Daily Quiz: UPSC Prelims Marathon- September 29

• Mid-Ocean Ridge Volcanoes: These volcanoes occur in the oceanic areas on the system of mid-ocean ridges that stretches through all the ocean basins. The central portion of this ridge experiences frequent eruptions.
• Composite volcanoes: These volcanoes are characterized by eruptions of cooler and more viscous lavas than basalt. These volcanoes often result in explosive eruptions. Along with lava, large quantities of pyroclastic material and ashes find their way to the ground. This material accumulates in the vicinity of the vent openings leading to formation of layers, and this makes the mounts appear as composite volcanoes.
• Cinder cone volcanoes (also called scoria cones) are the most common type of volcano and are the symmetrical cone shaped volcanoes. They may occur as single volcanoes or as secondary volcanoes on the sides of stratovolcanoes or shield volcanoes.

Shield Volcanoes: These volcanoes are mostly made up of basalt. For this reason, these volcanoes are not steep. They become explosive if somehow water gets into the vent; otherwise, they are characterized by low-explosivity. Ex. Hawaiian volcanoes. The upcoming lava moves in the form of a fountain and throws out the cone at the top of the vent and develops into cinder cone.

Discontinuities are expressed as follows –

1.Gutenberg discontinuity -Between outer liquid core and the solid mantle

2. Mohorovicic discontinuity-Between crust and asthenosphere

3. Conrad discontinuity- Between oceanic (Basaltic or SIMA layer) and continental (Granites or SIAL layer) Crust- Up to 30-40 km beneath the continents (greater depth in mountainous regions). 10 km deep beneath the oceans

Jet streams are fast flowing, narrow, meandering air currents found in the atmosphere, jet streams are located near the altitude of the Tropopause and are westerly winds (flowing west to east).

The Factors which affects the flow of Jet stream are:

• The atmospheric heating by solar radiation that produces the large scale Polar, Ferrel, and Hadley circulation cells.
• The Coriolis force is caused by the planet’s rotation on its axis also plays an important role.
• Landmasses interrupt the flow of the jet stream through friction and temperature differences. So the jet stream meanders across the earth, like a river meanders before it reaches the sea. The meandering sections of the jet stream continue to change as they interact with landmasses once again, creating an ever-changing state of flux and subsequent temperature differences.

A jet stream forms high in the upper troposphere between two air masses of very different temperature. The greater the temperature difference between the air masses, the faster the wind blows in the jet stream.

• The ‘tide-generating’ force is the difference between these two forces; i.e. the gravitational attraction of the moon and the centrifugal force.
• Normally, there is a seven day interval between the spring tides and neap tides.
• At this time the sun and moon are at right angles to each other and the forces of the sun and moon tend to counteract one another.
• When the earth is closest to the sun (perihelion), around 3rd January each year, tidal ranges are also much greater, with unusually high and unusually low tides.

When the earth is farthest from the sun (aphelion), around 4th July each year, tidal ranges are much less than average

Statement 1 and 2 is correct”

• Eco-Sensitive Zone is created to act as a buffer for further protection around Protected Areas (PAs) such as National Parks and Wildlife sanctuaries.
• The Environment Protection Act, 1986 does not mention the word “Eco-sensitive Zones”.The section 3(2)(v) of the Act, says that Central Government can restrict areas in which any industries, operations or processes or class of industries, operations or processes shall not be carried out or shall be carried out subject to certain safeguards

Statement 3 is incorrect:

ESZ Guidelines classify activities under three categories:

• Prohibited:Commercial Mining, Setting of Saw Mill, Setting of industries causing pollution, establishment of major hydroelectric projects etc.
• Regulated: Felling of Trees, Establishment of hotels and resorts, erection of electrical cables, Drastic change of agricultural systems etc.

Permitted : Ongoing agriculture and horticulture practices by local communities, rain water harvesting, organic farming etc.

All are incorrectly matched.

• The Irminger Currentis a north Atlantic ocean current setting westward off the southwest coast of Iceland.
• The Humboldt Current System (HCS),also called the Peru Current, is a major Eastern Boundary Upwelling Ecosystem that flows north along the western coast of South America.
• The Agulhas Return Current(ARC) is an ocean current in the South Indian Ocean.

• The tundra climate is characterized by a very low mean annual temperature.
• In mid-winter temperatures are as low as 40 – 50 °C below freezing.
• There are no trees in the tundra (Ground is frozen). Lowest form of vegetation like mosses, lichens are found here and there.
• Coastal lowlands support hardy grasses and the reindeer moss which provide the only pasturage for reindeers.
• In the brief summer, berry-bearing bushes and Arctic flowers bloom.
• In the summer, birds migrate north to prey on the numerous insects which emerge when the snow thaws.
• Insects have short life cycles which are completed during favourable period of the year.
• Animals like the reindeer, arctic fox, wolves, musk-ox, polar bear, lemming, arctic hare, arctic willow  live in tundra region.
• Reptiles and amphibians are almost absent.
• Most of the animals have long life e.g. arctic willow has a life span of 150 to 300 years.
• They are protected from chillness by the presence of thick cuticleand epidermal hair or fur.
• Mammals of the tundra region have large body size and small tail and ear to avoid the loss of heat from the surface [less surface area = less heat loss = less food required to produce heat.