Wednesday, 24 June 2015

Environment & Ecology

NCERT Class - XII Biology Chapter - 14: Ecosystem - http://schools.aglasem.com/18719

1. Consider the following statements
  1. Sun is the only source of energy for all ecosystems on Earth
  2. Of the incident solar radiation more than 50 per cent of it is Photosynthetically Active Radiation (PAR)
Select the correct code
1. Only 1
2. Only 2
3. Both
4. None

Solution: 4
Explanation: Except for the deep sea hydro-thermal ecosystem, sun is the only source of
energy for all ecosystems on Earth. Of the incident solar radiation less than 50 per cent of it
is photosynthetically active radiation (PAR).
The largest source of energy for an ecosystem is the sun. Energy that is not used in an ecosystem is eventually lost as heat.

Photosynthetically active radiation, often abbreviated PAR, designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to the human eye. Photons at shorter wavelengths tend to be so energetic that they can be damaging to cells and tissues, but are mostly filtered out by the ozone layer in the stratosphere. Photons at longer wavelengths do not carry enough energy to allow photosynthesis to take place.

  • Phytoplankton are the autotrophic components of the plankton community and a key factor of oceans, seas and freshwater basin ecosystems. The name comes from the Greek words φυτόν (phyton), meaning "plant", and πλαγκτός (planktos), meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye. However, when present in high enough numbers, some varieties may be noticeable as colored patches on the water surface due to the presence of chlorophyll within their cells and accessory pigments such as phycobiliproteins, xanthophylls, etc.) in some species.
  • Phytoplankton are photosynthesizing microscopic organisms that inhabit the upper sunlit layer of almost all oceans and bodies of fresh water. They are agents for "primary production," the creation of organic compounds from carbon dioxide dissolved in the water, a process that sustains the aquatic food web.Phytoplankton obtain energy through the process of photosynthesis and must therefore live in the well-lit surface layer (termed the euphotic zone) of an ocean, sea, lake, or other body of water. Phytoplankton account for half of all photosynthetic activity on Earth. Their cumulative energy fixation in carbon compounds (primary production) is the basis for the vast majority of oceanic and also many freshwater food webs (chemosynthesis is a notable exception). The effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Changes in the vertical stratification of the water column, the rate of temperature-dependent biological reactions, and the atmospheric supply of nutrients are expected to have important effects on future phytoplankton productivity. Additionally, changes in the mortality of phytoplankton due to rates of zooplankton grazing may be significant. As a side note, one of the more remarkable food chains in the ocean – remarkable because of the small number of links – is that of phytoplankton-feeding krill (a crustacean similar to a tiny shrimp) feeding baleen whales.
  • Some examples of phytoplankton are diatoms and dinoflagellates, which are responsible for seasonal algae blooms. Zooplankton are consumers that eat other plankton. Examples include copepods, krill, daphnia and jelleyfish(it is also a plankton).
  • Phytoplankton - Plankton that consists of minute plants and other photosynthetic organisms, including cyanobacteria, diatoms, and dinoflagellates.
2. Arrange the following in increasing order of ‘Productivity in Ecosystem’ (metric tonne per year)

  1. Woodland and shrubland < tropical rain forest < Continental shelf < Open sea
  2. Continental shelf < Woodland and shrubland < Tropical rain forest < Open ocean
  3. Tropical rain forest< Continental shelf< Woodland and shrubland < Open ocean
  4. Woodland and shrubland < Continental shelf < Tropical rain forest < Open ocean

Select the correct codes

  1. 1
  2. 2
  3. 3
  4. 4
Solution: 4


In ecology, productivity or production refers to the rate of generation of biomass in

an ecosystem. It is usually expressed in units of mass per unit surface (or volume) per unit
time, for instance grams per square metre per day (g m^−2d?^-1). The mass unit may relate
to dry matter or to the mass of carbon generated. Productivity of autotrophs such as
plants is called primary productivity, while that of heterotrophs such as animals is
called secondary productivity.

