Definitions of Biology IGCSE <3
movement: an action by an organism or part of an organism causing a change of
position or place
respiration: the chemical reactions in cells that break down nutrient molecules
and release energy for metabolism
sensitivity: the ability to detect or sense stimuli in the internal or external
environment and to make appropriate responses
growth: a permanent increase in size and dry mass by an increase in cell
number or cell size or both
excretion: the removal from organisms of the waste products of metabolism
(chemical reactions in cells including respiration), toxic materials, and
substances in excess of requirements
nutrition: taking in of materials for energy, growth, and development; plants
require light, carbon dioxide, water, and ions; animals need organic compounds
and ions and usually need water
reproduction: the processes that make more of the same kind of organism
species: a group of organisms that can reproduce to produce fertile offspring
the binomial system of naming species: an internationally agreed system in
which the scientific name of an organism is made up of two parts showing the
genus and species
tissue: a group of cells with similar structures, working together to perform a
shared function
organ: a structure made up of a group of tissues, working together to perform
specific functions
organ system: a group of organs with related functions, working together to
perform body functions
diffusion: the net movement of particles from a region of their higher
concentration to a region of their lower concentration down a concentration
gradient, as a result of their random movement
, osmosis: the net movement of water molecules from a region of higher water
potential (dilute solution) to a region of lower water potential (concentrated
solution), through a partially permeable membrane, down its concentration
gradient
active transport: the movement of particles (ions) through a cell membrane
from a region of lower concentration to a region of higher concentration, up
their concentration gradient, by carrier proteins using energy from respiration
(ATP)
metabolism: all the chemical changes that takes place withing an organism
catabolism: metabolic reactions through which complex substances are broken
into simpler ones, eg. digestion and respiration
anabolism: metabolic reactions through which complex substances are built
from simpler ones, eg. photosynthesis, growth, and tissue repair
catalyst: a substance that increases the rate of a chemical reaction and is not
changed by the reaction
biological catalyst: substances that speed up metabolic reactions without being
changed by the reaction and without changing the products
enzymes: proteins that function as biological catalysts
-they speed up a reaction
-build up (synthesise) or break down molecules
-enzymes lower the activation energy needed for the reaction to take place
substrate: -the molecule(s) before they are made to react
-it is the substance (chemical compound) on which an enzyme acts on
-each enzyme binds to a specific substrate to form an enzyme-substrate
complex
photosynthesis: the process by which plants manufacture carbohydrates from
raw materials using energy from light
limiting factor: something present in the environment in such short supply that
it restricts life processes
movement: an action by an organism or part of an organism causing a change of
position or place
respiration: the chemical reactions in cells that break down nutrient molecules
and release energy for metabolism
sensitivity: the ability to detect or sense stimuli in the internal or external
environment and to make appropriate responses
growth: a permanent increase in size and dry mass by an increase in cell
number or cell size or both
excretion: the removal from organisms of the waste products of metabolism
(chemical reactions in cells including respiration), toxic materials, and
substances in excess of requirements
nutrition: taking in of materials for energy, growth, and development; plants
require light, carbon dioxide, water, and ions; animals need organic compounds
and ions and usually need water
reproduction: the processes that make more of the same kind of organism
species: a group of organisms that can reproduce to produce fertile offspring
the binomial system of naming species: an internationally agreed system in
which the scientific name of an organism is made up of two parts showing the
genus and species
tissue: a group of cells with similar structures, working together to perform a
shared function
organ: a structure made up of a group of tissues, working together to perform
specific functions
organ system: a group of organs with related functions, working together to
perform body functions
diffusion: the net movement of particles from a region of their higher
concentration to a region of their lower concentration down a concentration
gradient, as a result of their random movement
, osmosis: the net movement of water molecules from a region of higher water
potential (dilute solution) to a region of lower water potential (concentrated
solution), through a partially permeable membrane, down its concentration
gradient
active transport: the movement of particles (ions) through a cell membrane
from a region of lower concentration to a region of higher concentration, up
their concentration gradient, by carrier proteins using energy from respiration
(ATP)
metabolism: all the chemical changes that takes place withing an organism
catabolism: metabolic reactions through which complex substances are broken
into simpler ones, eg. digestion and respiration
anabolism: metabolic reactions through which complex substances are built
from simpler ones, eg. photosynthesis, growth, and tissue repair
catalyst: a substance that increases the rate of a chemical reaction and is not
changed by the reaction
biological catalyst: substances that speed up metabolic reactions without being
changed by the reaction and without changing the products
enzymes: proteins that function as biological catalysts
-they speed up a reaction
-build up (synthesise) or break down molecules
-enzymes lower the activation energy needed for the reaction to take place
substrate: -the molecule(s) before they are made to react
-it is the substance (chemical compound) on which an enzyme acts on
-each enzyme binds to a specific substrate to form an enzyme-substrate
complex
photosynthesis: the process by which plants manufacture carbohydrates from
raw materials using energy from light
limiting factor: something present in the environment in such short supply that
it restricts life processes
