Surviving the heat
360 words over 34 numbered lines, then 6 parts worth 12 marks (Modular Unit 2 (4WBI2) style, 12–13 marks). Read the article, answer each part, then open its mark scheme and set your mark.
Illustrative article written for Scholar Lab, not a Pearson text. The biology is real; the studies, people and figures are invented or rounded for practice.
Surviving the heat
Heatwaves are becoming longer and more frequent. In the summer of
2022, scientists estimated that more than 60 000 people in Europe died
because of the heat. Most of them were over the age of 75. Doctors now
treat heatwaves as a serious threat to health, not just as
uncomfortable weather. Cities are often hotter than the surrounding
countryside, because concrete and roads absorb heat during the day and
release it at night.
Our core body temperature stays close to 37 °C. When the body becomes
too warm, temperature receptors in the brain detect the change. Sweat
glands in the skin release more sweat, and arterioles supplying the
capillaries near the surface of the skin widen. This vasodilation
means that more blood flows near the surface, so more heat is lost to
the surroundings.
Sweating only cools the body if the sweat evaporates. In dry air,
sweat evaporates quickly. In humid air, which already contains a lot
of water vapour, sweat drips off the skin instead. This is why a hot,
humid day can be more dangerous than a hotter, dry one.
A person doing hard physical work in the heat can lose about 1.2
litres of sweat every hour. Sweat is mostly water but also contains
salts. In an illustrative study of farm workers, each litre of sweat
contained about 0.9 g of sodium. If the water is not replaced, the
volume of the blood falls and the kidneys produce a small volume of
concentrated urine.
Older people are at greater risk. They often sweat less, they may not
feel thirsty even when they are short of water, and many take
medicines that affect their kidneys or heart. If the core temperature
rises above about 40 °C, enzymes in the body start to stop working
properly, and the person may collapse with heatstroke.
Simple measures save lives: drinking water regularly, staying in the
shade, keeping rooms cool, and checking on elderly neighbours. Some
cities now open cool public buildings during heatwaves and plant more
trees to shade the streets. Employers are also advised to give outdoor
workers regular breaks and to move heavy work to the cooler early
morning.
Read the article. Use the information in the article and your own knowledge to answer the questions. The lines in brackets show where to look; select them to highlight the text.
Use the information in the article and your own knowledge to answer the questions. The lines in brackets show you where to look; select them to highlight the text.
State what is meant by the term vasodilation.
(1)Explain how sweating cools the body.
(2)Explain why a hot, humid day can be more dangerous than a hotter, dry day.
(2)A farm worker works for 4.5 hours in the heat. Calculate the mass of sodium lost in sweat. Give your answer to 2 significant figures.
(2)Explain how the body causes the kidneys to produce a small volume of concentrated urine when a person is short of water.
(3)Suggest why older people are more likely to die during a heatwave.
(2)Total for this question: 12 marks
0 / 12 marks · 0 of 6 parts rated
Open each mark scheme, compare it with your answer and set your mark. Only your marks are kept, in this browser on this device; your written answers are never saved. Green is full marks, amber is half or more, red is under half.