Imp Questions For All Chapters – General Science Class 7
Cell Structure and Micro-organisms
Short Questions
1. What is a cell?
→ A cell is the smallest unit of life and the basic structural and functional unit of all living organisms.
2. Who discovered the cell?
→ Robert Hooke discovered the cell in 1665 by observing cork under a microscope.
3. What did Anton van Leeuwenhoek observe under the microscope?
→ He was the first to observe live bacteria and protozoa in 1673.
4. Who proposed the cell theory?
→ M. J. Schleiden and Theodor Schwann in 1838.
5. What is the function of the nucleus in a cell?
→ The nucleus controls all activities of the cell and contains genetic material (DNA).
6. What is the cytoplasm?
→ Cytoplasm is the jelly-like fluid inside the cell that contains cell organelles.
7. What is the function of mitochondria?
→ Mitochondria are the powerhouse of the cell as they produce energy.
8. What are the two main types of cells?
→ Plant cells and Animal cells.
9. What is the function of chloroplasts?
→ Chloroplasts help in photosynthesis by capturing sunlight in plant cells.
10. Which part of the plant cell gives it a definite shape?
→ The cell wall provides shape and protection.
11. What is the function of the Golgi body?
→ The Golgi body processes and packages proteins.
12. What are lysosomes known as?
→ Lysosomes are called the suicide bags of the cell as they digest unwanted materials.
13. What are micro-organisms?
→ Micro-organisms are tiny living organisms that can only be seen with a microscope.
14. Name any two unicellular organisms.
→ Amoeba and Paramecium.
15. Where are micro-organisms found?
→ They are found in air, water, soil, food, and living organisms.
16. What are the types of micro-organisms?
→ Bacteria, fungi, protozoa, algae, and viruses.
17. Who discovered the process of fermentation?
→ Louis Pasteur.
18. How do micro-organisms help in agriculture?
→ They increase soil fertility by converting nitrogen into useful compounds.
19. What is an antibiotic?
→ An antibiotic is a medicine that kills or stops the growth of bacteria.
20. What is a vaccine?
→ A vaccine is a weakened form of a microbe that helps in developing immunity against diseases.
21. Give one example of a bacterial disease.
→ Tuberculosis (TB).
22. Why do doctors advise completing an antibiotic course?
→ To completely kill bacteria and prevent resistance.
Long Questions
1. Why are plant cells different from animal cells?
→ Plant cells have a cell wall and chloroplasts, which are absent in animal cells. Also, plant cells have a large vacuole, while animal cells have small vacuoles.
What is the role of micro-organisms in the environment?
→ Micro-organisms help in decomposing waste, fertilizing soil, and recycling nutrients. Some also help in making food and medicines.
What precautions should be taken while using antibiotics?
→ Take antibiotics only when prescribed, complete the full course, and never use expired medicines to avoid bacterial resistance.
How do micro-organisms help in food production?
→ Bacteria help in making yogurt and cheese, yeast helps in making bread and alcohol, and fungi help in fermenting foods.
What are harmful effects of micro-organisms?
→ Some micro-organisms cause diseases like tuberculosis and cholera, spoil food, and damage crops by spreading infections.
Why is vaccination important?
→ Vaccination protects us from deadly diseases by developing immunity against harmful microbes like measles, polio, and hepatitis.
What is food poisoning, and how can it be prevented?
→ Food poisoning occurs due to toxins released by bacteria and fungi in stale food. It can be prevented by eating fresh, covered, and properly stored food.
How are antibiotics made?
→ Antibiotics are made using micro-organisms like bacteria and fungi in laboratories and are used to treat bacterial infections.
Why does yeast make dough rise?
→ Yeast undergoes fermentation, releasing carbon dioxide gas, which forms air bubbles in the dough and makes it rise.
What are the differences between prokaryotic and eukaryotic cells?
→ Prokaryotic cells (like bacteria) do not have a nucleus, while eukaryotic cells (plant and animal cells) have a well-defined nucleus and organelles.
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