12th Class Biology Chapter 12 Some Major Ecosystems Short Questions Answer

The angular distance on a meridian north or south of the equator,expressed in degrees and minutes is called latitude.While height in relation to equator is called altitude.

The open water area is divided into two regions;the upper Limnetic zone and the lower profundal zone.

Hydrospheric ecosystem is a system in water where living and non-living components exchange material and transfer of energy also takes place within place within water.

Living among the anchored plants are microscopic organisms called plankton.Simply the small floating organisms aare known as plankton.These can be divided into two groups. 1) Phytoplankton: They include photosynthetic protista bacteria and algae. 2) Zooplankton: Such as protozoa and tiny curstaceans.

Decomposers and detritus feeders such as snails and certain insect larvae bacteria fungi and fishes are present in it.

It is further sub-divided into; i) Tropical Rain forests ii) Temperate Deciduous forest iii)Coniferous Alpine and Boreal forests.

Some very common animals are Macaca mulatta Solenorotos tibitanus Felis bengalensis deer and wolves with various types of micro-organisms to convert the litter into organic matter such as bacteria fungi and earthworms.

In Pakistan these forest are in upper Kaghan Dir and chilas malam jaba in Swat valley.In world they stretch across Eurasia and North America.Canada just south of the tundra.

Grassland ecosystems are found is Gilgit ,Kashmir ,Waziristan,lower Chirtral and North Kallat.

Layering is the characteristic of grassland.Tall grasses from the first layer mid high gresses form teh second layer and third layer is formed by short grasses and forbs warfare species with mosses and lichens.

Productivity can be defined as the rate of production of new biomass during the period under consideration.Productivity is generally expressed in terms of grams or kilocalories per sq.meter or hector per sq.meter per year.

i) Littoral zone – Shallow water area. ii) Limnetic zone – Open water area with light penetration. iii) Profunbdal zone – Deep dark water area without light penetration.

10 biomes are present in the world e.g. Tropical rain forest Tropical decidouous forest Tropical scrub forest Savanna Temperate grassland Temperate deciduous forest Desert Taiga Tundra and Chaparral.

i) Temperate Deciduous forest. ii)Coniferous Alpine and Boreal forests. iii) Grass land ecosystem. iv) Desert ecosystem. v) Tundra ecosystem.

Major requirements for life are: i) light ii) Nutrient iii) water iv) Temperature v) Air

Weather refers to short-term fluctuations in temperature humidity cloud cover wind and precipitation over periods of hours or days.Climate in contrast refers to overall patterns of weather that prevail from year to year even century-to-century in a particular region.

In this zone the water is shallow and plants find abundant light anchorage and adequate nutrients from the bottom sediments.

In Pakistan temperate moist conditions are present in Neelam valley and Shogran.These forests originally covered India Southeast Asia, Eastern North America, Europe, China, Australia japan,North and South America.

The average rainfall is between 750-1500 mm.Moderate temperature ranges from 4ᵒC – 30ᵒC.

Some dominant trees are:Taxus baccata, Pinus wallichiana, Berberis lyceum usually with height 8 to 30 meters.

Northern coniferous forests are also called Taiga.

Coniferous forests located at high altitude are called alpine while coniferous forests located at high latitude are called boreal.

Large mamals bison wolf black bear deer marco polo sheep and smaller animals such as small Kashmir flying squirrel snowshoe hare wolverine crossbills are present.

Plants like pinus wallichiana pinus roxburgii abies pindrow Picea smithiana Cederous deodara are present.

Grasslands present in temperate climates are also called Prairies such as prairies of North America pampas of Argentina.These grasslands do not have woody plants so they are know as prairies.

The grasslands in tropic climates have woody trees and are called Savanna.

Annual rainfall is about 250 to 750 mm.The grasslands usually face severe rains, which in tropical and subtropical grassland reaches about 1500 mm.

The predators are reptiles amphibians and mammals such as lizards toads and turtles prey on insects.Foxes and wolves among mammals are very common.

