Ecosystems and Biodiversity Questions and Answers

Answer: A

The pyramid of energy cannot be inverted.

Energy is lost as heat at every step of a food chain, so each higher level always has less energy than the level below it. The pyramid of energy is therefore always upright.

The pyramids of number and biomass can be inverted, as when one tree feeds many insects (number) or when phytoplankton, which grow and are eaten fast, hold less biomass than the zooplankton eating them. Dry weight is a measure of biomass and behaves like it.

Answer: B

Temperature is responsible for cyclomorphism.

Cyclomorphism is the cyclic change in the form of an organism over the seasons, as in the water flea Daphnia, which grows a taller helmet in warm water. The changes follow the seasonal change in temperature, which affects the density and viscosity of the water.

Moisture, photoperiod and wind are not named as the cause of this change in form.

Answer: A

Clostridium is the anaerobic soil bacterium.

Clostridium species grow only without oxygen and form spores that survive in soil, so they are obligate anaerobes.

Azotobacter is an aerobic nitrogen fixer, Bacillus species are aerobic or facultative spore formers, and Thiobacillus oxidises sulphur compounds in the presence of oxygen, so none of them is a strict anaerobe.

Answer: A

The lichen and moss stages occur in a lithosere.

A lithosere is a succession that starts on bare rock. Crustose lichens are the pioneers, which are followed by moss, then herbs, shrubs and trees.

A psammosere starts on sand, and a hydrosere starts in water, where its early stages are plankton and submerged plants. Hydrarch is the general term for succession beginning in water, so it does not name the rock succession.

Answer: C

The Ramsar Convention on Wetlands was held in 1971 and came into force in 1975, option (C). It was adopted in the Iranian city of Ramsar on 2 February 1971, which is why World Wetlands Day is observed on that date, and it entered into force four years later after enough countries had joined. The pairs 1951 and 1955 (A), 1961 and 1965 (B) and 1981 and 1985 (D) are a decade too early or too late.

Answer: B

The relationship in which one organism gains at the cost of the other is parasitism, option (B). The parasite lives on or in the host and feeds on it, and the host is harmed though usually not killed at once. In predation (A) the predator kills and eats the prey, and scavenging (C) is the feeding on dead remains. Symbiosis (D) is a close association in which both partners usually benefit, so it is not a relation in which one loses.

Answer: A

Species diversity increases as one proceeds from higher to lower altitude and from higher to lower latitude, option (A). Diversity is greatest in the warm, stable and productive tropics near the equator and falls towards the poles, and it also falls as one climbs a mountain because temperature drops and conditions grow harsher. Options (B), (C) and (D) state that diversity rises with altitude or with latitude, or both, and they are the opposite of the observed pattern.

Answer: D

The mountain gorilla is not an IUCN-designated threatened species found in India, option (D). It lives in the mountain forests of Central Africa, in Rwanda, Uganda and the Democratic Republic of the Congo. The Asiatic lion (A), the Bengal tiger (B) and the Indian white-rumped vulture (C) are all listed as threatened by the IUCN and occur in India.

Answer: C

The open ocean has the lowest net primary production per square metre among the ecosystems listed, option (C). Its surface water is poor in nutrients such as nitrogen and phosphorus, so the phytoplankton are few for the area, even though the ocean as a whole is huge. A grassland (A) is moderately productive, and a coral reef (B) and a tropical rain forest (D) are among the most productive ecosystems on Earth.

Answer: C

The establishment of a species in a new area is called ecesis, option (C). It is the stage in ecological succession at which the seeds or propagules that have arrived germinate, grow and reproduce successfully in the new place. Stabilisation (A) is a later stage of succession when the community is steady, aggregation (B) is the grouping of the individuals of a species, and migration (D) is the arrival of the propagules or the movement of the organisms, before they are established. The word comes from the Greek for a dwelling or home, and it names the first step of settling in the new site.