Download Chapter 2 Worksheet

Science 10
Chapter 2 Worksheet
Chapter 2 – Energy flow and nutrient cycles support life in ecosystems.
Be sure to use the website at http://www.bcscience.com/bc10/pgs/links_u1.html and scroll down
to the section for Chapter 2.
Chapter 2.1 - Energy Flow in Ecosystems
1.
Describe the flow of energy in an ecosystem.
C Energy flows from producers (plants) to primary consumers (herbivores) to secondary
and tertiary consumers (carnivores).
2.
Name two methods used to model the flow of energy in ecosystems.
C Food webs and food chains
3.
How do food pyramids differ from food webs or food chains?
C Food pyramids model how energy is lost at each trophic level and food webs and
chains model the energy flow and feeding relationships.
4.
The total mass of living organisms and organic matter is called
5.
Why are plants called producers?
biomass
.
C Plants are called producers because they produce food in the form of carbohydrates
during photosynthesis. Carbohydrates stored in plants become an energy source for
other life forms.
Decomposition
6.
is the breaking down of organic wastes and dead organisms. The action of
living organisms to break down dead organic matter is called biodegradation .
7.
Each step in a food chain is called a trophic level
niche relationships
between organisms.
8.
What is the difference between a food chain and a food web?
which shows the
feeding
and
C A food chain models the flow of energy from plant to animal and from animal to
animal. A food web is a model of the feeding relationships within an ecosystem.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 1 of 9
9.
Be prepared to draw a food chain, a food web and a food pyramid!
10. What is a detrivore and at what trophic level do they feed?
C Detrivores are consumers that obtain their energy and nutrients by eating the bodies
of small dead animals. Detrivores feed at all trophic levels.
11. A food pyramid is a model that shows the loss of energy from one
another. This is represented by the decreasing size of the block
pyramids are often referred to as ecological pyramids .
trophic level
to
at each level. Food
12. What determines the amount of life that an ecosystem can support?
C The amount of life that an ecosystem can support is determined by the amount of
energy captured by producers.
13. Because of the 90 % decrease in energy from trophic level to trophic level, an ecosystem
supports fewer organisms at the higher trophic levels.
14. Name two important factors that food pyramids illustrate.
C Most of the Sun’s energy that is trapped by plants flows out of an ecosystem.
C They show how important plant life is for making energy available in ecosystems.
15. Check out the Math Connect exercise on p. 66.
Chapter 2.2 - Nutrient Cycles in Ecosystems
1.
Name the three nutrient cycles.
C Carbon, Nitrogen, and Phosphorous cycles.
2.
Nutrients are accumulated for short or long periods of time in Earth’s atmosphere ,
oceans , and
land masses . Scientists refer to these accumulations as
stores .
3.
What affect has human activities had on nutrient cycles?
C Human activities can increase the amount of nutrients in the cycle faster than
natural biotic and abiotic processes can move them back to the stores.
4.
List the five chemical elements that limit the amount and types of life possible in an ecosystem.
C Carbon, hydrogen, oxygen, nitrogen, and phosphorous.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 2 of 9
carbon atoms
5.
All living things contain
in their cells.
6.
Short term stores of carbon on found both on
7.
On land, long-term stores of carbon are found in
deposits which formed millions of years ago.
8.
The largest carbon store on Earth is in
9.
How is carbon cycled through ecosystems?
land
and in the
coal deposits
marine sediments
and
upper parts of the ocean.
and in
oil and gas
sedimentary rock
.
C Photosynthesis, respiration, decomposition, ocean processes, volcanic eruptions, and
large-scale forest fires.
10. Describe the process of photosynthesis.
C During photosynthesis, carbon in the form of carbon dioxide in the atmosphere,
enters through the leaves of plants and reacts with water in the presence of sunlight
to produce energy-rich sugars (carbohydrates) and oxygen.
11. During photosynthesis, six molecules of carbon dioxide plus 6 molecules of water will produce how
many molecules of sugar and oxygen?
C One molecule of sugar and 6 molecules of oxygen.
12.
Cellular respiration
is the process in which plants and animals release carbon
dioxide back into the atmosphere. This chemical reaction is the reverse of photosynthesis .
13. What effect does burning fossil fuels have on the carbon cycle?
C Burning fossil fuels have reintroduced carbon into the cycle that was removed long
ago. So much carbon is released so quickly into the atmosphere that the natural
carbon cycle can no longer move all of it to other stores.
C Scientists estimate that carbon stores in the atmosphere could rise from 1/3 to 3.4
times by the end of the century.
C Carbon dioxide, a greenhouse gas, contributes to global climate change.
14. Name two other human activities that affect the carbon cycle.
C Land clearing & urban growth.
15. Nitrogen is an important component of
is the atmosphere .
© ProActive C urriculum Ltd. - R ev: 7/27/08
DNA
and
proteins
. The largest store of nitrogen
Page 3 of 9
16. About 78% of the Earth’s atmosphere is nitrogen gas, but most organisms cannot use this
form of nitrogen until it is made available in the form of nitrates or ammonium through
the process of nitrogen fixation .
17. Explain three processes of nitrogen fixation.
C Atmospheric - nitrogen gas is converted to nitrates and other nitrogen-containing
compounds by lightening which provides the energy for the conversion. These
compounds are then made available to terrestrial and aquatic ecosystems in rain.
Only a small amount of nitrogen containing compounds result from this process.
C Soil - bacteria convert nitrogen gas into ammonium during the decomposition process.
Nitrogen fixing bacteria form symbiotic relationships with other plants to play a
significant role in nitrogen fixing.
C Aquatic - certain species of cyanobacteria also fix nitrogen into ammonium. These
blue-green bacteria manufacture their own food during photosynthesis and make
nitrogen compounds available to plants in the surface of oceans, wetlands, and lakes.
18. How do plants that do not live in association with nitrogen-fixing bacteria obtain nitrogen?
C In a process called nitrification, ammonium is converted into nitrate.
C Nitrification takes place in two stages and involves nitrifying bacteria.
C In the first stage, certain species of bacteria convert the ammonium into nitrite and
in the second stage, different species of bacteria convert the nitrite into nitrate.
C Once nitrates are made available, they can enter plant roots and be used by the
plants to make proteins.
19. Once the nitrates are made into proteins by plants, how do other organisms use them?
C When herbivores and carnivores eat plants, they incorporate nitrogen into the
proteins in their tissues.
C Other types of decomposer bacteria and fungi are able to take the nitrogen trapped
in the proteins and DNA of dead organisms and convert it back to ammonium.
C Some bacteria decompose urea that is excreted by animals and then convert it into
ammonium.
20. Explain how nitrogen returned to the atmosphere.
C Nitrogen is returned to the atmosphere in a process called denitrification. This
involves denitrifying bacteria which convert nitrate back to nitrogen gas through a
series of chemical reactions. Nitrogen is also returned back to the atmosphere in
volcanic ash and nitrogen oxide gases.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 4 of 9
21. In a balanced ecosystem, the amount of fixed nitrogen is equal
nitrogen
returned to the atmosphere through denitrification .
to the amount of
22. Excess nitrate and ammonium that are not taken up by plants mix with rainwater and are
washed from the soil into ground water and streams. Unused nitrogen may settle as sediments
to ocean , lake , or river bottoms.
23. How do human activities affect the nitrogen cycle?
C Human activities have doubled the available nitrogen in the biosphere in the past 50
years due to the burning of fossil fuels in power plants and sewage treatment.
C Clearing forests and grasslands by burning also release nitrogen into the atmosphere.
C The nitrogen oxide and nitrogen dioxide combine with water in clouds and return to
the Earth as nitric acid (acid precipitation).
24. How does excess nitrogen enter waterways?
C Leaching and eutrophication.
25.
Phosphorous
is an essential element in the molecule that carries energy to plant and
animal cells. In plants, phosphorous contributes to root development , stem strength ,
and seed production . In humans, it works with calcium in the development of strong
bone tissue .
26. Phosphorous in not stored in the
atmosphere
27. Phosphate is released by the process of
28. Two type of weathering are
chemical
, but instead is trapped in
weathering
and
phosphate
.
.
physical
.
29. Explain how phosphorous is cycled through ecosystems.
C On land, plants take up phosphate through their roots and animals obtain phosphate
by eating the plants.
C Decomposers break down animal waste and dead organisms, which returns phosphorous
to the soil to become available to the producers again.
C Phosphate enters aquatic systems as a result of erosion, leaching and run-off.
C Water plants take up some of the dissolved phosphate and pass it through the
aquatic food chain.
C Most phosphate in run-off settles on lake and ocean bottoms eventually forming
sedimentary rock, trapping the phosphate for millions of years.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 5 of 9
30. How do human activities affect the phosphorous cycle?
C Commercial fertilizers, detergents, animal wastes, industrial waste, and untreated
human sewage all enter waterways through run-off and leaching. Too much
phosphorous can negatively affect species like fish that are sensitive to this
nutrient.
31. How do changes in the nutrient cycles affect biodiversity? Give an example from each cycle.
C An excess or lack of nutrients can affect the abiotic and biotic conditions necessary
for biodiversity. (Many other examples could be used below as well)
C Carbon: changes in climate (temperature, rainfall, wind) patterns can affect plants
and animals to where they can no longer survive in the altered habitats. E.g. Fraser
River sockeye salmon.
C Nitrogen: in high nitrogen environments, grasses may outcompete tree seedlings.
C Phosphorous: decreased levels could reduce algae populations in aquatic systems
resulting in harm to all the consumers in the aquatic food web.
Chapter 2.3 - Effects of Bioaccumulation on Ecosystems
1.
Synthetic chemicals
enter the environment in air , water , and soil . Plants
take up some of these chemicals, and the chemicals bioaccumulate in the fat tissue of
herbivores and carnivores. Synthetic chemicals become biomagnified in food pyramids and
harm organisms.
2.
A major cause of frog malformations is a
parasite
whose population may be increased by
fertilizer
runoff and the presence of cattle manure near water habitats. These
pollutants produce large algae blooms that feed snail hosts, increasing their numbers.
3.
What are some of the other causes of amphibian population declines?
C
C
C
C
C
C
4.
depletion of the ozone layer
habitat loss
pollution
over hunting
diseases
pesticides
What is one of the biggest causes of the global loss of species?
C The introduction into the environment of synthetic chemicals.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 6 of 9
5.
What is bioaccumulation and how does it affect species?
C It is the gradual build-up of chemicals in living organisms.
C A chemical will accumulate if it is taken up and stored faster than it can be broken
down and excreted.
C These chemicals can be harmful to an animal if they are not metabolized or
excreted.
C Bioaccumulation of these chemicals can cause birth defects in offspring or a complete
failure to reproduce.
C When keystone species are affected, the entire ecosystem is affected.
6.
Biomagnification
concentrated at each
7.
more
is the process in which chemicals not only accumulate but become
trophic level .
What are persistent organic pollutants (POPs)? Give an example.
C POPs are carbon-containing compounds that remain in water and soil for many years.
Many enter ecosystems in the form of insecticide sprays. POPs bioaccumulate in
plants and then in the tissues of animals that eat the plants.
C DDT is one example.
8.
Heavy metals are metallic elements with a high density that are toxic to organisms at
low concentrations . Within the biosphere, they do not
degrade
and cannot be
destroyed .
9.
The three most polluting heavy metals are
lead
,
cadmium
, and
mercury
.
10. How might you reduce the amount of lead in landfills?
C Recycle old electronic devices and lead-acid batteries.
C Other reasonable answers are possible as well.
11. What are some of the harmful effects of lead in humans?
C Anaemia, nervous system damage, sterility in men, low fertility rates in women,
impaired mental development, and kidney failure.
12. Identify some human activities release cadmium into the environment.
C Manufacture of plastics, nickel-cadmium rechargeable batteries
C Burning slash from forestry operations
C Zinc production and phosphate ore mining.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 7 of 9
13. The most serious source of cadmium poisoning in humans comes from
14. The half-life of cadmium in the kidneys and bone is
30 years
smoking
.
.
15. Every year, up to 6000 tonnes of mercury are released through natural sources. In the
past 150 years this annual amount has doubled through the burning of fossil fuels ,
waste incineration ,
mining , and
industrial uses . Coal burning accounts for more
than 40 % of mercury released into the atmosphere.
16. First Nations and Inuit people have suffered mercury poisoning by eating
contaminated fish .
17. Mercury poisoning can affect nerve cells , the heart , kidneys , and lungs
and suppress the immune system . In fish, levels of methylmercury depend on what they
eat , how long they
live , and how high they are in the
food chain .
18. How can the effects of chemical pollution be reduced?
C Trapping the contaminant in the soil
C Using bioremediation techniques:
- using microorganisms that feed on chemicals, reducing them to non-toxic compounds.
- using enzymes from bacteria or insects.
- using plants to trap biodegradable hazardous wastes.
- using bacteria to clean up oil spills and leaks.
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 8 of 9
Vocabulary to Know
Write a concise definition of each of these terms found in this chapter.
bioaccumulationbiodegradationbioremediationcellular respirationconsumersdecomposersdenitrificationfood chainfood pyramidfood webheavy metalskeystone speciesnitrificationnutrientsparts per millionPCBsphotosynthesisproducerssedimentationtrophic levelweathering-
© ProActive C urriculum Ltd. - R ev: 7/27/08
Page 9 of 9