Download Lesson 8: Ecosystems, Genetics and Evolution

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Lesson 8: Ecosystems, Genetics and Evolution
Student Reference Sheet:
Food Chain: shows how each living thing gets its food. Some animals eat plants
and some animals eat other animals. For example, a simple food chain links the
trees & shrubs, the giraffes (that eat trees & shrubs), and the lions (that eat the
giraffes). Each link in this chain is food for the next link. A food chain always starts
with plant life and ends with an animal.
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Asexual Reproduction: describes reproduction in which there is no fusion of male
and female sex cells gametes, e.g. vegetative reproduction or budding
o
Examples: archaea, bacteria, protists, many plants and fungi
Sexual Reproduction: reproduction that involves the union of male and female
gametes, each contributing half of the genetic makeup of the resulting zygote
o
Examples: humans and animals
Abiotic: not containing or supporting life
o
Examples: Environmental factors such habitat (pond, lake, ocean, desert,
mountain) or weather such as temperature, cloud cover, rain, snow,
hurricanes or the sun
Biotic: relating to life and living organisms, or caused by living organisms
o
Examples: Plants, animals, fungi, protist and bacteria
Adaptations: the development of physical and behavioral characteristics that
allow organisms to survive and reproduce in their habitats
o
Examples: Insects that look like trees; Polar Bears have white fur to blend
in with the snow; giraffe has a long neck to eat leaves in tall tress; bird
migrates in the winter for warmth; porcupine has sharp stiff quills to defend
against enemies; chipmunk hibernates; dolphin has a tail to help it swim;
reptiles have lungs to breathe air
Mutualism: a relationship between two organisms of different species that
benefits both and harms neither.
o
Examples: lichens are a fungus and an alga living in mutualism: The fungus
provides a protective structure, and the alga produces a carbohydrate as
food for the fungus.
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Parasitic: living in or on another host organism, usually causing it harm
o
Examples: tapeworms, fleas, and barnacles. Tapeworms are segmented
flatworms that attach themselves to the insides of the intestines of animals
such as cows, pigs, and humans. They get food by eating the host's partly
digested food, depriving the host of nutrients. Fleas harm their hosts, such
as dogs, by biting their skin, sucking their blood, and causing them to itch.
The fleas, in turn, get food and a warm home. Barnacles, which live on the
bodies of whales, do not seriously harm their hosts, but they do itch and
are annoying.
Predation: the relationship between two groups of animals in which one species
hunts, kills, and eats the other
o
Examples: Barn owl and a field mouse; Salamander capturing insect with
sticky tongue; lynx and a snow hare; frog and a fly
Commensalism: the relationship between organisms of two different species in
which one derives food or other benefits from the association while the other
remains unharmed and unaffected
o
Examples: clownfish have a close relationship with sea anemones;
Monarch butterfly feeds as a larva on species of milkweeds; : birds
following army ant raids on a forest floor
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Student Practice:
1. The food web shows the interactions between organisms in a meadow
ecosystem.
Which organism gets food energy directly from both plants and animals?
A. fox
B. grass
C. grasshopper
D. snake
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2. Planaria are flatworms that are found in shallow streams, often attached to the
bottoms of rocks. A class is studying a population of planaria in a nearby shallow
stream. The graph below shows data collected over 11 weeks.
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The population started to decrease after 5 weeks. The students concluded that
the stream did not have enough food to support a large population of planaria.
If this trend continues, how many planaria will be living in the stream by
the 12th week?
A. 600
B. 500
C. 400
D. 300
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3. The illustration below shows how a strawberry plant reproduces by asexual
reproduction to form a new plant.
In your Answer Document, describe how the new plant compares genetically
with the parent plant.
Describe one advantage that asexual reproduction might offer the Strawberry
plant. (2 points)
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4. Use the following pictures to answer question 4.
The reproductive success of an organism depends in part on the ability of the
organism to survive.
How does the physical appearance of these organisms help them survive?
A. Their physical appearance helps them find a habitat.
B. Their physical appearance helps them resist parasites.
C. Their physical appearance helps them avoid predators.
D. Their physical appearance helps them defend a territory.
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5. Termites eat wood but cannot digest it. Protozoans live in the termites’ stomachs
and use enzymes to break down the wood.
The digested wood provides nutrition for both the termites and the protozoans.
What type of relationship is this?
A. mutualism
B. parasitism
C. predation
D. commensalism
6. Highways allow people to travel between towns and cities. These highways also
divide ecosystems into smaller pieces. Animals can become separated from
lakes they use for breeding. For example, tiger salamanders travel long distances
to breed at lakes.
How could highway systems affect animals such as the tiger salamander?
