Organisms and Populations Test

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Organisms and Populations Test - 83

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Weekly Quiz Competition

Question 1
1 / -0

Read the passage and answer the following question.
An investigator went to Central America to study oropendolas, which are communal nesting birds. Another species of bird, the cowbird, sometimes lay its eggs in the nests of oropendolas. Some of the populations of oropendolas throw the cowbird eggs out of the nest, and some don't. The investigator was interested in finding out why some birds would raise other species as their own but others would toss them out. By watching the nests closely, he found that blowflies lay their eggs in the nests of oropendolas and that the young larvae, maggots, feed on the young birds. If young cowbirds are in the nest, the precocious cowbirds eat the blowfly larvae, protecting the young oropendolas. In colonies of oropendolas that discriminate against cowbirds, throwing them from the nest, the blowflies are not eaten by cowbirds. These colonies of oropendolas build their nests close to a particular wasp colony, and the wasps eat the blowflies.
The relationship between the oropendolas and the cowbirds is

A
Commenslism

B
Predation

C
Mutualism

D
Competition

E
Amensalism

Solution

Oropendolas young ones are eaten by blowfly larva and maggots. Cowbirds lay their eggs in Oropendolas nest thereby getting shelter. The precocious cowbirds feed on blowfly larvae thereby protecting the cowbirds young ones from blowfly. Both Oropendolas and cowbirds are benefited from the association. Mutualism is the association of organisms wherein both are benefitted. Thus, the correct answer is option C.
Question 2
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Directions For Questions

The given graph shows the results of the study carried out by ecologists to know the effect of herbivory on plant defensive structures. The thorny shrub Hromathophylla spinosa is a food source for grazers. The ecologists surrounded some areas containing this plant with a fence and left other areas open to grazers.

...view full instructions

The greatest number of thorns per plant are found in

A
Unfenced, year 0

B
Unfenced, year 1

C
Unfenced, year 2

D
Fenced, year 1

E
Fenced, year 2

Solution

The fenced area exhibits numbers of thorns per plant in year 0 as compared to those found in plants of the unfenced area in the same year. In year 2, plants of fenced area exhibit the lesser number of thorns as compared to those found in plants of the unfenced area. The minimum number of thorns per plant is exhibited by unfenced area in year 2 while a maximum number of thorns per plants is exhibited by plants of the unfenced area in year 1. Thus, the correct answer is B.
Question 3
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Directions For Questions

The given graph shows the results of the study carried out by ecologists to know the effect of herbivory on plant defensive structures. The thorny shrub Hromathophylla spinosa is a food source for grazers. The ecologists surrounded some areas containing this plant with a fence and left other areas open to grazers.

...view full instructions

Choose the correct statement that best explains the data.

A
H. spinosa grows thorns in response to grazing.

B
H. spinosa thorns are involved in reproduction.

C
Grazing selects for plants with a greater number of thorns.

D
Grazing decreases the number of thorns on H. spinosa plants.

E
Plants with more thorns have greater fitness than plants with fewer thorns.

Solution

The fenced area exhibits the lesser number of thorns per plant compared to those found in plants of the unfenced area. The minimum number of thorns per plant is exhibited by unfenced area in year 2 while a maximum number of thorns per plants is exhibited by plants of the unfenced area in year 1. Since plants in unfenced area exhibit the greater number of thorns as compared to those found in the fenced area, grazing increases the growth of thorns. The role of thorns in reproduction and fitness of plants can not be concluded from given data. Thus, the correct answer is A.
Question 4
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What relationship between two populations can you reasonably deduce when comparing curves I and II?

A
The relationship is neutral

B
There is strong evidence of competition but with resource partitioning

C
The population designated II appears to be an invasive species that outcompetes the other

D
The population designated I appears to be an invasive species that could not survive in a new niche

E
The population designated II appears to be a parasitic species that uses the other as its host.
Question 5
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Directions For Questions

Along the North Atlantic coastline two types of barnacles, Chthamalus and Balanus, grow on rock surfaces exposed at low tide and covered at high tide. At the beginning of a study of competition between these barnacles, a researcher removed selected Balanus from a region and followed the changes in distribution of both species for $$12$$ months. The given figures show the distribution of Chthamalus and Balanus.

...view full instructions

The best explanation for the change in the distribution of Chthamalus observed $$3$$ months after removal of the larger Balanus individuals is that

A
Balanus feeds on Chthamalus larvae.

B
Balanus does not reproduce as quickly as Chthamalus.

C
Balanus has less tolerance for wet conditions.

D
Balanus adults are mobile.

E
Balanus is less susceptible to predators.

Solution

When present together, Balanus dominated in wet conditions of low and mid tide region while removal of Balanus from mid tide region led to the growth of Chthamalus population in the area. It suggests Balanus feeds on Chthamalus larva and prevents the growth of their population. Thus, the correct answer is A.
Question 6
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A fungus that lives symbiotically with plants is

A
Mycorrhizae

B
Lichens

C
Mushrooms

D
Morels

E
Truffles

Solution

In a symbiotic relationship, both the host and the parasite benefit from each other. In mycorrhizae, fungi reside inside the living root tissue of the plant. This fungus helps the plant absorb nutrients and also helps protect the plant from animals. In return, the host plant provides nutrients to the mycorrhizae fungus.
Question 7
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Competition between the members of a woodchuck population in a large field is increased by the increase in

