Question 1

Which of the following chemical conversions does NOT directly occur in the nitrogen cycle?

Accepted Answer

A)  Nitrate ions to atmospheric nitrogen gas 
B)  Nitrite ions to nitrate ions 
C)  Nitrate ions to ammonium ions 
D)  Ammonium ions to nitrite ions 
E)  Atmospheric nitrogen gas to nitrite ions 
A)  Nitrate ions to atmospheric nitrogen gas 
B)  Nitrite ions to nitrate ions 
C)  Nitrate ions to ammonium ions 
D)  Ammonium ions to nitrite ions 
E)  Atmospheric nitrogen gas to nitrite ions C

Question 2

The small number of trophic levels uniformly found in food chains

Accepted Answer

A)  can be explained by energy reduction up the trophic scale. 
B)  is due to the uniformly low energy base (primary productivity) of all ecosystems. 
C)  is a phenomenon for which ecologists do not yet have a satisfactory explanation. 
D)  is because there are few predatory organisms in the chain. 
E)  is a result of the greenhouse effect. 
A)  can be explained by energy reduction up the trophic scale. 
B)  is due to the uniformly low energy base (primary productivity) of all ecosystems. 
C)  is a phenomenon for which ecologists do not yet have a satisfactory explanation. 
D)  is because there are few predatory organisms in the chain. 
E)  is a result of the greenhouse effect. C

Question 3

Under some conditions, trophic diagrams may be inverted (i.e. broader at the top). Under which of the following conditions would you expect a biomass pyramid to be inverted?

Accepted Answer

A)  When primary producers are slow growing and long lived. 
B)  When grazers are rare. 
C)  When primary producers are heavily grazed. 
D)  When predators are slow and hunt inefficiently. 
E)  When the ecosystem is dominated by large herbivores. 
A)  When primary producers are slow growing and long lived. 
B)  When grazers are rare. 
C)  When primary producers are heavily grazed. 
D)  When predators are slow and hunt inefficiently. 
E)  When the ecosystem is dominated by large herbivores. C

Question 4

A prokaryotic cyanobacteria has no chloroplasts but does contain chlorophyll as well as having the ability to fix atmospheric nitrogen. Its chlorophyll content gives it the ability to convert atmospheric CO2 into photosynthates, meaning that it must be a

Accepted Answer

A)  heterotroph. 
B)  decomposer. 
C)  detritivore. 
D)  chemotroph. 
E)  autotroph. 
A)  heterotroph. 
B)  decomposer. 
C)  detritivore. 
D)  chemotroph. 
E)  autotroph.

Question 5

Which of the following raw materials is required for life and is NOT cycled through a global cycle?

Accepted Answer

A)  Oxygen 
B)  Silicon 
C)  Carbon 
D)  Hydrogen 
E)  Manganese 
A)  Oxygen 
B)  Silicon 
C)  Carbon 
D)  Hydrogen 
E)  Manganese

Question 6

Eucalypt leaves are eaten by beetles, which are eaten by birds, which are preyed upon by quolls. This is an example of a

Accepted Answer

A)  trophic pyramid. 
B)  food web. 
C)  food chain. 
D)  forest ecosystem. 
E)  a trophic relationship. 
A)  trophic pyramid. 
B)  food web. 
C)  food chain. 
D)  forest ecosystem. 
E)  a trophic relationship.

Question 7

A farmer with a stand of eucalyptus trees that appear to be suffering from rural dieback wants to arrest the problem. His best course of action would be to

Accepted Answer

A)  spray the trees to poison the flying insects that defoliate the trees and monitor them carefully in case they return. 
B)  decrease stocking rates around trees, reduce fertiliser application and plant more trees and shrubs. 
C)  fertilise the soil with superphosphate to enable better growth. 
D)  increase stocking rates to reduce weeds and grasses that compete with the trees for soil moisture. 
E)  reduce the density of other, less-desirable native trees in the area to reduce the available feed for the defoliating insects. 
A)  spray the trees to poison the flying insects that defoliate the trees and monitor them carefully in case they return. 
B)  decrease stocking rates around trees, reduce fertiliser application and plant more trees and shrubs. 
C)  fertilise the soil with superphosphate to enable better growth. 
D)  increase stocking rates to reduce weeds and grasses that compete with the trees for soil moisture. 
E)  reduce the density of other, less-desirable native trees in the area to reduce the available feed for the defoliating insects.

Question 8

Approximately what fraction of the world's water is stored in biologically inaccessible forms such as glaciers and ice-caps?

