Topic 2 Organisms & Energy
Aerobic respiration
Respiration that needs oxygen
Glucose
A simple sugar that is broken down in cells to release energy during
respiration. Also produced during photosynthesis
Capillaries
Tiny blood vessels with thin walls to allow diffusion of substances in
and out of the blood
Diffusion
The random movement (and spreading) of particles. When there is a
concentration gradient, there is an overall (net) movement of
particles from a place of high to low concentration
Concentration
gradient
Gas exchange
When a solute in a is in a gradually increasing concentration from one
area to another
A process in the lungs where oxygen diffuses from the lungs into the
blood (and carbon dioxide diffuses from the blood to the lungs)
Stroke volume
The volume of blood the heart can pump out in each heartbeat
Anaerobic
respiration
Excess post
exercise oxygen
consumption
(EPOC)
Respiration that does not need oxygen
Period of time after exercise where a greater that usual amount of
oxygen is needed by the body (including removal of lactic acid). AKA
oxygen debt
Plants & energy
Starch
A carbohydrate. Made by joining together thousands of glucose
molecules
Photosynthesis
Series of enzyme-catalysed reactions carried out in chlorophyll.
Carbon dioxide + water  glucose + oxygen (+ energy)
Chloroplasts
Organelle in plant cells that contain chlorophyll. Where
photosynthesis takes place
Chlorophyll
Green substance in chloroplasts that absorb energy form sunlight
Stoma (sing)
Stomata (plural)
Tiny pore in the lower surface of a leaf. When open allows gasses to
diffuse in & out of the cell
Surface area to
volume ratio
Total amount SA
Smaller organism = higher SA to V ratio
Volume
larger organism = low SA to V ratio
(wrinkled V’s smooth SA)
Limiting factors
A single factor that when in short supply, can limit the rate of a
process (eg photosynthesis)
Root hair cells
Cells found near the tip of roots. Have thin hair like extensions that
gives a large surface area. Water enters by osmosis.
Osmosis
Diffusion of water from a high to a low concentration – through a
partially permeable membrane
Partially permeable
membrane
Thin sheet of material that allows certain molecules to diffuse through
it (eg water) but not other larger molecules
Active transport
Movement of molecules into a cell using energy from respiration.
Allows a high concentration of molecules inside the cell (against the
concentration gradient). Eg in plant root hair cells
Xylem
Tissue made of dead hollow cells. Transports water and dissolved
minerals from the roots to other parts of the plant
phloem
Living tissue that transports sugars around a plant
Transpiration
Evaporation of water from the surface of a plant
Plants & environment
Environment
An organisms surroundings. Made up of many different factors (air,
water, soil, other organisms)
Biodiversity
The variety of a species within a given area
Ecosystem
Area where all the living organisms and non living features form a
stable relationship (that needs no input from the outside area to
remain stable)
Habitat
A place where an organism usually lives
distribution
Places in which a certain organism can be found in an area
Population size
The number of individuals of a species in an area
Sampling
Looking at a small portion of an area or population
Random sampling
Method of sampling where locations are selected randomly
Pooter
A simple device used to collect small invertebrates
Sweep net
Used to collect insects from long grass or tree canopies.
Pond net
Item used to collect aquatic organisms from ponds, rivers & streams
Pitfall traps
A device used to catch small animals that move on the ground.
Quadrats
A square frame of a known area (eg 1m2). Placed on the ground to
get a sample of organisms lining in an area
Method of sampling where samples are selected from the population
at regular intervals (eg every 1 metre / every 3rd person)
Systematic
sampling