Download Chapter 1 Review Questions

Chapter 1 Review Questions
Knowledge
1. a.
e.
population
producer
b.
f.
trophic level
habitat
c.
g.
mutualism
competition
d.
transpiration
2. a.
3.
4.
5.
6.
7.
Biodiversity refers to the number of species. Biomass refers to the dry mass of living
tissue.
b.
Abiotic refers to non-living factors, such as temperature, soil type, climate, and pH.
Biotic refers to the living organisms in an environment, such as producers and
decomposers.
c.
A food chain has a single path, whereas a food web has multiple paths for the flow of
energy through feeding relationships.
d.
Producers make their own food, usually through the process of photosynthesis.
Consumers eat other organisms as their source of food.
e.
Habitat destruction means the habitat is destroyed. Habitat fragmentation refers to the
dividing up of what was once continuous habitat.
Sample answers may include the following. Abiotic factors of a forest ecosystem include wind
speed, soil pH, air temperature, and the amount of precipitation. Biotic factors include trees,
birds, squirrels, ants, earthworms, and fungi.
A food web is more realistic than a food chain, since living things will likely eat a variety of
nutrient sources. A food chain only shows one example of the feeding pattern in an
ecosystem.
Sunlight provides the input energy for nearly all ecosystems. And sunlight enables producers
to make organic compounds that become the energy source for other living things in the
ecosystem.
A biogeochemical cycle is a diagram that represents the movement of elements, chemical
compounds, and other forms of matter from the abiotic and biotic factors of an ecosystem.
Only about 10% of the energy and matter is passed from one trophic level to the next level
because the organisms at each level need some of the energy to complete their life functions.
Eventually, all of the energy is lost as heat to the environment.
Applying Concepts
8. Note that answers may vary in the Example column of the completed table.
INTERACTIONS BETWEEN SPECIES
Type of
Interaction
mutualism
commensalism
Effect on Effect on
Species Species
#1
#2
+
+
Description
Example

form of symbiosis in which both
organisms benefit
butterflies
and purple
coneflowers

form of symbiosis in which one
organism benefits while the other is
neither helped nor harmed
+
0

parasitism
+
–
form of symbiosis in which one
organism—the parasite—benefits while
the other organism—the host—is
harmed
cowbirds and
bison
tapeworms
and
bison
predation
competition
+
–

interaction in which one organism—the
predator—benefits by killing and eating
the other organism—the prey

