2. A population is a group of individuals of
one species that interbreed together in a
particular living place. Members of the one
species have the capacity to interbreed and
produce fertile offspring.
3. The community represents all of the living
organisms found living together in a
particular area or habitat.
4.
5. The ecosystem represents the sum of all
organisms living in a particular area, along
with the habitat and the physical
component of the environment that affects
organisms.
9. A particular community will usually have a
variety of populations of organisms –
including producers, consumers and
decomposers
Populations in the community interact with
one another in a variety of ways
Competing for resources
Hunting or killing prey
Symbiotic relationships
10.
11. Producers
Mainly consist of photosynthetic organisms
Consumers
Feed on others to obtain essential
requirements
Decomposers
Feed on dead and decaying material,
recycling essential elements
12. Competition
Organisms which compete for the same
resources
E.g. light, space, oxygen, and food.
Predation
Where one organism feeds on or eats
another live organism
Predation shapes the community and
affects the number or biodiversity of the
community
13.
14. Plant defense against Predation
Physical
Thorns, spikes, hair, waxy or silica
secretions
Chemical
Some plants produce chemicals that deter
herbivores from eating them
15. Animal defense against Predation
Chemical
Poison from snakes , spiders, bees,
wasps etc.
Colouration
Camouflage is used to hide themselves
i.e. grasshoppers
Some species use mimicry – mimic the
appearance of another species which
does have protection
16. Symbiosis
Symbiotic relationships exist between organism
of two different species
Mutualism
A relationship where both species benefit
E.g.
Algae (photosynthesis) and fungi (moist
environment)
Bacteria in the stomach of a cow which breaks
down cellulose
17. Commensalism
One species benefits and the other species
remains unharmed
E.g.
Barnacles attach themselves to shellfish etc.
acting as filter feeders but do no harm
18. Parasitism
The prey is harmed or eaten by an organism that
is smaller than it is.
E.g.
Parasites include lice, ticks, fleas
19. Both benefit One benefits,
neither is harmed
One benefits, the
other is harmed
Parasitism x
Mutualism x
Commensalism x
21. Mechanisms that maintain reproductive
isolation
Members of the one species have a
unique gene pool or total set of genes in
the species.
A biological feature that prevents gene
flow between two closely related species,
even though the groups habitats may
overlap.
22. Reproductive barriers form isolating
boundaries around closely related species
Barriers that prevent fertilisation
Different mating calls
Use of species specific chemicals to attract
members of the opposite sex
Different in flower shape or genitalia
Different seasons or times for
reproduction
Inability of sperm to survive in the
reproductive tract
Pollen tube unable to grow towards the
ovules
23. Barriers that prevent the development
of fertile adults
Zygotes fail to develop
Young fail to reach sexual maturity
Offspring are infertile
24.
25. There are two types of nutrition that organisms
use to obtain their essential requirements:
Autotrophs or Producers can make their own
food from inorganic materials
Heterotrophs (herbivores, carnivores or
omnivores) need to feed on others to obtain
their nutritional requirements
26. Trophic levels in a community represent the
feeding levels or trophic structure of the
community
Producers trap the Sun’s energy and are
autotrophs
Consumers feed on others to obtain their
nutrition
Decomposers break down dead material to
obtain their essential requirements