3. Consider the following statements about ecological pyramids
  1. Grassland and forest ecosystem have similar Pyramid of Numbers.
  2. Pyramid of Biomass is the most accurate among three ecological pyramids-Number, Biomass and Energy.
  3. Pyramid of Energy is always upright in nature irrespective of type of ecosystem.
Select the correct code
  1. 1 and 2
  2. 1, 2 and 3
  3. Only 2
  4. Only 3
Solution: 4
There are three ways an ecological pyramid can be represented. A Pyramid of Numbers can be generated by counting all the organisms at the different feeding levels. As you might
guess, this can be a very difficult task since we are not just identifying each species in the
ecosystem. We are also counting how many of each species is present. On occasion, this
approach will not work. For example, one tree (a producer) can represent an ecosystem
and harbor numerous populations of herbivores and carnivores. Thus, the bottom of the
pyramid would be very small and not flared out.
A second type of pyramid is called a Pyramid of Biomass where organisms are collected
from each feeding level, dried and then weighed. This dry weight (biomass) represents the amount of organic matter (available energy) of the organisms. [Note that there are
alternate, nonlethal ways to determine biomass.] While this approach will generally create a
pyramid that illustrates energy flow, its use can also produce an inverted pyramid. For
example, in aquatic ecosystems, phytoplankton could reproduce and then be eaten rapidly by zooplankton. Therefore, it would be possible to have few herbivores and a lot of carnivores when a collection is taken.
A third type of pyramid called a Pyramid of Energy Flow tends to resolve these problems.
This approach necessitates measuring the caloric value of the different organisms that make up the community. It nicely shows how energy is continually decreasing along the food chain from producers to top level carnivores.
The pyramids of numbers and biomass may be upright or inverted depending upon the nature of the food chain in the particular ecosystem, whereas pyramids of energy are always upright.
In a forest ecosystem, however, the pyramid of numbers is somewhat different in shape. The producers, which are mainly large-sized trees, are lesser in number, and form the base of the pyramid. The herbivores, which are the fruit-eating birds, elephants, deer’s etc. are more in number than the producers.

4. Which among the following can effectively be examples of ‘Secondary Succession’?
  1. Formation of a new Island after volcanic eruption
  2. The renewal of a forest after a fire
  3. A flooded land
  4. The renewal of a crop after harvesting
Select the correct option
  1. 1, 2 and 3
  2. 2, 3 and 4
  3. 1, 3 and 4
  4. All
Answer: 2
Examples of secondary succession include:
The renewal of a forest after a fire: The fire itself destroys a majority of different
types of trees and plant life. Because seeds and roots and other plant and tree parts
remain in and on the soil, gradually the plants and trees begin to grow again and
eventually return to the state of the original ecosystem.
The renewal of a crop after harvesting: A crop is completed harvested when it
becomes ripe. Without new seeds being planted, the crop can regenerate the
following year due to the plants and seeds that remained after harvesting.
A forest renews after logging: A large amount of trees were chopped down by
loggers in order to create building materials. Over time, trees grow in and the area
returns to its previous state.
Renewal after disease: A plant population can be very negatively affected by a
variety of infectious plant diseases. If the entire population dies, but the soil and
roots remain, it is possible for secondary succession to occur and for the population
of those plants to to return.
A flood can ruin farmlands. However, because the soil remains after the waters
recede, over the course of many years a natural secondary succession can occur and
the vegetation that had previously grown there can grow again.
Plants can be very susceptible to attack from pests, particularly if there is an
overpopulation of those pests. When this occurs, the plant population in one area
can be completely destroyed. However, when the pest overpopulation is resolved,
the plants are able to live again and thrive in the soil in which they previously had

5. If the concentration of oxygen gets doubled in the atmosphere, what can be the possible effects of the same?
  1. We will die young
  2. Most insects will grow bigger in size
  3. We will be less prone to sickness
  4. Our Vehicle will give better mileage
Select the correct option
  1. 1, 2 and 3
  2. 1, 3 and 4
  3. 1, 2, 3 and 4
  4. 2, 3 and 4
Answer: 3
  • More oxygen will generate more free radical that will exacerbate the aging process through Oxidative Stress. Oxidative Stress will interfere in numerous cellular processes like protein production, DNA replication etc. Hence age will get reduced.
  • Immune system will get a boost as a result of oxidation and hence will help in fighting diseases (Less sickness)
  • Many insects rely on gaseous diffusion for respiration therefore the maximum body size depends on the proportion of oxygen gas in the atmosphere. Hence size of insects will increase.
  • Oxygen-enriched air improves engine performance by producing hotter reactions and reducing the proportion of nitrogen, which reduces heat transfer and hence will give better mileage. 
Ecological Footprint
Human activities consume resources and produce waste, and as our populations grow and global consumption increases, it is essential that we measure nature’s capacity to meet these demands. The Ecological Footprint has emerged as one of the world’s leading measures of human demand on nature. Simply put, Ecological Footprint Accounting addresses whether the planet is large enough to keep up with the demands of humanity.

