BY2 WJEC revision

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  • Created on: 20-05-12 08:19
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Parasitic Nutrition
21 May 2011
= organisms that live on or in another organism obtaining nourishment at the expense of the host and causing harm.
Gut parasite (Taenia solium) = tapeworm
Primary host = human (eat uncooked infected pork)
Secondary host = pig (drainage channels contaminated by human faeces)
- Suckers & hookers (attachment)
- Body covering (immune responses)
- Thick cuticle (inhibitory substances = enzymes)
- Simple body systems (reproduction)
- Very thin & large surface area (food absorbed over whole body surface = diffusion)
- Male & female sex organs (gut can only accommodate 1 tapeworm)
- Number of eggs produced (increase chance of survival)
- Eggs have resistant shells (survive until eaten)
Dormant embryos can form cysts in organs - damage surrounding tissue
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Adaptions to different diets
21 May 2011
Reptiles & Amphibians = swallow food whole
Mammals = cut up and chew (palate separates nasal cavity & mouth - kept in mouth longer)
Carnivore = short gut (easily digest protein)
Herbivore = long gut (plant digestion difficult)
Mechanical digestion = easier to swallow & increases surface area for enzyme action
Herbivore Carnivore
Incisors Lower jaw, cuts against horny pad (upper jaw) Sharp (tear flesh from bone)
Canines Indistinguishable from incisors Large, curved, pointed = seizing…read more

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21 May 2011
= the break down of large insoluble molecules into smaller soluble molecules. Physical & chemical. Food
passes through alimentary canal where it is digested & absorbed into the body.…read more

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- Lining folded = large surface area
- Villi = finger like projections
- Epithelial cells = surface of villi (microscopic projections - microvilli)
- Large number of mitochondria = lots of energy required
Glucose & Amino-acids = epithelium of villi (diffusion & active transport) into capillary network - hepatic portal vein to liver
Fatty acids & Glycerol = lacteal (blindly ending lymph capillary) - lymphatic system into bloodstream (thoracic duct)
Fatty acids, Glycerol & most vitamins = diffusion through epithelial cell membrane
Glucose,…read more

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Structure of the gut
24 May 2011
Peristalsis = aids movement of food through alimentary canal
1) Ingestion
2) Digestion (mechanical = increase surface area/chemical = enzymes, glands in wall/outside wall)
3) Absorption
4) Egestion
Structure of Mammalian Gut
- Outer serosa = layer of connective tissue (protection/reduces friction from other organs as it moves)
- Muscle layer = inner circular/outer longitudinal muscles = peristalsis
- Sub-mucosa = connective tissue, contains blood/lymph vessels - absorption & nerves (co-ordinate muscular
contractions - peristalsis)
- Mucosa…read more

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1) Large glands outside gut - secretions pass through tubes/ducts into lumen
Eg. Salivary gland, liver, pancreas
2) Glands in form of cells in sub-mucosa
Eg. Secrete mucus in duodenum (Brunner's glands - alkaline juices also)
3) Glands in form of cells in mucosa
Eg.…read more

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Adaptions for nutrition
24 May 2011
Nutrition = obtain energy to maintain life functions and matter to create/maintain structure (from nutrients)
Autotrophic plants Use simple organic materials CO2 & H2O to manufacture energy &
make complex compounds (make own food) - provide food for others =
- Photosynthesis Plants/algae/ Green plants build up complex organic molecules eg sugars from CO2
certain bacteria & H2O.…read more

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Reproductive Strategies
24 May 2011
Life cycle = sequence of changes through which it passes during its life from origin in reproduction until death.
Reproduction = ability to produce other individuals of the same species
- Rapidly produces large numbers (identical genetic composition = clone)
- Binary fission (eg. Unicellular organisms - bacteria/amoeba)
- Budding (eg. Hydra/yeast)
- Bulbs (eg. Onion/daffodil)
- Runners (eg. Strawberry)
- Tubers (eg.…read more

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Less chance of gametes being wasted
- Allows male gamete to be independent of water for movement
- Fertilized egg can be enclosed with protective covering before leaving female.…read more

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Brightly coloured flowers & scent = attraction by insects (carry pollen to stigma)
- Male gametes travel through pollen tube to female part and egg (no longer needs film of water to reach egg)
- Fertilised egg develops into seed containing food store (with resistant coat)
- Key to success = relationship with animals (attract insects which pollinate/seed dispersal) & enclosure of eggs in
ovary and evolution of seed - Can survive adverse conditions
Flowering plants are so successful because of...…read more


Kimberley Wilkins

Not all content in it, missing circulatory system, adaptations for gas exchange in different classes etc

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