Biology Test - 10

Concept:

Explanation:

• The question is talking about a species 'X' which is only found in western ghats.
• So, the species 'X; is only located in the region of western ghats and nowhere else on the planet. 
• Hence, the correct answer to this question is - Endemic species, as they are the ones that can only be found in a certain area or a specific geographical location.

The correct answer is only C and D.

Explanation:

• Statement A is incorrect:
  • Biodiversity cannot refer to only fauna because animals depend on the flora for food.
  • Animals need a producer in the ecosystem to survive.
• Statement B is incorrect:
  • The total number of individuals of a particular species in a given area is called species population.
  • Only one species does not show any diversity in that area.
• Statement C is correct:
  • Biodiversity refers to the different kinds of species of flora and fauna present in the given area.
  • The term 'biodiversity' was given by Edward Wilson.
• Statement D is correct:
  • Ecologists believe that communities with more species tend to be more stable than those with less species.
  • Forests are hotspots for biodiversity. They are biodiversity-rich areas that are also the most threatened due to high levels of exploitation and human intervention. 

Additional Information

• Biodiversity is divided into three levels:
  • Genetic diversity - It is the measure of variation in genetic information contained in the organisms.
  • Species diversity - It is a measure of the variety of species and their relative abundance present within a region.
  • Ecological diversity -  It is a measure of the diversity at community and ecosystem levels.

Explanation-

• In general, loss of biodiversity in a region may lead to (a) decline in plant production, (b) lowered resistance to environmental perturbations such as drought, and (c) increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycles.
• Causes of biodiversity losses- The accelerated rates of species extinctions that the world is facing now are largely due to human activities.
• There are four major causes (‘ The Evil Quartet’ is the sobriquet used to describe them). 
• The four causes are-
  1. Habitat loss and fragmentation
  2. Over-exploitation
  3. Alien species invasions
  4. Co-extinctions

Therefore “Jared Diamond has described “the evil quartet”; the four major causes of biodiversity losses.”​ Pollution is not included in the quartet.

Additional InformationHabitat-loss and fragmentation

• This is the most important cause driving animals and plants to extinction.
• The most dramatic examples of habitat loss come from tropical rainforests.
• Once covering more than 14 per cent of the earth’s land surface, these rain forests now cover no more than 6 per cent.
• They are being destroyed fast.
• By the time you finish reading this chapter, 1000 more hectares of rainforest would have been lost.
• The Amazon rain forest (it is so huge that it is called the ‘lungs of the planet’) harbouring probably millions of species is being cut and cleared for cultivating soya beans or for conversion to grasslands for raising beef cattle.

Over-exploitation

• Humans have always depended on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to overexploitation of natural resources.
• Many species extinctions in the last 500 years (Steller’s sea cow, passenger pigeon) were due to overexploitation by humans.
• Presently many marine fish populations around the world are over-harvested, endangering the continued existence of some commercially important species.

Co-extinctions

• When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct.
• When a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate.
• Another example is the case of a coevolved plant-pollinator mutualism where extinction of one invariably leads to the extinction of the other. 

The correct answer is (wrong statement) Loss of biodiversity causes deforestation.

Concept:

• Desertification is the process by which land becomes a desert as the quality of the soil deteriorates over time. When trees are cut down, the roots no longer hold the soil together, making it more susceptible to soil erosion.
• The process of removing trees and converting a forest into cleared land is known as deforestation.

Explanation:

• "One form of soil degradation is soil erosion, which is the displacement of the upper layer of soil." The dynamic activity of erosive agents, such as plants, animals, water, ice (glaciers), snow, air (wind), and humans, causes soil erosion.
• The soil particles are loosened or washed away in valleys, streams, oceans, rivers, or distant lands during this process. This has gotten worse as a result of human activities like agriculture and deforestation.
• Soil erosion is a major factor in desertification. It transforms the habitable regions into deserts.
  • Thus, statement 1 is correct.
• The soil's water holding capacity decreases as a result of deforestation. As a result, water movement from the soil surface into the ground is reduced. This causes the groundwater level to decrease.
• The presence of forest cover and forest cover vegetation is critical for slowing the flow of rainwater. This results in the gradual absorption of rainwater by the soil, which is critical for maintaining groundwater levels. Rainwater is not effectively absorbed by the soil as a result of deforestation, resulting in a decrease in water level.
  • Thus, statement 2 is correct.
• Overgrazing reduces the productivity, usefulness, and biodiversity of the land and is a contributing factor to deforestation.
  • Thus, statement 3 is correct.
• The variety of living organisms in a given area is referred to as biodiversity.
• Deforestation reduces biodiversity by disrupting the hydrologic cycle, destroying habitat, causing soil erosion, and, in extreme cases, can lead to desertification. Thus, the loss of biodiversity does not cause deforestation.
  • Thus, statement 4 is incorrect.

Concept:

• Biodiversity is not uniformly distributed throughout the world.
• There are certain patterns of distribution, which can be explained by:
  • Latitudinal Gradients - This shows that species diversity decreases as we move away from the equator.
  • Species-area relationship - This is a mathematical approach to explain the relation between species richness and the area covered.

