Ch 13, 14, 15, 16 Flashcards
Two grassland communities, A and B, cover a similar area, but community A has a greater number of populations than community B.
a ) Which community has the greater species richness?
b ) Which community is expected to be closer to the equator?
a) Community A with its greater number of populations has the greater species richness.
b) Because of its greater species richness, community A is expected to be closer to the equator.
Give one possible explanation for a clumped distribution in a population.
A clumped distribution of a population suggests that, within an area, only some parts have conditions suitable for survival of individuals. In the case of an animal population, it may be because only these parts provide an adequate source of food or shelter for the animals. In the case of a plant population, it may be that these parts alone have a suitable soil pH or water availability for the plants.
Give five reasons a biologist would estimate the population size of one or more species.
Population size might be estimated for several reasons including:
• to monitor the abundance of a pest population so that control measures can be introduced
• to monitor the frequency of occurrence of a population ‘explosion’ in a particular pest species
• to record changes over time in the population of an ‘at-risk’ species to identify whether the population size is stable, increasing or decreasing so that decisions about appropriate conservation measures can be made
• to monitor the effects of environmental change, such as prolonged drought, on the population of a species
• to record the abundance of various species in a community as part of identifying the biodiversity of that community.
Identify three problems with total counts of populations.
Problems include:
• For an animal species, a total count poses problems because the animals may be very small so some may be missed.
• For an animal species, a total count poses problems because the animals may be very mobile so some may be missed.
• For species with a very scattered distribution over a very large area, the cost of a total census is likely to be too expensive.
Which is more common: a total count or a sampling of a population?
Sampling of populations is more common because of the problems associated with most total counts of populations.
What is the area of one belt transect that is 200 metres wide and 500 metres long?
The area of this strip transect is 100 000 square metres or 0.1 square kilometre.
List four variables that affect the size of an open population.
Variables that affect the size of an open population include: • birth rate • death rate • immigration to the population • emigration from the population.
In a closed population with zero population growth, how do birth and death rates compare?
In a closed population with zero population growth, birth and death rates are expected to be equal.
What is the name given to the curve for logistic population growth?
The curve that illustrates logistic population growth is called an S-shaped curve.
In which pattern(s) of growth is a deceleration phase present?
A deceleration phase in growth occurs in the logistic growth pattern.
Identify a density-dependent factor that would be expected to limit population growth.
Density-dependent factors that would be expected to limit population growth include:
• competition for food
• competition for shelter
• predation
• infectious diseases
• parasites.
In each case, as the population becomes larger, the impact of these factors on the population becomes greater.
Give one cause for the ‘crash’ of a prey population.
A prey population would be expected to ‘crash’ if the population of its predators is drastically reduced or eliminated.
17 Which species, r-selected or K-selected, would be expected:
a ) to recover more quickly after its population was reduced?
b ) to be at greater risk of extinction through habitat destruction?
a ) An r-selected species would be expected to recover more quickly than a K-selected species after its population was reduced because of its higher growth rate.
b ) A K-selected species would be at greater risk of extinction through habitat destruction than an r-selected species.
Give an example of: a K-selected species
K-selected species include elephants, gorillas, whales and albatross etc
Give an example of: an r-selected species
r-selected species include cane toads, many reef fish species, clams, coral polyps, crown-of-thorns starfish, rabbits and mice etc
List the three essential components of an ecosystem.
The three essential components of an ecosystem are:
• a living community of various populations
• the physical surroundings of that community
• the interactions between members of the community and their physical surroundings.
Give an example of an organism that is:
a producer in a terrestrial ecosystem
Typical producers in a terrestrial ecosystem would be expected to include flowering plants, conifers, ferns and mosses.
Give an example of an organism that is: a producer in an aquatic ecosystem
In an aquatic ecosystem, producers would be expected to include phytoplankton and algae.
Give an example of an organism that is: a consumer of chemical energy
A consumer of chemical energy is any herbivore, such as a leaf-eating insect, or any carnivore, such as a quoll.
Give an example of an organism that is: a tertiary consumer
A tertiary consumer is at the fourth trophic level and would be any animal that eats a carnivore. One example would be an eagle that eats small predatory mammals.
Give an example of an organism that is: an organism at the first trophic level.
Organisms at the first trophic level include any producer organisms, such as plants, algae and cyanobacteria.
