Uploaded August 2023 | Updated September 2026, 3 hours ago
You can find all my A Level Biology videos fully indexed at freesciencelessons.co.uk/a-level-revision-videos/a-level-biology
In this video, we look at the factors affecting genetic biodiversity. This includes factors that increase genetic biodiversity such as mutations and gene flow, as well as factors that reduce genetic biodiversity such as the bottleneck effect, the founder effect and genetic drift.
Image credits:
Alpacas
commons.wikimedia.org/wiki/File:Alpacas.JPG
Philippe Lavoie, Public domain, via Wikimedia Commons
Herd of cows
commons.wikimedia.org/wiki/File:Herd_of_cows_on_the_sea_bank_-_geograph.org.uk_-_3665300.jpg
Herd of cows on the sea bank by Mat Fascione, CC BY-SA 2.0 creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons
Wheat field
commons.wikimedia.org/wiki/File:Vehn%C3%A4pelto_6.jpg
kallerna, CC BY-SA 4.0 creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Charles Darwin
commons.wikimedia.org/wiki/File:Charles_Darwin_seated_crop.jpg
Charles_Darwin_seated.jpg: Henry Maull (1829–1914) and John Fox (1832–1907) (Maull & Fox) [3]derivative work: Beao, Public domain, via Wikimedia Commons
Sumatran tiger
commons.wikimedia.org/wiki/File:Sumatran_Tiger_Berlin_Tierpark.jpg
Captain Herbert, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Manx loaghtan
commons.wikimedia.org/wiki/File:Manx_loaghtan.jpg
Chris Bramhall at English Wikipedia, Public domain, via Wikimedia Commons
Stem Cutting
commons.wikimedia.org/wiki/File:Stem_Cutting.jpg
Kumar83, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Black robin
commons.wikimedia.org/wiki/File:Black_Robin_on_Rangatira_Island.jpg
frances schmechel, CC BY-SA 2.0 creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons
Wolf
commons.wikimedia.org/wiki/File:Front_view_of_a_resting_Canis_lupus_ssp.jpg
Gary Kramer, Public domain, via Wikimedia Commons
Isle Royale
commons.wikimedia.org/wiki/File:Isle_Royale_-_Beach_Near_Mouth_of_Washington_Creek.JPG
Jhodkiewicz at the English Wikipedia, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons
Moose
commons.wikimedia.org/wiki/File:Alces_alces.jpg
bcameron54, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
You can find all my A Level Biology videos fully indexed at freesciencelessons.co.uk/a-level-revision-videos/a-level-biology
In this video, we look at the factors affecting genetic biodiversity. This includes factors that increase genetic biodiversity such as mutations and gene flow, as well as factors that reduce genetic biodiversity such as the bottleneck effect, the founder effect and genetic drift.