Accepted Answer

A)  <1% 
B)  2% 
C)  5% 
D)  3% 
E)  8% 
A)  <1% 
B)  2% 
C)  5% 
D)  3% 
E)  8%

Question 9

Plants inhabiting ecosystems with low levels of phosphorous are able to achieve high rates of productivity by

Accepted Answer

A)  recycling phosphorous stores contained within the living biomass. 
B)  having a low absolute requirement for phosphorus. 
C)  efficiently utilising phosphorus extracted from soil and litter by mycorrhizal associations. 
D)  mycorrhizal recycling of phosphorous to make it readily available. 
E)  All of the answers are correct. 
A)  recycling phosphorous stores contained within the living biomass. 
B)  having a low absolute requirement for phosphorus. 
C)  efficiently utilising phosphorus extracted from soil and litter by mycorrhizal associations. 
D)  mycorrhizal recycling of phosphorous to make it readily available. 
E)  All of the answers are correct.

Question 10

In general, marine ecosystems

Accepted Answer

A)  have a low net primary productivity. 
B)  are more productive than terrestrial ecosystems. 
C)  have productivity similar to terrestrial ecosystems. 
D)  contain adequate phosphate levels but are limited by nitrogen. 
E)  are limited by light more than by nutrients. 
A)  have a low net primary productivity. 
B)  are more productive than terrestrial ecosystems. 
C)  have productivity similar to terrestrial ecosystems. 
D)  contain adequate phosphate levels but are limited by nitrogen. 
E)  are limited by light more than by nutrients.

Question 11

The limited number of tropic levels is most likely due to

Accepted Answer

A)  reduction in energy up the tropic scale. 
B)  the large proportion of energy that is transferred from one tropic level to the next. 
C)  the high level of energy available at the top of the ecological pyramid. 
D)  the constant level of energy available at the base of different ecosystems. 
E)  The constant energy flowing from one energy level to the next. 
A)  reduction in energy up the tropic scale. 
B)  the large proportion of energy that is transferred from one tropic level to the next. 
C)  the high level of energy available at the top of the ecological pyramid. 
D)  the constant level of energy available at the base of different ecosystems. 
E)  The constant energy flowing from one energy level to the next.

Question 12

What is the productivity of an ecosystem?

Accepted Answer

A)  The rate at which the main primary producers of an ecosystem synthesise energy. 
B)  The rate at which primary consumers use energy. 
C)  The rate at which energy is synthesised by primary producers plus the rate at which it is recycled by degraders. 
D)  The total amount of material present at any time. 
E)  The difference between the energy produced by primary producers and that consumed by consumers. 
A)  The rate at which the main primary producers of an ecosystem synthesise energy. 
B)  The rate at which primary consumers use energy. 
C)  The rate at which energy is synthesised by primary producers plus the rate at which it is recycled by degraders. 
D)  The total amount of material present at any time. 
E)  The difference between the energy produced by primary producers and that consumed by consumers.

Question 13

When ecosystems are considered in terms of trophic interactions, which of the following is NOT found at the base of a food chain?

Accepted Answer

A)  Algae 
B)  Decomposer bacteria 
C)  Cyanobacteria 
D)  Green plants 
E)  All of these could be found at the base. 
A)  Algae 
B)  Decomposer bacteria 
C)  Cyanobacteria 
D)  Green plants 
E)  All of these could be found at the base.

Question 14

Which of the following is thought by some to govern the stability of a food chain?

Accepted Answer

A)  The number of links 
B)  Energy limitations in the ecosystem 
C)  The number of autotrophs 
D)  The number of carnivores 
E)  The number of omnivores 
A)  The number of links 
B)  Energy limitations in the ecosystem 
C)  The number of autotrophs 
D)  The number of carnivores 
E)  The number of omnivores

Question 15

Most animals obtain nitrogen by

Accepted Answer

A)  fixing it. 
B)  ingesting amino acids. 
C)  ingesting nitrites. 
D)  ingesting ammonia. 
E)  ingesting nitrates. 
A)  fixing it. 
B)  ingesting amino acids. 
C)  ingesting nitrites. 
D)  ingesting ammonia. 
E)  ingesting nitrates.

Question 16

Ecosystems

Accepted Answer

A)  are explained by analysing the flow of energy up the tropic scale. 
B)  consist of a simple sequence of organisms eating and being eaten. Generally the reasons are unknown. 
C)  realistically consist of food webs which are a series of interlocking food chains. 
D)  require scavengers and degraders. 
E)  All of the answers are correct about ecosystems. 
A)  are explained by analysing the flow of energy up the tropic scale. 
B)  consist of a simple sequence of organisms eating and being eaten. Generally the reasons are unknown. 
C)  realistically consist of food webs which are a series of interlocking food chains. 
D)  require scavengers and degraders. 
E)  All of the answers are correct about ecosystems.

