Mastery

The Invisible Living World: Beyond Our Naked Eye — Mastery

30 questions 30 min Full-chapter mastery

Q1. In Activity 2.1, a round-bottom flask filled with water is placed on an open book and letters appear larger when seen through it. This happens because the flask filled with water acts like a
- A. Plane mirror
- B. Real magnifying glass
- C. Concave mirror that absorbs light
- D. Black screen
Q2. The chapter compares the body of a living organism to a wall. In this analogy, the cell is best compared to
- A. The cement between bricks
- B. A single brick — the basic unit of the wall
- C. The whole wall itself
- D. The paint coating on the wall
Q3. Two students debate the size of vacuoles in plant and animal cells. Using the chapter, which conclusion is correct?
- A. Both plant and animal cells have equally large vacuoles.
- B. Plant cells have no vacuoles; only animal cells have them.
- C. Animal cells have no vacuoles; only plant cells have them.
- D. Plant cells have a large vacuole; in animal cells, vacuoles are usually not present, or if present, are usually small.
Q4. Cells in all parts of a plant have tiny rod-shaped structures that include chloroplasts and others. These rod-shaped structures are collectively called
- A. Vacuoles
- B. Plastids
- C. Nucleoids
- D. Mitochondria
Q5. A teacher tells the class: 'Cells called neurons carry messages in our body.' A student asks why their long branched shape matters. The best answer is that this shape
- A. Helps them reach different parts of the body and pass on messages quickly
- B. Helps them store food and water for the body
- C. Helps them make their own food using sunlight
- D. Helps them divide rapidly into many similar cells
Q6. Aanandi's mother says digestion in the stomach is helped by acid that breaks down food. According to the chapter, this acid and the digestive juices are produced by
- A. Muscle cells in the stomach wall
- B. Nerve cells branching through the stomach
- C. Cheek cells in the mouth lining
- D. Cells in the inner lining of the stomach
Q7. Some plant cells form long tubes that run through the whole plant. According to the chapter, the main job of these tube-like plant cells is to
- A. Capture sunlight for food-making
- B. Carry water throughout the plant
- C. Protect the plant from microbes
- D. Store food for the plant
Q8. Inner cheek cells are thin and flat. According to the chapter, the most likely reason for this shape is that they
- A. Help carry messages across the body
- B. Form a protective lining on the inner surface of the cheek
- C. Push food down to the stomach in waves
- D. Make food using sunlight
Q9. Mouth, food pipe, stomach, and intestine together perform one major job — digestion of food. As per the chapter's levels of organisation, these organs together are best called
- A. A tissue
- B. An organ
- C. An organism
- D. An organ system
Q10. According to the chapter, what is the relationship between organ systems and an organism?
- A. An organism is made of just one organ system.
- B. Each organ system is itself a complete organism.
- C. Organ systems are smaller than tissues in the same body.
- D. All the organ systems together make up a complete organism.
Q11. Three statements about a tissue, as the chapter defines it, are given: I. A tissue is made up of similar types of cells. II. A single cell by itself can be called a tissue. III. Different tissues organise to form an organ. The correct statements are
- A. II and III only
- B. I and II only
- C. I and III only
- D. All three
Q12. The chapter says some microorganisms can be found even in extreme climatic conditions. Which pair of places best matches this point?
- A. Pond water and garden soil
- B. Hot water springs and snow-cold zones
- C. Refrigerator and lukewarm milk
- D. Roots of cowpea and the human gut
Q13. The chapter gives Amoeba as a clear example of
- A. A unicellular microorganism made of just one cell
- B. A multicellular fungus with branched filaments
- C. A virus that needs a host to reproduce
- D. A microalga that makes food using sunlight
Q14. The chapter gives an interesting contrast in the fungi category — yeast is unicellular while mould is multicellular. This tells us that fungi
- A. Are always single-celled organisms
- B. Are always multi-celled organisms
- C. Can be either unicellular or multicellular
- D. Are not microorganisms at all
Q15. When a lemon left out for a few days develops a powdery or cotton-like growth on it, the most likely organism growing on it is
- A. Spirulina, a microalga
- B. Rhizobium, a bacterium
- C. Mould, a multicellular fungus
- D. Amoeba, a protozoan
Q16. The chapter says some microorganisms 'like some fungi and algae' have many cells. From this, we infer that algae can be
- A. Only unicellular
- B. Either unicellular or multicellular
- C. Only multicellular
- D. Always made of nuclei without cytoplasm
Q17. Table 2.2 describes one organism as 'a branched filament without chlorophyll having sac-like structure'. This description matches
- A. Algae
- B. Bacteria