Image credits:
Alpacas
commons.wikimedia.org/wiki/File:Alpacas.JPG
Philippe Lavoie, Public domain, via Wikimedia Commons
Herd of cows
commons.wikimedia.org/wiki/File:Herd_of_cows_on_the_sea_bank_-_geograph.org.uk_-_3665300.jpg
Herd of cows on the sea bank by Mat Fascione, CC BY-SA 2.0 creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons
Wheat field
commons.wikimedia.org/wiki/File:Vehn%C3%A4pelto_6.jpg
kallerna, CC BY-SA 4.0 creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Charles Darwin
commons.wikimedia.org/wiki/File:Charles_Darwin_seated_crop.jpg
Charles_Darwin_seated.jpg: Henry Maull (1829–1914) and John Fox (1832–1907) (Maull & Fox) [3]derivative work: Beao, Public domain, via Wikimedia Commons
Sumatran tiger
commons.wikimedia.org/wiki/File:Sumatran_Tiger_Berlin_Tierpark.jpg
Captain Herbert, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Manx loaghtan
commons.wikimedia.org/wiki/File:Manx_loaghtan.jpg
Chris Bramhall at English Wikipedia, Public domain, via Wikimedia Commons
Stem Cutting
commons.wikimedia.org/wiki/File:Stem_Cutting.jpg
Kumar83, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Black robin
commons.wikimedia.org/wiki/File:Black_Robin_on_Rangatira_Island.jpg
frances schmechel, CC BY-SA 2.0 creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons
Wolf
commons.wikimedia.org/wiki/File:Front_view_of_a_resting_Canis_lupus_ssp.jpg
Gary Kramer, Public domain, via Wikimedia Commons
Isle Royale
commons.wikimedia.org/wiki/File:Isle_Royale_-_Beach_Near_Mouth_of_Washington_Creek.JPG
Jhodkiewicz at the English Wikipedia, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons
Moose
commons.wikimedia.org/wiki/File:Alces_alces.jpg
bcameron54, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons


![GCSE Chemistry Revision Development of the Periodic Table
Find your 9s with PLUS. Click the link to try for free https://www.freesciencelessons.co.uk/modules/gcse-chemistry-1-triple/
Teachers, to get PLUS for your school, email schools@freesciencelessons.co.uk
In this video, we look at the development of the periodic table. First we look at what is meant by groups in the periodic table and why the periodic table is called periodic. We then look at how the scientists Döbereiner and Newlands made early attempts to categorise elements and why these were not successful. You are not expected to learn the work of these scientists but you could be provided with information about them in the exam and asked questions on them. We then look at the scientist Dmitri Mendeleev. We see how he produced a successful periodic table by arranging the elements by atomic weight. We look at how he switched the order of elements when required and left gaps for undiscovered elements. We finish by looking at how the modern periodic table arranges the elements by atomic number and how this solves the problem of elements being in the wrong order.
This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Chemistry. 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:
Dobereiner https://commons.wikimedia.org/wiki/File:Johann_Wolfgang_D%C3%B6bereiner.jpg
By Carl August Schwerdgeburth, 1785-1878 (engraver), and Fritz Ries, 1826-1857 (painter) [Public domain], via Wikimedia Commons
Newlands https://commons.wikimedia.org/wiki/File:John_Alexander_Reina_Newlands.jpg
By The original uploader was DALIBRI at German Wikipedia. (Transferred from de.wikipedia to Commons.) [Public domain], via Wikimedia Commons
Mendeleev https://commons.wikimedia.org/wiki/File:Mendeleev_c1880.jpg
See page for author [Public domain], via Wikimedia Commons GCSE Chemistry Revision Development of the Periodic Table](https://i.ytimg.com/vi/IoldeyRWgz8/mqdefault.jpg)




![GCSE Biology Revision Microscopy
Find your 9s with PLUS. Click the link to try for free https://www.freesciencelessons.co.uk/modules/gcse-biology-1-triple/
Teachers, to get PLUS for your school, email schools@freesciencelessons.co.uk
In this video, we look at microscopes. First we explain the advantages of an electron microscope over a light microscope and then we learn how to carry out calculations based on magnification.
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:
Light microscope By Kitmondo Marketplace - Olympus BH-2 BHT Trinocular Laboratory Microscope, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=50226403
Leewanhoek microscope By Jeroen Rouwkema, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3657142
Electron microscope By Cjp24 - Own work, GFDL, https://commons.wikimedia.org/w/index.php?curid=13317336
Fibroblast By SubtleGuest - slika uzeta sa engl. vikipedije [1], CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=2903074
Nucleus Public Domain, https://commons.wikimedia.org/w/index.php?curid=3266416
Ruler By Luigi Chiesa - Photo taken by Luigi Chiesa, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1137573
Cheek cells
https://commons.wikimedia.org/wiki/File:Cheekcells_stained.jpg
Mulletsrokk, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons GCSE Biology Revision Microscopy](https://i.ytimg.com/vi/L5StAE_uuxM/mqdefault.jpg)