Question 17

The ecosystem which occupies the largest area of the earth is

Accepted Answer

A)  tropical rainforest. 
B)  savanna. 
C)  semiarid desert. 
D)  woodlands. 
E)  continental shelf. 
A)  tropical rainforest. 
B)  savanna. 
C)  semiarid desert. 
D)  woodlands. 
E)  continental shelf.

Question 18

Which type of food web do models predict would enable the persistence of an ecosystem in a variable environment? One with

Accepted Answer

A)  many linkages. 
B)  a low level of complexity. 
C)  many omnivores. 
D)  many complex interactions. 
E)  long food chains. 
A)  many linkages. 
B)  a low level of complexity. 
C)  many omnivores. 
D)  many complex interactions. 
E)  long food chains.

Question 19

Primary productivity of an ecosystem

Accepted Answer

A)  is relatively constant. 
B)  is similar between different ecosystems. 
C)  is determined by the activity of plants and algae. 
D)  is highest in marine ecosystems. 
E)  depends on its state of regeneration since regenerating ecosystems are more productive than mature ecosystems. 
A)  is relatively constant. 
B)  is similar between different ecosystems. 
C)  is determined by the activity of plants and algae. 
D)  is highest in marine ecosystems. 
E)  depends on its state of regeneration since regenerating ecosystems are more productive than mature ecosystems.

Question 20

Fungi can be classified as

Accepted Answer

A)  omnivores. 
B)  detritivores. 
C)  autotrophs. 
D)  decomposers. 
E)  parasites. 
A)  omnivores. 
B)  detritivores. 
C)  autotrophs. 
D)  decomposers. 
E)  parasites.

Exam 45: Ecosystems

Which of the following chemical conversions does NOT directly occur in the nitrogen cycle?

The small number of trophic levels uniformly found in food chains

Under some conditions, trophic diagrams may be inverted (i.e. broader at the top). Under which of the following conditions would you expect a biomass pyramid to be inverted?

A prokaryotic cyanobacteria has no chloroplasts but does contain chlorophyll as well as having the ability to fix atmospheric nitrogen. Its chlorophyll content gives it the ability to convert atmospheric CO2 into photosynthates, meaning that it must be a

Which of the following raw materials is required for life and is NOT cycled through a global cycle?

Eucalypt leaves are eaten by beetles, which are eaten by birds, which are preyed upon by quolls. This is an example of a

A farmer with a stand of eucalyptus trees that appear to be suffering from rural dieback wants to arrest the problem. His best course of action would be to

Approximately what fraction of the world's water is stored in biologically inaccessible forms such as glaciers and ice-caps?

Plants inhabiting ecosystems with low levels of phosphorous are able to achieve high rates of productivity by

In general, marine ecosystems

The limited number of tropic levels is most likely due to

What is the productivity of an ecosystem?

When ecosystems are considered in terms of trophic interactions, which of the following is NOT found at the base of a food chain?

Which of the following is thought by some to govern the stability of a food chain?

Most animals obtain nitrogen by

Ecosystems

The ecosystem which occupies the largest area of the earth is

Which type of food web do models predict would enable the persistence of an ecosystem in a variable environment? One with

Primary productivity of an ecosystem

Fungi can be classified as

Nature of Molecules

Biomolecules

The Chemistry of Life

Functioning Cells

Movement Across Membranes

Harvesting Energy

Cells, Tissues and Signals

Cell Division

Inheritance

Genes, Chromosomes and Dna

The Genetic Code

Gene Expression

Genomes, Mutation and Cancer

Viruses

Genetic Engineering and Biotechnology

Reproduction, Growth and Development of Flowering Plants

Structure of Plants

Plant Nutrition, Transport and Adaptation to Stress

Plant Hormones and Growth Responses

Animal Reproduction

Animal Development

Homeostasis: Water, Solutes and Excretion

Gas Exchange in Animals

Circulation

Metabolism, Temperature Regulation and Environmental Stress

Animal and Human Nutrition

Innate Defences and the Immune System

Hormonal Control in Animals

Nervous Systems

Animal Movement

Animal Behaviour

Evolving Life

Evolving Earth

Mechanisms of Evolution

Bacteria

The Protists

Plants

Fungi

Simple Animals: Sponges to Flatworms

Annelids, Molluscs, Nematodes and Arthropods

Echinoderms and Chordates

Australian Biota

Population Ecology

Living in Communities

Human Impacts

Filters

A prokaryotic cyanobacteria has no chloroplasts but does contain chlorophyll as well as having the ability to fix atmospheric nitrogen. Its chlorophyll content gives it the ability to convert atmospheric CO₂ into photosynthates, meaning that it must be a