The Footprint represents two sides of a balance sheet. On the asset side, biocapacity represents the planet’s biologically productive land areas including our forests, pastures, cropland and fisheries. These areas, especially if left unharvested, can also absorb much of the waste we generate, especially our carbon emissions.

Biocapacity can then be compared with humanity’s demand on nature: our Ecological Footprint. The Ecological Footprint represents the productive area required to provide the renewable resources humanity is using and to absorb its waste.  The productive area currently occupied by human infrastructure is also included in this calculation, since built-up land is not available for resource regeneration.

Our current global situation: Since the 1970s, humanity has been in ecological overshoot with annual demand on resources exceeding what Earth can regenerate each year.

It now takes the Earth one year and six months to regenerate what we use in a year.

We maintain this overshoot by liquidating the Earth’s resources. Overshoot is a vastly underestimated threat to human well-being and the health of the planet, and one that is not adequately addressed.

By measuring the Footprint of a population—an individual, city, business, nation, or all of humanity—we can assess our pressure on the planet, which helps us manage our ecological assets more wisely and take personal and collective action in support of a world where humanity lives within the Earth’s bounds.

Conceived in 1990 by Mathis Wackernagel and William Rees at the University of British Columbia, the Ecological Footprint is now in wide use by scientists, businesses, governments, agencies, individuals, and institutions working to monitor ecological resource use and advance sustainable development.

6. The ecological footprint is a measure of human demand on the Earth’s ecosystems. It measures-
  1. How much of the biological capacity of the planet is demanded by a given human activity or population
  2. Ecological Footprints is calculated for overall activity of a nation or population and activities such as industrialization etc.
  3. The disadvantage of Ecological Footprint is that it cannot be calculated for individual people or area.
 Select the wrong statement/s
  1. 1 and 2
  2. Only 2
  3. 1 and 3
  4. Only 3
Answer: 1
Explanation: The Ecological Footprint is a resource accounting tool that measures how much biologically productive land and sea is used by a given population or activity, and compares this to how much land and sea is available. Productive land and sea areas support human demands for food, fibre, timber, energy, and space for infrastructure. These areas also absorb the waste products from the human economy. The Ecological Footprint measures the sum of these areas, wherever they physically occur on the planet. The Ecological Footprint is used widely as a management and communication tool by governments, businesses, educational institutions, and non-governmental organizations.

7. Which of the following describes the relationship of Mutualism?
  1. Pollination
  2. Rhizobium
  3. Human and Bacteria
  4. Zoochory
Select the correct code-
  1. 1, 2 and 3
  2. 3 and 4
  3. 2 and 4
  4. All
Answer: 4
Mutualistic Relationships
A mutualistic relationship is when two organisms of different species "work together," each benefiting from the relationship. One example of a mutualistic relationship is that of the oxpecker (a kind of bird) and the rhinoceros or zebra. Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control. Also, when there is danger, the oxpeckers fly upward and scream a warning, which helps the symbiont (a name for the other partner in a relationship).
Organisms in a mutualistic relationship evolved together. Each was part of the other's environment, so as they adapted to their environment, they "made use of" each other in a way that benefited both.
Here are three other examples of mutualistic relationships:

The bee and the flower. Bees fly from flower to flower gathering nectar, which they make into food, benefiting the bees. When they land in a flower, the bees get some pollen on their hairy bodies, and when they land in the next flower, some of the pollen from the first one rubs off, pollinating* the plant. This benefits the plants. In this mutualistic relationship, the bees get to eat, and the flowering plants get to reproduce.

The spider crab and the algae. Spider crabs live in shallow areas of the ocean floor, and greenish-brown algae lives on the crabs' backs, making the crabs blend in with their environment, and unnoticeable to predators. The algae gets a good place to live, and the crab gets camouflage.

The bacteria and the human. A certain kind of bacteria lives in the intestines of humans and many other animals. The human cannot digest all of the food that it eats. The bacteria eat the food that the human cannot digest and partially digest it, allowing the human to finish the job. The bacteria benefit by getting food, and the human benefits by being able to digest the food it eats.

A mutualistic relationship is when two organisms of different species "work together," each benefiting from the relationship. In mycorrhizal associations between plant roots and fungi with the plant providing carbohydrates to the fungus in return for primarily phosphate but also nitrogenous compounds.
Other examples include rhizobia bacteria that fix nitrogen for leguminous plants in return
for energy-containing carbohydrates
Pollination in which nectar or pollen (food resources) are traded for pollen dispersal (a
service) or ant protection of aphids, where the aphids trade sugar-rich honeydew (a byproduct of their mode of feeding on plant sap) in return for defense against predators such as ladybugs.
Zoochory is an example where animals disperse the seeds of plants. This is similar to
pollination in that the plant produces food resources (for example, fleshy fruit,
overabundance of seeds) for animals that disperse the seeds (service).
The bacteria and the human. A certain kind of bacteria lives in the intestines of humans and
many other animals. The human cannot digest all of the food that it eats. The bacteria eat
the food that the human cannot digest and partially digest it, allowing the human to finish
the job. The bacteria benefit by getting food, and the human benefits by being able to digest
the food it eats.

