Biology AQA AS Unit 2 Cellular Organisation

Made these notes for my year 12 summer exam to revise and read over. There are spelling mistakes in most of my files but due to the busy exam schedule I had no time to correct them (sorry).

Most files have more information than what is needed but I feel it helps you feel more confident walking into the exam if you have a greater knowledge background and may help when having to apply knowledge to questions. Good luck :)

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  • Created by: Chelcie
  • Created on: 02-09-13 12:43
Preview of Biology AQA AS Unit 2 Cellular Organisation

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Cellular Organisation
CELL DIFFERENTITION
The process by which cells become specialised for different functions.
In the fertilised egg e.g. only a few genes are expressed "switched on"
The cells of multicellular organisms have therefore evolved to one function; they have lost
their ability for other functions.
TISSUES
A group of similar cells organised into a structural unit that serves a particular
function.
Epithelial tissues found in animals and consist of sheets of cells. They line surfaces of organs
and protect/secrete also (e.g. alveoli)
Xylem is made of a number of cell types, they transport water and mineral ions and for
mechanical support.
ORGANS
Tissues aggregated into organs.
E.g. stomach- muscle to churn, epithelium to protect and secrete, connective tissue to hold
together other tissues.
E.g. leaf- palisade mesophyll made of mesophyll cells to carry out photosynthesis, spongy
mesophyll adapted for gaseous diffusion, epidermis to protect the leaf and allow gaseous
diffusion, xylem to transport water and ions into the leaf.
Capillaries are not organs but veins/arteries are (made of up many tissues).
ORGAN SYSTEMS
Organs work together in a group as a single unit.
E.g. digestive, respiratory, circulatory.

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