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#1 With reference to photochemical smog, consider the following statement: 1. It occurs mainly in warm, dry and sunny weather. 2. It results in the creation of ground level ozone. Which of the statement given above is/ are correct? ?Ans- c
- Photochemical smog occurs in warm, dry and sunny weather because sunlight (UV Rays) is needed for the reaction to start.
- The main components of the photochemical smog result from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories.
- Photochemical smog has a high concentration of oxidizing agents and is, therefore, called as oxidizing smog.
- Photochemical smog leads to the creation of ground level ozone.
- It is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight.
- It can trigger a variety of health problems, particularly for children, the elderly, and people of all ages who have lung diseases such as asthma.
- Ground level ozone can also have harmful effects on sensitive vegetation and ecosystems.
#2 Which of the following coral reefs may be separated by a lagoon from the coastline? 1. Fringing Reef 2. Barrier Reef 3. Atoll . Select the correct answer using the code given below.?Ans- a
#3 Which of the following is/are effects of ozone depletion? 1. Genetic disorders 2. Disturbs ecological balance in acquatic life. 3. Brittling of plastic. Select the correct answer using the code given below.?Ans- d
Harmful Effects of Ozone depletion on Humans
- Increased susceptibility to skin-cancer
- Increase cataract (a medical condition in which the lens of the eye becomes progressively opaque, resulting in blurred vision)
- Damage DNA (DNA mutations) and cause genetic disorders.
- Damage to cornea and causes retinal diseases
- Suppresses human immune systems
Effects on terrestrial plants
- Inhibits photosynthesis
- Inhibits metabolism
- Represses growth
Effects on aquatic ecosystems
- Exposure to solar UV-B radiation has been shown to affect both orientation mechanisms and motility in phytoplankton, resulting in reduced survival rates for plankton population adversely affecting marine food chain. Hence, it disturbs the ecological balance in acquatic life.
- Marine/freshwater organisms are very sensitive to UV-rays. E.g. Corals
UV rays damage the physical and chemical properties of complex chemical substance. Plastics become brittle when it comes in contact with UV rays.
#4 With reference to biosphere reserves, consider the following statements: 1. The core zone consists of an undisturbed and legally protected ecosystem. 2. The buffer zone is the outermost zone of the biosphere reserve. Which of the statements given above is/are correct? ?Ans- a
- A biosphere reserve is a special area of land or coastal environment in which multiple use of land is permitted by dividing it into certain zones.
- The natural or core zone consists of an undisturbed and legally protected ecosystem.
- The buffer zone surrounds the core area, and is managed to accomodate a greater variety of resource use strategies.
- The transition zone, the outermost part of the biosphere reserve is an area of active cooperation between the management and the local people.
#5 Which of the following statements regarding Eutrophication process is not correct??Ans- c
- Enrichment of an aquatic system by addition of nutrients, primarily phosphates & nitrates runoffs from chemical fertilizers
- Nutrient enrichment accelerates the growth of algae which soon covers almost entire surface layer, known as algae bloom.
- Algae bloom restricts the penetration of sunlight, which restricts process of photosynthesis among underwater plants, leading to depletion of oxygen which results in death of aquatic organisms.
- Depletion of oxygen also occurs due to decomposition of dead algae by microorganisms which require oxygen for decomposition process
- New anaerobic condition also promotes growth of bacteria (clostridium botulinum) which produces toxins deadly to aquatic organisms, birds & mammals
- Harmful Algae bloom is commonly known as Red tide, which is basically a misnomer as blooms are not always red in colour & certainly not associated with tides, Scientifically referred as Harmful algal blooms (HABs)
- Common cause for algae blooms are nutrient enrichment of water (esp. of nitrates & phosphates) & rise in water temperature.
RISE = Temperature and Nutrient