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.
Female mosquitoes feed on the blood of other animals to promote the development of their eggs. During this process, infected mosquitoes can transmit the Plasmodium parasite.
The Plasmodium parasite causes the disease malaria.
The photograph shows a female Anopheles mosquito.
Calculate the magnification of the Anopheles mosquito in this photograph.
Give your answer to one decimal place.
The drawing shows a speckled chicken. These chickens have a mixture of black and white feathers.
The colour of the feathers of a chicken is an example of codominance.
One parent of this speckled chicken had white feathers and the other parent had black feathers.
In an experiment, several pairs of speckled chickens were mated together.
They produced 480 chicks.
The table shows the expected number of speckled chicks, white chicks and black chicks. It also shows the actual number of each type of chick.
This table can be used in a statistics test.
Explain how a critical value table could be used to accept or reject a null hypothesis for this experiment.
This photograph, taken through a light microscope, shows three of the stomata on the underside of a leaf.
The area of a sample of pores in fossil leaves was investigated and the means calculated.
These means were correlated with estimates of atmospheric carbon dioxide concentration at the time the fossil was formed.
The results are shown in the table.
The data in the table were plotted on a graph.
Atmospheric carbon dioxide concentration / ppm
Draw the standard deviation for the mean area of the pores and on the graph.