The Invisible Living World Beyond Our Naked Eye Class 8 MCQs with Answers are designed to help students understand and revise important concepts from the chapter. These multiple-choice questions cover key topics related to the microscopic world, microorganisms, and the living things that cannot be seen with the naked eye. The MCQs are useful for quick revision, practice, class tests, and exam preparation.
The Invisible Living World Beyond Our Naked Eye Class 8 MCQ with Answers
Conceptual Recall MCQs
Q. Lens is shaped like:
a) A cube
b) A lentil seed
c) A rectangle
d) A triangle
Answer: b) A lentil seed
Explanation: Thick in the middle, thin at edges, like a lentil seed.
Q. Organisms are:
a) Only plants
b) Only animals
c) All living beings
d) Non-living things
Answer: c) All living beings
Explanation: Both plants and animals are called organisms.
Q. Basic parts of a cell are:
a) Cell wall, vacuole, chloroplast
b) Cell membrane, cytoplasm, nucleus
c) Cytoplasm, mitochondria, plastids
d) Nucleus, ribosome, vacuole
Answer: b) Cell membrane, cytoplasm, nucleus
Explanation: These three are common in all cells.
Q. Cell wall is present in:
a) Animal cells only
b) Plant cells only
c) Both plant and animal cells
d) Neither plant nor animal cells
Answer: b) Plant cells only
Explanation: Cell wall gives rigidity and strength to plants.
Q. Muscle cells are shaped like:
a) Cube
b) Spindle
c) Round
d) Polygon
Answer: b) Spindle
Explanation: Thin, flexible, spindle-shaped for contraction and relaxation.
Q. Nerve cells are:
a) Short and round
b) Very long with branches
c) Flat and thin
d) Rectangular
Answer: b) Very long with branches
Explanation: Their elongated, branched shape helps carry messages quickly.
Q. The correct order of levels of organisation is:
a) Tissue → Cell → Organ → Organ system → Organism
b) Cell → Tissue → Organ → Organ system → Organism
c) Organ → Cell → Tissue → Organism → Organ system
d) Cell → Organ → Tissue → Organ system → Organism
Answer: b) Cell → Tissue → Organ → Organ system → Organism
Explanation: Cells are the basic unit, then tissues, organs, systems, and finally organism.
Q. The largest known cell is:
a) Human nerve cell
b) Onion peel cell
c) Ostrich egg yolk
d) Amoeba
Answer: c) Ostrich egg yolk
Explanation: Ostrich egg yolk is a single cell, about 130–170 mm in diameter.
Q. Preservatives in pickles prevent microbial growth because:
a) They add oxygen
b) They contain high salt/sugar
c) They remove water
d) They contain yeast
Answer: b) They contain high salt/sugar
Explanation: High concentration of salt/sugar stops microbes from growing.
Q. Rhizobium bacteria live in:
a) Human cheek cells
b) Onion peel cells
c) Root nodules of legumes
d) Stomach lining
Answer: c) Root nodules of legumes
Explanation: Rhizobium fixes nitrogen in roots of beans, peas, lentils.
Q. Microalgae produce:
a) Only food for humans
b) More than half of Earth’s oxygen
c) Only biofuel
d) Only medicines
Answer: b) More than half of Earth’s oxygen
Explanation: Microalgae release oxygen while making food using sunlight.
Q. Spirulina is called a superfood because:
a) It is rich in protein and vitamin B12
b) It has no nutrients
c) It is harmful to humans
d) It contains only sugar
Answer: a) It is rich in protein and vitamin B12
Explanation: Spirulina has 60% protein, very little fat and sugar.
Application-Based MCQs
Q. A person uses reading glasses to:
a) Make letters smaller
b) See letters more clearly
c) Change colour of letters
d) Hide letters
Answer: b) See letters more clearly
Explanation: Lenses magnify and make vision clearer.
Q. If you look at an ant with a magnifying glass, you will:
a) See fewer details
b) See more details of its body
c) Not see the ant at all
d) See the ant in black and white
Answer: b) See more details of its body
Explanation: Magnifying glass enlarges small structures.
Q. Onion peel cells look rectangular because:
a) They are loosely arranged
b) They have a rigid cell wall
c) They lack cytoplasm
d) They are polygon-shaped
Answer: b) They have a rigid cell wall
Explanation: Cell wall makes plant cells firm and compact.
