Biology Unit 1 Exam Study Guide
Ecology
1. Define the following:
-parasitism: A symbiotic relationship where one organisms benefits (parasite) and the other
organisms (host) is harmed in the process (+,-)
-predator/prey: A relationship where predator kills and eats prey (not a form a parasitism, because
parasites do not benefit from killing the host).
-commensalism: A symbiotic relationship where one organism benefits from the relationship, but
the other is neither harmed nor benefitted (+,0)
-mutualism: A symbiotic relationship where both organisms benefit (+,+)
2. For each biome, name some limiting factors and adaptations organisms possess in order to survive
Grassland
Desert
Tropical Rain
Deciduous
Taiga
Tundra
Limiting factors:
• Periods without
rain
Limiting factors:
• Temperature,
lack of water and
shelter.
Limiting factors:
• Poor soil,
competition for
light.
Adaptations:
• Plants grow
quickly when
water is
available.
• Animals have the
ability to move
quickly and use
available
resources.
Adaptations:
• Plants have thick
stems and waxy
leaves to store
water.
• Many animals
sleep during the
day and some
have salt glands
that allow them
to get rid of
wastes without
the loss of water.
Adaptations:
• Plants must have
the ability to
tolerate shade or
compete for
sunlight. Also
root adaptations
to help them deal
with the high
moisture content
and lack of
nutrients.
• Animals have
developed the
ability to feed in
niches
unoccupied by
other animals.
Limiting factors:
• Seasonal changes
in available
sunlight and
rainfall.
Adaptations:
• Plants tend to
lose their leaves
when sunlight
patterns change
preventing a loss
of energy during
winter.
• Many animals
migrate or
hibernate.
Limiting factors:
• Long cold
winters,
poor(highly
acidic) soil.
Adaptations:
• Plants are
adapted by their
shape, leaf type
and color.
• Animals
hibernate,
migrate and
some have the
ability to change
their fur/feather
color by seasons.
Limiting factors:
• Temperature,
sunlight,
permafrost.
Adaptations:
• Plants grow low
to the ground and
close together.
They have
shallow root
systems because
of the
permafrost.
• Animals migrate
or have
developed a thick
layer of fur or fat
as insolation.
3. Describe the difference between a habitat and a niche.
• A habitat is the place where an organism usually lives.
• A niche is the (way of life) of a species in an ecosystem where the species lives and the function
of the species in the biological community. What it does to survive.
4. Describe the difference in the transfer of matter versus energy.
• Matter is transferred from one trophic level to the next and then recycled. Energy comes from
the sun but is not recycled back to the sun therefore you can think of energy as linear.
5. What do arrows indicate in a food chain/web? Explain. Berries → Mice → Bear
• The flow of energy from one trophic level to the next. 10% of the energy makes it to the next
level. The other 90% is lost to the environment in the form of heat due to metabolism/activity.
6. What is a decomposer’s role in a food web?
• Decomposers recycle nutrients back into the environment by breaking down large molecules
(decaying organisms) into smaller elements that other organism can use.
7. How can the removal of one organism in a food web affect the others? Explain.
• Removal of one organism from a food chain destabilizes the food chain
by disrupting the organism both above and below it. If one organism
is removed, the organisms above it will suffer due to the loss of a food
source. The number of organisms below it (because of the lack a
predator) will increase, which in turn could put pressure on available
resources.
8. Where is most energy found in a food chain, web, and ecological pyramid?
Explain your answer.
• Most of the energy is found at the bottom of a pyramid of energy (beginning of a food chain or
web) due to the fact that producers get their energy directly from the sun and much of that
energy has yet to be lost as it flows from one trophic level to the next.
9. Using the ecological pyramid, where are the least amount of organisms usually found?
• At the top (tertiary or quaternary consumers) because there is not enough energy available
due to the loss of energy (90%) at each trophic level below them.
10. Explain the role of bacteria in the nitrogen cycle.
• Bacteria convert nitrogen into a form in which plants are able to use.
11. In the carbon cycle, describe how carbon enters biotic factors from abiotic.
• Atmospheric carbon (CO2 in the air / abiotic) is taken in by plants (photosynthesis) and
converted into glucose (sugar) and then incorporated into plant tissues (biotic). As animals
eat the plants, the carbon in the plants tissues (biotic) are then incorporated (changed into)
animal tissue (biotic) or released through respiration (CO2 / abiotic) back into the atmosphere.
12. Explain the graph to the right (J shape, then S shape).
• The J shaped part of the curve represents exponential
growth (1 2, 2 4, 4 8, 8 16 and so on). It is
transformed into an S shape as the population reaches
the environments carrying capacity.
13. Explain the difference between primary and secondary succession.
Also, draw a visual of each below to supplement your explanation.
• Primary succession occurs on land where no previous life existed, while secondary succession
occurs as the result of the process where one community replaces another community that has
been partially or totally destroyed (by natural disaster or human intervention).
Other Vocab: Also be familiar with the following words/definitions.
Competition, adaptation, permafrost, coniferous trees, climax community, pioneer species, abiotic,
aerates, and antibiotics. (look them up)
TEKS tested:
11: The student knows that biological systems work to achieve and maintain balance.
The student is expected to:
D: describe how events and processes that occur during ecological succession can change populations
and species diversity.
12: The student knows that interdependence and interactions occur within an environmental system.
The student is expected to:
A: interpret relationships, including predation, parasitism, commensalism, mutualism, and competition
among organisms
B: compare variations and adaptations of organisms in different ecosystems
C: analyze the flow of matter and energy through trophic levels using various models, including food
chains, food webs, and ecological pyramids
D: recognize that long-term survival of species is dependent on changing resource bases that are limited
E: describe the flow of matter through the carbon and nitrogen cycles and explain the consequence of disrupting these cycles
F: describe how environmental change can impact ecosystem stability