BIOLOGY END OF YEAR
TOPIC 1: NATURE AND VARIETY OF ORGANISMS
MRS H GREN
o Movement- able to change position
o Reproduction- can produce offspring sexually or asexually
o Sensitivity- can adapt and respond to environment and stimuli
o Homeostasis- can maintain and control their internal environment
o Growth- can increase in mass and develop
o Respiration- can produce energy aerobically or anaerobically
o Excretion- can remove toxic waste products from body
o Nutrition- can absorb nutrients and use them for development such as growth
Variety of organisms
Eukaryotes (cells)
o Organisms that have a nucleus and organelles
Organelles
Nucleus- contains genetic material
Cytoplasm- jelly-like substance where reactions occur
o Contains enzymes
Cell membrane- controls what enters and leaves the cell
Mitochondria- where aerobic respiration occurs producing energy
Ribosomes- where protein synthesis occurs
o Plant cells
Multicellular
Contains chloroplasts where photosynthesis
occurs
Cell walls are made of cellulose, making the cell
firm and protecting it
Vacuole stores cell sap and keeps rigidity
Carbs stored as starch
o Animal cells by Unknown Author is licensed
E.g. mammals under
Multicellular
No chloroplasts, don’t photosynthesise
No cell walls
Carbs stored as glycogen
o Fungi
Cell walls made of chitin
E.g. yeast
Stores carbs as glycogen
Food from saprophytic digestion, where digestive
enzymes break down food so it can be absorbed
Contains mycelium: a network of hyphae in a thread
like structure
, o Protoctists
Single celled organisms
Some have features which
resemble animal cells for example
amoeba
Others resemble plant cells and
have chloroplasts, such as euglena
Prokaryotes
o No nucleus or organelles bound by a membrane
o Bacteria
E.g lactobacillus, used to make yoghurt
Single celled, small
Have a cell wall made of peptigoglycan
No nucleus but have circular chromosomes of DNA
Mainly eat off of other organisms but can do
photosynthesis
Have cytoplasm and plasmids
o Virus
Not a living organism
Need a host to live
Parasitic
No cellular structure except DNA or RNA and a
protein coat
o Protists
E.g. malaria
Parasitic- use animals as hosts
SPECIALISED CELLS
o Red blood cell
Bi-concave shape maximises SA
Haemoglobin carries oxygen
Thin shape is mobile and flexible
Nucleus breaks down to capacitate more oxygen
o Ciliated cell
Lots of cilia (200) which clear passages
Lots of mitochondria for maximum energy
Cilia stops infections in the airways and lungs
o Nerve Cell
Long axon to transmit messages
Different sizes optimises message transmission
Myelin sheath allows electrical impulses to travel quickly
o Sperm Cell
Streamline
, Large nucleus
Mitochondria releases energy for movement
Long tail to navigate through reproductive system
Acrosomes store digestive enzymes to break down the outer layer of the
egg
o Palisade leaf cell
Tightly packed, no gaps
Lots of chloroplasts to optimise photosynthesis
o Root hair cell
Large surface area for maximum water absorption
Vascular bundle carries water, glucose and minerals
Large vacuole speeds up movement of water
TOPIC 2: MOVEMENT ACROSS MEMBRANES
Diffusion
o Random movement of particles from an area of higher concentration
to an area of lower concentration
o Factors affecting rate of diffusion
Concentration gradient (steeper = faster)
Surface area : volume ratio (larger SA = faster)
Distance (shorter = faster)
Temperature (higher = faster)
o Substances that enter cells
Glucose
Water
Oxygen
Amino acids
Minerals
o Substances that are removed from cells
Urea
Carbon dioxide
Osmosis
o Net movement of water from an area of higher WP to an area of
lower WP down a WP gradient
WP: water potential, concentration of water molecules
Through a partially permeable membrane
o Hypertonic solution: cell has a higher WP than solution
Net movement out of cell
Causes cells to shrivel
o Hypotonic solution: cell has a lower WP than solution
Net movement into cell
Can cause cell to explode or swell
