Principles of Ecology Trivia Quiz

Answer: All the individuals of one species in an area at a given time

In more general usage the word population refers to the number of species, usually humans, present in anything from a village to the global community. In ecology, the term is far more precise. Whereas in everyday usage the population of a village would stay the same even if someone has gone on vacation, for example, in ecology this just isn't the case. For an individual to be included in ecological population statistics, the individual must be in the area at the time.

The sum of all living organisms in an area is the definition of a 'community'. All biotic and abiotic factors in an area defines an 'ecosystem' and the sum of all conditions in an ecosystem is the 'environment'. All of these are standard definitions and can be found in a variety of biology and ecology text books or scientific journals.

Answer: Niche

This standard textbook definition gives a general description of how an organism lives and feeds in a particular habitat. It is essentially the basis of ecology in that the niche of a particular organism shows how a population interacts with the surroundings.

This is very similar, if not identical, to its everyday counterpart which describes the purpose of an individual or a business in society.

Answer: Succession

Succession is at the very heart of ecology and it often begins with a colonising species settling in a harsh area. Such species are usually autotrophic (self-feeding) by means of photosynthesis, for example. These colonies die and provide essential nutrients for new species to survive in the area.

This cycle eventually encourages more and more species to establish a population in the area and diverse communities are then formed. An example of succession would be microscopic organisms in mud deposits at a river's mouth. Upon death, these provide nutrients and organic matter to the mud such that small plants can grow.

The cycle continues until you have a diverse range of flora and fauna.

Answer: Pioneering Species

Pioneering species are usually microorganisms that colonise in extreme conditions in which most species would not be able to survive. Due to the lack of nutrients in the area the microorganisms (pioneering species), such as phytoplankton, often have to create their own food by photosynthesising.

The succeeding species are all created using the foundations of the pioneers and environmental stability is generally the end result.

Answer: Climax Community

Climax communities tend to be very stable due to the number and diversity of species present. All organisms must get their energy from food and those organisms who cannot photosynthesise must do so by feeding on other organisms. So, in stable climax habitats, there are more complex food webs such that if one species of plant dies out there will be less of an effect on organisms who fed on that plant.

This is because they can feed on many other plants. Conversely, in a system where there isn't a great diversity of plants and animals, if one species dies out it has a huge ripple effect on organisms that feed on that species.

Answer: Quadrat

Quadrats are useful in sampling techniques when trying to establish the frequency and population of a particular species of plant in a specific area. It is also useful in ecological sampling to determine how diverse an area is. Quadrats can further be used in a specific type of transect which monitors the succession across a large area such as a sand dune or coastline.

Answer: Detritus food chain

Detritus food chains are dependent upon two fundamental aspects - dead material and a saprophage. Saprophages, like woodlice and millipedes, are generally classed as primary consumers (a specific trophic level). The general order of trophic levels are as follows: producer, primary consumer, secondary consumer, tertiary consumer and so on. It will carry on until the energy provided by feeding on the trophic level below is very limited (energy gained decreases further along the chain).

Grazing food chains usually start with a photosynthesising plant as the producer and the chain from there on is rather similar to that of a detritus food chain. The main difference between the two chains however is at the starting points; one begins with self-feeding plants and the other with dead material.

Answer: False

Heterotrophs are organisms that feed on other organisms. Organisms that self-feed are actually known as autotrophs. Autotrophs are more often than not photosynthesising plants. The general idea of photosynthesis is that the plant uses carbon dioxide (CO2), water (H2O) and light to produce glucose and a by-product of oxygen (O2).

As this process uses light, plants are described as photoautotrophs. In more recent times, scientists have discovered other autotrophs that do not require sunlight to photosynthesise.

This exciting biological discovery showed that many microorganisms such as the single-celled archaea (also found in less harsh environments) could self-feed but by chemosynthesis. They gained the necessary inorganic raw products from deep sea thermal vents called black smokers.

Answer: Lincoln Index

The Lincoln Index is as follows: [(number of individuals caught at first attempt) x (number of individuals caught at second attempt)] / (number of individuals caught on both occasions). As you can see from this, the marking of the organisms is important as it allows us to see both how mobile the population is and ultimately how large the population is. If you catch a great number of already marked individuals on your second attempt, the population is generally smaller and vice versa.

Ethical considerations include the need for inconspicuous marking of the organisms as it could lead them to be more obvious to predators.

Answer: Simpson's Index

There are three closely linked indices that go by this name including Simpson's Index, Simpson's Index of Diversity and Simpson's Reciprocal Index.

Simpson's Index measures the probability that two organisms that are picked by a random sampling process belong to the same species. The index of diversity measures something very similar to the index above, but, this time the probability relates to picking individuals of different species. The reciprocal index just inverts the calculations so that instead of getting a value of biodiversity between zero and one*, (which is always the result of the first two indices), the value is from one upwards.

*The scale of zero to one quantitatively displays whether a particular area is diverse (one) or not (0). Of course, there are very many values in between.

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