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Biotechnology & Applied Biology — Homi Bhabha Class 9 Biology MCQs with Solutions
Free Homi Bhabha Class 9 Biology Biotechnology & Applied Biology MCQs with step-by-step solutions covering Tissue Culture, Agriculture Technology, Useful & Harmful Micro-organisms, Diseases & Immunity. Practise online on Prepizo — no login needed.
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Sample questions with solutions
Q1 — Tissue Culture · easy · theory
In plant tissue culture, the mass of undifferentiated cells that first grows on the nutrient medium from a piece of tissue is called the:
A. Callus ✓ Correct
B. Nodule
C. Clone
D. Explant
Solution: The unorganised, dividing mass of cells that forms on the medium is the callus. The explant is the original piece placed on the medium; a clone is the set of identical plants finally produced.
Q2 — Tissue Culture · easy · theory
Plants produced by tissue culture from a single parent are genetically identical to that parent. Such a group of identical plants is called a:
A. Mutant
B. Hybrid
C. Variety
D. Clone ✓ Correct
Solution: Because they arise by mitosis from one parent without fertilisation, all the plants are genetically identical and together form a clone. A hybrid results from a cross between two different parents.
Q3 — Agriculture Technology · easy · theory
The technique of growing plants without soil, with the roots dipped in a nutrient-rich water solution, is called:
A. Apiculture
B. Horticulture
C. Hydroponics ✓ Correct
D. Sericulture
Solution: Hydroponics grows plants in a balanced mineral solution instead of soil. Sericulture is silkworm rearing, apiculture is bee-keeping and horticulture is the cultivation of garden crops.
Q4 — Useful & Harmful Micro-organisms · easy · theory
Milk is set into curd (dahi) by the action of which microorganism?
A. Lactobacillus bacteria ✓ Correct
B. Amoeba
C. Blue-green algae
D. Rhizobium bacteria
Solution: Lactobacillus bacteria convert the milk sugar (lactose) into lactic acid, which curdles the milk into dahi. Rhizobium fixes nitrogen in roots and is not involved in curd formation.
Q5 — Useful & Harmful Micro-organisms · easy · theory
Which microorganism is added to dough to make bread rise and become soft and spongy?
A. Protozoan
B. Alga
C. Yeast ✓ Correct
D. Virus
Solution: Yeast is a fungus that ferments the sugars in dough, releasing gas that makes the dough rise. Viruses and protozoans are not used in baking.
Q6 — Diseases & Immunity · easy · theory
Malaria, spread by the bite of a female Anopheles mosquito, is caused by which kind of organism?
A. A bacterium
B. A virus
C. A protozoan (Plasmodium) ✓ Correct
D. A fungus
Solution: Malaria is caused by the protozoan Plasmodium, which the female Anopheles mosquito transfers into the blood while biting. It is neither a bacterium nor a virus.
Q7 — Diseases & Immunity · easy · theory
A preparation given to a healthy person to make the body build protection against a particular disease in advance is called a:
A. Vaccine ✓ Correct
B. Antacid
C. Painkiller
D. Antibiotic
Solution: A vaccine contains weakened or dead germs (or their parts) that train the immune system to make defences, so the person is protected before the real infection. Antibiotics instead treat existing bacterial infections.
Q8 — Tissue Culture · hard · theory
A small part of a plant taken for tissue culture is called a(n):
A. clone
B. gamete
C. explant ✓ Correct
D. embryo
Solution: An explant is the piece of tissue used to start a tissue culture.
Q9 — Tissue Culture · hard · theory
Producing a large number of plants quickly from small tissues by tissue culture is called:
A. germination
B. pollination
C. fermentation
D. micropropagation ✓ Correct
Solution: Micropropagation rapidly multiplies plants from tiny explants.
Q10 — Tissue Culture · hard · theory
One major advantage of tissue culture is the production of:
A. weeds
B. more insects
C. disease-free plants ✓ Correct
D. polluted soil
Solution: Tissue culture can produce healthy, disease-free planting material.
