Practise Edexcel A-Level Biology handling data through magnification calculations, graph and table conclusions, correlation comments and statistical-test decisions.
The effect of atropine and propranolol on heart rate was investigated.
One group of people, group 1, were given propranolol each day for four days followed by atropine for four days.
A second group of people, group 2, were given atropine each day for four days followed by propranolol for four days.
The graph shows the results of this investigation.
Mean heart rate/ beats
Calculate the mean length of the cardiac cycle for group 2 on day 4.
Answer seconds
Obesity increases the risk of cardiovascular disease (CVD).
Body mass index (BMI), waist-to-hip ratio (WHR) and skinfold thickness are indicators of obesity.
The diagram shows how a skinfold thickness measurement is taken over the triceps muscle at the back of the arm.
Skinfold thickness measures the thickness of the layer of fat under the skin.
Measurements are taken from several sites on the body.
The table shows the skinfold thickness at four sites on a 42-year-old female.
The table shows a body fat interpretation chart.
The values in the table are the means of the four skinfold thickness measurements.
Determine the level of body fat of this female.
Most Bengal tigers are orange with black stripes but there is a very small number of Bengal tigers that are white with black stripes.
The photograph shows a white Bengal tiger with black stripes.
White tiger offspring are produced by two Bengal tigers that each carry at least one recessive allele for a gene affecting coat colour.
The pedigree diagram shows the phenotypes in one family of tigers, bred in captivity.
Key female orange tiger female white tiger male orange tiger male white tiger
State the probability that the next tiger born to these two parents will be female.