interaction where two or more
organisms compete for limited
resources
–
–
9. This simplified energy pyramid outlines an Arctic ecosystem.
10 This food chain represents the Arctic ecosystem.
.
red-tailed
hawks
and blacktailed
prairie dogs
lynx and great
horned owls
11 There are no tertiary consumers for this ecosystem because the total energy available at each level
. is quite small. The first trophic level has a small amount of energy available for the next level
because the Arctic growing season is so short that there is little opportunity for producers to build
significant quantities of organic molecules for primary consumers. It follows that there is less
energy at the level of the primary consumers to pass on to the secondary consumers. At this point,
the secondary consumers have to hunt over such a large range to sustain themselves that the
system cannot support a level of tertiary consumers.
12 a. The graph showing the annual population changes for Arctic foxes living in this same area
.
would likely show peaks in the years following the peaks in the lemming population. This
means that the Arctic fox population would likely peak in 1994, 1998, and 2002. The reason
for this is that the four-year cycle shown in the lemming population would be shadowed by a
similar four-year cycle in the Arctic fox population. This is because the availability of lemmings
is closely tied to the population of Arctic foxes, since the lemming is the primary food source
for the Arctic fox. In the years that the lemming population peaks, the Arctic foxes take
advantage of the plentiful food source and produce many offspring that show up in the
following year. The crash in the lemming population triggers a corresponding crash in the
Arctic fox population. Therefore, the twinning of the two cycles continues.
b. The years in which the lemming population peaks would be very stressful for the lemmings’
favourite vegetation. In the following year, the vegetation may not be able to produce much
foliage due to the stress it was subjected to in the previous year. The result is that there would
be much less vegetation available in the year following a lemming population peak. This would
cause the lemming population to crash. During the years of reduced lemming numbers, the
vegetation would have a period of recovery, only to be followed by the next boom in the
lemming population.
13 An example of mutualism is the lichen, which is the symbiotic relationship between a fungi and an
. alga. Competition is demonstrated by individual lemmings competing for food and by snowy owls
and Arctic foxes competing for lemmings. Mosquitoes and black flies are parasites that take a blood
meal from a host species.
14 a. Since the ground is cold and low in oxygen because it is saturated with water, decomposition
.
occurs very slowly. Since decomposition is a process that releases carbon dioxide back into the
atmosphere, the peat bogs and muskeg act as sinks for carbon if this process is impeded.
b. If global warming occurs, then the rise in temperature will accelerate the process of
decomposition. The peat bogs and muskeg could then become sources of carbon instead of
sinks.
15 a. The person who eats the vegetable salad has the role of a primary consumer or herbivore,
.
while the person eating chicken has the role of a secondary consumer or a carnivore. Since
tuna is a high-level predator in the ocean ecosystem, a person who eats tuna is a tertiary
consumer or a top predator.
b. The salad eater is in the second trophic level, the person eating the chicken is in the third
trophic level, and the tuna eater is in the fourth or fifth trophic level.
c. Most people would be classified as omnivores because they eat food from both plant and
animal sources. A typical lunch for many people includes both plant and animal products—a
glass of fruit juice, a tuna sandwich, and a piece of fruit.
d. It is impossible for a person to be a producer because humans are incapable of photosynthesis.
16 As energy moves from lower trophic levels to higher levels, there is less and less energy available
.
because only about 10% of the energy at one level is passed on to the next level. By the time the
energy has been passed to the sixth trophic level, there is such a small amount of energy available
that it is unlikely to be able to support life.
17 Producers are organisms that assemble complex organic compounds from elements and simple
. compounds. Organisms like spruce trees and freshwater algae do this through photosynthesis.
18 An organism that feeds on other living organisms as its source of essential elements and
. compounds is called a consumer. Primary consumers or herbivores feed on producers. Black-tailed
prairie dogs, grasshoppers, and mosquito larvae are all herbivores. Secondary consumers or
predators feed on primary consumers. This group includes the swift fox, the yellow warbler, and
dragonfly larvae. The final group of consumers are the tertiary consumers—these carnivores feed
on other carnivores. These top predators are represented by the red-tailed hawk, the peregrine
falcon, and the northern pike.
19 Bacteria and fungi are two types of micro-organisms that obtain their essential nutrients and
. compounds from feeding on dead and decaying matter. These organisms are also called
decomposers.
20 The decomposers release simple inorganic molecules used by producers in the process of
. photosynthesis. Prairie grasses and freshwater algae are examples of producers that use these
simple inorganic compounds.
21. The carbon cycle could be described in the following way.
step 1: Terrestrial plants and marine plants remove carbon dioxide from the air and combine
this with water to produce glucose and other organic compounds. In this process—
called photosynthesis—oxygen is released as a waste product.
step 2: As primary consumers feed on the plants, the complex organic compounds are
transferred. Compounds are transferred again as primary consumers become prey of
secondary consumers, and as secondary consumers are fed upon by tertiary
consumers.
step 3: As the tissues of dead producers and consumers are fed upon by the decomposers,
complex organic molecules are broken down into simpler inorganic forms. In this
case, carbon dioxide is released into the atmosphere.
step 4: Atmospheric carbon dioxide is used by the producers and the whole cycle begins
again.
22. a.
Forest fragmentation creates more open spaces and edge habitats, which cowbirds prefer
over dense forests. As roads and farms push north into forests, cowbirds could follow
these roads as extensions of the open spaces they are accustomed to on open fields and
grasslands.
b. Although cowbirds originally followed herds of bison and ate insects that the bison stirred
up, in agricultural areas cowbirds will follow cattle in the same way. Cowbirds are
classified as brood parasites because they will lay their eggs in other bird’s nests and let
the other birds raise the cowbird chicks. Songbirds that prefer edge habitats are prime
candidates for brood parasitism by the cowbirds. It follows that as farmland adds to
forest fragmentation, cowbirds that follow agricultural expansion soon begin to reduce
the numbers of area songbirds.
23. When excess nitrogen compounds leach into local streams and lakes, a harmful algal bloom
can develop where the population of algae explodes to create thick floating mats of green
ooze. Eventually, the algae population cannot sustain itself and the algae die in significant
numbers. As bacteria feast on masses of algae, the oxygen concentration in the water drops
dramatically. This disrupts the balance within the ecosystem so much that fish begin to die
from a lack of oxygen in the water.
24. Parasitism is a long-term relationship in which the parasitic organism benefits while the host
organism is harmed. It is not in the interest of the parasite to kill the host because then its
source of nutrients is gone. Predation is also an interaction in which one organism benefits
and another is harmed. However, in predation the prey is killed and the interaction only lasts
as long as it takes the predator to kill the prey.
25. If more people switched to vegetarian diets, there would be fewer energy losses. As animals
are raised for food, the animals use energy to maintain their body functions, move around,
and keep warm. Using the idea that only 10% of available energy at one trophic level can be
passed to the next level, the simplified arithmetic looks like this:

