Forests Our Lifeline - Free MCQ Test with solutions, Class 7 Science

The amount of CO₂  in the air will increase if the forests disappear.

• Increase in carbon dioxide will result in global warming.The surplus carbon is stored in the plant, helping it to grow.
• When trees are cut down and burned or allowed to rot, their stored carbon is released into the air as carbon dioxide.
• And this is how deforestation and forest degradation contribute to global warming.

The average temperature in tropical rainforests typically ranges from 21 to 30°C (70 to 85°F). This range is crucial for the diverse ecosystems found in these regions.

Key points about tropical rainforests:

• Temperature: Generally warm, supporting various life forms.
• Flora and Fauna: Home to a wide variety of plants and animals.
• Climate Influence: Plays a significant role in global weather patterns.

The second trophic level in the ecosystem consists of organisms that eat the producers (green plants). These are called primary consumers, or herbivores. Deer, rabbit, and many types of birds are herbivores. Therefore, the option 'Bird, rabbit, elephant' are primary consumers as they feed on plants.

Forests influence temperature through:

• Shading: Trees provide shade that lowers ground temperatures.
• Evapotranspiration: The process where water is transferred from land to the atmosphere, cooling the air.

Forests also affect climate by:

• Regulating precipitation: They play a crucial role in the water cycle, influencing rainfall patterns.
• Managing water cycles: Forests help maintain the balance of water in the environment.

Additionally, forests provide habitats for:

• Animals: Diverse species depend on forests for shelter and food.

These factors collectively impact all three aspects of environmental stability.

• Forests are often called "green lungs" because they help us breathe by releasing oxygen into the air through a process called photosynthesis.
• Just like how our lungs help us breathe in oxygen, forests provide oxygen for animals and humans to breathe and stay healthy.
• So, forests are like our planet's lungs, giving us the fresh air we need to live and thrive.

• In the forest, animals play a big role in helping it grow and renew. They scatter seeds and give nutrients for the plants to grow big and strong.
• Think of it like how your toys need care to stay nice and new - the forest needs help too, and animals are like its caretakers, making sure it stays healthy and green.

• When it rains in the forest, the uppermost layer of the forest canopy stops the raindrops. This means most of the water comes down through the branches and stems of the trees.
• This is like a big umbrella made by the trees to keep the rain from directly hitting the ground.
• So, the statement is True.

Forests play a crucial role in maintaining various environmental factors:

• Temperature: Forests regulate temperature by providing shade and releasing moisture through transpiration, which cools the air.
• Water Table: They help maintain the water table by facilitating the infiltration of rainwater into the ground.
• Rainfall: Forests contribute to the water cycle by releasing moisture into the atmosphere, which can increase local rainfall.

Therefore, forests help maintain all of these elements, making D: All of the above the correct answer.