Download Ecology Review Answers

 (1
pt for order; 1 pt ea for what gets added = 6 pts)
 organism + more organisms of the same species =
population
 population + all the organisms in an area that
interact = community
 community + abiotic factors = ecosystem
 ecosystem + similar ecosystems with same climate
and landscape = biome
 biome + all organisms on earth and their
interactions with the environment = biosphere
 (1
pt for 3 correct answers on each = 2 pts)
 biotic – parasites, predators, prey, disease,
competition, availability of producers
 abiotic – elevation, condition of soil, amount
of precipitation, amount of sunshine…
1
pt
 sun supplies most of the energy to the earth
2 pts ea (1 for correct def, 1 for correct ex. = 6 pts)
 mutualism: symbiosis in which both species benefit.
ex: sunfish and smaller fish that eat the parasites
off them
 commensalism – symbiosis in which one species
benefits and the other is neither harmed nor
helped. ex: bird nests in tree; cameleon is
camouflaged in bush
 parasitism – symbiosis in which one organism
benefits (parasite) and the other, usually a larger
orgaism (host) is harmed. ex: tick (parasite) sucks
blood from a mammal (host)

2
pts
 The energy is taken by the organism that
gets it and used for life functions.
1
pt
 10%
2
pts: 1 for correct method, 1 for correct answer
 5000 x .1 = 500 x .1 = 50 x .1 = 5 cal
 The
arrows represent transfer of energy from one
organism to the next. (1 pt)
 If a snake eats a mouse, the arrow should go from
the mouse to the snake, since the mouse passes its
energy to the snake. (1 pt)
2
pts for a well constructed answer
 A food web is a bunch of interconnected food
chains. A food chain shows just one pathway
for energy to be transferred, while a food
web shows the many pathways for energy
transfer in a community.
2
pts for a well constructed answer
 If a top predator is removed from an
ecosystem, the effect can be devastating to
the entire balance of the ecosystem. The
large herbivores population will boom, and
they in turn will eat up the producers, which
will affect the smaller herbivores that rely
on the producers. Ultimately, all the
organisms in the food web will be affected
and the populations will shift dramatically.
The lack of a top predator leads to an
unhealthy ecosystem.
2
pts for a well constructed answer
 An ecosystem must have a broad and varied
producer base to support many trophic levels
above it. The smaller the amout of energy
available at the producer level, the lower
the amount of trophic levels the ecosystem
can support above it. This is why deserts,
even though they get plenty of sunshine,
have so few animals – because the conditions
are too dry to support many plants.
1
pt
 Energy leaves a food chain as heat. Even
decomposers produce heat – this is why
compost piles and landfills produce steam.
5
pts
 first producers; then herbivores, followed by
omnivores, and finally, carnivores. Of course
decomposers can eat at any level.
2
pts for a well constructed answer
 A habitat is where an organism lives, that
provides the needs for the organism. The
niche is the special role the organism plays,
the food it eats, the resources it uses for
shelter, the organisms that feed on it, etc.,
within its habitat.
2
pts for a well constructed answer
 This is competition. In a severely
competitive situation, one species will die
off. Species tend to avoid competitive
situations over time. ex: hawk hunts by day
and owl hunts same type of prey by night.
ex: different species of birds nest in
different specific levels of the same type of
tree.
 Plants
absorb carbon in the form of CO2 and
use to produce glucose, an energy rich
compound. (photosynthesis)
2
pts
 Combustion of fossil fuels, wood, peat and
other carbon compounds.
 Deforestation reduces the number of plants
that can absorb carbon dioxide from the
atmosphere.
 cellular
respiration (1 pt)
2
pts for a well constructed answer
 There are special nitrogen fixing bacteria
that live in nodules (little bumps) on plant
(legumes) roots. These bacteria and the
plants have a mutualistic relationship. The
bacteria get a place to live and also absorb
some of the nutrients produced by the
plants’ leaves and sent to the roots. The
plants get the nitrogen fixed. Legumes
include clovers, beans, & soy.
1
pt
 Nitrogen is an element in all 20 amino acids.
So nitrogen is used to make amino acids
which are used to make proteins.
 Also, nitrogen is an element in the nitrogen
bases, the steps of the DNA ladder.
 Carbon
is combusted by decomposers and returned
as CO2 gas through cellular respiration, or the
carbon compounds sink into the earth and remain
there for long periods. 2 pts for a well constructed
answer
 Nitrogen compounds cycle back through the soil and
are taken back up through plants, or they are
returned to their gas form by special archaea in a
process called denitrification. 2 pts for a well
constructed answer
 Water is also a waste product of cellular
respiration. 1 pt
 Both
(1 pt)
2
pts for a well constructed answer
 The process of establishing new life in an
area where the ecosystem has to “start over”
due to a natural (forest fire, lava flow, etc)
or unnatural (agriculture, deforestation, etc)
event.
 Primary
succession has to start by building up soil,
as after a lava flow from a volcano. (1 pt)
 Secondary succession already has soil to begin, as
after an area that has been used for crops is
allowed to go back to nature. (1 pt)
5
pts
 lichen,
 moss and other nonvascular low plants,
 ferns and other small plants,
 small bushes and shrubs,
 small trees, and finally
 the larger trees of the climax community
that are well adapted to the area.
2
pts for a well constructed answer
 The environment is changing all the time.
Communities are in a constant state of flux.
The only permanent thing is change.