key word Flashcards
photosynthesis
A chemical reaction in green plants that uses sunlight to make food.
chloroplast
An organelle containing chlorophyll found in some plant cells. The reactions of photosynthesis happen in chloroplasts.
chlorophyll
A pigment that absorbs light and splits water into hydrogen and oxygen in the first stage of photosynthesis.
enzyme
A protein with an active site that catalyses a chemical reaction.
catalyst
A catalyst is a substance that increases the rate of a chemical reaction, but which is left unchanged by the reaction.
active site
The part of an enzyme where the chemical reaction takes place. The reacting molecules fit into the active site.
substrate
A substance that is changed by the action of a particular enzyme. each molecule of the substrate must be the correct shape to fit into the enzyme’s active site.
optimum
The most favourable condition for an enzyme at which it catalyses a reaction at its fastest rate.
Diffusion
The spreading out of molecules.
Stomata
Tiny holes in the outer surface of a leaf enable a plant to exchange gases with its surroundings.
Osmosis
The diffusion of water molecules from an area where they are in high concentration to an area where they are at lower concentration through a partially permeable membrane.
partially permeable membrane
A membrane that acts as a barrier to some molecules but allows others to diffuse through freely.
active transport
Molecules are moved in or out of a cell using energy.
ATP
Adenosine triphosphate a substance made by cellular respiration.
turgid
When a plant cell takes in water it bulges and becomes stretched.
xylem
Plant tissue that transports water and dissolved minerals through a plant.
phloem
A plant tissue that transports sugar through a plant.
transpiration
The process of water movement through a plant and its evaporation from cells in the leaves.
potometer
It is a device that measures the rate at which a plant draws up water.
translocation
The process of moving sugars amino acids and other substances through a plant.
producer
An organism that is able to make its own food.
consumer
An organism that eats others in a food chain
biomass
All the tissues that make up an organism.
amino acid
Amino acids are joined in long chains to make proteins.
carbohydrate
A substance made of carbon, hydrogen, and oxygen.
lipid
A substance made from glycerol and fatty acids. Lipids are used for storage and making cell membranes
interdependence
The size of a population of organisms affects and is affected by the sizes of other populations in an ecosystem.
food chain
A model of the feeding relationships between populations of organisms.
food web
A model of the feeding relationships between populations of organisms.
competition
Organisms that require the same resources must compete for the resources
decomposition
Process in which dead organisms are broken down and substances in their bodies are returned to the environment
biotic
The living parts of an ecosystem.
abiotic
The non-living parts of an ecosystem
Carbon cycle
The natural processes that recycles carbon through the living and non-living parts of an ecosystem.
water cycle
Processes that cycle water through the abiotic and biotic parts of an ecosystem.
biotic factors
The living parts of an ecosystem that affect the distribution and abundance of organisms.
abiotic factors
A non-living factor that can affect the distribution and abundance of living organisms
bioaccumulation
An increase in the concentration of a substance in organisms in the higher trophic levels of a food chain.
eutrophication
A type of environmental damage. Excess nitrate or phosphate in water causes rapid growth of algae followed by the death and decomposition of water plants.
quadrat
A square grid of a known area that is used when measuring the abundance of non-moving or slow-moving organisms in a location
transect
A technique used to measure the distribution and abundance of organisms at regular intervals along a straight line through an ecosystem
representative sample
The characteristics of a representative sample are very similar to the characteristics of the whole population.
