Ecosystems and Biodiversity Questions and Answers

Answer: D

Genetic diversity is the sum of total genetic information in genes of individuals of a species.

Genetic diversity is the variation in genes within a species: the different alleles carried by its individuals and populations, together making up its gene pool. It is what allows a species to adapt, and it is why, for example, India has thousands of rice varieties.

Chromosome number is fixed for a species (46 in humans), so counting chromosomes in an individual or a species measures no diversity at all. The genes in a single individual are only that individual's genome; diversity arises from the differences between individuals, which is why the definition must cover all the individuals of the species.

Answer: A

The water body is an Estuary.

An estuary is the partly enclosed coastal water at the mouth of a river where fresh river water meets and mixes with salt sea water, giving brackish conditions and strong tidal influence. Estuaries trap nutrients and sediments, support mangroves and are nursery grounds for many fish, as at the Hooghly and the Narmada mouths.

A coast is the land along the sea, and a river bank is the land along a river, neither a body of water. Lakes are inland water bodies, usually fresh, not open to the tides.

Answer: A

A taxon confined to one particular geographical region is called endemic.

Endemism describes distribution: the species, genus or family occurs naturally in that region and nowhere else, such as the lion-tailed macaque of the Western Ghats.

The other three are IUCN threat categories that describe risk of extinction, not range. 'Low risk' was an older category for taxa not threatened, 'Threatened' groups the vulnerable, endangered and critically endangered categories, and 'Critically endangered' is the highest risk short of extinction in the wild. An endemic species may or may not be threatened.

Answer: C

The sequencing of rRNA led to the three domains.

Carl Woese and George Fox compared sequences of small-subunit ribosomal RNA (16S in prokaryotes) in the 1970s. rRNA suits this because every cellular organism has it, it performs the same function everywhere, and it changes slowly. The comparisons showed that methanogens and their relatives were as distinct from bacteria as from eukaryotes, giving the domains Bacteria, Archaea and Eukarya.

DNA in general was not the marker used. Cytochrome c and haemoglobin are proteins limited to some lineages (haemoglobin to a few) and were used for trees within eukaryotes, not to define domains.

Answer: A

The key's answer is that detrital food webs can contribute energy to grazing food webs.

An earthworm feeds on dead organic matter, so it belongs to the detrital food web, which starts from detritus rather than living plants. A robin is a predator in the grazing web. When the robin eats the earthworm, energy that entered the system as detritus passes into the grazing food web, showing that the two webs are linked.

The reverse direction, grazing to detrital, happens when organisms die or excrete, not here. The earthworm is a detritivore, not a herbivore, so the eating is not a transfer from producers to primary consumers, nor from primary to secondary consumers of the grazing chain.

Answer: D

The sedimentary cycle is the phosphorus cycle.

Biogeochemical cycles are classed as gaseous, with the atmosphere or ocean as reservoir, or sedimentary, with the earth's crust as reservoir. Phosphorus has no significant gaseous phase. Its reservoir is phosphate rock and sediments, from which it is released slowly by weathering, used by organisms, and returned to ocean sediments.

The carbon and nitrogen cycles are gaseous cycles with large atmospheric pools of CO₂ and N₂, and the hydrologic cycle cycles water through the atmosphere and oceans. Sulphur is often described as intermediate, with both gaseous and sedimentary phases.

Answer: D

M-STrIPES is associated with the maintenance of tigers.

M-STrIPES (Monitoring System for Tigers: Intensive Protection and Ecological Status) is the software-based patrolling and monitoring system of the National Tiger Conservation Authority. Forest staff record patrol routes, wildlife sightings and threats with GPS devices, so tiger reserves can be protected and their ecological status tracked.

It has nothing to do with captive breeding. India's satellite navigation system is NavIC (IRNSS), and highway security is not its purpose.

Answer: A

Mangrove swamps are found along tropical and subtropical coastlines.

Mangroves are salt-tolerant trees and shrubs of the intertidal zone, roughly between latitudes 30° N and 30° S. They need warm water and air (they do not survive frost), and grow best on sheltered, muddy shores, estuaries and deltas, such as the Sundarbans of the Ganga-Brahmaputra delta.

Rocky, exposed coastlines lack the soft sediment their roots need. Temperate and arctic coasts are too cold, and there salt marshes occupy the equivalent intertidal niche.

Answer: D

The lotic ecosystem is the river.

Freshwater ecosystems are divided into lotic (from Latin lotus, washing), with flowing water, and lentic, with standing water. Rivers and streams are lotic: unidirectional current, high oxygen and organisms adapted to cling or swim against the flow.

Lakes, ponds and pools are all lentic, still-water systems, with layering by temperature and light, and plankton-based food webs.

Answer: D

The intertidal zone is a zone between low and high tides.

Also called the littoral zone, it is the strip of shore covered at high tide and exposed at low tide. Its organisms, such as barnacles, mussels, limpets and seaweeds, must cope with drying, wave action and swings in temperature and salinity.

Deep water and the open sea (the pelagic zone) lie well beyond it, and the intertidal zone is defined by tide levels, not by sediment, since many intertidal shores are rocky.