Keystone species are those that have a large impact on an ecosystem relative to their population size. In the absence of a keystone species, many ecosystems would fail to exist. Small predators that consume herbivores are considered keystone species as they prevent overgrazing of plants.

1. 1.KEYSTONE SPECIES:
Keystone species are those which have an extremely high impact on a particular ecosystem relative to
its population. Keystone species are also critical for the overall structure and function of an ecosystem,
and influence which other types of plants and animals make up that ecosystem. Thus, in the absence of a
keystone species, many ecosystems would fail to exist. A common example of keystone species in the
context of conservation biology is the predator-prey relationship. Small predators that consume
herbivorous species prevent such herbivores from decimating the plant species in the ecosystem, and are
considered keystone species.
2. Suggest why the Montreal Protocol has been more effective at controlling CFC emissions
than the Kyoto Protocol has been at controlling greenhouse gas emissions
The Montreal Protocol led to a global phase-out of most substances that deplete the ozone layer, such as
chlorofluorocarbons (CFCs). A happy side-effect of the gradual ban of these products is that Earth's
climate has also benefited because CFCs are also potent greenhouse gases. However, now a "rebound
effect" threatens to accelerate the rate of global warming. HFC-134a, also known as R-134a, for
example, which is used in automobile air conditioning units, is 1430 more active than the "classic"
greenhouse gas carbon dioxide (CO2).
3. India as a Mega Diversity Nation.
A mega-diverse country is one that harbors the majority of the Earth's species and is therefore considered
extremely biodiverse. India is rich in biodiversity from north to south and from east to west. India
containsmany species that world's gone country have.
4. Biomes :
Biomes are very large ecological areas on the earth’s surface, with fauna and flora (animals and plants)
adapting to their environment. Biomes are often defined by abiotic factors such as climate, relief,
geology, soils and vegetation.
EG:The Desert Biomes, The Aquatic Biomes, Forest Biomes, Grassland Biomes, Tundra Biomes
5. Suggest why Tundra has the lowest ecological stability
Tundra, a major zone of treeless level or rolling ground found in cold regions, mostly north of the Arctic
Circle (Arctic tundra) or above the timberline on high mountains (alpine tundra). Tundra is known for
large stretches of bare ground and rock and for patchy mantles of low vegetation such as mosses, lichens,
herbs, and small shrubs. Observed patterns are likely the result of complex interactions between various
biotic and abiotic factors. Abiotic factors include lower available energy and area at high latitudes, and
the relatively young age of Arctic ecosystems. Among biotic factors, latitudinal differences in rates of
diversification have been suggested, but empirical evidence for this as a general principle is lacking.
Recent evidence suggests that ‘tropical niche conservatism’ plays a role in structuring latitudinal
diversity.

