Summary WJEC (England) Eduqas A-Level Biology 3. Requirements for life - 3. Nutrition
13 views 0 purchase
Course
3. Requirements for life
Institution
WJEC
I achieved a high A* Grade in my final A-Level exams using these notes!!!
I believe you can achieve an A* if you can memorise these notes! Simply use blurting, a method of active recall, to write everything you remember from the notes, then identify the parts you couldn’t remember, then repeat ...
a. Autotrophic = complex organic molecules from simple inorganic + energy source
Photoautotrophic – photosynthesis: energy = sunlight
plants + some protoctista + some bacteria
Chemoautotrophic – chemosynthesis: energy = from exergonic chemical reactions
some bacteria
b. Heterotrophic (saprotrophic/holozoic/parasitic) = eat other organism for complex organic molecules
c. Saprotrophic = external digestion – fungi (hyphae grow over matter) + some bacteria
1. secrete enzymes onto dead organic matter
2. extracellularly digest food material
3. absorb digestion products – diffusion & active transport
d. Holozoic = internal digestion in gut – most animals
1. Ingestion: take in food
2. Digestion: break down molecules
- Mechanical: reduces size – increase SA for chemical digestion
- Chemical: enzymes hydrolyse large/insoluble/complex → small/soluble/simple molecules
3. Absorption into blood stream
4. Assimilation into cells
o synthesise other needed molecules (enzymes)
o respire (to release energy)
5. Egestion: eliminate undigested food
e. unicellular organisms
Amoeba – holozoic: nutrients through cell membrane
- endocytosis: engulf other unicellular organisms (bacteria/algae) into vacuole
- intracellular digestion: lysosomes fuse with vacuole – release digestive enzymes
- absorption of products into cytoplasm
- exocytosis: egest undigested material
f. multicellular organisms
Hydra: unspecialised sac-like gut + single opening
- tentacles paralyse fleas Daphnia: move through opening into gut cavity
- extracellular digestion: endodermis secretes protease & lipase
- intracellular digestion: phagocytosis moves partially digested food into endodermal cells
- egest undigested material via opening
Human alimentary canal: tube gut + different openings for ingestion & egestion
+ specialised regions for digestion of different food substances
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller tnotes. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.86. You're not tied to anything after your purchase.