In temperate grassland the rate of primary production is about 700 – 1500 g/m annually.In sub humid tropical grassland it is more than 4000 g/m.

In Pakistan the desert ecosystems are found in western punjab where it is known as Thal. In southern punjab areas like fort abbas Bahawal nagar Yazman Bahawal pur khan pur and Rahim yar khan also have deserts.In Sindh this desert ecosystem is called Thar.

While human activities are reducing the extent of many biomes they are causing the spread of deserts a process called desertification.

It is used to describe types of vegetation in treeless high latitudes between taiga and polar ice caps and at high altitude across the mountain above timberline such as mountain of Karakorum and Koh Hindukush in Pakistan.

The ground is carpeted with small perennial flowers and dwarf willows on more than a few centimetres tall often with large lichen called rein deer moss.

The standing pools provide superb mosquito habitat.The mosquitoes and other insects provide food for numerous birds.The tundra vegetation supports lemmings which are eaten by wolves snowy owls arctic foxes and even grizzly bears.

The ecosystem present on land or soil is called terrestrial or lithospheric ecosystem.

The floating plants are called phytoplankton while floating animals are called zooplankton.

These are the weather and the climate.

Weather means short-term fluctuations in temperature, humidity, cloud cover, wind and precipitation (rainfall) of a locality over periods of hours or days.

Climate means the overall patterns of weather that prevail from year to year and country to country.

These are the aquatic or hydrospheric ecosystem and the terrestrial or land or lithospheric ecosystem.

Fresh water, marine water and land comprise 1%, 71% and 28% of earth’s surface, respectively.

The depth is beyond 600 feet.

In the aquatic ecosystem, the nutrients are concentrated near the bottom sediments supporting life, where light is too little to allow photosynthesis.

These factors are the energy and nutrients.

Productivity can be defined as the rate of production of new biomass (photosynthate) during the period under consideration. It is indicated by the consumption of CO₂ and evolution of oxygen in the process of photosynthesis.

Aquatic ecosystem is classified into fresh-watered and marine ecosystems.

It is the light (solar energy).

These are the littoral zone, the limnetic zone and the profundal zone.

It is the shallow water region near the edge of the lake, with light penetrating to the bottom.

Plankton is the large community of the floating or drifting organisms, mostly microscopic. It is of two kinds viz. phytoplankton and zooplankton.

A group of floating animals is known as the zooplankton.

The phytoplankton’s of the littoral zone of the lakes consist of photosynthetic Protista, bacteria and algae whereas the zooplanktons include protozoans and tiny crustaceans.

The littoral invertebrates include crustaceans, insect larvae, snails, flatworms and Hydra etc., whereas the vertebrates are the frogs, aquatic snakes and turtles etc.

This is the open water zone away from the edge of the lake to the depth of effective light penetration.

These are the cyanobacteria (blue-green algae).

This is the zone of deep water of the lake, below the limnetic zone, beyond the reach of light penetration, whereas the common animals are black bear leopard cat deer, wolf and rhesus monkey. This zone is obviously absent in ponds and shallow lakes.

Since the profundal zone is a dark zone, its inhabitants depend for food (detritus) on the littoral and limnetic zones.

The decomposers and detritus feeders of the profundal zone are the bacteria, fungi, insect, larvae, snails and fishes.

These adaptations are the supporting tissue, conservation of water and regulation of temperature.

The supporting structures of the plants are the xylem and phloem (supporting tissues) and that of animals is the skeleton.

These structures are the bark in plants and sin in animals.

The temperate deciduous forests are found in areas with abundant evenly distributed rainfall (750 to 1500mms annual) and moderate temperature.

The common trees in these valleys are Taxus baccata, Pinus wallichiana and Berberis lyceum, whereas the common animals are black bear, leopard cat deer wolf and rhesus monkey.

It is comprised of grasses, other herbaceous plants and ferns.

The soil of temperate deciduous forest is grayish brown, very fertile, rich in organic matter and has great water holding capacity.

The coniferous forests are of two kinds, alpine and boreal, of which the former are located at high altitude and the latter at high attitude.