- C. Paramecium
- D. Bread mould (a fungus)
Q18. Table 2.2 describes bacteria observed in soil suspension as 'spherical, comma, spiral or rod-shaped, one long hair-like structure and many small hair-like projections around the cell.' From this we conclude that bacteria
- A. Show variety in shape and have hair-like projections in addition to cell parts
- B. Are all exactly the same shape and have no projections
- C. Are larger than plant cells and are green
- D. Cannot be seen under a school microscope
Q19. Three rows of Table 2.1 (pond water) describe organisms based only on 'single cell' and movement features. From this table alone, which conclusion is best supported?
- A. Pond water contains only multicellular organisms.
- B. Pond water organisms are exclusively bacteria.
- C. Pond water organisms are entirely viral.
- D. Pond water can contain a variety of single-celled organisms with different movement patterns.
Q20. Three students draw different bacterial shapes after observing soil suspension. According to the chapter, all of the following are real bacterial shapes EXCEPT
- A. Spherical
- B. Star-shaped with five rigid arms
- C. Rod-shaped
- D. Spiral
Q21. The chapter notes that we already know some microbes live inside our bodies. It then says that our intestine has many bacteria that help in
- A. Photosynthesis
- B. Producing biogas in our gut
- C. Digestion
- D. Carrying messages to the brain
Q22. Three statements about Rhizobium are given: I. Rhizobium lives freely in the air, never inside plants. II. Rhizobium lives in swollen regions called nodules in roots of legumes such as beans, peas, and lentils. III. Rhizobium traps nitrogen from air and makes it useful for the plant. The correct statements are
- A. II and III only
- B. I and II only
- C. I and III only
- D. All three
Q23. Assertion (A): A virus cannot multiply by itself on a clean glass slide kept on the table. Reason (R): Viruses multiply only when they enter a living host cell. Choose the correct option
- A. Both A and R are true, but R is NOT the correct explanation of A.
- B. A is true, R is false.
- C. Both A and R are true, and R is the correct explanation of A.
- D. A is false, R is true.
Q24. The chapter notes that viruses may cause disease. Which option best describes the range of organisms that viruses can infect?
- A. Only humans
- B. Only bacteria
- C. Plants, animals, or bacterial cells
- D. Only plants and never animals
Q25. A gardener in Snehal's school collects dry leaves and plant waste and puts them into pits. As per the chapter, the gardener mainly wants to
- A. Burn the waste to make ash for the soil
- B. Hide the waste from the school children
- C. Sell the waste to local farmers as fuel
- D. Let microorganisms slowly turn the waste into natural manure
Q26. Indian-origin scientist Ananda Mohan Chakrabarty (1938-2020) is remembered in this chapter for developing in 1971 a special bacterium that could
- A. Break down oil spills, helping to clean the environment
- B. Make Spirulina richer in vitamin B12
- C. Replace nitrogen fertilisers in wheat fields
- D. Ferment milk faster than Lactobacillus
Q27. A health-shop assistant tells Ravi's grandmother that Spirulina is sold as a 'superfood'. According to the chapter, the main reason Spirulina is called a superfood is that it
- A. Is the world's only edible algae
- B. Is rich in protein (over 60% of its body weight) and is a good source of vitamin B12
- C. Cures all diseases of the human gut
- D. Is grown only in cold mountain water
Q28. In the chapter's end-question, Aanandi attaches balloons to test tubes A (sugar solution only) and B (sugar solution with yeast) and keeps them warm. After 3-4 hours, balloon B inflates. Which is the best explanation for this observation?
- A. Water evaporated in test tube B and filled the balloon with water vapour.
- B. The warm atmosphere expanded the air inside test tube B, which inflated the balloon.
- C. Yeast produced a gas inside test tube B, which inflated the balloon.
- D. Sugar reacted with warm air, which produced gas, eventually inflating the balloon.
Q29. A Class 8 student says 'all microorganisms are harmful and should be killed.' Going by the chapter, the best response by the teacher is to
- A. Agree, because all microorganisms cause diseases.
- B. Explain that microbes can be beneficial or harmful — many help in food, soil fertility, decomposition and biogas.
- C. Tell the student to forget about microbes since the topic is not in the exam.
- D. Recommend using strong disinfectants everywhere to kill all microbes.
Q30. A Class 8 teacher wants children to actually 'see' cells for the first time. Going by the chapter, the best first activity is to
- A. Show a printed diagram of a cell from a chart on the wall.
- B. Read aloud the paragraph defining the cell from the textbook.
- C. Ask students to memorise the names of cell parts before any observation.
- D. Demonstrate Activity 2.2 — peel and stain onion membrane and observe under a microscope.

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