WJEC A Level Biology
WJEC A Level Biology 2.2 Adaptations for Gas Exchange Exam Questions
Free WJEC A Level Biology exam questions on 2.2 Adaptations for Gas Exchange, with mark schemes. Covers gas exchange in single-celled organisms, insects, fish, mammals and plants.
2.2 Adaptations for Gas Exchange exam questions
1 question pack of real past exam questions with its mark scheme. Answer every question without notes, then mark your answers line by line against the mark scheme.
StemUp mark scheme flashcards
WJEC A Level Biology Flashcards (Anki & Quizlet)
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Use them on Anki or Quizlet, then test yourself with the questions on this page.
£16.99View flashcards
About WJEC A Level Biology 2.2 Adaptations for Gas Exchange
This topic compares how organisms of different sizes exchange gases. Expect comparison questions and lung ventilation.
What you need to know
- Surface area to volume ratio Small organisms use diffusion across their surface; larger ones need specialised surfaces.
- Insects and fish Insects use a tracheal system and spiracles; fish use gills with lamellae and countercurrent flow.
- Mammals Alveoli, ventilation by intercostal muscles and diaphragm, and pressure changes.
- Plants Leaves exchange gases through stomata, with the spongy mesophyll providing air spaces.
Common mistakes in 2.2 Adaptations for Gas Exchange
- Saying countercurrent flow means blood and water flow the same way.
- Saying the lungs push air out actively at rest.
- Forgetting stomata close at night in most plants.
Try three 2.2 Adaptations for Gas Exchange exam-style questions
1. Explain how countercurrent flow increases gas exchange in fish. (2 marks)
Show the mark scheme answer
Blood and water flow in opposite directions (1), so a diffusion gradient is maintained along the whole lamella (1).
2. Describe inspiration in mammals. (3 marks)
Show the mark scheme answer
External intercostal muscles contract and the diaphragm contracts and flattens (1); thoracic volume increases (1) so pressure falls below atmospheric and air enters (1).
3. Explain why large organisms need specialised gas exchange surfaces. (2 marks)
Show the mark scheme answer
They have a small surface area to volume ratio (1), so diffusion across the body surface is too slow to meet their needs (1).
2.2 Adaptations for Gas Exchange FAQs
What does Adaptations for Gas Exchange cover?
Gas exchange in unicellular organisms, insects, fish, mammals and plants.
Do I need to know dissection?
Yes, observing gas exchange surfaces such as fish gills or lungs.
How does it link to surface area to volume ratio?
The ratio explains why larger organisms need specialised exchange surfaces.
Revise this topic with flashcards: WJEC A Level Biology Flashcards, with mark scheme answers for Anki and Quizlet.
