Exchange surfaces in leaves and fish
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Explainer Video
Summary
Exchange surfaces in leaves and fish
In a nutshell
Multicellular organisms need to have exchange surfaces to perform basic functions for survival, including respiration and photosynthesis. In this lesson, you will learn about exchange surfaces in leaves and fish.
Exchange surfaces in leaves
Stomata
Stomata are small holes that are found underneath a leaf. Carbon dioxide, which is needed for photosynthesis, diffuses through the stomata into the leaf. Water vapour and oxygen diffuse out of the leaf through the stomata. Guard cells control the size of stomata and the leaf’s flattened shape increases the area of its exchange surfaces.
Cell walls
Another exchange surface is the walls of the cells inside the leaf. Gases can diffuse into and out of the cells through these walls. Between cells, there are air spaces which increase the area of these surfaces.
Gas exchange in fish
Fish have gills which are their main gas exchange surface. Water containing oxygen flows into the mouth and out through the gills. In the gills, oxygen diffuses into the blood and carbon dioxide diffuses into the water.
Gills are adapted for gas exchange as they are made from many small, thin plates which gives them an increased surface area. The gill plates also have a good blood supply which increases the rate of diffusion. The diffusion distance is short, as the gill plates have a thin layer of surface cells.
FAQs - Frequently Asked Questions
How are gills adapted for gas exchange?
Gills are adapted for gas exchange as they are made from many small, thin plates which gives them an increased surface area.
What happens in the gills of a fish?
Fish have gills which their the main gas exchange surface. Water containing oxygen flows into the mouth and out through the gills. In the gills, oxygen diffuses into the blood and carbon dioxide diffuses into the water.
What are stomata in plants?
Stomata are small holes that are found underneath a leaf.