Science chapter practice
Practise 80+ Plant Biology and Applied Biology MCQs for UPSC Prelims in Science, including 11+ previous year questions. The sample set below is shown with correct answers and explanations.
12 sample questions are shown here; sign up free to practise all 80.
Consider the following: 1. Birds 2. Dust blowing 3. Rain 4. Wind blowing Which of the above spread plant diseases?
Explanation
Correct. Birds carry pathogens on their bodies, dust particles transport fungal spores, rain splash disperses bacteria and spores, and wind is the most common long-distance carrier of plant disease agents.
Which of the following statements is/are correct? Viruses can infect: 1. Bacteria 2. Fungi 3. Plants Select the correct answer using the code given below.
Explanation
Correct. Bacteriophages infect bacteria, mycoviruses infect fungi, and plant viruses like TMV infect plants; viruses are obligate parasites capable of infecting all major life forms.
Which one of the following is the process involved in photosynthesis?
Explanation
Correct. Photosynthesis captures free energy from sunlight and converts it into potential energy stored in the chemical bonds of glucose (C₆H₁₂O₆).
Which of the following statements is/are correct regarding vegetative propagation of plants? 1. Vegetative propagation produces clonal population. 2. Vegetative propagation helps in eliminating the virus. 3. Vegetative propagation can be practiced most of the year. Select the correct answer using the code given below.
Explanation
Correct. Vegetative propagation produces genetically identical offspring (clones) and can be practiced in most seasons; however, it does not eliminate viruses as the pathogen persists in vegetative tissues.
Many transplanted seedlings do not grow because:
Explanation
Correct. Root hairs are delicate extensions of epidermal cells that are destroyed during uprooting; their loss severely reduces the plant's ability to absorb water and minerals, often causing transplant failure.
Which of the following types of light are strongly absorbed by plants?
Explanation
Correct. Chlorophyll a and b have peak absorption in the blue (~430–450 nm) and red (~640–680 nm) regions of the visible spectrum, which is why leaves reflect green light.
Epiphytes are plants which depend on other plants for:
Explanation
Correct. Epiphytes such as orchids and ferns grow on other plants solely for physical support to access better light; they absorb water and nutrients from air and rain.
Which one of the following organisms can serve as a biofertiliser for rice crop?
Explanation
Correct. Blue-green algae (cyanobacteria) such as Anabaena and Nostoc fix atmospheric nitrogen in waterlogged paddy fields, serving as natural biofertilisers for rice.
Match List I with List II and select the correct answer: List I: (I) Fruit (II) Seed (III) Wood (IV) Starch List II: (A) Ovule (B) Leaf (C) Stem (D) Ovary
Explanation
Correct. Fruit develops from the ovary after fertilisation, seed develops from the ovule, wood (secondary xylem) is a product of the stem, and starch is primarily synthesised in leaves during photosynthesis.
It is possible to produce seedless tomato fruits by:
Explanation
Correct. Spraying plant hormones such as auxins or gibberellins on unpollinated flowers induces parthenocarpy, allowing fruit to develop without seed formation.
Most of the desert plants bloom during night time because:
Explanation
Correct. Desert insects and herbivores consume flowers during the hot daytime; blooming at night protects flowers from being eaten and allows pollination by nocturnal pollinators like moths.
Grafting is a horticultural technique that is most successful when the stock and scion belong to:
Explanation
Correct. Grafting succeeds when the vascular cambium of stock and scion are compatible, which requires close genetic affinity typically within the same species, genus, or family.
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