Plants, also called green plants ,are living organisms of the kingdom Plantae including such multicellular groups as flowering plants, conifers, ferns and mosses, as well as, depending on definition, the green algae, but not red or brown seaweeds like kelp, nor fungi or bacteria.
Green plants have cell walls with cellulose and characteristically obtain most of their energy from sunlight via photosynthesis usingchlorophyll contained in chloroplasts, which gives them their green color. Some plants are parasitic and may not produce normal amounts of chlorophyll or photosynthesize. Plants are also characterized by sexual reproduction, modular and indeterminate growth, and an alteration of generations, although asexual reproduction is common, and some plants bloom only once while others bear only one bloom.
Most plants grow in the ground, with stems above, and roots below. Water and some nutrients come from the roots. The evaporation of water from pores in the leaves pulls water through the plant. This is called transpiration.
A plant needs sunlight, carbon dioxide, minerals and water to make food. A green substance in plants called chlorophyll traps theenergy from the Sun needed to make food. Chlorophyll is mostly found in leaves, inside plastids, which are inside the leaf cells. The leaf can be thought of as a food factory. Leaves of plants vary in shape and size, but they are always the plant organ best suited to capture solar energy. Once the food is made in the leaf, it is transported to the other parts of the plant such as stems and roots.
Plants are one of five big groups (kingdoms) of living things. They are autotrophic eukaryotes, which means they have complexcells, and make their own food. Usually they cannot move (not counting growth).
Plants include familiar types such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant (living) species of plants. Fungi and non-green algae are not classed as plants.
Five Kingdom Classification
1.Protista
(the single-celled eukaryotes)
Protists are single-celled and
usually move by cilia, flagella, or by amoeboid mechanisms. There is usually no cell wall,
although some forms may have a cell wall. They have organelles including a
nucleus and may have chloroplasts, so some will be green and others won't be.
They are small, although many are big enough to be recognized in a dissecting
microscope or even with a magnifying glass. Nutrients are acquired by
photosynthesis, ingestion of other organisms, or both.
2. Fungi
(fungus and related organisms)
Fungi are multicellular, with
a cell wall, organelles including a nucleus, but no chloroplasts. They have no
mechanisms for locomotion. Fungi range in size from microscopic to very large (
such as mushrooms). Nutrients are acquired by absorption. For the most part,
fungi acquire nutrients from decaying material.
3.
Plantae (the plants)
Plants are multicellular
and most don't move, although gametes of some plants move using cilia or
flagella. Organelles including nucleus, chloroplasts are present, and cell
walls are present. Nutrients are acquired by photosynthesis (they all require
sunlight).
4. Animalia
(the animals)
Animals are
multicellular, and move with the aid of cilia, flagella, or muscular organs
based on contractile proteins. They have organelles including a nucleus, but no
chloroplasts or cell walls. Animals acquire nutrients by ingestion.
5. Monera
(the prokaryotes)
Individuals
are single-celled, may or may not move, have a cell wall, have no chloroplasts
or other organelles, and have no nucleus. Monera are usually very tiny,
although one type, namely the blue-green bacteria, look like algae. They are
filamentous and quite long, green, but have no visible structure inside the
cells. No visible feeding mechanism. They absorb nutrients through the cell
wall or produce their own by photosynthesis.
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