calorimeter
2) Measure the absorbance/transmission (of light);
Reject if samples are filtered unless filtering to remove debris
Accept descriptions
3) Example of how method can be standardised
e.g. same volume of water, zeroing colorimeter, same wavelength of light, shaking the sample;
Ignore references to calibration curves
Explain what error bars mean when overlapping and not overlapping?
Overlap in standard deviation/ error bars = no significant difference
No overlap in standard deviation/ error bars = significant difference
How should you write comparison questions?
Say a comparison point
Then compare it to the other one / say why it’s different or same
Eg.
1) Ethanol / alcohol is formed by seeds whereas lactate by muscle cells
2) Carbon dioxide is released by seeds but not by muscle cells
