Practise Edexcel A-Level Biology arithmetic and numerical computation through ratios, percentage change, standard form, unit conversion and formula substitution.
An abdominal aortic aneurysm (AAA) is a swelling of the aorta in the abdomen due to weakening of the wall of the aorta. Patients with an AAA frequently have atherosclerosis. An AAA can be fatal if the aorta bursts causing internal bleeding. The diagram shows an AAA.
The presence of an AAA can be detected by scanning the abdomen. The image shows a scan of a healthy abdominal aorta.
An aorta with a diameter greater than 5.5 cm is classed as a large AAA. Calculate how many times wider this large AAA is than the aorta with a diameter of 17.3 mm . Give your answer to three significant figures.
A screening programme found that 1 in 92 men had an AAA and 1 in 1000 men had a large AAA. Calculate the proportion of AAA that are large AAA.
There are many water-stressed countries in the world, mostly in the Middle East, North Africa and South Asia. Water-stressed countries have a shortage of fresh water needed for humans, animals and crops. Fresh water can be produced from sea water by desalination processes. The map shows the most water-stressed countries (shaded) in the world.
The estimate of the volume of water on Earth is . Fresh water makes up 2.5\% of this volume. 90\% of this fresh water is not available as it is frozen in ice caps and glaciers. Calculate the volume of available fresh water on Earth. Give your answer in standard form.
A student used a microscope to study the tissues in a plant stem and the cell of an animal.
The photograph shows a vascular bundle in a transverse section of the plant stem, as seen using a light microscope.
A cell in tissue B of the vascular bundle has a cross-sectional area of .
Calculate how many times larger the cross-sectional area of cell F is than this cell in tissue B.
Give your answer to three significant figures.
Answer