Download EndofUnitTestReviewA.. - hrsbstaff.ednet.ns.ca

Science 10
Answer Key
Sustainability of Ecosystems
End of Unit Test Review
True/False
Indicate whether each statement is true or false. Correct each false statement.
1.
Plants add carbon dioxide to the atmosphere through the process of
cellular respiration.
True.
2.
Organisms require nitrogen to make proteins.
True.
3.
Decomposers are an essential part of all nutrient cycles.
True.
4.
Green plants occupy the second trophic level in food chains.
False. Green plants occupy the first trophic level in food chains.
5.
The biomass of herbivores in an ecosystem is generally greater than the
biomass of plants.
False. The biomass of herbivores in an ecosystem is generally
smaller than the biomass of plants.
6.
The process of biomagnification tends to increase the concentration of
chemical pollutants in organisms at the bottom of the food chain.
False. The process of biomagnification tends to increase the
concentration of chemical pollutants in organisms at the top of the
food chain.
Completion
Complete each statement with the correct term or phrase.
7.
The build-up of nitrogen in lakes produces eutrophication.
8.
The process of cellular respiration uses oxygen and produces carbon
dioxide.
9.
The process of photosynthesis combines water with carbon dioxide gas
to produce carbohydrates.
10.
Denitrifying bacteria convert nitrates into nitrogen gas.
11.
Lichen is a pioneer species in this type of succession primary
succession
12.
Primary consumers are animals that eat plants.
13.
There is a loss of energy at each trophic level.
14.
The largest population of a species that an environment can support over
the long term is called the carrying capacity of the environment for this
species.
15.
Competition among members of the same species is called intraspecific
competition.
Matching
Match each description in column A with the correct term in column B. Place the
letter for the term beside the description.
A
B
C
16. process used by green plants to make
(a) consumers
carbohydrates
B
17.
role of green plants in an ecosystem
(b) producers
A
18.
role of animals in an ecosystem
(c) photosynthesis
E
G
F
H
D
19. network of links that channel energy
and materials through the organisms in an
ecosystem
20. continual
movement
of
elements
between the living and non-living parts of
the environment
21. process by which pollutants become
more concentrated as they move along a
food chain
22. something captured by producers from
the Sun
23. organisms that help to recycle valuable
nutrients
(d) decomposers
(e) food web
(f) biological
magnification
(g) nutrient cycle
(h) energy
Multiple Choice
Circle the correct answer.
24.
Which process removes carbon dioxide from the air?
(a)
(b)
(c)
(d)
25.
respiration
photosynthesis
acid precipitation
eutrophication
Which process removes nitrogen from the air?
(a)
(b)
(c)
(d)
nitrogen fixation
denitrification
photosynthesis
nitrification
26.
The amount of usable energy that is used for growth and reproduction of
organisms at each link in a food chain is about
(a)
(b)
(c)
(d)
27.
10 percent
30 percent
50 percent
90 percent
Which of the following is NOT a result of a change in the nitrogen cycle?
(a)
(b)
(c)
(d)
eutrophication
acid precipitation
global warming
increased crop production
Short Answer
Write a sentence or two to answer each of the following questions.
28.
Explain why a nutrient cycle on Earth is called a closed system.
A nutrient cycle on Earth is called a closed system because there is
little or no input of new nutrients from outside the cycle, which is
maintained through continual recycling of nutrients.
29.
Write an equation that summarizes the process of photosynthesis.
6 CO2 + 6H2O + energy  C6H12O6 + 6O2
30.
Do the materials that make up a tree come mainly from the soil, water,
or air? Explain.
The biomass of a tree comes from all three sources. As a plant, a
tree adds to its biomass chiefly through photosynthesis, which
requires carbon dioxide from the air and water drawn up from the
soil. A tree’s growth is also increased by nitrogen from the air and
soil (through compounds that are absorbed by the roots) and
phosphorous, from the soil.
31.
How does the combustion of fossil fuels affect the carbon cycle?
The combustion of fossil fuels adds to the air large amounts of
carbon that have been stored for millions of years below the
Earth’s surface. Such excessive amounts of carbon cannot be
recycled as rapidly as it is being added to the biosphere. In this
way, the carbon cycle has been disrupted.
32.
Why might an organic farmer add manure to a field?
Animal manure, which contains nitrogen compounds, can be used
as a natural plant fertilizer. The manure is broken down by
decomposers in the soil to release ammonia, which can be used
directly by some plants as a source of nitrogen. The ammonia can
be converted by nitrifying bacteria back into nitrates, which can be
absorbed by plants that use nitrogen in this form. Because this
fertilizer contributes to natural recycling, it does not release
excess nitrates into the soil or adjacent waterways, as artificial
fertilizers do. An organic farmer would prefer to use a fertilizer
that supports the agricultural ecosystem without causing harm to
it or neighbouring ecosystems.
33.
Why do food webs require a continual input of energy from the Sun?
Food webs require a continual supply of energy from the Sun
because so much is lost through consumption from producers to
other organisms. About ten percent of energy produced by plants
from the Sun’s energy transfers to organisms at each successive
trophic level. Some energy is used by consumers to support life
functions; much of it is lost as heat given off as a result of such
functions. This lost energy is continually replaced, so that plant
growth can continue and consumers can continue to acquire
energy.
34.
Give an example of a way in which technology affects sustainability.
Biotechnology can support the production of new types of food, as
well as disease and pest resistant see varieties, by altering or
adding genes in animals or plants. This technology could increase
the sustainability of human populations by increasing the
reliability of food supply. It is also possible that the sustainability
of natural ecosystems could be reduced by this technology through
competition or predation by genetically modified organisms, or
through expansion of agricultural ecosystems.