Q11 — Tissue Culture · hard · theory
Compared with growing plants from seeds, tissue culture allows:
A. only one plant per year
B. rapid multiplication of many identical plants in a small space ✓ Correct
C. no control over quality
D. slower and fewer plants
Solution: Tissue culture rapidly yields many uniform, high-quality plants in limited space and time.
Q12 — Agriculture Technology · hard · theory
HYV seeds used in modern agriculture stand for:
A. Highly Volatile seeds
B. Hybrid Yellow Variety
C. High-Yielding Variety seeds ✓ Correct
D. Heavy-Yielding Vegetables
Solution: HYV = High-Yielding Variety — seeds bred to give a larger yield.
Q13 — Agriculture Technology · hard · theory
A water-saving irrigation method that delivers water drop by drop to plant roots is:
A. sprinkler over the whole field
B. rain only
C. flood irrigation
D. drip irrigation ✓ Correct
Solution: Drip irrigation supplies water directly to the roots, minimising wastage.
Q14 — Agriculture Technology · hard · theory
Growing different crops on the same field in a planned sequence to maintain soil fertility is called:
A. deforestation
B. crop rotation ✓ Correct
C. over-irrigation
D. monoculture
Solution: Crop rotation alternates crops (e.g. cereals and legumes) to keep the soil fertile.
Q15 — Useful & Harmful Micro-organisms · hard · theory
Medicines that are produced from microorganisms and used to treat bacterial diseases are called:
A. vaccines
B. antibiotics ✓ Correct
C. hormones
D. vitamins
Solution: Antibiotics (e.g. penicillin) are made from microbes and kill or stop bacteria.
Q16 — Useful & Harmful Micro-organisms · hard · theory
Food is preserved by methods like refrigeration and salting mainly to:
A. slow down or stop the growth of microorganisms ✓ Correct
B. increase spoilage
C. add colour
D. add more microbes
Solution: Preservation prevents microbial growth that would otherwise spoil the food.
Q17 — Useful & Harmful Micro-organisms · hard · theory
The mould Penicillium is important because it produces the antibiotic:
A. vinegar
B. insulin
C. penicillin ✓ Correct
D. ethanol
Solution: Penicillium yields penicillin, the first widely used antibiotic.
Q18 — Diseases & Immunity · hard · theory
A preparation that gives the body immunity against a particular disease is a:
A. vaccine ✓ Correct
B. painkiller
C. antibiotic
D. vitamin
Solution: A vaccine trains the immune system to protect against a specific disease.
Q19 — Diseases & Immunity · hard · theory
Antibiotics are effective against ______ but NOT against ______:
A. viruses; bacteria
B. plants; animals
C. bacteria; viruses ✓ Correct
D. fungi; bacteria
Solution: Antibiotics work on bacteria; they do not kill viruses, so they cannot cure viral diseases like the common cold.
Q20 — Diseases & Immunity · hard · theory
Which of the following is caused by a virus?
A. Cholera
B. Tuberculosis
C. Tetanus
D. AIDS ✓ Correct
Solution: AIDS is caused by the HIV virus; the others are bacterial diseases.
Q21 — Diseases & Immunity · hard · theory
Giving vaccines to children to protect them from diseases is called:
A. digestion
B. fermentation
C. immunisation (vaccination) ✓ Correct
D. pollination
Solution: Immunisation uses vaccines to build immunity and prevent diseases such as polio and measles.
Q22 — Tissue Culture · hard · numerical
A laboratory starts with 1 explant. In every subculture cycle the number of plantlets becomes 5 times the previous number, and one cycle takes 3 weeks. How many plantlets are present after 9 weeks?
A. 25
B. 15
C. 125 ✓ Correct
D. 45
Solution: 9 weeks is 3 cycles. Each cycle multiplies by 5, so the count is 5 × 5 × 5 = 5³ = 125. Choosing 15 comes from adding (5+5+5) and 25 from stopping at 5² after only two cycles.
