parasitism A symbiotic relationship between two species in which there is a parasite and
a host. The parasite gains nutrition from the host. The host in a parasitic relationship
is harmed but usually not killed.
photosynthesis The process in which plants use carbon dioxide and water to produce
sugar and oxygen: 6CO 2 + 12H 2 O + solar energy C 6 H 12 O 6 + 6O 2 + 6H 2 O.
population All the individuals of a species that occur together in a given place and time.
predator An animal that kills and eats other animals.
prey An animal that could be killed and eaten by a predator.
producer An organism that creates chemical energy to be used as food. Most producers
use photosynthesis but a very small number use chemosynthesis.
scavenger Animals that eat animals that are already dead.
species A classification of organisms that includes those that can or do interbreed and
produce fertile offspring; members of a species share the same gene pool.
symbiosis Relationships between two species in which at least one species benefits.
trophic level Energy levels within a food chain or food web.
vertebrate Animals with backbones.
Points to Consider
- What happens if two species attempt to fill the same niche?
- Thereisatleastoneexceptiontotherulethateachecosystemhasproducers,consumers
and decomposers. Excluding hydrothermal vent, what does the deep sea ecosystem
lack? - Where do humans fit into a food web?
- Most humans are omnivores, but a lot of what we eat is at a high trophic level. Since
ecosystems typically can support only a few top predators relative to the number or
lower organisms, why are there so many people?