CBSE Questions for Class 10 Biology Our Environment Quiz 3 - MCQExams.com

• Consumers are categorised into primary, secondary and tertiary consumers.
• Primary consumers are herbivores that feed on producers or green plants. They vary according to the type of ecosystem. For example, in a forest ecosystem, a giraffe or deer is the primary consumer while in a grassland ecosystem, a cow or goat is the primary consumer.
• Secondary consumers are carnivores that feed on primary consumers. For example, crows, hawks, wolves etc.
• Tertiary consumers are top carnivores that feed on other carnivores. For example, lion, vulture etc.

• Decomposers play the main role in recycling the elements in the environment. They release enzymes to break down complex substances into simple substances. 
• The energy released in this process is utilized by decomposers. The things which can be degraded by decomposers are termed as 'bio-degradable'. 
• But some human-made things cannot be degraded by decomposers, as they do not possess enzymes to degrade such things. These things are termed as 'non-biodegradable'. These things are plastic, paint, aluminium container, and lead batteries etc. They are not used as compost.

• The different trophic level of an ecosystem interacts with each other and they are interdependent on each other. 
• Biological magnification is a process where pollutants such as pesticides or heavy metals move up the food chain, passes into rivers or lakes and are consumed by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans.
•  It occurs when the concentration of a substance, such as DDT or mercury, in an organism, exceeds the background concentration of the substance in its diet. 

$$\textbf{Correct answer: D}$$  

$$\textbf{Option (A):}$$  

$$\bullet$$ In a clean environment, the producers are important because it is responsible for the generation of energy from solar energy. 

$$\bullet$$ The producers from the base of the ecosystem start the generation of nutrients. 

$$\textbf{Option (B):}$$  

$$\bullet$$ All the consumers in the clean environment improve the primary consumers, secondary consumers and tertiary consumers.

$$\bullet$$ The consumers get the organic nutrients from the producers which are metabolized to produce energy. 

$$\textbf{Option (C):}$$  

$$\bullet$$ The decomposers break down the complex organic substances in the dead and decaying matter.

$$\bullet$$ This breakdown is important for the complex molecules to be converted into a simpler form.

$$\bullet$$ These simple molecules can enter the environment and maintain balance in the ecosystem. 

$$\textbf{Option (D):}$$  

$$\bullet$$ Plastics are man-made substances that are non-biodegradable.

$$\bullet$$ This is why they do not decompose in the environment and they should not be present in any clean environment.

Hence, the correct answer is option (D).

$$\textbf{Correct option:}$$ $$\textbf{(C)}$$

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ The action of microorganisms can break down and break down biodegradable wastes into simpler molecules. 

$$\bullet$$ Plant and animal wastes are the most common sources of these wastes.

$$\textbf{Option (B)}$$

$$\bullet$$ Corrosives are substances that can attack and damage exposed bodily tissues chemically.

$$\bullet$$ Metal can be corroded or destroyed by corrosives.

$$\textbf{Option (C)}$$

$$\bullet$$ One of the negative effects of developing civilization is the development of non-biodegradable materials that are incapable of being broken down by bacteria into simple, harmless substances.

$$\bullet$$ They are destructive to the earth where they are deposited and can last for centuries, and their burning releases poisonous chemicals that are harmful to human and animal health in a variety of ways.

$$\bullet$$ Because such compounds do not deplete water bodies, they occupy space in water bodies and are devoured by animals, causing serious health problems and death.

$$\bullet$$ Plastic, or polythene, is toxic, non-biodegradable trash.

$$\textbf{Option (D)}$$

$$\bullet$$ Garbage, building debris, business rubbish, and sludge from water treatment or waste treatment plants are all examples of solid waste.

$$\bullet$$ Solid waste can arise from a variety of sources, including industrial, commercial, mining, and domestic and community activities.

$$\textbf{Thus the Correct option is (C)}$$

• The food chain is the feeding habits or the nutrition relationship of different organisms in an ecosystem i.e., who eats whom. 
• The food chain starts with autotrophs as they can prepare food on their own. 
• The diagram represents a food chain where grass (green plant) is the producer, the second position is occupied by grasshopper (heterotroph) which feeds on grass which in turn is eaten by frog (secondary consumers/ primary carnivore). 
• The last position (tertiary position) is occupied by top-level heterotroph or secondary carnivores. 
• Thus, the grass represents the producers. 
• Hence, the correct answer is option A.