Ecosystems and Biodiversity Questions and Answers

Answer: A

They are ecotypes (printed 'Ecotypics').

An ecotype, a term coined by Gote Turesson, is a genetically distinct population or subspecies within a species, adapted to a particular set of local conditions such as altitude, soil or climate. Ecotypes of the same species can interbreed, but keep their differences when grown together, showing they are genetic, not just responses to the environment.

A species is the whole interbreeding group, and genera are groups of species, so both are broader than subspecies. 'Bioacous' is not a term of ecology.

Answer: A

The keyed answer is National capital, as printed, which stands for natural capital.

In ecological economics, just as economic (manufactured) capital produces goods and services, natural capital, the stock of forests, soils, water, fisheries and the atmosphere, provides ecosystem services such as clean water, pollination, climate regulation and fertile soil.

Exponential expansion describes a pattern of growth, disposal is the getting rid of waste, and manufacturing is an economic activity. None of them is the ecological counterpart of economic capital.

Answer: A

The correct ecological spectrum is Gene → Cell → Organs → Organism → Population → Communities.

The levels of biological organisation run from the smallest to the largest: genes are carried in cells, cells form tissues and organs, organs make up an organism, organisms of one species form a population, and populations of different species living together form a community, which with its non-living environment forms an ecosystem.

The other sequences break this order: one puts the gene above the cell, one runs from the organism downwards and then jumps to the population, and one starts at the community and drops to genes and cells.

Answer: D

Denitrification is nitrates → nitrogen.

In denitrification, anaerobic bacteria such as Pseudomonas and Paracoccus use nitrate in place of oxygen for respiration, reducing it step by step (nitrate, nitrite, nitric oxide, nitrous oxide) to nitrogen gas, which returns to the atmosphere. It closes the nitrogen cycle and is used in wastewater treatment to remove nitrogen.

Organic matter to ammonia is ammonification (mineralisation). Ammonia to nitrites and nitrites to nitrates are the two steps of nitrification, carried out by Nitrosomonas and Nitrobacter.

Answer: C

The greatest mass extinction came at the end of the Permian period (printed 'Peronian').

The end-Permian extinction, about 252 million years ago, wiped out roughly 90 per cent of marine species and some 70 per cent of land vertebrate species. It is linked to the vast Siberian Traps volcanic eruptions, which caused global warming, ocean acidification and oxygen loss.

The end-Cretaceous extinction, which ended the dinosaurs, is the best known but smaller. The end of the Jurassic saw no comparable event, and the end of the Tertiary is not a major extinction boundary.

Answer: C

The benthic biota suffer most.

In a stratified, nutrient-rich lake, dead organic matter sinks and decomposes in the bottom water (the hypolimnion), using up the dissolved oxygen. Because this layer is cut off from the air, it becomes anoxic, and the animals living on or in the bottom sediments, such as insect larvae, worms, molluscs and bottom-feeding fish, suffer or die.

Floating and surface organisms live in the upper water, which stays in contact with the air and with photosynthesising algae, so it keeps its oxygen. 'Peripheral' is not a standard lake community in this sense.

Answer: A

PCR is used to study genetic diversity.

The polymerase chain reaction amplifies chosen stretches of DNA from tiny samples, and almost every molecular marker used to measure genetic diversity depends on it: RAPD, AFLP, microsatellites (SSRs) and DNA barcoding. Comparing the amplified fragments shows how much variation exists within and between populations and species.

RNA, mRNA and tRNA are kinds of molecule, not methods. Messenger RNA carries the code from DNA to the ribosome and transfer RNA brings amino acids to it; neither is a technique for measuring diversity.

Answer: A

The life zone system was proposed by Holdridge.

Leslie Holdridge published it in 1947. It classifies vegetation formations by three climatic variables, mean annual biotemperature, annual precipitation and the ratio of potential evapotranspiration to precipitation, drawn on logarithmic axes as a triangle of hexagons, with latitudinal regions and altitudinal belts along the sides.

Robert Whittaker (printed 'Wittakar') is known for his biome diagram of temperature against precipitation, Frederic Clements for the theory of succession and the climax, and Eugene Odum for ecosystem ecology. None devised the life zone system.

Answer: A

Such a community is a climax community.

Ecological succession ends in a community that is stable, self-perpetuating and in equilibrium with the regional climate and soil. F.E. Clements called it the climax; its species composition changes little as long as conditions stay the same.

Seral communities (printed 'Serol') are the intermediate, changing stages of a sere, and the pioneer community is the very first to colonise bare ground. A mixed community is simply one with several dominant species and says nothing about stability or equilibrium.

Answer: B

The key gives tropical countries.

Most of the world's endangered plants and animals live in the species-rich tropics: tigers, rhinos, pangolins, great apes, parrots, orchids and tropical timbers. Poaching and illegal collection, the supply end of the trade, are concentrated there, helped by long forest frontiers, poverty and weak enforcement, which makes tropical countries the place where the illegal trade is most prevalent.

Developed and industrialized countries, many of them temperate, are largely the markets that buy the products, but the trade as practised, from poaching to smuggling out, is centred in the tropical source countries.