Q. Cheek cells are polygon-shaped because:
a) They have a cell wall
b) They lack a cell wall
c) They are stained with safranin
d) They contain chloroplasts
Answer: b) They lack a cell wall
Explanation: Animal cells don’t have a cell wall, so they are irregular/polygon-shaped.
Q. Cheek cells are thin and flat because:
a) They help in digestion
b) They form a protective lining
c) They carry oxygen
d) They store food
Answer: b) They form a protective lining
Explanation: Flat cells cover and protect the inner surface of the mouth.
Q. Plant tube-like cells help in:
a) Photosynthesis
b) Carrying water
c) Storing food
d) Producing digestive juices
Answer: b) Carrying water
Explanation: Tube-like plant cells transport water throughout the plant.
Q. Multicellular organisms begin life from:
a) Many cells together
b) A single cell (egg)
c) A tissue
d) An organ
Answer: b) A single cell (egg)
Explanation: Egg divides repeatedly to form a complete organism.
Q. A student observes pond water under a microscope and sees green organisms. These are most likely:
a) Fungi
b) Algae
c) Bacteria
d) Protozoa
Answer: b) Algae
Explanation: Algae look green due to chlorophyll pigment.
Q. Gardeners collect dry leaves and plant waste in pits because:
a) To burn them
b) To make natural manure using microbes
c) To store food
d) To prevent pollution only
Answer: b) To make natural manure using microbes
Explanation: Microbes decompose waste into nutrient-rich manure.
Q. Yeast makes dough fluffy because:
a) It absorbs water
b) It releases carbon dioxide bubbles during respiration
c) It produces lactic acid
d) It removes sugar from flour
Answer: b) It releases carbon dioxide bubbles during respiration
Explanation: CO₂ bubbles make dough rise and become soft.
Q. Farmers grow legumes in rotation with other crops because:
a) They need less water
b) They contain Rhizobium bacteria that fix nitrogen
c) They produce more oxygen
d) They prevent soil erosion
Answer: b) They contain Rhizobium bacteria that fix nitrogen
Explanation: Rhizobium enriches soil naturally without chemical fertilisers.
Q. Yeast helps in bread-making by:
a) Producing lactic acid
b) Producing carbon dioxide bubbles
c) Removing sugar from flour
d) Producing nitrogen gas
Answer: b) Producing carbon dioxide bubbles
Explanation: CO₂ makes dough rise and fluffy.
Assertion–Reason MCQs
Q. Assertion (A): Robert Hooke coined the term “cell.”
Reason (R): He saw empty compartments in cork that looked like a honeycomb.
a) Both A and R are true, and R explains A
b) Both A and R are true, but R does not explain A
c) A is true, R is false
d) A is false, R is true
Answer: a) Both A and R are true, and R explains A
Q. Assertion (A): Vacuoles in plant cells help maintain shape and store substances.
Reason (R): Vacuoles in animal cells are large and provide rigidity.
a) Both A and R are true, and R explains A
b) Both A and R are true, but R does not explain A
c) A is true, R is false
d) A is false, R is true
Answer: c) A is true, R is false
Q. Assertion (A): Muscle cells in the food pipe push food down to the stomach.
Reason (R): Their spindle shape allows contraction and relaxation in a wave-like manner.
a) Both A and R are true, and R explains A
b) Both A and R are true, but R does not explain A
c) A is true, R is false
d) A is false, R is true
Answer: a) Both A and R are true, and R explains A
Q. Assertion (A): Microorganisms cannot be seen with the naked eye.
Reason (R): They are very small and need a microscope for observation.
a) Both A and R are true, and R explains A
b) Both A and R are true, but R does not explain A
c) A is true, R is false
d) A is false, R is true
Answer: a) Both A and R are true, and R explains A
Q. Assertion (A): Curd forms faster in warm milk than in cold milk.
Reason (R): Lactobacillus bacteria grow well in warm conditions and produce lactic acid.
a) Both A and R are true, and R explains A
b) Both A and R are true, but R does not explain A
c) A is true, R is false
d) A is false, R is true
Answer: a) Both A and R are true, and R explains A
Q. Assertion (A): Bacteria do not have a well-defined nucleus.
Reason (R): Their genetic material is present in a region called nucleoid.
a) Both A and R are true, and R explains A
b) Both A and R are true, but R does not explain A
c) A is true, R is false
d) A is false, R is true
Answer: a) Both A and R are true, and R explains A
Case-Based MCQ
Q. Case Study: A student fills a round-bottom flask with water, closes it with a cork, and places it on a book. He notices the letters look bigger.