8. Bioluminescence is the production and emission of light by a living organism. Which of the following exhibit the phenomenon of Bioluminescence?
  1. Krill
  2. Fungi
  3. Bacteria
  4. Winged beetles
  5. Octopus
Select the correct code/s
  1. 1, 2, 4 and 5
  2. 1, 3, 4 and 5
  3. 2, 3, 4 and 4
  4. All
Answer: 4
Explanation: All are bioluminescent species. Winged Beetles are also called Fireflies. Specific types of bacteria and fungi show this property. The Bioluminescent Octopus, scientifically known as: Stauroteuthis syrtensis, is a deep sea species that has been relatively little studied. Krill are bioluminescent animals having organs called photophores that can emit light.

Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria and terrestrial invertebrates such as fireflies. In some animals, the light is produced by symbiotic organisms such as Vibrio bacteria.

9. A transition area between two adjacent but different landscape patches’ is called as
  1. Ecozone
  2. Ecoregion
  3. Ecotone
  4. Ecosystem
Answer: 3
Biome: A biome /ˈbaɪoʊm/ is a climatically and geographically contiguous area with similar climatic conditions, such as communities of plants, animals, soil organisms, and viruses.They are often referred to as ecosystems.

Major ecosystems, for example,parts of the earth have more or less the same kind of abiotic and biotic factors spread over a large area, creating a typical ecosystem over that area are referred to as biomes. Other defining factors of biomes can be things such plant structures (such as trees, shrubs, and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (such as a forest, woodland, or savanna), and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic, or historical similarities. Biomes are often identified with particular patterns of ecological succession and climax vegetation (quasiequilibrium state of the local ecosystem). An ecosystem has many biotopes and a biome is a major habitat type. A major habitat type, however, is a compromise, as it has an intrinsic inhomogeneity. Some examples of habitats are ponds, trees, streams, creeks, under rocks and burrows in the sand or soil.

Ecotone: An ecotone is a transition area between two biomes.It is where two communities meet and integrate. It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and grassland ecosystems). An ecotone may appear on the ground as a gradual blending of the two communities across a broad area, or it may manifest itself as a sharp boundary line.
The word ecotone was coined from a combination of eco(logy) plus -tone, from the Greek tonos or tension – in other words, a place where ecologies are in tension.

EcozoneAn ecozone is the broadest biogeographic division of the Earth's land surface, based on distributional patterns of terrestrial organisms.
Ecozones delineate large areas of the Earth's surface within which organisms have been evolving in relative isolation over long periods of time, separated from one another by geographic features, such as oceans, broad deserts, or high mountain ranges, that constitute barriers to migration.

EcoregionAn ecoregion (ecological region) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than an ecozone. All three of these are either less or greater than an ecosystem.[citation needed] Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions.

10. If you travel through the villages and interior of Central India and Northern India, the

traditional Water Harvesting System to be witnessed will be-

  1. Zing
  2. Johad
  3. Kunds
  4. Surangam
  5. Kere

Select the correct codes
  1. 1, 2, and 3
  2. 1, 3, 4 and 5
  3. 2, 4 and 5
  4. All
Answer: 1
Zing- Ladakh
Johad- Central India
Kunds- Rajasthan
Surangam- Western Ghats
Kere- Karnataka

11. Tropical cyclones occur in –
  1. tropics only
  2. tropics and sub tropics only
  3. subtropics only
  4. tropic, subtropics and extra-tropics
Answer: 4
In addition to tropical cyclones, there are two other classes of cyclones within the spectrum

of cyclone types. These kinds of cyclones, known as extratropical cyclones and subtropical
cyclones, can be stages a tropical cyclone passes through during its formation or
dissipation. An extratropical cyclone is a storm that derives energy from horizontal
temperature differences, which are typical in higher latitudes. A tropical cyclone can
become extratropical as it moves toward higher latitudes if its energy source changes from
heat released by condensation to differences in temperature between air masses; although
not as frequently, an extratropical cyclone can transform into a subtropical storm, and from
there into a tropical cyclone. From space, extratropical storms have a characteristic
"comma-shaped" cloud pattern. Extratropical cyclones can also be dangerous when their
low-pressure centres cause powerful winds and high seas.

