B4

Science Section B4 OCR Gateway

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Leaf Structure

Waxy Cuticle- protective layer above epidermis, minimises water loss, reduces pathogen entry, cacti have thick cuticles to reduce risk of drying out in hot climate.

Epidermis- absorbs nutrients, protects from water loss, and protects leaf in case of damage to cuticle.

Chloroplasts- contain chlorophyll, pigments make leaf appear green, and helps carry out photosynthesis.

Xylem- transports and stores water, minerals and nutrients.

Phloem- distributes sugars and nutrients.

Stoma- pore found on underside of leaf, allows gases to pass in and out of leaf.

Guard Cell- two cells side of stoma, protects stoma, and allows oxygen, carbon dioxide and water in and out of leaf.

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Food Chanins and Pyramids

Pyramid of Numbers- Could be any shape not just a pyramid. E.G. Could be 40 of a species on the bottom, 100 above that, 10 above that. Does not have to be perfect pyramid shape.

Pyramid of Biomass- Has to be pyramid shape.

Energy- lost through each stage of food chain through:

  • Excretion
  • The whole animal not being consumed
  • Growth
  • Movement (living in general)
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Comments

pj.c

Thanks

ruth2

This is good but it wouldn't hurt to make the font a bit larger :)

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