Consider the amount of vegetation it takes to raise enough meat to feed 100 people.

This same amount of vegetation could feed about 1000 people if they ate it directly
instead of using it for animal feed.
This is oversimplified. However, a more efficient use of food is generated by producers if
humans eat as first-order consumers (herbivores) and not as second-order consumers
(carnivores).
26. A raptor is a bird of prey. These birds have sharp talons and hooked beaks for tearing meat
from the animals that they hunt for food. Examples of raptors include owls, falcons, hawks,
and eagles.
27. DDT was a pesticide used to control insect populations. Small amounts of this compound
were absorbed into the bodies of insects. When secondary consumers, such as fish and small
birds, fed on huge numbers of insects, the concentration of DDT increased in their bodies so
that it exceeded the concentration in the insects. Further magnification of the concentration
of DDT occurred when raptors, such as eagles and peregrine falcons, fed on the secondary
consumers. In the case of peregrine falcons, the concentration of DDT was sufficient to make
the shells of their eggs very thin and susceptible to damage. This caused the population of
these birds to decline.
28. If the population of raptors within an ecosystem begins to decline, then the population of the
animals that the raptors prey upon will likely increase. For example, if the number of owls in
an area declines, the population of mice that the owls feed upon will increase. This, in turn,
can have a negative effect on the plant community as the increased numbers of mice eat
more vegetation.
In questions 29 to 31, students can reconsider their own eating habits in light of these ideas.
29. According to data from 2002, the ecological footprint of the average Albertan was 10.7 ha
and for the average Canadian it was 7.7 ha. The difference is that in other parts of Canada,
hydroelectric power is more common than it is in Alberta. Hydroelectric power has a smaller
ecological footprint than burning coal, which is more common in Alberta. Albertans also have
20% more vehicles registered per capita than the Canadian average. A larger percentage of
these vehicles are light trucks and SUVs, which consume more fossil fuels.
30. The following are two sample calculations:

number of Earths needed to support the human race if everyone on the planet lived
like an Albertan

number of Earths needed to support the human race if everyone on the planet lived
like a Canadian
31. For most students, significant changes have to do with food eaten and transportation used. If
students switched to a diet containing less meat, their footprints would be smaller because of
the efficiencies associated with eating plants directly instead of feeding plants to animals.
Science 20 © 2006, Alberta Education