12. When water droplets freeze on ice crystals, process known as

  1. Bergeron process
  2. Snowflakes process
  3. Ice Shelves process
  4. Water crystallization
Answer: 1

Explanation: The Bergeron Process often results in precipitation. As the crystals grow and fall, they pass through the base of the cloud, which may be above freezing. This causes the crystals to melt and fall as rain.

14. Below are the statements that differentiate the types of diabetes. If you notice your friend is a diabetic, then how will you differentiate if he/she is type 1 or type 2?
  1. Your friend is having the most common type of diabetes.
  2. His/Her familiar background shows strong hereditary reasons for being diabetic.
Select the correct code
  1. Your friend is suffering from Type 2 diabetes
  2. Your friends is suffering from Type 1 diabetes
  3. Both
  4. None
Answer: 1
Explanation: Both are the symptoms of Type 2 diabetes. Type 2 is the most common form of diabetes mainly found in adults and constituting 90-95% as compared to type 1. Genetically both type 1 and type 2 can be found but type 2 has strong genetic correlation than type 1.

15. Arrange the following countries from West to East (Horizontally) along Mediterranean
  1. Tunisia
  2. Egypt
  3. Jordan
  4. Syria
Select the correct code
  1. 1-2-3-4
  2. 2-4-3-1
  3. 3-4-2-1
  4. 1-2-4-3
Answer: 1
Explanation: See Map

16. A geographical indication (GI) is a name or sign used on certain products which corresponds to a specific geographical location or origin. Match the following Indian GI correctly

  1. Bidriware- Kerala
  2. Chanderi Fabric- Madhya Pradesh
  3. Nirmal Paintings- Telangana
  4. Kaipad Rice- Karnataka

Select the correct code

  1. 1, 2, 3 and 4
  2. 1, 3 and 4
  3. 2 and 3
  4. 1 and 4
Answer: 3
Explanation: https://en.wikipedia.org/wiki/List_of_Geographical_Indications_in_India

17. Which of the following air pollutant is not produced by coal thermal power plant? [A]Carbon dioxide [B]Sulfur dioxide [C]Carbon monoxide [D]Nitrogen oxide

Solution: A.Carbon monoxide Coal plants are the top source of carbon dioxide (CO2), Sulfur dioxide and nitrogen oxide emissions, which are the primary cause of global warming.

18. Which of the following is the largest produced variety of silk in India? [A]Mulberry [B]Tasar [C]Eri [D]Muga

Solution: [A]Which of the following is the largest produced variety of silk in India? [A]Mulberry [B]Tasar [C]Eri [D]Muga.

19. Consider the following regarding ‘Uranium Enrichment’

  1. Low Enriched Uranium (LEU) has lower than 30% concentration of Uranium-235 that is a weapons grade.
  2. Highly enriched Uranium (HEU) has more than 30% concentration of Uranium-235 and used in nuclear reactors and research.
  3. Uranium in natural condition is found as U-235 but unless processed through ‘enrichment’, cannot be used for civilian or weapons-grade technologies.

Select the correct statement/s

  1. 1 and 2
  2. 2 and 3
  3. 1, 2 and 3
  4. None
Solution: 4
Explanation: Natural Uranium is 99 % U-238 isotope. LEU has lower than 20% concentration of U-235- used in civilian purpose/nuclear reactors. HEU – more than 20 % of U-235, used for weapons-grade

20. Amongst the following that is/are not a ‘STAR–

  1. Pulsar
  2. Supernova
  3. Quasars
  4. Pluto
Select the correct code
  1. 1, 2 and 3
  2. 2, 3 and 4
  3. 1, 3 and 4
  4. All
Solution: 2
Explanation: Only Pulsar is a star. Pulsars are simply rotating neutron stars.

21. ‘Recently NASA has solved the mystery of formation of Quasars’. Consider the following statements in its reference
  1. Quasars are the brightest object in the universe.
  2. They exhibit similar properties as galaxies.
Select the wrong statement/s

14. Recently RBI announced ‘Strategic Debt Restructuring (SDR) Scheme’. It is-
  1. To allow flexible norms for lenders to pay debt.
  2. To allow lenders only Public and Private Banks to convert their loans into equity stake
  3. To allow banks and non-banking lending institutions to convert their loans into equity stake
Select the correct code
  1. 1 and 3
  2. 2 and 3
  3. Only 2
  4. Only 3