Class 8 Science Practice Assignments: CBSE Class 8 Science Cell Eye Light and Electrolysis Assignment Set 06
Review targeted academic assignments with the CBSE Class 8 Science Cell Eye Light and Electrolysis Assignment Set 06. Built according to official CBSE standards for the 2026-27 term, these downloadable Class 8 Science worksheets support effective daily practice for All topics.
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Access the complete assignment PDF for Class 8 Science below. Regular practice with these targeted academic tasks builds familiarity with standard question patterns and helps secure higher marks in final school evaluations.
Assignment I: MCQs
1. 1-12.
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Answer: 1. (c) Hydra; 2. (c) reproduction (non-living things cannot grow or reproduce on their own); 3. (a) protoplasm; 4. (a) RNA; 5. (b) distant; 6. (b) retina; 7. (c) iris; 8. (b) violet; 9. (a) positive; 10. (a) good; 11. (b) LED; 12. (b) electrolysis.
Teacher's Note: Use the key term in your answer.
Assignment II: Very Short Answers
1. Anode and cathode. 2. A magnetic compass.
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Answer: The anode is the electrode connected to the positive terminal of the cell and the cathode is the electrode connected to the negative terminal. A magnetic compass is an instrument with a magnetised needle that always points north-south and is used to find directions.
Teacher's Note: Give an example if the question allows.
3. Three effects of current in an electrolytic cell. 4. Two superior metals for electroplating.
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Answer: The heating effect, the chemical effect and the magnetic effect. Chromium and nickel are used as the superior metals (gold and silver are also used).
Teacher's Note: Write a short, clear answer.
5. Spectrum of light. 6. Cataract.
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Answer: A spectrum is the band of seven colours (violet, indigo, blue, green, yellow, orange, red) formed when white light passes through a prism. Cataract is the clouding of the eye lens, which makes vision blurred and can be cured by surgery.
Teacher's Note: Remember this for your exam.
7. Laws of reflection. 8. Function of the optic nerves.
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Answer: First law: the incident ray, the reflected ray and the normal at the point of incidence all lie in the same plane. Second law: the angle of incidence equals the angle of reflection. The optic nerves carry the messages (electrical signals) from the retina to the brain.
Teacher's Note: Learn this point and write it in your own words.
9. Why are chromosomes called hereditary vehicles? 10. Who gave the term cell? 11. Which part has organelles? 12. Function of mitochondria.
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Answer: Chromosomes carry genes and pass the characters from parents to children. Robert Hooke gave the term cell (in 1665). The cytoplasm holds the organelles. Mitochondria are the 'powerhouse' of the cell and release energy from food by respiration.
Teacher's Note: Use the key term in your answer.
Assignment II: Short Answers I
13. Unicellular and multicellular organisms.
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Answer:
| Unicellular | Multicellular |
|---|---|
| Body is made of one cell | Body is made of many cells |
| All life activities are done by that cell | Cells are specialised for different jobs |
| Amoeba, Paramecium, Euglena | Hydra, plants, humans |
Teacher's Note: Give an example if the question allows.
14. Technological aids for visually challenged people.
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Answer: Braille books and Braille writers, talking books and audio books, screen readers for computers, Braille displays, magnifiers, talking watches and calculators, and the white cane.
Teacher's Note: Write a short, clear answer.
15. The number of images when the mirrors are at 45 degrees.
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Answer: Number of images = 360/45 - 1 = 8 - 1 = 7.
Teacher's Note: Remember this for your exam.
16. How is internal reflection prevented in the eye?
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Answer: The inner surface of the eye is covered by a dark layer (the choroid) which absorbs the extra light, so no light is reflected inside the eye.
Teacher's Note: Learn this point and write it in your own words.
17. Where are chromosomes found? What is their function?
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Answer: Chromosomes are found in the nucleus of the cell. They carry genes, which control the characters of an organism and pass them from one generation to the next.
Teacher's Note: Use the key term in your answer.
18. Electroplating and two uses.
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Answer: Electroplating is the coating of a thin layer of one metal on another by passing an electric current. Uses: it protects iron from rusting (for example with chromium or zinc), and it makes things look attractive and shiny (gold and silver plating of jewellery and utensils).
Teacher's Note: Give an example if the question allows.
19. How can we take care of our eyes?
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Answer: Eat food rich in vitamin A (carrots, green vegetables, milk), wash the eyes with clean water, do not rub them with dirty hands, read in good light and at a proper distance, avoid looking at the Sun or at screens for long, have regular check-ups, and wear glasses if advised.
Teacher's Note: Write a short, clear answer.