What is the correct explanation?
a) Water absorbs the letters
b) Flask acts like a magnifying glass
c) Cork changes the letters
d) Letters naturally enlarge under glass
Answer: b) Flask acts like a magnifying glass
Q. Case Study: A student scrapes the inside of his cheek, stains the sample with methylene blue, and observes polygon-shaped cells under a microscope.
What conclusion can be drawn?
a) Cheek cells have a cell wall like onion cells
b) Cheek cells lack a cell wall but have membrane, cytoplasm, and nucleus
c) Cheek cells are rectangular like plant cells
d) Cheek cells contain chloroplasts for photosynthesis
Answer: b) Cheek cells lack a cell wall but have membrane, cytoplasm, and nucleus
Explanation: Cheek cells are animal cells, so no cell wall or chloroplast.
Q. Case Study: A group of students observe onion peel cells, cheek cells, and nerve cells under a microscope. They notice different shapes: rectangular, polygon, and branched.
What conclusion can they draw?
a) All cells have the same shape
b) Cell shape is linked to its function
c) Only plant cells vary in shape
d) Shape does not matter in cells
Answer: b) Cell shape is linked to its function
Explanation: Different shapes allow cells to perform specific jobs (movement, protection, message transfer).
Q. Case Study: Grade 8 students collected pond water and soil suspension. They observed Amoeba, Paramecium, algae, fungi, and bacteria.
What conclusion can be drawn?
a) Microorganisms live only in pond water
b) Microorganisms are found everywhere — water, soil, air, and even inside our body
c) Microorganisms are visible without a microscope
d) Microorganisms are only multicellular
Answer: b) Microorganisms are found everywhere — water, soil, air, and even inside our body
Explanation: Both pond water and soil suspension showed microbes.
Q. Case Study: A student adds fruit peels to soil in a container. After 3 weeks, the peels turn into dark manure.
What is the correct explanation?
a) Soil absorbs peels naturally
b) Microorganisms decompose peels into nutrient-rich manure
c) Peels change colour due to sunlight
d) Peels dissolve in water
Answer: b) Microorganisms decompose peels into nutrient-rich manure
Explanation: Fungi and bacteria break down waste → manure → fertile soil.
Q. Case Study: A student sets up two tanks — one with Spirulina in pond water under moderate temperature, and another in direct sunlight without shade. After 4 weeks, only the shaded tank shows Spirulina growth.
What conclusion can be drawn?
a) Spirulina grows only in cold water
b) Spirulina needs moderate temperature and shade for growth
c) Spirulina grows only in direct sunlight
d) Spirulina does not grow in pond water
Answer: b) Spirulina needs moderate temperature and shade for growth
Explanation: Spirulina farming requires controlled conditions, not harsh sunlight.
Diagram/Visual-Based MCQ
Q. Look at Robert Hooke’s microscope. What was its magnification power?
a) 20–30 times
b) 200–300 times
c) 1000 times
d) 10 times
Answer: b) 200–300 times
Explanation: His microscope enlarged objects 200–300 times.
Q. In Figure, which structure is present only in plant cells?
a) Nucleus
b) Cytoplasm
c) Chloroplast
d) Cell membrane
Answer: c) Chloroplast
Explanation: Chloroplasts with chlorophyll are unique to plant cells.
Q. In soil suspension, bacteria appear as:
a) Only spherical
b) Only rod-shaped
c) Spherical, comma, spiral, or rod-shaped
d) Only branched filaments
Answer: c) Spherical, comma, spiral, or rod-shaped
Explanation: Bacteria show different shapes and may have hair-like projections.
Q. In Figure, the swollen regions in cowpea roots are:
a) Vacuoles
b) Nodules containing Rhizobium
c) Chloroplasts
d) Fungi filaments
Answer: b) Nodules containing Rhizobium
Explanation: Nodules trap nitrogen and enrich soil naturally.
Q. In Figure, the nucleoid region represents:
a) A well-defined nucleus
b) Genetic material without nuclear membrane
c) Vacuole storing food
d) Chloroplast for photosynthesis
Answer: b) Genetic material without nuclear membrane
Explanation: Bacteria lack a true nucleus; DNA is in nucleoid region.
Disclaimer: The content that is present on our website is based on the NCERT Class 8 Science textbook and is provided for educational purposes only. All the content and images have been taken from Science Class 8 NCERT Textbook. Images and content shown above are the property of individual organizations and are used here for reference purposes only. To make it easy to understand, some of the content and images are generated by AI and cross-checked by the teachers.