A. Tiger salamander habitats may be exposed to less pollution.
B. Tiger salamanders may be cut off from important resources.
C. Tiger salamanders could improve their ability to remember roads.
D. Tiger salamander habitats within ecosystems could become larger.
7. What interaction between organisms would be described as parasitic?
A. a mosquito feeding on the blood of a dog
B. a bee gathering nectar and pollen from a flower
C. a cleaner shrimp picking dead skin off a large fish
D. a nonpoisonous snake mimicking a poisonous snake
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8. A park is home to a large number of robins, squirrels and rabbits. The robins and
squirrels live in the park’s trees. The robins feed on earthworms and insects that
live on the ground. The squirrels eat the acorns produced by the park’s oak trees.
The rabbits hide in the bushes and feed on the grass. Which factor would directly
limit the number of rabbits that could live in this park?
A. number of robins
B. number of bushes
C. number of acorns
D. number of squirrels
9. In which environment is white fur color an advantage for survival?
A. desert
B. grassland
C. arctic tundra
D. temperate forest
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Use the information below to answer questions 10–11.
10. Paramecia usually reproduce asexually. Fish reproduce sexually. Suppose the
environmental conditions in the lagoon change. What advantage will the fish
population have over the paramecium population?
A. Sexual reproduction produces offspring that are identical to the parents.
B. Sexual reproduction decreases the genetic variability in the fish populations.
C. Sexual reproduction limits the spread of harmful characteristics in fish
populations.
D. Sexual reproduction allows populations to adapt to new conditions over fewer
generations.
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11. Choose one of the organisms in the diagram. In your Answer Document, identify
two nonliving resources the organism needs to live. Explain how the organism
uses each of the two nonliving resources. (2 points)
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12. Male mussels release sperm into the water. Female mussels take the sperm into
their gill chambers where fertilization occurs. Young mussel larvae are released
into the water where they float freely until they attach to the gill of a host fish.
After a few weeks, they reach the juvenile stage and drop off. After the juvenile
drops off the fish gill, it burrows into the river bed and begins the life cycle all over
again.
The parasitic behavior of the larvae benefits the mussel in two ways. One benefit
is that the fish provides nutrition for the larvae when they are attached to its gill.
What is the second way this behavior enhances the survival of the mussel
species?
A. The large size of the fish provides the mussel larvae with plenty of room to
grow.
B. The parasitism increases the opportunity for the mussels to mate with other
mussel species.
C. The mobility of the fish spreads the mussels to areas they would otherwise be
unable to reach.
D. The location of the larvae on the gills of fish reduces the exposure of the
larvae to oxygen-rich water.
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13. Bass tapeworms attach to the gills and intestines of bass fish. These worms
survive by taking nutrients from the bass.
What type of relationship does this represent?
A. predation
B. parasitism
C. mutualism
D. commensalism
14. Aphids are small insects that sometimes live near ants. The ants protect the
aphids from predators. The aphids produce a sweet substance that the ants eat.
Which statement describes the relationship between ants and aphids?
A. Both ants and aphids benefit.
B. Both ants and aphids are unaffected.
C. The ants benefit and the aphids are harmed.
D. The aphids benefit and the ants are unaffected.
Use the following information and food web to answer question 15.
15. Sea otters are marine mammals that live in giant kelp forests along the Pacific
coast of North America. Sea otters have an important role in the food web of this
ecosystem. When sea otters are removed from the giant kelp forest, the kelp also
begins to disappear.
In your Answer Document, explain why the absence of sea otters would lead to
a decrease in the giant kelp.
Then, choose another organism in the food web and explain why the decreasing
amount of giant kelp would affect that organism. (2 points)
Question 15 Diagram on Next Page
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15) Continued
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16. Aphids are a common plant-pest insect. They alternate between asexual
and sexual reproduction. During the summer, aphid populations grow quickly by
asexual reproduction. As winter approaches, aphids switch to sexual
reproduction.
What advantage does the switch to sexual reproduction give the aphids?
A. Sexual reproduction maintains a constant level of variation in the
population and requires less energy.
B. Sexual reproduction decreases variation in the population and prevents
the spread of harmful mutations.
C. Sexual reproduction increases variation in the population and provides for
adaptability in a changing environment.
D. Sexual reproduction produces individuals that are clones and allows rapid
population growth under stable environmental conditions.
17. The shape of an animal’s body is related to where it lives and how it feeds.
Which fish has a body shape that is best suited for feeding at the bottom of a
lake?
A.
B.
C.
D.
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18. Aphids, ants and plants interact with one another through symbiotic
relationships. Aphids are small insects that poke holes in plants and suck out sap.
Aphids may cause the plant’s leaves to wilt and curl. Ants protect aphids and
eat the sugary liquid that aphids produce.
In your Answer Document, choose two of the organisms in this symbiosis.
Describe the relationship between the two organisms in terms of the benefit or
harm to each organism. (2 points)
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