Test: Our Environment- 2 - UPSC MCQ

• The correct answer is A: Rainfall.
• In ecosystems, biotic components are living organisms like plants, animals, and humans.
• Rainfall, while crucial for ecosystem function, is an abiotic factor—non-living and not considered a biotic component.

• The correct answer is C: primary consumer to secondary consumer.
• In this food chain scenario, the grasshopper serves as the primary consumer because it consumes plants (producers), and the frog acts as the secondary consumer by feeding on the grasshopper.
• Energy transfer in ecosystems progresses from one trophic level to the next, where organisms at higher trophic levels (like the frog) obtain energy from those at lower trophic levels (such as the grasshopper). 

• The correct answer is B: Plastic bag.
• Plastic bags are not biodegradable, unlike grass, paper, and wood, which are natural materials that can decompose over time.
• Plastic bags are synthetic materials. These are not degraded by bacteria.

• The organisms in an ecosystem are related through food requirements.
• This relationship is called food chain.
• In option (i) grass is eaten by rabbit, rabbit is consumed by wolf and lion eats wolf.
• In option (iv) grasshopper eats grass, frog eats grasshopper, snake eats frog and eagle consumes snake.
• In option (ii) grasshopper is found in terrestrial ecosystems not aquatic ecosystems. In option (iii) there is no herbivore animal to consume grass. Thus, the correct answer is option C.

• The correct answer is D: 10%.
• Solution: In ecological systems, energy and biomass decrease as you move up trophic levels from producers (plants) to primary consumers (herbivores) to secondary consumers (carnivores or omnivores), and so on.
• This decrease occurs primarily due to inefficiencies in energy transfer and metabolic losses.
• Typically, around 10% of the energy or biomass from one trophic level is transferred to the next. This is known as the 10% rule or the 10% energy transfer efficiency.

• The correct answer is C: (i) and (iii).
• Excessive exposure of humans to UV-rays, especially ultraviolet radiation from the sun, can have several harmful effects:
• Damage to immune system (i): UV radiation can suppress the immune system, making individuals more susceptible to infections and diseases.
• Skin cancer (iii): UV radiation is a known carcinogen and excessive exposure increases the risk of developing skin cancers such as melanoma, basal cell carcinoma, and squamous cell carcinoma.

• The correct answer is C: biological magnification.
• Biological magnification, also known as biomagnification or bioamplification, refers to the process by which the concentration of certain substances, such as pesticides or pollutants, increases in organisms at higher trophic levels in a food chain or food web.
• Human beings occupy the top level of many food chains, especially when it comes to terrestrial ecosystems, and therefore, substances like insecticides can accumulate to higher concentrations in our bodies compared to organisms lower in the food chain.

• The correct answer is C: Grasses.
• In the garden ecosystem, producers are organisms that produce their own food through photosynthesis.
• They are typically plants or algae that convert sunlight into energy through the process of photosynthesis.
• Grasses, like other plants, are producers because they can manufacture their own food using sunlight, water, and carbon dioxide

• The correct answer is C: both living organisms and non-living objects.
• An ecosystem includes both living organisms (biotic components) and non-living objects (abiotic components).
• These components interact within a specific environment, influencing each other's existence and functioning.

• The correct answer is C: Tree.
• Trees are autotrophs because they can produce their own food through photosynthesis, utilizing sunlight, water, and carbon dioxide to generate energy in the form of glucose.

• The correct answer is B: Crop field.
• An artificial ecosystem is one that has been created or significantly altered by human activity. A

• The correct answer is A: carnivores. 
• In a food chain, trophic levels represent the position an organism occupies in the transfer of energy and nutrients.
• The third trophic level typically consists of organisms that consume herbivores, which are at the second trophic level.
• These organisms are known as carnivores, as they primarily feed on other animals.

• The correct answer is A: producer → consumer → decomposer.
• A food chain represents the flow of energy and nutrients through an ecosystem, typically starting with producers (organisms that produce their own food through photosynthesis or chemosynthesis), followed by consumers that feed on producers or other consumers, and ending with decomposers that break down organic matter from dead organisms.

According to 10% rule, energy available at producer level will be 5 x 10 x 10 x 10 = 5000 kJ.

• There are many food chains which are interconnected to form the food web and so one organism can feed at different trophic levels in the different food chain.
• There is a gradual decrease in the energy of the increasing trophic levels due to the loss of energy with each transfer.
• The producers are the organisms which can synthesize food and the organisms which feed on the other sources are known as consumers.
• The detrivores are the organisms which feed on the dead matter of the organisms which belong to all the trophic levels. 

Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the food web.

• The correct answer is C: they alone have the capacity to synthesize food using sunlight.
• In any food chain, the first link is typically occupied by green plants (producers) because they are capable of photosynthesis.
• Photosynthesis is the process by which green plants and some bacteria convert sunlight, carbon dioxide, and water into glucose (a form of food) and oxygen.
• This ability to synthesize food from sunlight is unique to producers like green plants.

Depletion of ozone layer is mainly due to chlorofluorocarbon compounds.

• A food chain comprising birds, green plants, fish and man.
• Food chain in ecology, the sequence of transfers of matter and energy in the form of food from one organism to another organism.
• Food chains intervined locally into a food web because most organisms consume more than one type of animal or plant.
• Each level of a food chain represents a different trophic level.
• Humans are to be present at the top of the food chain because they eat all kinds of plants and animals.
• The human food chain starts with plants.
• Humans are dominant consumers.
• They affect food webs through energy production and agriculture, pollution, habitat destruction, overfishing and hunting it affect both soil and aquatic ecosystem.

• The correct answer is C: Producers.
• Producers, such as plants, algae, and certain bacteria, are the original source of food in every food chain within an ecosystem.
• They are able to produce their own food through processes like photosynthesis or chemosynthesis, making them fundamental to sustaining life in ecosystems.