Q23 — Agriculture Technology · hard · numerical
An old wheat variety yields 4 tonnes per hectare. A new high-yielding variety yields 6 tonnes per hectare. If a farmer plants the new variety on 3 hectares, how many extra tonnes does it give compared with the old variety on the same land?
A. 6 ✓ Correct
B. 2
C. 18
D. 12
Solution: Extra yield per hectare = 6 − 4 = 2 tonnes. Over 3 hectares the extra is 2 × 3 = 6 tonnes. The distractor 18 is the total new yield, 12 is the old total and 2 is only the per-hectare gain.
Q24 — Agriculture Technology · hard · theory
Assertion (A): Rotating a cereal crop with a legume crop keeps the soil fertile. Reason (R): The root nodules of legumes contain bacteria that fix atmospheric nitrogen into the soil. Choose the correct option:
A. A is true but R is false
B. Both A and R are true but R does not explain A
C. Both A and R are true and R correctly explains A ✓ Correct
D. A is false but R is true
Solution: The assertion is correct and the reason is the exact mechanism: Rhizobium in legume root nodules fixes nitrogen, replenishing what the cereal removed. So both are true and the reason correctly explains the assertion.
Q25 — Useful & Harmful Micro-organisms · hard · theory
Penicillin, the first antibiotic discovered by Alexander Fleming, is obtained from which type of microorganism?
A. A protozoan called Plasmodium
B. A blue-green alga
C. A bacterium called Lactobacillus
D. A mould (fungus) called Penicillium ✓ Correct
Solution: Penicillin is produced by the mould Penicillium, a fungus. Fleming noticed that this mould killed bacteria around it, which led to the antibiotic. Lactobacillus is a helpful bacterium, not the source of penicillin.
Q26 — Useful & Harmful Micro-organisms · hard · theory
A student lists four processes: (i) fixing nitrogen in soil, (ii) causing tuberculosis, (iii) setting curd, (iv) spoiling stored food. Which pair shows micro-organisms acting in a HARMFUL way?
A. (iii) and (iv)
B. (i) and (ii)
C. (i) and (iii)
D. (ii) and (iv) ✓ Correct
Solution: Causing tuberculosis (a disease) and spoiling stored food are both harmful actions of micro-organisms. Fixing nitrogen and setting curd are useful roles, so the harmful pair is (ii) and (iv).
Q27 — Diseases & Immunity · hard · theory
Assertion (A): A person who has had chickenpox once usually does not catch it again. Reason (R): After an infection the body keeps special memory cells that quickly fight the same germ if it returns. Choose the correct option:
A. Both A and R are true but R does not explain A
B. A is true but R is false
C. A is false but R is true
D. Both A and R are true and R correctly explains A ✓ Correct
Solution: Recovery from chickenpox gives lasting immunity, and the reason is correct: memory cells remain and mount a fast, strong response on re-exposure, preventing the disease. So R correctly explains A.
Q28 — Tissue Culture · medium · theory
Tissue culture is a technique of growing cells, tissues or organs in a(n):
A. open field
B. artificial nutrient medium under sterile conditions ✓ Correct
C. salt water
D. ordinary pot of soil
Solution: Tissue culture grows plant/animal cells in a sterile nutrient medium in the laboratory.
Q29 — Tissue Culture · medium · theory
The plants produced by tissue culture from a single parent are:
A. seed-grown
B. always hybrids
C. genetically identical (clones) ✓ Correct
D. all different
Solution: Tissue-cultured plants are clones — genetically identical to the parent.
Q30 — Tissue Culture · medium · theory
Tissue culture must be carried out under sterile (aseptic) conditions to:
A. reduce the yield
B. add more microbes
C. prevent contamination by microbes ✓ Correct
D. increase temperature
Solution: Sterile conditions stop bacteria and fungi from spoiling the culture.