20 questionswith explanationsfor RAS, Patwari, VDO and other Rajasthan exams
In which layer of the atmosphere is the ozone layer mainly found?
Answer: (2) Stratosphere
Explanation
The ozone layer lies in the stratosphere and absorbs most of the Sun's harmful ultraviolet radiation.
The Ramsar Convention is related to the conservation of?
Answer: (4) Wetlands
Explanation
The Ramsar Convention is an international treaty for the conservation and wise use of wetlands.
Which gas released by human activities contributes most to the enhanced greenhouse effect?
Answer: (1) Carbon dioxide
Explanation
Carbon dioxide from burning fossil fuels and deforestation is the largest human-caused contributor to global warming.
World Environment Day is observed on which date?
Answer: (3) 5 June
Explanation
World Environment Day is observed on 5 June every year; 22 April is Earth Day.
Which of the following chemicals is mainly responsible for depletion of the ozone layer?
Answer: (3) Chlorofluorocarbons (CFCs)
Explanation
CFCs release chlorine in the stratosphere, which breaks down ozone molecules.
The Montreal Protocol (1987) deals with?
Answer: (1) Phasing out ozone-depleting substances
Explanation
The Montreal Protocol aims to protect the ozone layer by phasing out substances such as CFCs.
Keoladeo National Park in Bharatpur, Rajasthan, is famous mainly for?
Answer: (4) Birds, including migratory birds
Explanation
Keoladeo is a famous bird sanctuary visited by many migratory birds; it is a Ramsar site and UNESCO World Heritage Site.
In a food chain, which organisms are the producers?
Answer: (2) Green plants
Explanation
Green plants make their own food by photosynthesis, so they are producers at the first trophic level.
Ranthambore National Park is located in which district of Rajasthan?
Answer: (3) Sawai Madhopur
Explanation
Ranthambore National Park is in Sawai Madhopur district; Sariska is in Alwar and Keoladeo is in Bharatpur.
In which year was the Ramsar Convention on wetlands signed?
Answer: (2) 1971
Explanation
The Ramsar Convention was signed in 1971 at Ramsar, Iran.
The '10 per cent law' of energy transfer in ecosystems was proposed by?
Answer: (1) Raymond Lindeman
Explanation
Raymond Lindeman (1942) stated that only about 10% of energy passes from one trophic level to the next.
The Desert National Park, a key habitat of the Great Indian Bustard, lies in which districts of Rajasthan?
Answer: (4) Jaisalmer and Barmer
Explanation
Desert National Park spreads over Jaisalmer and Barmer districts and protects the Great Indian Bustard (Godawan).
Arrange the following IUCN Red List categories in decreasing order of extinction risk (highest first): 1. Vulnerable 2. Critically Endangered 3. Near Threatened 4. Endangered
Answer: (2) 2, 4, 1, 3
Explanation
Risk falls in the order Critically Endangered > Endangered > Vulnerable (the three 'threatened' categories) > Near Threatened.
Consider the following statements about biodiversity hotspots: 1. A region must have at least 1,500 species of endemic vascular plants to qualify. 2. A region must have retained at least 70% of its original natural vegetation to qualify. 3. The concept was first put forward by Norman Myers in 1988. Which of the statements given above is/are correct?
Answer: (3) 1 and 3 only
Explanation
A hotspot needs at least 1,500 endemic vascular plant species and must have LOST at least 70% of its original habitat; Norman Myers proposed the idea in 1988.
The Nicobar Islands of India form part of which global biodiversity hotspot?
Answer: (4) Sundaland
Explanation
The Nicobar Islands belong to the Sundaland hotspot, while the Andaman Islands fall in the Indo-Burma hotspot.
Which of the following biogeochemical cycles is a sedimentary cycle with no significant gaseous phase in the atmosphere?
Answer: (3) Phosphorus cycle
Explanation
The reservoir of phosphorus is rocks (phosphates); unlike carbon, nitrogen and oxygen it has no significant gaseous exchange with the atmosphere.
Match List-I (process in the nitrogen cycle) with List-II (bacterium mainly associated): A. Nitrogen fixation in root nodules of legumes B. Conversion of ammonia to nitrite C. Conversion of nitrate to free nitrogen gas D. Conversion of nitrite to nitrate 1. Pseudomonas 2. Rhizobium 3. Nitrosomonas 4. Nitrobacter
Answer: (4) A-2, B-3, C-1, D-4
Explanation
Rhizobium fixes nitrogen in legume nodules; Nitrosomonas oxidises ammonia to nitrite and Nitrobacter nitrite to nitrate; Pseudomonas carries out denitrification.
Consider the following statements about ecological pyramids: 1. The pyramid of energy is always upright. 2. The pyramid of numbers in a grassland ecosystem is inverted. Which of the statements given above is/are correct?
Answer: (1) 1 only
Explanation
Energy decreases at each trophic level, so its pyramid is always upright; in a grassland the numbers pyramid is upright (many grasses, fewer herbivores, still fewer carnivores).
In the food chain Grass → Grasshopper → Frog → Snake → Hawk, the frog occupies which trophic level?
Answer: (2) Third trophic level (secondary consumer)
Explanation
Grass is the first level, the grasshopper (herbivore) the second, so the frog that eats it is at the third trophic level as a secondary consumer.
The increase in the concentration of a non-biodegradable pollutant such as DDT at successively higher trophic levels of a food chain is called:
Answer: (3) Biomagnification
Explanation
Biomagnification is the rise in concentration of a persistent toxin like DDT or mercury at each higher trophic level.