Practise Edexcel A-Level Biology handling data through magnification calculations, graph and table conclusions, correlation comments and statistical-test decisions.
Human serum albumin is a globular protein found in blood plasma.
Albumin has a molecular mass of 66300 daltons.
It consists of 585 amino acids.
At pH 7.4 albumin has over 200 negative charges on the surface of each molecule.
Calculate the mean molecular mass of an amino acid in albumin.
Give your answer to an appropriate number of significant figures.
Light is essential for photosynthesis.
The photograph shows thale cress, a small flowering plant found in Europe, Asia and Africa.
The effect of wavelength of light on thale cress was investigated. Three groups of plants were treated with a different wavelength of light. One group of plants was treated with blue light, one group with amber light and one group with red light. The following were measured:
- rate of photosynthesis
- leaf biomass
- pigment content of the leaves
- changes in transcription of genes in the leaves.
Another group of these plants had a control light shone on them.
The table shows the results for the pigment content of the leaves.
Describe three conclusions that can be made from these results.
Quince are fruit that grow on trees.
When a quince falls from the tree, two processes take place: browning and decomposition.
A quince fruit is made up of cells and contains a lot of juice.
The table shows the composition of carbohydrates in the juice of one species of quince.
Which row of the table shows the carbohydrates with the median concentration and modal concentration in quince juice?
□ A
□ B
□ C
□ D
Mycobacterium tuberculosis (Mtb) and human immunodeficiency virus (HIV) are two pathogens that infect people. When people infected with either pathogen become infected with the other pathogen the disease is worse.
The graph shows the number of people who have TB and the percentage of the population who have HIV. Each plotted point represents data from a different country.
Number of people who have TB per 100000 population
Comment on the relationship between the number of people who have TB and the percentage of people who have HIV.
Soil contains many types of organisms such as earthworms.
The photograph shows earthworms collected from the soil of a pineapple plantation in North East India.
The actual earthworm labelled A in the photograph is 13.5 cm long. Estimate the magnification of this photograph.
Mycobacterium tuberculosis (Mtb) and human immunodeficiency virus (HIV) are two pathogens that infect people. When people infected with either pathogen become infected with the other pathogen the disease is worse.
The graph shows the number of people who have TB and the percentage of the population who have HIV. Each plotted point represents data from a different country.
Number of people who have TB per 100000 population
Describe how the strength of the relationship between the number of people who have TB and the percentage of people who have HIV could be determined.
Soil contains many types of organisms such as earthworms.
A scientist investigated the mass of earthworms present in the soil of a 5-year-old plantation and a 15-year-old plantation. The method used in each plantation was:
- five sample sites were selected at random
- a block of soil with an area of and to a depth of 10 cm was removed at each site
- the total mass of earthworms present in each block of soil was recorded.
The tables show the results of this investigation.
Calculate the standard deviation for the mass of earthworms present in the soil of the 15-year-old plantation. Use the formula:
Where: n is the number of sample sites X is the mass of earthworms from one sample site is the mean mass of earthworms
Describe how the means and standard deviations could be used to compare the results from these two plantations.