PLANTS
“Plants are autotrophs which means that they manufacture food molecules from simple, inorganic sources by the process of photosynthesis using light as a source of energy. Plants all contain the light-absorbing pigment called chlorophyll inside cells which have a definite cellulose cell wall.
AN AUTOTROPH – a living thing that makes its own food from simple chemical substances
A HETEROTROPH - a living thing that gets its food from other plants or animals
TO MANUFACTURE - to produce (in large numbers)
PHOTOSYNTHESIS
CHLOROPHYLL - a light-absorbing pigment
DEFINITE – fixed
A CELL WALL – the hard outer covering, consisting mainly of cellulose, that surrounds a plant cell
The first plants lived in water, but as living organisms evolved, plant forms developed that could live on land.
The classification of plants into groups follows the sequence of evolution and so we can list: algae, mosses, ferns and seed plants. Algae and mosses cannot grow far away from water, but ferns and flowering plants (angiosperms) are much better adapted to life on land.
ALGAE (pl) –very simple, usually small plants that do not have ordinary leaves or roots
MOSSES – very small, green or yellow plants that grow especially on rocks and tree trunks
FERNS – green plants with long stems, leaves like feathers and no flowers
SEED PLANTS – a big group of plants that grow from seeds
FLOWERING PLANTS = ANGIOSPERMS - they are a subgroup of seed plants and have enclosed seeds
The angiosperms or flowering plants are the most successful of plants. They have evolved into many species and have colonised almost every available habitat. More than 80% of all plants are angiosperms (plants with enclosed seeds).
There are two major subgroups within the angiosperms. In one group there is a single cotyledon in the seed – these are the monocotyledons. In the other group there are two cotyledons – these are the dicotyledons.
Plants respond to many stimuli, but two are of particular importance: light (the photo-stimulus) and gravity (the gravi-stimulus). A growth response carried out by a plant in response to the direction of a stimulus is called a tropism.”
HABITAT – the natural environment of a plant
A COTYLEDON – a type of leaf that is part of the developing plant inside a seed and either stores food or grows from the seed to produce food
MONOCOTYLEDONS
DICOTYLEDONS
A TROPISM – a growth response carried out by a plant in response to the direction of a stimulus
Reference: Pickering Ron “Complete Biology for Cambridge IGCSE” (2017)
Love,
Micha
