Our Home Earth A Unique Life Sustaining Planet Class 8 Notes

Our Home Earth A Unique Life Sustaining Planet Class 8 Notes

Our Home Earth A Unique Life Sustaining Planet Class 8 Notes

1. Habitable: Suitable or good enough to live in.
2. Cosmic rays: Particles from outer space that travel across the universe.
3. Hydrosphere: The total amount of water on a planet.
4. Geosphere: The layer of Earth made up of solid rock and other rocky materials.
5. Geodiversity: The variety of earth materials, forms and processes that constitute and shape the Earth.
6. Biodiversity: The variety of life on Earth at all its levels.
7. Biosphere: The sum of all ecosystems.
8. Greenhouse gases: The gases in the earth's atmosphere that trap heat.
9. Genes: The basic units of heredity in living organisms, made up of DNA. Genes carry the instructions for the development, functioning, growth, and reproduction of all known organisms.
10. Reproduction: The biological process by which new individual organisms are produced. It can occur through asexual or sexual means, ensuring the continuation of a species.
11. Asexual Reproduction: A mode of reproduction where a single parent organism produces offspring that are genetically identical to itself, without the involvement of gametes.
12. Sexual Reproduction: A type of reproduction that involves the combination of genetic material from two parents (male and female), resulting in offspring that have genetic variation.
13. Gametes: Specialised reproductive cells (sperm in males and eggs in females) that carry half of the genetic information from each parent, which combine during fertilisation.
14. Vegetative Propagation: A form of asexual reproduction in plants where new individuals are produced from vegetative parts such as stems, roots, or leaves, rather than from seeds.
15. Microbes: Microscopic organisms, which can be unicellular (like bacteria) or multicellular (like fungi), that can reproduce asexually or sexually.
16. Hydra: A simple freshwater animal that reproduces asexually by budding, where small buds grow on its body and eventually detach to form new individuals.
17. Planaria: A type of flatworm known for its remarkable ability to regenerate lost body parts, often studied in scientific research for understanding regeneration.
18. Evolution: The process through which species undergo changes over time, often leading to the development of new traits or entirely new species due to genetic variation and natural selection.
19. Adaptation: A characteristic that enhances an organism's ability to survive and reproduce in its environment, often resulting from evolutionary processes.

Earth:

1. The only known planet that sustains life.
2. Has diverse landscapes (mountains, oceans, deserts, forests).
3. Crust is a thin layer where all life exists.

Geodiversity:

1. Variety of landforms, rocks, soils, and processes that shape them.
2. Importance: Creates unique habitats for different life forms.

Biosphere:

1. The global sum of all ecosystems, including land, water, and air.

Components: Plants, animals, microorganisms.

Interdependence:

1. Living beings rely on each other and their environment.

Balance in Nature:

1. All elements (land, air, water, life) work together.
2. Small changes (e.g., deforestation) can have significant effects on ecosystems.
3. Importance of preserving clean air, water, and soil for future generations.

Reproduction and Continuity of Life:

1. Importance of reproduction: Ensures the survival of species.
2. Mechanism: Offspring inherit traits from parents (e.g., cows have calves).

Earth's Unique Conditions for Life:

1. Right distance from the Sun
2. Appropriate size
3. Gravity retains atmosphere and supports life.
4. Presence of oxygen
5. Ozone layer protects life by blocking harmful UV rays.