ENERGY & ECOSYSTEMS - AQA A LEVEL BIOLOGY + EXAM QUESTIONS RUN THROUGH

In this video, I explain ALL of the content required for the "Energy and Ecosystems" section for AQA A Level Biology (A2). This includes: how biomass is measured, energy loss + efficiency through food chains, gross primary production, net primary production, net production and productivity.
The content crosses over with other exam boards too!
I also go through a few exam questions and explain the mark schemes.
Please comment if you have any questions, I'll be more than happy to answer them!! :)

[@AlevelBiologyHelp]

00:29 = What is meant by an ecosystem?
01:00 = How organisms obtain energy
02:02 = How biomass is measured
02:27 = Energy flow + loss + efficiency through food chains
05:22 = Measuring energy loss : Gross primary production and net primary production
06:55 = Measuring energy loss : Net Production
07:49 = Primary and secondary productivity
08:45 = Exam questions and mark schemes

[@bye5212]

I've realised that watching your videos before doing any practice questions has significantly improved the number of questions i get correct - thank you for all your hard work in providing these videos

[@jhianeblake2665]

I love your videos thank you so much!

[@shafinabi6318]

Thank you so much these videos are so helpful! would you be able to make past paper walkthroughs please ?

[@emiliepreedy6851]

Thank you for this! Helped me so much!

[@AlevelBiologyHelp]

No problem! Glad I could help!

[@123reletive123]

Very helpful, thank youuuu 😊

[@hadiraheem6224]

Great video!

[@martynakonieczka6260]

Thank you!

[@user-my7te8ot8l]

Hi,what is a respiratory substrate?

[@fatima-de8gv]

heyy, this video is really helpful, but i just wanted to make sure is this everything we have to know for energy and ecosystems in the spec. tyyy

[@AlevelBiologyHelp]

Yes, this is everything you need to know!

[@munig625]

Hi, thank you so much for this! xx Please could you explain how you know respiration increases in part C?

[@AlevelBiologyHelp]

There is an increase in respiration because the biomass is showing little increase after 100 years. This suggests that an increase in respiration could be a cause for this, as respiration affects productivity and therefore biomass. I hope that makes sense? :)

[@techbuilder1147]

fantastic video

[@AlevelBiologyHelp]

Thank you so much!

[@whomerdoodles]

so gpp is plant only?

[@sonadent]

At 14:29, i thought net primary productivity was NP = GPP minus RL and Net productivity = I- ( F added to R)

[@AlevelBiologyHelp]

Hi! You're right, however the question is referring to plants here, and plants obviously don't excrete faeces or urine, so you need to do GPP - respiratory loss. It's a bit confusing as the exam questions like to change the terms around but you need to focus on whether they're talking about plants or consumers higher up in the food chain. :) Hope this makes sense?

[@amelia-cv6oo]

Do you need to know in detail about the way biomass is measured? Great video! Xx

[@AlevelBiologyHelp]

Hi! You don't need to know it in much detail, just at the level of what I said in the video :) .

[@razzyysf8435]

please explain, what is HA^-1 ?

[@AlevelBiologyHelp]

Hi! It means "per hectare". A hectare is a measure of an area size. The graph is showing gross productivity in an area (as the text says) so that's why you include it in the units. Hope this helps!

[@bombaclart3910]

5:07 you did that 6/9 on purpose you cheeky legend😂😂😂

[@AlevelBiologyHelp]

Honestly I didn't even realise!!!