2. 6. Indicator species is an organism whose presence, absence or abundance reflects a specific
environmental condition. Indicator species can signal a change in the biological condition of a particular
ecosystem, and thus may be used as a proxy to diagnose the health of an ecosystem. For example, plants
or lichens sensitive to heavy metals or acids in precipitation may be indicators of air pollution.
PART C
OMEGA 3 : Q.NO:
SOLUTIONS:Phytoplankton is the base of several aquatic food webs. In a balanced ecosystem, they
provide food for a wide range of sea creatures including whales, shrimp, snails, and jellyfish.
Phytoplankton, also known as microalgae, are similar to terrestrial plants in that they contain chlorophyll
and require sunlight in order to live and grow. Most phytoplankton are buoyant and float in the upper part
of the ocean, where sunlight penetrates the water. Phytoplankton also require inorganic nutrients such as
nitrates, phosphates, and sulfur which they convert into proteins, fats, and carbohydrates.
The two main classes of phytoplankton are dinoflagellates and diatoms. Dinoflagellates use a whip-like
tail, or flagella, to move through the water and their bodies are covered with complex shells. Diatoms also
have shells, but they are made of a different substance and their structure is rigid and made of interlocking
parts. Diatoms do not rely on flagella to move through the water and instead rely on ocean currents to
travel through the water.
In a balanced ecosystem, phytoplankton provide food for a wide range of sea creatures including whales,
shrimp, snails, and jellyfish. When too many nutrients are available, phytoplankton may grow out of
control and form harmful algal blooms (HABs). These blooms can produce extremely toxic compounds
that have harmful effects on fish, shellfish, mammals, birds, and even people.
Organic wastes causes deoxygenation ,nutrient enrichment increased turbidity escapes affects wild gene
pool non-native species affect food webs lice/spread of disease pesticide pollution dichlorvos/hydrogen
peroxide/cypermethrin loss of habitat/biodiversity impact on tourism coastal erosion due to mangrove
loss effects of harvesting wild fish populations to provide food pellets bird/seals caught in nets ref case
studies/examples;; ref ER = O/I comparison of commercial fishing and aquaculture. ERs fish farming is
unsustainable ref food miles/imports from Asia fish farming = consumption at 4th trophic level
Sustainability of fish farming includes: rearing vegetarian carp sea urchins litter detritus in Scottish
salmon farms equipment treated with antifouling paints algae brushed off cages new, lower stocking
densities sites of cages rotated goldsinny wrasse in salmon coops eat sea lice.
Fish Oil Omega-3
Fish and fish oil contain eicosapentaenoic acid, or EPA, and docosahexaenoic acid, which is called DHA.
These two types of omega-3 fatty acids have shown cardio-protective properties. The National Institutes
of Health state that fatty fish provides about 1 gram of omega-3 fatty acids in 3.5 ounces of fish. It is
recommended that you broil or bake your fish. Frying fish in other oils will cancel its protective
properties.
Phytoplankton Omega-3

3. Marine microbes called phytoplankton live in cooler, nitrogen-rich parts of the ocean, such as the north
Atlantic and Pacific areas. These single-celled creatures live in the upper levels of the ocean, where they
use solar energy to create molecules important to life. Omega-3 fatty acids make up half the body weight
of phytoplankton called thraustochytrids. Analysis by Enviro-Health Research Laboratories determined
total EPA and DHA levels to be 14.4 milligrams per gram of powdered phytoplankton.
Q.NO:AGROCHEMICALS:
Products
• Pesticides, such as DDT, endrin, dieldrin, and benzene hexachloride (BHC).
• Alkylbenzene sulfonate (ABS) synthetic detergents.
• Polychlorinated biphenyls (PCBs).
• Chlorofluorocarbons (CFCs).
• Lead used in gasoline and paint.
• Some chlorinated solvents.
• Wood preservatives.
• Processes
• Chlorination for disinfection (in some situations).
• Mercury release from chlor-alkali cells.
• Bottom of Form
• Older coal gasification (now replaced with modern, but expensive, technologies).
• Dioxin release from incineration and some chemical reactions.
Q. Figure shows features associated with a buffer strip. The buffer strip reduces the amounts of
eroded soil reaching a river from nearby farmland
(i) Explain how the buffer strip may reduce the amount of eroded soil reaching the river

4. (ii) Explain why subsidy payments may be needed to encourage farmers to use buffer strips. (7+8)
ANS:
Vegetation/roots slow water flow; sediments/silt trapped by buffer strip/vegetation; buffer strip/vegetation
acts as wind break reducing erosion; roots bind soil/interception reduces raindrop impact/erosion;
(compensation/payments for) lost productive area/buffer strip produces no income;
(compensation/payments for) labour/materials;
A buffer strip is an area of land maintained in permanent vegetation that helps to control air, soil,
and water quality, along with other environmental problems, dealing primarily on land that is used
in agriculture. Buffer strips trap sediment, and enhance filtration of nutrientsand pesticides by slowing
down runoff that could enter the local surface waters. The root systems of the planted vegetation in these
buffers hold soil particles together which alleviate the soil of wind erosion and stabilize stream
banks providing protection against substantial erosionand landslides. Farmers can also use buffer strips to
square up existing crop fields to provide safety for equipment while also farming more efficiently.
Buffer strips can have several different configurations of vegetation found on them varying from simply
grass to combinations of grass, trees, and shrubs. Areas with diverse vegetation provide more protection
from nutrient and pesticide flow and at the same time provide
better biodiversity amongst plants and animals.
•
• BUFFER STRIP