The Invisible Living World Beyond Our Naked Eye Class 8 Notes

The Invisible Living World Beyond Our Naked Eye Class 8 Notes

The Invisible Living World Beyond Our Naked Eye Class 8 Notes

1. Invisible: Impossible or nearly impossible to see.
2. Complexity: The state of having many parts and being difficult to understand.
3. Neurons: Cells which carry messages in our body.
4. Lens: A curved piece of glass or other transparent material that bends light rays to magnify objects.
5. Foldscopes: Low-cost, foldable paper microscope.
6. Microscope: An optical instrument that uses lenses to magnify small objects, making them visible to the human eye.
7. Microorganisms (microbes): The tiny living organisms that can only be seen with a microscope.
8. Soil suspension: A non-uniform mixture in which solute particles do not dissolve but remain suspended.
9. Acellular: Not made up of true cells.
10. Unicellular: Made up of a single cell.
11. Multicellular: Composed of multiple cells that work together.
12. Fermentation: A metabolic process that converts sugar to acids, gases, or alcohol using microorganisms, primarily yeast and bacteria.
13. Spirulina: A type of microalga that is considered a superfood due to its high nutritional value, including protein and vitamins.
14. Microalgae: Microscopic plant-like organisms.
15. Cell: The basic unit of life, the smallest structural and functional unit of an organism.
16. Observation: The action of closely monitoring or examining something to gain information.
17. Nourishment: The substances necessary for growth, health, and good condition.

Structure:

Components:

1. Cell membrane
2. Cytoplasm
3. Nucleus (except bacteria)
4. Cell wall (in plants, fungi, bacteria)
5. Mitochondria

Cell Characteristics:

1. Shape and size vary
2. Shape relates to function

Multicellular organisms:

Made up of many cells

The levels of organisation:

Cell →Tissue → Organ → Organ system → Organism

Types:

(i) Bacteria:

1. Unicellular
2. No well-defined nucleus
3. Cell wall present

(ii) Protozoa:

1. Unicellular
2. Well-defined nucleus

(iii) Fungi:

1. Uni-or multicellular
2. Cell wall present
3. Well-defined nucleus

(iv) Algae:

1. Single cell
2. Looks green because of the presence of chlorophyll

Viruses:

1. Microscopic and acellular (Not true cells)
2. Multiply when they enter a living cell

Habitats of microorganisms

Found in:

1. Soil
2. Water
3. Air
4. Inside plants and animals

Roles of Microorganisms:

Beneficial:

1. Decomposition: Break down waste (Source of biogas)
2. Nitrogen Fixation: In root nodules of legumes (peas, beans, lentils)
3. Food Production: Spirulina
4. Yeast: Breads, cakes, idlis, dosas, bhaturas
5. Lactobacillus: Curd formation, fermentation

Harmful:

1. Can cause diseases in plants and animals, including humans
2. Viruses may infect plants, animals, or bacterial cells and may cause disease.