20. Why is distilled water a poor conductor? How can its conductivity be improved?
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Answer: Distilled water has no ions, and free ions are needed to carry current. Dissolving a little salt, acid or base in it gives ions and makes it a good conductor.
Teacher's Note: Remember this for your exam.
Assignment III: Short Answers II
1. Defects of the eye; explain one.
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Answer: Myopia (short-sightedness), hypermetropia (long-sightedness), cataract and presbyopia are defects of the eye. In myopia a person can see nearby objects clearly but not distant ones, because the eyeball is too long or the lens is too curved, so the image forms in front of the retina. It is corrected by wearing a concave lens.
Teacher's Note: Learn this point and write it in your own words.
2. Electrolysis and four applications.
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Answer: Electrolysis is the breaking up of a compound (electrolyte) into its elements by passing an electric current through it. Applications: (1) electroplating, (2) extraction of metals like sodium and aluminium, (3) purification of metals like copper, (4) preparation of gases and chemicals such as hydrogen, oxygen and chlorine.
Teacher's Note: Use the key term in your answer.
3. How an electric tester works; why it may fail and how to repair it.
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Answer: An electric tester has a cell, a bulb or LED and two wires. When the free ends are touched to a conducting liquid, current flows and the bulb glows. If the liquid is a bad conductor the current is very small, so use an LED. A tester may fail because of a weak or dead cell, a fused bulb, loose or broken connections, or a poor conductor; it is repaired by changing the cell or bulb and tightening the connections.
Teacher's Note: Give an example if the question allows.
4. Function of the cell membrane and the list of organelles.
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Answer: The cell membrane gives shape, protects the cell and controls what enters and leaves it. The organelles are the nucleus, endoplasmic reticulum, Golgi bodies, mitochondria, ribosomes, lysosomes, plastids (in plant cells) and vacuoles.
Teacher's Note: Write a short, clear answer.
5. A labelled diagram of a compound microscope and magnification of the electron and compound microscopes.
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Answer: Here is the diagram. A compound microscope magnifies up to about 1,000 to 2,000 times, and an electron microscope magnifies up to millions of times (about 2,000,000 times).
Teacher's Note:
6. Levels of organisation and division of labour.
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Answer: In a many-celled organism cells make tissues, tissues make organs, organs make organ systems and the systems make the organism. Division of labour means different cells, tissues and organs do different jobs, so the work is done well.
Teacher's Note: Learn this point and write it in your own words.
7. Characteristics and uses of a plane mirror.
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Answer: The image is virtual and erect, of the same size as the object, as far behind the mirror as the object is in front, and laterally inverted. Uses: in homes and shops, dressing tables, periscopes, kaleidoscopes and vehicles' mirrors.
Teacher's Note: Use the key term in your answer.
8. Curable blindness.
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Answer: Curable blindness is blindness due to cataract or a damaged cornea, which can be cured by surgery or a cornea transplant (eye donation).
Teacher's Note: Give an example if the question allows.
9. Dispersion of light, and monochromatic light.
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Answer: Dispersion is the splitting of white light into its seven colours by a prism. When monochromatic (single-colour) light falls on a prism, there is no spectrum, since it does not split: the ray is only bent.
Teacher's Note: Write a short, clear answer.
Assignment III: Long Answers
10. What happens when an electrolyte is dissolved in water and current is passed through it?
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Answer: The electrolyte breaks up into positive and negative ions in water. When current is passed, the positive ions (cations) move to the cathode and the negative ions (anions) to the anode. They gain or lose electrons and are deposited as atoms or released as gases, which is a chemical change.
Teacher's Note: Remember this for your exam.
11. Lateral inversion, with a diagram.
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Answer: In a plane mirror the left of the object appears as the right of the image, and the right as left. This is lateral inversion. The diagram shows how the image of a point is formed: the reflected rays seem to come from a point behind the mirror, as far behind as the object is in front.
Teacher's Note:
12. Regular and irregular reflection.
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Answer:
| Regular reflection | Irregular (diffuse) reflection |
|---|---|
| From a smooth, polished surface | From a rough surface |
| Reflected rays are parallel | Reflected rays go in many directions |
| Forms a clear image | Does not form an image |
| Example: a mirror, still water | Example: wall, paper, wood |
Teacher's Note: Use the key term in your answer.
13. Diagrams of a plant cell and a prokaryotic cell.
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Answer: The plant cell has a cell wall, a large vacuole and chloroplasts, and a nucleus with a nuclear membrane. A prokaryotic cell has no true nucleus: its DNA lies free in the cytoplasm in a region called the nucleoid.
Teacher's Note:
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