Free Man and His Environment MCQs with Answers

371. The first stage in development of Xerosere is appearance of:

• A. Foliose lichens
• B. Crustose lichens
• C. Fruticose lichens
• D. Climax stage

Explanation: Due to great exposure to the sun and extreme deficiency of water, the first pioneers in the bare rock area are a few simple organisms. The most successful of such organisms is crustose lichens.

372. What is the direction of energy flow in an ecosystem:

• A. Always unidirectional
• B. Always bidirectional
• C. In any direction
• D. Always down directional

Explanation: In an ecosystem, energy flows in a unidirectional manner, primarily from producers (such as plants) to consumers (such as herbivores, carnivores, and omnivores). This flow occurs through feeding interactions in a food chain or food web.Producers capture energy from sunlight through photosynthesis and convert it into chemical energy. This energy is then passed on to consumers as they eat the producers. Energy is gradually lost as heat at each trophic level, making it a one-way flow. Therefore, option a is correct.

373. The rate at which the new individuals are added to a population in a unit time is:

• A. Density
• B. Natality
• C. Mortality
• D. Dispersion

Explanation: Natality refers to the rate at which new individuals are added to a population in a unit of time. It is also known as birth rate. Natality is an important factor in determining population growth. Therefore, option b is correct.

374. In succession lithoseres takes place on:

• A. Sand
• B. Water
• C. Forest floor
• D. Bare rocks

Explanation: Lithosere is a specific type of ecological succession that occurs on bare rocks. It involves the colonization of plant species on a substrate of rock or stone. Over time, through the action of pioneer species and their interactions with the environment, soil gradually forms, allowing for more complex plant communities to establish. Therefore, option d is correct.

375. The largest demand of energy is generally fulfilled by

• A. Hydroelectric power
• B. Nuclear power
• C. Solar energy
• D. Fossil fuels

Explanation: Fuels that are generated very deep under the earth from the debris of plants and animals, which existed millions of years ago, are called fossil fuels. Coal, oil and natural gases are fossil fuels. Fossil fuel energy sources, such as coal, natural gas, and oil are used to meet energy demands for much of the world. Fossil fuel accounts for 84% of world's primary consumption while hydroelectric power accounts for 6%, renewables for 5%, and nuclear power for 4%.

376. Food is renewable resource due to:

• A. Mechanical forming
• B. Improved crop varieties
• C. Continuous photosynthesis
• D. Pest control

Explanation: Food is considered a renewable resource primarily because of continuous photosynthesis, which allows plants to convert sunlight into energy, produce food, and support life on Earth. This natural process ensures that plants, which form the base of most food chains, can constantly produce food. Options A, B, and D refer to techniques and methods that enhance food production but do not inherently make food renewable. Mechanical forming prepares land for cultivation, improved crop varieties increase productivity, and pest control protects crops, but none of these address the natural regenerative process of photosynthesis.

377. Which of the following does not bring erosion of soil?

• A. Carolers forming
• B. Extensive ploughing
• C. Moderate grazing
• D. Heavy grazing

Explanation: Moderate grazing refers to controlled or balanced grazing practices where the number of livestock and their grazing duration are managed in a sustainable manner. It involves maintaining a healthy vegetation cover and avoiding overgrazing. This practice can actually be beneficial for the soil and ecosystem as it helps in maintaining biodiversity, nutrient cycling, and organic matter accumulation.

378. Gas·evolved in bioconversion of solid waste is:

• A. Methane
• B. Sulpher dioxide
• C. Nitrogen dioxide
• D. Ethane

Explanation: Solid wastes are biologically converted into value added products by physiological action of microorganisms. These processes occur under controlled environmental condition. It could be in the form of submerged fermentation or as solid-state fermentation technology. The gas released during this conversion is methane and carbon dioxide. Usually, carbon dioxide is released during aerobic conversion of solid waste while methane is released during anaerobic conversion of solid waste.

379. All of the following are non-renewable resources of energy EXCEPT:

• A. Forests
• B. Iron
• C. Petroleum
• D. Natural gas

Explanation: Forests are not considered non-renewable resources of energy. Forests have various uses and can provide energy through biomass, they are renewable resources that can be managed and replenished.

380. The ozone layer present in the

• A. troposphere
• B. stratosphere
• C. mesosphere
• D. atmosphere

Explanation: Ozone Layer: It is a thin part of Earth's atmosphere that absorbs almost all of the sun's harmful ultraviolet light. EARTH'S ATMOSPHERIC LAYERS: Earth's atmosphere has a series of layers, each with its own specific traits. Moving upward from ground level, these layers are called the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The Ozone layer is around 15-30 km above the earth's surface. From the above diagram, we know that this region lies in the stratosphere. Thus, option 'B' is correct.