Gaseous Exchange in Plants and Small Animals

Syllabus tag: KCSE | Biology | Form 2 | Topic 3 Gaseous Exchange

Lesson objectives

By the end of this topic, you should be able to:

• State the necessity for gaseous exchange and the features of a respiratory surface.
• Describe gaseous exchange in plants through stomata and lenticels.
• Describe gaseous exchange in protozoa, insects and fish.
• Relate each structure to its habitat and mode of life.

Summary

Every organism must take in oxygen and remove carbon dioxide. All respiratory surfaces share four features: they are thin, moist, have a large surface area and a good supply to maintain the diffusion gradient. Plants use stomata and lenticels; Amoeba uses its whole cell membrane; insects use tracheae; fish use gills with a counter-current flow.