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root hair	absorb water and minerals from soil	hair like projections to increase the surface area
xylem	carry water and minerals	TRANSPIRATION - dead cells cell walls toughened by lignin flows in one direction
phloem	carry glucose	TRANSLOCATION - living cells cells have end plates with holes flows in both directions

B01a) CELL STRUCTURE

Eukaryotes complex organisms

animal cell

Prokaryotes simpler organisms

plant cell

contains all the parts of animal cells plus extras

Specialised cells

specialised plant cells

specialised animal cells

Cell differentiation

how a cell changes and becomes specialised

Undifferentiated call are called STEM cells

animal cell differentiation

plant cell differentiation

Bacterial cells are much smaller than plant and animal cells

cytoplasm	site of chemical reactions in the cell	gel like substance containing enzymes to catalyse the reactions
nucleus	contains genetic material	controls the activities of the cell and codes fro proteins
cell membrane	semi permeable	controls the movement of substances in and out of the cell
ribosome	site of protein synthesis	mRNA is translated to an amino acid chain
mitochondrion	site of respiration	where energy is released for the cell to function

permanent vacuole	contains cell sap	keeps cell turgid, contains sugars and salts in solution
cell wall	made of cellulose	supports and strengthens the cell
chloroplast	site of photosynthesis	contains chlorophyll, absorbs light energy

all stages of life cycle the stem cells are grouped together in meristems

nerve	carry electrical signals	long branched connections and insulating sheath
sperm	fertilise an egg	streamlined with a long tail acrosome containing enzymes large number of mitochondria
muscle	contract to allow movement	contains a large number of mitochondria long

early stages of development

only for repair and replacement

cell membrane	site of chemical reactions in the cell	gel like substance containing enzymes to catalyse the reactions
bacterial DNA	not in nucleus floats in the cytoplasm	controls the function of the cell
cell wall	NOT made of cellulose	supports and strengthens the cell
plasmid	small rings of DNA	contain additional genes
cytoplasm	semi permeable	controls the movement of substances in and out of the cell

Microscopy

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B01b) CELL TRANSPORT

Diffusion No energy required	Movement of particles in a solution or gas from a higher to a lower concentration	E.g. O₂ and CO₂in gas exchange, urea in kidneys. Factors that affect the rate are concentration, temperature and surface area.
Osmosis No energy required	Movement of water from a dilute solution to a more concentrated solution	E.g. Plants absorb water from the soil by osmosis through their root hair cells. Plants use water for several vital processes including photosynthesis and transporting minerals.
Active transport ENERGY required	Movement of particles from a dilute solution to a more concentrated solution	E.g. movement of mineral ions into roots of plants and the movement of glucose into the small intestines.

Small intestines	Villi – increase surface area, Good blood supply – to maintain concentration gradient, Thin membranes – short diffusion distance.
Lungs	Alveoli– increase surface area, Good blood supply – to maintain concentration gradient, Thin membranes – short diffusion distance.
Gills in fish	Gill filaments and lamella – increase surface area, Good blood supply – to maintain concentration gradient, Thin membranes – short diffusion distance.
Roots	Root hair cells - increase surface area.
Leaves	Large surface area, thin leaves for short diffusion path, stomata on the lower surface to let O₂ and CO₂ in and out.

ADAPTATIONS FOR DIFFUSSION

The greater the difference in concentrations the faster the rate of diffusion.