MrBadmusAI

Year 8 · Autumn First Half

Biology

4 lessons from 1 unit.

Unit B4 · lessons 1 to 4 of 5

Breathing and gas exchange

You breathe about twenty thousand times a day without deciding to. This unit is about what the air is for, how it gets in and out when your lungs contain no muscle at all, and why the same problem has the same solution in a lung and in a leaf.

  1. 01The gas exchange systemSystemBreathe out into a bag and analyse it. There is four times more oxygen in there than carbon dioxide. Most people are surprised, and the surprise is worth taking seriously.Open this lesson
  2. 02How breathing worksModelYour lungs contain no muscle at all. They cannot pull air in, and they never have. Something else moves, and the air follows.Open this lesson
  3. 03Alveoli: built for exchangeModelOxygen molecules cross from your alveoli into your blood, and at the same moment other oxygen molecules cross the other way. You survive on the difference between two numbers.Open this lesson
  4. 04Exercise, asthma and smokingSystemThree things that change how well you breathe, and they act on three different parts of the system. Naming which part is most of the answer.Open this lesson

Back to all three sciences this half term The whole KS3 Biology course