In an ecosystem, which energy flow would be greater?
a energy flow from primary to secondary consumers
b energy flow into producers
In an ecosystem, (b) would be greater than (a). The energy flow into producers is expected to be greater than the energy flow from primary to secondary consumers since some energy is lost as heat energy at each trophic level, leaving less usable energy available for transfer to the next higher trophic level.
Identify two sources of ‘lost’ energy in a consumer organism.
The ‘lost’ energy in a consumer, such as a mammal, can be accounted for as:
• heat energy generated by metabolic processes for maintaining life
• organic matter in urine
• organic matter in faeces.
Which has the higher energy cost of production: one gram of herbivore tissue or one gram of carnivore tissue?
One gram of carnivore tissue has a much higher energy cost of production that one gram of herbivore tissue. In general, carnivore tissue is about 10 times more expensive in energy cost to produce relative to herbivore tissue.
Consider a mountain ash tree and the consumers that live on it as an ecosystem. What would be distinctive about the pyramid of numbers for this ecosystem?
In this particular ecosystem, the pyramid of numbers would be inverted with just one very large producer organism but with many primary and secondary consumers.
Which of GPP and NPP supports the consumers in an ecosystem?
The consumers in an ecosystem are supported by the net primary production (NPP) in an ecosystem.
Give an example of a limiting factor for primary productivity in:
a desert ecosystems
A limiting factor for primary productivity in a desert ecosystem is the availability of water.
Give an example of a limiting factor for primary productivity in:
b tropical rainforest ecosystems.
A limiting factor for primary productivity in a tropical rainforest ecosystem is the availability of light.
Explain the equation: NPP = GPP – R.
GPP (gross primary production) is the total organic matter produced by the producers in an ecosystem.
NPP (net primary production) is the remainder after the producer’s own energy needs through cellular respiration has been met.
R is the organic matter used in cellular respiration by the producers.
The equation NPP = GPP – R shows this relationship.
From where do the hydrothermal bacteria obtain energy to make organic matter?
The chemosynthetic bacteria in hydrothermal vent ecosystems make organic matter using energy released by reactions involving inorganic matter. For example, chemosynthetic sulfur bacteria use the energy released from the oxidation of hydrogen sulfide to sulfur.
What is the source of carbon atoms in both photosynthesis and chemosynthesis?
In both photosynthesis and chemosynthesis, the source of carbon atoms is carbon dioxide.
Give an example of the following:
an inorganic form in which carbon atoms can be present
Inorganic forms of carbon include carbon dioxide.
Give an example of the following:
an organic form in which nitrogen atoms can be present.
Nitrogen is present in organic form in amino acids and in proteins.
Identify a cycle that fits the following:
one that depends on the action of many kinds of bacteria
The nitrogen cycle depends on the action of many kinds of bacteria including:
• nitrogen-fixing bacteria to convert nitrogen from the air to ammonium ions
• nitrifying bacteria to convert ammonium ions to nitrates and nitrites
• decomposer bacteria to convert organic nitrogen to an inorganic form.
Identify a cycle that fits the following:
one that does not involve the atmosphere as a store.
The phosphorus cycle does not involve the atmosphere as a gaseous store of the element concerned
Chemical A is water-soluble and can be excreted; chemical B dissolves in lipids and is non-biodegradable. Which would be expected to accumulate?
Because chemical B is not biodegradable, if it is present in an ecosystem, it will tend to persist. So, chemical B would be expected to accumulate in body tissues because it can dissolve in lipids. Since chemical B is not water soluble, it cannot be readily excreted from the body.
Which group of organisms in an ecosystem would be expected to have the highest accumulation of a persistent chemical? Explain.
The highest accumulation of a persistent chemical in an ecosystem would be expected in the highest order consumers. An increasing concentration or bio-accumulation of a persistent chemical occurs as the trophic level of an organism increases. This is due to the fact that each gram of tissue built up at one trophic requires the consumption of 10 times that amount of tissue from the trophic level below it
What are the three parts of a ecosystem?
- The community
- Its Physical Surroundings
- Interactions within and between them
Biosphere
A name for all ecosystems on earth. It can also be described as being made up of a series of terrestrial and aquatic biomes (major ecological groupings)
Define biome
a large naturally occurring community of flora and fauna occupying a major habitat, e.g. forest or tundra.
Types of Aquatic Biomes
- Lakes
- Oceans
- Rocky Shores