Uploaded February 2026 | Updated September 2026, 7 hours ago
Find your 9s with PLUS. Click the link to try for free freesciencelessons.co.uk/modules/gcse-biology-1-triple
Teachers, to get PLUS for your school, email schools@freesciencelessons.co.uk
In this video, we explore what is meant by the surface area to volume ratio of an organism. We then look at how to calculate the surface area to volume ratio. We then explore how gills are used by fish to increase the absorption of oxygen into the bloodstream.
This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Biology. Please consult your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks.
Image credits:
Amoeba By dr.Tsukii Yuuji - protist.i.hosei.ac.jp/PDB2/PCD1761/D/79.jpg, CC BY-SA 2.5, commons.wikimedia.org/w/index.php?curid=7780521
Fish Public Domain, commons.wikimedia.org/w/index.php?curid=672084
Gills By User:Uwe Gille - Own work, CC BY-SA 3.0, commons.wikimedia.org/w/index.php?curid=1184299
Kitten
commons.wikimedia.org/wiki/File:Black_kitten_July_August_2009-1.jpg
Alvesgaspar, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Cheek cells
commons.wikimedia.org/wiki/File:Cheekcells_stained.jpg
Mulletsrokk, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Find your 9s with PLUS. Click the link to try for free freesciencelessons.co.uk/modules/gcse-biology-1-triple
Teachers, to get PLUS for your school, email schools@freesciencelessons.co.uk
In this video, we explore what is meant by the surface area to volume ratio of an organism. We then look at how to calculate the surface area to volume ratio. We then explore how gills are used by fish to increase the absorption of oxygen into the bloodstream.
This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Biology. Please consult your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks.
Image credits:
Amoeba By dr.Tsukii Yuuji - protist.i.hosei.ac.jp/PDB2/PCD1761/D/79.jpg, CC BY-SA 2.5, commons.wikimedia.org/w/index.php?curid=7780521
Fish Public Domain, commons.wikimedia.org/w/index.php?curid=672084
Gills By User:Uwe Gille - Own work, CC BY-SA 3.0, commons.wikimedia.org/w/index.php?curid=1184299
Kitten
commons.wikimedia.org/wiki/File:Black_kitten_July_August_2009-1.jpg
Alvesgaspar, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Cheek cells
commons.wikimedia.org/wiki/File:Cheekcells_stained.jpg
Mulletsrokk, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
