ICAR JRF Plant Science Practice Series Memory Based 2024 (Module 1) (1 – 40 MCQ) 

 

Question 1

The cause of the great Bengal Famine was:

1. Blast of rice
2. Brown spot of Rice
3. Rust of wheat
4. Karnal bunt of wheat

Correct Answer: 2

 

Explanation:

• The Great Bengal Famine (1943)was primarily caused by Brown spot of rice (Cochliobolus miyabeanus, anamorph Bipolaris oryzae).
• The epidemic destroyed a large portion of the rice crop, leading to severe food shortages and the death of approximately 2-3 million people.
• Blast of rice(Pyricularia oryzae) is also a serious disease but was not the primary cause of the Bengal famine.
• Rust of wheatand Karnal bunt of wheat are diseases of wheat, not rice.

 

 

Question 2

Chloroplast contains disc-like membranous structures arranged in a stack is called:

1. Cisternae
2. Grana
3. Stroma
4. Thylakoids

Correct Answer: 2

 

Explanation:

• Grana– Stacks of disc-like membranous structures (thylakoids) in chloroplasts. Each stack is called a granum (plural: grana).
• Thylakoids– Individual disc-like membrane structures that contain chlorophyll and are the site of light reactions.
• Stroma– The fluid-filled matrix of the chloroplast where the Calvin cycle occurs.
• Cisternae– Flattened membrane sacs in the Golgi apparatus and endoplasmic reticulum.
• Therefore, the correct answer is Grana→ Option 2.

 

 

Question 3

The causal organism of bunchy top of banana is transmitted by:

1. Pentalonia nigronervosa
2. Bemisia tabaci
3. Lipaphis erysimi
4. Pollen

Correct Answer: 1

 

Explanation:

• Bunchy top of bananais caused by Banana bunchy top virus (BBTV) , a ssDNA virus (genus Babuvirus).
• It is transmitted by the banana aphid Pentalonia nigronervosa(persistent circulative transmission).
• Bemisia tabaci– Transmits begomoviruses (e.g., cotton leaf curl, tomato leaf curl).
• Lipaphis erysimi– Transmits turnip mosaic virus and other crucifer viruses.
• Pollen – Not involved in BBTV transmission.

 

 

Question 4

Khaira disease is associated with which crop?

1. Wheat
2. Paddy
3. Barley
4. Maize

Correct Answer: 2

 

Explanation:

• Khaira diseaseof rice is caused by zinc (Zn) deficiency.
• Symptoms include bronzing, stunting, reduced tillering, and poor grain filling.
• It is commonly observed in alkaline and calcareous soils where zinc availability is low.
• Wheat, barley, maize– Can show zinc deficiency symptoms but not specifically called Khaira disease.

 

 

Question 5

Virus mediated transfer of genetic material from one bacterial cell to another is:

1. Transduction
2. Transformation
3. Conjugation
4. Reverse transcription

Correct Answer: 1

 

Explanation:

• Transduction– Transfer of bacterial DNA from one cell to another by a bacteriophage (virus) .
• Transformation– Uptake of free (naked) DNA from the environment.
• Conjugation– Direct cell-to-cell transfer of DNA through a pilus (mediated by F-plasmid).
• Reverse transcription– Synthesis of DNA from an RNA template (by reverse transcriptase).

 

 

Question 6

Seed plot technique is followed in:

1. Wheat
2. Bajra
3. Potato
4. Paddy

Correct Answer: 3

 

Explanation:

• Seed plot techniqueis a specialized method for producing virus-free potato seed tubers.
• It involves growing potato in high-altitude, cool, aphid-free areas (e.g., Shimla, Kufri) where virus vectors are less active.
• This technique is used to produce healthy seed potatoes for lowland cultivation.
• Wheat, bajra, paddy– Do not use seed plot technique.

 

 

Question 7

Southern corn blight epidemic of maize was due to susceptibility of:

1. T-cytoplasm
2. A-cytoplasm
3. HT-cytoplasm
4. D-cytoplasm

Correct Answer: 1

 

Explanation:

• The Southern corn leaf blight epidemic (1970)in the USA was caused by the fungus Bipolaris maydis (race T).
• The epidemic occurred because most commercial maize hybrids at the time had T-cytoplasm(Texas male-sterile cytoplasm), which made them highly susceptible.
• T-cytoplasm was widely used in hybrid seed production to eliminate the need for detasseling.
• A-cytoplasm, HT-cytoplasm, D-cytoplasm– Other cytoplasmic male sterility types not associated with this epidemic.

 

 

Question 8

Source of rust resistance gene in wheat is:

1. Triticum monococcum
2. Aegilops speltoides
3. Triticum timopheevi
4. Triticum durum

Correct Answer: 3

 

Explanation:

• Triticum timopheevi(wild wheat) is a valuable source of rust resistance genes (e.g., leaf rust, stem rust) transferred into cultivated wheat.
• Sr36(stem rust resistance) and Lr18 (leaf rust resistance) are derived from  timopheevi.
• Triticum monococcum– Donor of some resistance genes but not the primary source for rust.
• Aegilops speltoides– Source of B genome and some resistance genes.
• Triticum durum– Cultivated durum wheat, not a wild source.