TOPIC 1: NATURE AND VARIETY OF ORGANISMS
MRS H GREN
o Movement- able to change position
o Reproduction- can produce offspring sexually or asexually
o Sensitivity- can adapt and respond to environment and stimuli
o Homeostasis- can maintain and control their internal environment
o Growth- can increase in mass and develop
o Respiration- can produce energy aerobically or anaerobically
o Excretion- can remove toxic waste products from body
o Nutrition- can absorb nutrients and use them for development such as growth
Variety of organisms
Eukaryotes (cells)
o Organisms that have a nucleus and organelles
Organelles
Nucleus- contains genetic material
Cytoplasm- jelly-like substance where reactions occur
o Contains enzymes
Cell membrane- controls what enters and leaves the cell
Mitochondria- where aerobic respiration occurs producing energy
Ribosomes- where protein synthesis occurs
o Plant cells
Multicellular
Contains chloroplasts where photosynthesis
occurs
Cell walls are made of cellulose, making the cell
firm and protecting it
Vacuole stores cell sap and keeps rigidity
Carbs stored as starch
o Animal cells by Unknown Author is licensed
E.g. mammals under
Multicellular
No chloroplasts, don’t photosynthesise
No cell walls
Carbs stored as glycogen
o Fungi
Cell walls made of chitin
E.g. yeast
Stores carbs as glycogen
Food from saprophytic digestion, where digestive
enzymes break down food so it can be absorbed
Contains mycelium: a network of hyphae in a thread
like structure
, o Protoctists
Single celled organisms
Some have features which
resemble animal cells for example
amoeba
Others resemble plant cells and
have chloroplasts, such as euglena
Prokaryotes
o No nucleus or organelles bound by a membrane
o Bacteria
E.g lactobacillus, used to make yoghurt
Single celled, small
Have a cell wall made of peptigoglycan
No nucleus but have circular chromosomes of DNA
Mainly eat off of other organisms but can do
photosynthesis
Have cytoplasm and plasmids
o Virus
Not a living organism
Need a host to live
Parasitic
No cellular structure except DNA or RNA and a
protein coat
o Protists
E.g. malaria
Parasitic- use animals as hosts
SPECIALISED CELLS
o Red blood cell
Bi-concave shape maximises SA
Haemoglobin carries oxygen
Thin shape is mobile and flexible
Nucleus breaks down to capacitate more oxygen
o Ciliated cell
Lots of cilia (200) which clear passages
Lots of mitochondria for maximum energy
Cilia stops infections in the airways and lungs
o Nerve Cell
Long axon to transmit messages
Different sizes optimises message transmission
Myelin sheath allows electrical impulses to travel quickly
o Sperm Cell
Streamline
, Large nucleus
Mitochondria releases energy for movement
Long tail to navigate through reproductive system
Acrosomes store digestive enzymes to break down the outer layer of the
egg
o Palisade leaf cell
Tightly packed, no gaps
Lots of chloroplasts to optimise photosynthesis
o Root hair cell
Large surface area for maximum water absorption
Vascular bundle carries water, glucose and minerals
Large vacuole speeds up movement of water
TOPIC 2: MOVEMENT ACROSS MEMBRANES
Diffusion
o Random movement of particles from an area of higher concentration
to an area of lower concentration
o Factors affecting rate of diffusion
Concentration gradient (steeper = faster)
Surface area : volume ratio (larger SA = faster)
Distance (shorter = faster)
Temperature (higher = faster)
o Substances that enter cells
Glucose
Water
Oxygen
Amino acids
Minerals
o Substances that are removed from cells
Urea
Carbon dioxide
Osmosis
o Net movement of water from an area of higher WP to an area of
lower WP down a WP gradient
WP: water potential, concentration of water molecules
Through a partially permeable membrane
o Hypertonic solution: cell has a higher WP than solution
Net movement out of cell
Causes cells to shrivel
o Hypotonic solution: cell has a lower WP than solution
Net movement into cell
Can cause cell to explode or swell
