CBSE Class 7 Science Diversity of life on Earth Assignment

Question 1. Diversity of life mainly depends on______________ and_____________.
Answer: climate, terrain (or temperature, rainfall)
In simple words: The variety of living organisms in an area depends heavily on the local climate and land features.

Exam Tip: Remember that climate (temperature and precipitation) and landforms shape the habitats available for living things.

Question 2. Green plants produce their food by using food from___________,__________and_________
Answer: sunlight, carbon dioxide, water (along with minerals)
In simple words: Plants make their own food through photosynthesis using sunlight, carbon dioxide, and water.

Exam Tip: State the key ingredients of photosynthesis clearly: sunlight, carbon dioxide, and water.

Question 3. Natural Vegetation varies from region to region depending mainly on___________
Answer: temperature and moisture (or rainfall)
In simple words: Plant life changes across regions based on how warm and wet the climate is.

Exam Tip: Temperature and rainfall are the two most critical climatic factors determining vegetation type.

Question 4. What are the two main types of forests?
Answer: The two main types of forests are evergreen forests and deciduous forests.
In simple words: Forests are broadly classified into those that stay green year-round and those that shed their leaves annually.

Exam Tip: Keep the classification simple and direct: Evergreen and Deciduous.

Question 5. Define Evergreen Forest.
Answer: Evergreen forests are forests consisting of trees that do not shed all their leaves simultaneously in any particular season, remaining green throughout the year.
In simple words: Trees in evergreen forests never shed all their leaves at the same time, so they look green all year.

Exam Tip: Highlight the key characteristic that leaves are shed gradually rather than all at once.

Question 6. Complete the Table for Evergreen forest
Answer:

In simple words: Evergreen forests vary by region from heavy-rain tropical jungles to cold northern coniferous woods, maintaining foliage year-round.

Exam Tip: Memorize rainfall ranges and characteristic tree types for each sub-category of evergreen forests.

Question 7. Define Deciduous Forest.
Answer: Deciduous forests are forests composed of trees and shrubs that shed their leaves seasonally (typically during the dry or autumn season) to conserve water.
In simple words: Deciduous forests consist of trees that drop all their leaves in a particular season to save water.

Exam Tip: Contrast this directly with evergreen forests by emphasizing seasonal leaf shedding.

Question 8. Complete the Table for Deciduous forest
Answer:

In simple words: Tropical and temperate deciduous forests experience seasonal leaf shedding triggered by dry or cold weather.

Exam Tip: Note that Tropical Deciduous forests are also known as Monsoon forests.

Question 9. Define Grasslands
Answer: Grasslands are large, open areas of land dominated by grasses and herbaceous plants rather than large trees or shrubs, typically occurring in regions with moderate rainfall.
In simple words: Grasslands are expansive grassy regions where grass is the main plant life due to moderate rainfall.

Exam Tip: Mention that rainfall is too low to support large forests, hence grasses dominate.

Question 10. Complete the Table for Grasslands
Answer:

In simple words: Grasslands are split into tropical savannas and temperate prairies with distinct grass heights and animal species.

Exam Tip: Learn local names for temperate grasslands such as Prairies in North America and Steppes in Eurasia.

Question 11. What is Desert? What are its types?
Answer: A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. Its two main types are Hot Deserts and Cold Deserts.
In simple words: A desert is an extremely dry region with very little rainfall. It is classified into hot deserts and cold deserts.

Exam Tip: Always specify both hot and cold categories when answering types of deserts.

Question 12. Complete the Table for Hot Desert
Answer:

In simple words: Hot deserts have scorching temperatures, sparse rainfall, and specialized drought-resistant plants and animals.

Exam Tip: Highlight adaptations like thick skin, water storage, and nocturnal habits for hot desert animals.

Question 13. Complete the Table for Cold Desert
Answer:

In simple words: Cold deserts feature freezing temperatures, low precipitation, and stunted vegetation like mosses and lichens.

Exam Tip: Remember that cold deserts occur in high altitude plateaus or high latitude polar regions.

Question 14. What is Tundra region? Where it is found ?
Answer: The Tundra is a vast, flat, treeless Arctic region where the subsoil is permanently frozen (permafrost). It is found in the high latitudes of the Northern Hemisphere, encircling the North Pole and extending south to the coniferous forests of the taiga (e.g., northern parts of Canada, Russia, and Alaska).
In simple words: The tundra is a freezing, treeless polar region with frozen soil, located near the Arctic circle.

Exam Tip: Mention 'permafrost' as the defining characteristic of tundra regions.

Question 15. Write any five points how plants and animals are important for human being.
Answer:
1. Plants provide oxygen through photosynthesis, which is essential for human respiration.
2. Plants and animals serve as primary sources of food, including fruits, vegetables, grains, milk, and meat.
3. Many plants are used as medicinal herbs to cure various diseases and manufacture pharmaceuticals.
4. Animals and plants provide raw materials such as cotton, wool, timber, and leather for clothing and shelter.
5. Biodiversity maintains ecological balance, soil fertility, and pollination of crops necessary for agriculture.
In simple words: Plants and animals give us oxygen, food, medicines, clothing materials, and keep nature balanced.

Exam Tip: Use clear bullet points covering oxygen, food, medicine, raw materials, and ecological balance.

Question 16. Why do many plants and animals have become extinct or now threatened?
Answer: Many plants and animals have become extinct or threatened primarily due to human activities such as deforestation, habitat destruction, illegal poaching and hunting, climate change, pollution, and the introduction of invasive species.
In simple words: Human activities like cutting down forests, pollution, hunting, and global warming are destroying habitats and causing species to die out.

Exam Tip: Focus on anthropogenic (human-caused) pressures like habitat loss and poaching as main headings.