Written by students who passed Immediately available after payment Read online or as PDF Wrong document? Swap it for free 4.6 TrustPilot
logo-home
Document preview thumbnail
Preview 4 out of 53 pages
Lecture notes

AQA A-level Biology Energy Transfers A* Notes

Document preview thumbnail
Preview 4 out of 53 pages

Want to achieve top grades in AQA A-level Biology? These notes helped me secure an A*,and they can do the same for you! They’re designed to make revision straightforward by breaking down challenging AQA topics into clear concise and example focused explanations. These energy transfers notes include key processes and descriptions that match AQA mark schemes. Plus, they are aesthetically designed with clean layouts, colour coding, and visual diagrams to make revisions more engaging and easier to memorise.

Content preview

Energy
Trsfers

, Nutrient Cycles
• organisms made of 'recycled' chems
• Cycled between biotic + abiotic environment
• by producers + microbes
• Built into complex org mols (carbs, proteins, lipids etc.)
• Org mols passed thru food chains
• eventually returned to abiotic environment as simple inorganic mols - by decomposers
* no nutrient cycling + life w/o producers and decomposers




Producers
Simple inorganic mols Complex organic mols
Decomposers




* BIOTIC = LIVING
* ABIOTIC = NON-LIVING

• inorganic mols = nutrients
• Carbon , hydrogen + oxygen needed in largest amount
• Growth of producers limited by availability of minerals (eng: nitrate + phosphate)

, Phosphorous Cycle
* ion = PHOSPHATE
* element = PHOSPHOROUS
• phosphorous critical for all living things
• in DNA - for cell div/ pro synthesis , RNA , ATP - energy for growth
• Phospholipids in cell membr T
• Functioning of some enzymes

• in ph cycle main reservoir of phosphorus = minerals in rocks
• Phos cycle - no gaseous phases

* phosphorous mainly exists as phosphate ions in sedimentary rock deposits

Process
1. Sedimentary rock deposits formed by sea depositing layers of sediment
2. Brought to surf over time through geo activity
3. Weathering + erosion dissolve phosphate ions allowing them to be absorbed by Plants
4. Plants are eaten by animals
5. Animals excrete excess phosphate in waste products (e,g: guano (bird faeces ))
6. When animals + plants die, broken down by saprobiotic bac + fungi
7. Releases phosphate ions into water/soil
8. Dissolved ions trans into lakes + oceans
9. Ultimately form rocks via sedimentation





wh




&

, Saprobiotic baeria + fungi

• do not digest food
• Use extra cellular digestion - related ph ions + am comps
• secrete digestive enzymes
• Large to small sol mols
• Further broken down by aerobic resp into inorganic mols


Nitrogen Cycle
• crucial for DNA, RNA + ATP
• Main reservoir = nitrogen gas in atmosphere
• 90% of air = nitrogen
• Nit gas diff in + out of gas but can't be used in this form (need nitrate ions)

• nitrogen gas = N N
• Lots of energy to break bonds

>
4 processes in nitrogen cycle: - Don't forget to
sign an



1. Nitrogen fixation N
2. Nitrification N
3. Denitrification D
4. Ammonification A

Nitrogen Fixation
• nitrogen fixing bac - reduce nitrogen (using hyd mol from water ) into ammonia / ammonium
ions
• Live freely in soil/water
• Or in nodules on roots (e.g: legume / clover plants)

• Mutualist relationship (type of simbiotic relationship)
• Plant obtains AAs from bac + bac gets sugars from plant



* plant will be high in proteins as has lots of AAs
• Bac has nitrogenase (lowers AA of nitrogen) + ATP

Document information

Study Level
Uploaded on
June 10, 2025
Number of pages
53
Written in
2024/2025
Type
Lecture notes
Professor(s)
N/a
Contains
All classes
£5.46

Wrong document? Swap it for free Within 14 days of purchase and before downloading, you can choose a different document. You can simply spend the amount again.
Written by students who passed
Immediately available after payment
Read online or as PDF

Seller avatar
natty1
3.5
(2)
Sold
3
Followers
0
Items
26
Last sold
5 months ago



Why students choose Stuvia

Created by fellow students, verified by reviews

Quality you can trust: written by students who passed their exams and reviewed by others who've used these revision notes.

Didn't get what you expected? Choose another document

No problem! You can straightaway pick a different document that better suits what you're after.

Pay as you like, start learning straight away

No subscription, no commitments. Pay the way you're used to via credit card and download your PDF document instantly.

Student with book image

“Bought, downloaded, and smashed it. It really can be that simple.”

Alisha Student

Working on your references?

Create accurate citations in APA, MLA and Harvard with our free citation generator.

Working on your references?

Frequently asked questions