Zusammenfassung der Ressource
GCSE AQA Biology 2 Cells & Diffusion
- Animal & plant cells
- Animal cells have...
- Nucleus
Anmerkungen:
- Contains genetic material that conrols activities of cell
- Cytoplasm
Anmerkungen:
- Gel-like substance where most chemical reactions happen - contains enzymes
- Cell membrane
Anmerkungen:
- Hold cell together & controls what goes in/out
- Mitochondria
Anmerkungen:
- Where reactions for respiration take place - releases energy
- Ribosomes
Anmerkungen:
- Where proteins are made - protein synthesis
- Plant cells have the same plus...
- Cell wall
Anmerkungen:
- Rigid, made of cellulose - supports & strengthens cell
- Permanent vacuole
Anmerkungen:
- Contains cell sap - weak solution of sugars & salts
- Chloroplasts
Anmerkungen:
- Where photosynthesis happens (makes food for the plant) - contain green substance (chlorophyll)
- Diffusion
- Definition
Anmerkungen:
- The spreading out of particles from an area of high concentration to an area of low concentartion
- Happens in both
solutions & gases
- The bigger the difference
in concentration, the
faster the diffusion rate
- Cell membranes
- Allow small molecules through (e.g.
oxygen, glucose, amino acids, & water)
- Don't allow big molecules
through (e.g. starch & proteins)
- Particles move randomly but net
movement from high to low concentration
- Specialised cells
- Palisade leaf cells
- Packed with chloroplasts
- for photosynthesis
- Tall shape - large surface area exposed
down side for absorbing carbon dioxide
- Thin shape - can pack lots at top of leaf
- Guard cells
- Open & close stomata in leaf
- When plant has lots of water...
Anmerkungen:
- Guards cells fill with water & become turgid, making stomata open - gases can be exchanged for photosynthesis
- When plant is short of water...
Anmerkungen:
- Guard cells lose water & become flaccid, making stomata close - stops too much water vapour escaping
- Thin outer walls & thick inner walls
- Sensitive to light
& close at night
Anmerkungen:
- To save water - adapted to function of allowing gas exchange & controlling water loss within leaf
- Red blood cells
- Concave shape
Anmerkungen:
- Big SA for absorbing oxygen & helps them move smoothly through capillaries
- Packed with
haemoglobin
Anmerkungen:
- Pigment that absorbs oxygen
- No nucleus
Anmerkungen:
- More room for haemoglobin
- Sperm & egg cells
- Sperm cells
- Long tail &
streamlined head
Anmerkungen:
- Lots of
mitochondria
Anmerkungen:
- Carry enzymes
Anmerkungen:
- In head - to digest egg cell membrane
- Egg cells
- Huge food reserves
Anmerkungen:
- Membrane can
change structure
Anmerkungen:
- To stop more sperm getting in - offspring ends up with right amount of DNA
- Cell organisation
- Cell differentiation
Anmerkungen:
- Process by which cells become specialised for a particular job
- Occurs during development
- Tissue - group
of similar cells
Anmerkungen:
- That work together to carry out a particular function
- Examples of tissues
- Muscular tissue - contracts to move
- Glandular tissue - makes
& secretes chemicals e.g.
enzymes & hormones
- Epithelial tissue - covers parts of the body
- Organ - group of different tissues
Anmerkungen:
- That work together to perform a certain function
- e.g. Stomach is made of...
- Muscular tissue - moves stomach wall to churn food
- Glandular tissue - makes digestive juices to digest food
- Epithelial tissue - covers
outside and inside of stomach
- Organ system -
group of organs
Anmerkungen:
- Working together to perform a particular function
- e.g. Digestive system is made of these organs...
- Glands
Anmerkungen:
- Stomach & small intestine
Anmerkungen:
- Liver
Anmerkungen:
- Small intestine
Anmerkungen:
- Absorbs soluble food molecules
- Large intestine
Anmerkungen:
- Absorbs water from undigested food - leaving faeces
- Single-celled microorganisms
- Bacterial cells
- Has cytoplasm, cell membrane & wall
- No nucleus - strands of
genetic material instead
- Have flagella
Anmerkungen:
- Long protein strands - to move about
- Yeast cells
- Have a nucleus, cytoplasm,
cell membrane & wall