Important Points

• Species-area relationship was shown by Alexander von Humboldt.
• He was a German naturalist and geographer who explored the South American jungles extensively.
• Species-area relationship - Species richness within a region increased with increasing explored area but only up to a certain limit.
• It can be mathematically expressed as the following equation:

S = CA^Z

or, log S = log C + Z log A

where, S = Species richness,

A = Area,

Z = Regression coefficient or slope of the line,

C = Y-intercept

Explanation:

• When species richness is plotted against time, it gives a rectangular hyperbola for several taxa like angiosperms, birds, bats and freshwater fishes.
• On a logarithmic scale, the relationship is a straight line.
• The value of Z has been found to lie between 0.1 and 0.2.
• If the species-area relationship is for a large area like an entire continent, the slope of the line becomes steeper and the value of Z ranges from 0.6 to 1.2.
• Example - For frugivorous birds and mammals in tropical forests of different continents, Z = 1.15.

Concept-

• Pollution is any undesirable change in physical, chemical, or biological characteristics of air, land, water, or soil.
• Agents that bring about such an undesirable change are called pollutants.
• Pollution can be broadly classified into 4 types Air pollution, Water pollution, Noise pollution & Soil pollution.

Explanation-

• In order to control environmental pollution, the Government of India has passed the Environment (Protection) Act, 1986 to protect and improve the quality of our environment (air, water, and soil).
• In India, the Air (Prevention and Control of Pollution) Act came into force in 1981 but was amended in 1987 to include noise as an air pollutant.
• Realizing the importance of maintaining the cleanliness of the water bodies, the Government of India has passed the Water (Prevention and Control of Pollution) Act, 1974 to safeguard our water resources.

The correct answer is Eichhornia crassipes (Water hyacinth).

• World's most problematic aquatic weed also known as the terror of Bengal is Eichhornia Crassipes.
• This weed chokes ponds, lakes, and rivers resulting in an imbalance in the aquatic ecosystem.
• It accelerates eutrophication.

Key Points

• Eutrophication is the gradual increase in the biomass of phytoplankton resulting in 'algal blooms' due to increasing in the concentration of phosphorus, nitrogen, and other plant nutrients in an ageing aquatic ecosystem such as a lake.

Additional Information

• Lantana camara is a flower-bearing shrub.
• Parthenium hysterophorus is a flowering plant species.

Concept:

• We know that wastewater needs to be treated or purified before discharging it into water bodies or reusing it.
• Treatment of wastewater is usually done in sewage treatment plants or by other artificial means.
• But these processes are costly and sometimes even disturbs the natural ecosystems.
• Thus, we need integrated management systems for dealing with wastewater treatment.
• Such an integrated approach was initiated by a citizens group called FOAM.

Key Points

• FOAM stands for Friends of the Arcata Marsh, which is a group formed by the citizens of the town Arcata.
• Arcata is a town along the northern coast of California.
• The townspeople collaborated with some biologists from the Humboldt State University to develop an integrated waste water treatment system.
• This system utilizes both natural and artificial processes.

Stages of Treatment:

1. Stage 1 -
   • It involves conventional sedimentation, filtration and chlorine treatments.
   • This removes the floating debris, particulate matters and microbes.
   • But some pollutants like dissolved heavy metals still remain.
2. Stage 2 -
   • This involves the innovative approach taken by the biologists to remove the heavy metals.
   • A series of 6 marshes were developed over 60 hectares of marshland.
   • Appropriate plants, algae, bacteria and fungi were introduced into these areas.
   • These organisms helped in neutralizing, absorbing and assimilating the harmful pollutants.

Explanation:

• As the water flows through the marshes, it gets purified sequentially.
• The marshes also function as a natural sanctuary for a number of fishes, animals and birds that dwell there.
• Thus, it also helps in maintaining the biodiversity of the ecosystem.
• FOAM is associated with the upkeep and maintenance of this project.

The correct option is Eutrophication

Key Points

• Eutrophication refers to the addition of artificial or non-artificial substances, such as nitrates and phosphates, through fertilizers or sewage, to a freshwater system.
• It can be anthropogenic or natural.
• It leads to an increase in the primary productivity of the water body or “bloom” of phytoplankton.
• The overgrowth causes the loss of oxygen in the water leading to severe reductions in fish and other animal populations.

Additional Information

• Biomagnification is the accumulation of the increasing amount ​ of non-degradable pollutants through the food chain i.e the concentration of toxicants increases at successive trophic levels. It is measured in PPM (Part Per Million).

• Global Warming: An increase in the average temperature of the earth surface due to the greenhouse effect is called global warming It also refers to the increase in the average temperature of the air and sea at the earth's surface which causes climate change

Key Points

• CO₂ and clouds help in trapping the infrared radiation that is reflected off Earth's surface.
• Without CO₂, the average surface temperature would be near zero degrees Fahrenheit.
• The trapping of heat by CO₂ in the atmosphere is also referred to as the greenhouse effect.
• A greenhouse is a glass building that provides optimum temperature for plants to grow in cold climates. The glass traps the heat inside to keep it warm.
• As CO₂ acts in a very similar way for our atmosphere it is known as a greenhouse gas.

Additional Information

• It also plays an important role in carbon cycling.
• It is also vital for important life processes like photosynthesis and respiration.
• Excess of CO2 causes the Earth’s temperature to rise substantially leading to global warming, which is an environmental concern.
• Global warming, in turn, is responsible for melting of polar ice, increase in sea level, increased droughts, forest fires.