A
Woodchuck reproduction rate

B
Spread of disease among the woodchucks

C
Number of woodchucks killed by cars

D
Number of secondary consumers

E
Natality rate of their predators

Solution

The spread of disease, killing of woodchucks by cars, their predation by secondary consumers and increased birth rate of predators tend to decrease the woodchuck population. Decreased number of individuals would now face less intense competition for same resources. However, increased reproduction rate of woodchuck would increase its population size and thereby increase the intraspecific competition. Thus, the correct answer is A.
Question 8
1 / -0

An investigator went to Central America to study oropendulas, which are communal nesting birds. Another species of bird, the cowbird, sometimes lay its eggs in the nests of oropendulas. Some of the populations of oropendulas throw the cowbird eggs out of the nest, and some dont. The investigator was interested in finding out why some birds would raise other species as their own but others would toss them out. By watching the nests closely, he found that blowflies lay their eggs in the nests of oropendulas, and that the young larvae, maggots, feed on the young birds. If young cowbirds are in the nest, the precocious cowbirds eat the blowfly larvae, protecting the young oropendulas. In colonies of oropendulas that discriminate against cowbirds, throwing them from the nest, the blowflies are not eaten by cowbirds. These colonies of oropendulas build their nests close to a particular wasp colony, and the wasps eat the blowflies.
The relationship between the oropendulas that discriminate against cowbirds and the cowbirds is one of

A
Commensalism

B
Predation

C
Mutualism

D
Competition

E
Amensalism

Solution

Competition is process where organisms of same or different species compete for scarce resources. Oropendulas young ones are eaten by blowfly larva and maggots. Cowbirds lay their eggs in Oropendulas nest thereby getting shelter. The precocious cowbirds feed on blowfly larvae thereby protecting the cowbirds young ones from blowfly. The discriminating oropendulas population throw the cowbird eggs out of nest and hence their young ones are eaten by blowfly larve. Cowbirds and discriminating oropendulas exhibit competition for use of nest as their egg lying space. Thus, the correct answer is option D.
Question 9
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Large number of eggs are produced by a spider species but due to little parental care, only a few of them reach adulthood. The line representing the survivorship curve for this species is

A
Curve 1

B
Curve 2

C
Curve 3

D
Curves 1 and 2

E
Curves 1 and 3

Solution

Survivorship curves are the visual representation of demographic details. This curve is a graphical representation showing the survival pattern of organisms by plotting the number of individuals or organisms against age for a given species. There are three types of curves-
Type A is one which shows high age-specific survival probability with a rapid decline in survival in later life. These include ones with fewer numbers of offspring but with the larger investment in time and energy in parental care.
Type B shows cases a more or less constant mortality and survival rate irrespective of age.
Type C represents those with little or nil parental care and only a few reaching adulthood.
The case of spiders represented in the question shows the type 3 survivorship curve.
Thus, the correct answer is option C.
Question 10
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The origin of the predation ability of Venus flytraps is explained by

A
Only those plants with the ability to supplement the poor nutrient content of their soils could survive.

B
Predation allowed the Venus flytrap to outcompete other species because of its ability to move rapidly.

C
As consumers instead of produces, Venus flytraps have greater access to better nutrients.

D
Predation allowed the Venus flytrap to collect a wider variation of preformed organic materials.

E
Better nutrients allowed the Venus flytrap to grow faster than other plants.

Solution

Venus flytraps are green plants that are found in a habitat where nitrogen is not freely available in the soil. These plants have modified leaves and they have a scent that attracts insects. Trigger hairs on the leaf surface are sensitive to touch and detect the arrival of an insect causing the leaf to fold. The interlocked insect is then digested by enzymes of the leaf. The insects serve as a source of nitrogen for these plants and the modification imparts the survival advantage to the plants under nitrogen-deficient soil. Thus, the correct answer is option A.

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Re-Attempt Weekly Quiz Competition

Organisms and Populations Test - 83

Result

Organisms and Populations Test - 83

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SHARING IS CARING

Question 1

Commenslism

Predation

Mutualism

Competition

Amensalism

Solution

Question 2

Unfenced, year 0

Unfenced, year 1

Unfenced, year 2

Fenced, year 1

Fenced, year 2

Solution

Question 3

H. spinosa grows thorns in response to grazing.

H. spinosa thorns are involved in reproduction.

Grazing selects for plants with a greater number of thorns.

Grazing decreases the number of thorns on H. spinosa plants.

Plants with more thorns have greater fitness than plants with fewer thorns.

Solution

Question 4

The relationship is neutral

There is strong evidence of competition but with resource partitioning

The population designated II appears to be an invasive species that outcompetes the other

The population designated I appears to be an invasive species that could not survive in a new niche

The population designated II appears to be a parasitic species that uses the other as its host.

Question 5

Balanus feeds on Chthamalus larvae.

Balanus does not reproduce as quickly as Chthamalus.

Balanus has less tolerance for wet conditions.

Balanus adults are mobile.

Balanus is less susceptible to predators.

Solution

Question 6

Mycorrhizae

Lichens

Mushrooms

Morels

Truffles

Solution

Question 7

Woodchuck reproduction rate

Spread of disease among the woodchucks

Number of woodchucks killed by cars

Number of secondary consumers

Natality rate of their predators

Solution

Question 8

Commensalism

Predation

Mutualism

Competition

Amensalism

Solution

Question 9

Curve 1

Curve 2

Curve 3

Curves 1 and 2

Curves 1 and 3

Solution

Question 10

Only those plants with the ability to supplement the poor nutrient content of their soils could survive.

Predation allowed the Venus flytrap to outcompete other species because of its ability to move rapidly.

As consumers instead of produces, Venus flytraps have greater access to better nutrients.

Predation allowed the Venus flytrap to collect a wider variation of preformed organic materials.

Better nutrients allowed the Venus flytrap to grow faster than other plants.

Solution

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