Answer:
Plants provide us with food, fiber, shelter, medicine, and fuel. The basic food for all organisms is
produced by green plants. In the process of food production, oxygen is released. This oxygen, which we
obtain from the air we breathe, is essential to life. The only source of food and oxygen are plants; no
animal alone can supply these. Shelter, in the form of wood for houses; and clothing, in the form of
cotton fibers, are obvious uses of plant materials. But we must not forget fuel, furniture, paper
products, certain medicines like aspirin, and many other products like perfume and chewing gum. To
these tangible aspects of the plant world we must also add the importance of beauty and relaxation
derived from plants. Since animals are surrounded by and dependent upon plants, the factors that
influence plant growth, structure, and distribution, affect the animal world as well.
Plant - Animal Relationships
Forests, lawns, streams, and marshes are all habitats that are easily recognized as unique biotic
communities. A community is a naturally occurring, interactive assemblage of plants and animals living
in the same environment. The interaction between plants and animals often exists out of the need for
food, protection, transportation, and reproduction. The different kinds of interaction possible between
organisms are extremely important in determining the abundance of species. If the interaction between
species is beneficial, it is described as mutualism. Some of the most complex mutualistic relationships
evolved between plants and pollinators. If the interaction proves disadvantageous, it is referred to as
competition. Commensal relationships, in which one species benefits and the other is unaffected, are
common between plants and animals. For example, when a bird builds a nest in a tree, the bird benefits
and the tree is (usually) unharmed. Other relationships may positively affect one population and be
detrimental to the other. Such relationships involve predation and parasitism. In predation, one
organism directly kills and consumes its prey. Parasitism differs in that parasites live on or in the prey,
but may not kill it outright. A good example of parasitism is mistletoe growing on a tree.
Ecosystems
An ecosystem is the biotic (living) and abiotic (nonliving) factors
of an ecological community considered together. Ecosystems contain
four components: the physical environment (abiotic), living things
(biotic), energy input and use, and nutrients that cycle between the
biotic and abiotic components. Based on this definition, ecosystems
can vary from large unbroken tracts of forest to small ephemeral ponds
to backyards.
Step-by-step explanation: