CHAPTER
2
Review
SUGGESTED ANSWERS
WHAT DO YOU REMEMBER?
lithosphere; (b) cellular respiration; photosynthesis; (c) hydrosphere; (d) sustainable; (e) carrying
capacity; (f) marine; (g) ecosystem; (h) hydrosphere; lithosphere; thermal; (i) photosynthesis
1. (a)
2.
Decomposers break down dead organic material, such as dead plants, animals, and waste, and use it as
food. In doing so, they release nitrogen back into the soil, and carbon dioxide back into the atmosphere.
3. (a)
Raw materials needed for photosynthesis are sunlight (energy), carbon dioxide, and water. Raw
materials needed for cellular respiration are sugar and oxygen.
(b)
The products of photosynthesis are sugar and oxygen. The products of cellular respiration are carbon
dioxide, water, and energy.
(c)
Photosynthesis and cellular respiration occur in plants.
(d)
Cellular respiration occurs in animals.
(e)
Light is needed for photosynthesis (hence the “photo” part of the name), but not for cellular
respiration.
(f)
Energy is released during cellular respiration.
(g)
Light energy is needed for photosynthesis.
(h)
Chlorophyll is needed to capture light energy in photosynthesis.
4.
Sunlight warms the atmosphere, evaporates water, produces winds, and keeps Earth’s surface warm. It
is also required for photosynthesis. All of these are essential requirements that enable life to exist in the
biosphere.
5.
Trophic level refers to the feeding level of an organism along a food chain. Plants occupy the first level,
plant eaters the second level, meat eaters the third and fourth levels.
WHAT DO YOU UNDERSTAND?
6. (a)
(iii); (b) (iv); (c) (i); (d) (v); (e) (ii)
7.
A food chain shows a sequence of organisms, each feeding on the next. A food web shows many
interconnecting food chains.
8.
Oligotrophic water bodies have few nutrients, are often clear and deep, and good for swimming and
boating. Eutrophic water bodies have many nutrients, are often cloudy and shallow, have more algae
growth, and may have low oxygen levels.
9. (a)
Sample answer: Freshwater stream. Biotic features: fish, insects, turtles, frogs, aquatic plants. Abiotic
features: moving water, cool water temperatures, high oxygen levels, gravel bottom.
(b)
Sample answer: An open grassland. Biotic features: grasses, grasshoppers, bison, voles and mice, snakes,
hawks. Abiotic features: rich, fertile soil, 25 to 75 cm/yr of precipitation, longer growing season than
the boreal forest, higher temperatures than tundra or boreal forest
(c)
Sample answer: The Arctic tundra. Biotic features: small rapidly-flowering plants, mosses and lichens,
caribou, ptarmigan, lemmings, arctic foxes. Abiotic features: low temperatures, short growing season,
permafrost, 0 to 25 cm/yr of precipitation, poor soil
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10. (a)
Herbivores compete against each other by eating the same grasses or plants.
(b)
Carnivores compete against each other by hunting and eating the same prey.
(c)
Producers compete against each other by competing for sunlight, soil nutrients, and water.
11.
Plants get new energy from the Sun.
12.
Sample answer:
tertiary
consumers
8 owls
secondary consumers
80 shrews, 15 moles
primary consumers
30 000 grasshoppers,
5000 snails, 4000 slugs
producers
100 000 grass plants
13.
The energy originates from the Sun. It was converted to chemical energy by producers (plants) and then
has been passed along the food chain from one trophic level to the next. At each trophic level some of the
energy is lost when it is used by the organism or released as waste energy.
14.
Phytoplankton: producer; zooplankton: herbivore; whale: omnivore; mussel: omnivore; small fish:
carnivore; starfish: carnivore; lobster: carnivore; gull: carnivore; large fish: carnivore; squid: carnivore;
dolphin: carnivore; seal: carnivore
15.
Sample answer:
6th
trophic
level; dolphin
5th trophic level;
gull, seal
4th trophic level; squid,
large fish, lobster, starfish
3rd trophic level;
whale, small fish, mussel
2nd trophic level; zooplankton
1st trophic level; phytoplankton
16.
Dolphins, seals, and small fish would be directly affected by the over-harvesting of large fish.
17.
The elimination of whales would mean there would be more zooplankton and/or phytoplankton, which
would mean more mussels and more starfish. It would also mean more small fish, which would mean
more squid.
18.
If the seal population increased, squid, large fish, and small fish would decrease, which would mean
that dolphins and lobsters might decrease. If lobsters decreased, gulls might decrease, but mussels
might increase, which means zooplankton might decrease, and whales might decrease, which means
phytoplankton might increase.
19. (a)
(b)
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amount of precipitation: deciduous forest, grassland, boreal forest, tundra
average temperature: deciduous forest, grassland, boreal forest, tundra
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(c)
length of growing season: deciduous forest, grassland, boreal forest, tundra
(d)
biodiversity: deciduous forest, grassland, boreal forest, tundra
(e)
total biomass: deciduous forest, boreal forest, grassland, tundra
The reasoning is that the warmer and wetter the biome, the greater productivity and biodiversity. Growing
seasons are longer as you move toward the equator.
20.
In the tundra there is a much shorter growing season and cooler temperatures so all biological processes
like photosynthesis and cellular respiration are reduced and slowed down. In the tundra, some of the
carbon is also locked up in the permafrost.
SOLVE A PROBLEM
21.
Table 1
Precipitation
Temperature
Possible biomes
low
low
tundra
medium
medium
boreal forest, grasslands
high
high
temperature deciduous forest
22.
The biome might be boreal forest or grassland. It is difficult to tell because both biomes could sometimes
have 35–50 cm of precipitation and an average temperature of 10 ºC.
23.
The yellow crazy ants attack and feed on the red crabs. Red crabs are not the only organisms affected
because if red crabs decrease, then fewer fruits, flowers, leaves, and seedlings will be eaten by crabs. The
rainforest ecosystem and nutrient cycle might be disrupted.
CREATE AND EVALUATE
24.
Fertilizer runoff from the lawns of the cottages could cause algae to grow, which would make the water
cloudy. Too much algae could also reduce oxygen levels and kill fish.
REFLECT ON YOUR LEARNING
25. (a)
26.
Sample answer: I knew something about the water cycle, and I knew that people can harm or help
ecosystems.
(b)
Sample answer: The carbon cycle and trophic levels were completely new to me.
(c)
Sample answer: The new information makes me realize how important rainforests are to the carbon
cycle and to Earth’s atmosphere. It makes me want to work to plant trees for Earth.
Sample answer: mosquitoes and bats live in my ecosystem. The bats feed on mosquitoes and the
mosquitoes feed on me. The bats benefit me by reducing the number of mosquitoes.
WEB CONNECTIONS
27.
Sample answer: The wood bison is larger than the plains bison, and it lives much farther north. The plains
bison once lived throughout much of the plains of Canada and the United States, where they were hunted
almost to extinction. Until the late 1800s, 20 million plains bison roamed North America. By 1906, only
about 1000 remained. Today there are about 8000 wild plains bison, and 400 000 in private ownership.
Wood bison are the largest animal in North America. Wood bison were almost eliminated from North
American by the 1950s. However, conservation efforts have restored the species to a small degree. About
3000 wood bison now exist in Alberta, the Yukon, British Columbia, and the Northwest Territories.
28.
Answers will vary, but students should correctly identify freshwater ecosystems in your area. In addition,
students should tell whether or not they think the ecosystems are healthy, and why they think the way
they do.
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