 

 

Question 9

Cell wall lacking organism is:

1. Mycoplasma
2. Bacteria
3. Fungi
4. Virus

Correct Answer: 1

 

Explanation:

• Mycoplasma– Prokaryotic organisms that lack a cell wall. They are enclosed only by a plasma membrane (pleomorphic).
• Bacteria– Most have a cell wall (peptidoglycan), except Mycoplasma.
• Fungi– Have cell walls composed of chitin.
• Virus– Acellular; not considered a cell; has a protein coat (capsid), not a cell wall.

 

 

Question 10

Electron microscope was discovered by:

1. Anton van Leeuwenhoek
2. Knoll and Ruska
3. Korenberg
4. Robert Hooke

Correct Answer: 2

 

Explanation:

• Knoll and Ruska– Ernst Ruska and Max Knoll built the first electron microscope in 1931 (Ruska received Nobel Prize in 1986).
• Anton van Leeuwenhoek– Developed simple microscopes; observed microorganisms (17th century).
• Robert Hooke– Discovered cells using a compound microscope (1665).
• Korenberg– Not associated with microscope invention.

 

 

Question 11

Causal organism of first bacterial disease, fire blight of apple and pear (discovered by T.J. Burrill) is:

1. Erwinia carotovora
2. Erwinia amylovora
3. Erwinia atroseptica
4. Erwinia aroideae

Correct Answer: 2

 

Explanation:

• Fire blightof apple and pear is caused by Erwinia amylovora.
• It was the first bacterium proven to cause a plant disease(T.J. Burrill, 1878-1885).
• Erwinia carotovora– Causes soft rot.
• Erwinia atroseptica– Causes blackleg of potato.
• Erwinia aroideae– Causes soft rot of various plants.

 

 

Question 12

In gram staining, the alcohol acts on:

1. Teichoic acids
2. Peptidoglycan
3. Periplasm
4. Membrane lipids

Correct Answer: 2

 

Explanation:

• In Gram staining, alcohol (acetone or ethanol) acts as a decolorizer.
• It removes the crystal violet-iodine complex from Gram-negative bacteriaby dissolving the outer membrane lipids (not peptidoglycan directly). However, the decolorization effect is due to the thin peptidoglycan layer not retaining the stain.
• Peptidoglycan– In Gram-positive bacteria, thick peptidoglycan retains the crystal violet-iodine complex, making them appear purple.
• Teichoic acids– Found only in Gram-positive cell walls.
• Periplasm– Space between inner and outer membranes in Gram-negative bacteria.

 

 

Question 13

Seed Plot Technique of potato is used to produce:

1. Large sized tubers
2. Nematode free seeds
3. Insect-free seeds
4. Virus free seeds

Correct Answer: 4

 

Explanation:

• The Seed Plot Techniqueis used to produce virus-free seed potatoes.
• It involves growing potatoes in high-altitude, cool, aphid-free regions to avoid virus transmission (aphids are vectors).
• This technique ensures healthy seed tubers for planting.
• It does not primarily target nematodes, insects (other than aphids), or tuber size.

 

 

Question 14

Cotton leaf curl virus is transmitted by:

1. Mite
2. White fly
3. Aphid
4. Plant hopper

Correct Answer: 2

 

Explanation:

• Cotton leaf curl virus (CLCuV)is a begomovirus (ssDNA virus, family Geminiviridae).
• It is transmitted by the whitefly, Bemisia tabaci(persistent circulative transmission).
• Mite– Transmits some plant viruses (e.g., wheat streak mosaic virus).
• Aphid– Transmits many plant viruses (e.g., potyviruses).
• Plant hopper– Transmits rice tungro, rice grassy stunt, etc.

 

 

Question 15

Which of the following spores of Puccinia are considered perfect state spores?

1. Teletospores
2. Uredospores
3. Aecidiospores
4. Basidiospores

Correct Answer: 4

 

Explanation:

• Perfect state (teleomorph)– The sexual stage of a fungus, characterized by the production of basidiospores (in rust fungi, Basidiomycota).
• Basidiosporesare produced on basidia from teliospores.
• Teletospores (teliospores)– The thick-walled resting spores that germinate to produce basidia and basidiospores.
• Uredospores– Asexual spores (repeating stage).
• Aecidiospores (aeciospores)– Produced on the alternate host; function in dispersal but are not the perfect state.

 

 

Question 16

Coenocytic fungal hyphae are:

1. Non septate
2. Septate with uninucleate cells
3. Septate with multinucleate cells
4. None of these

Correct Answer: 1

 

Explanation:

• Coenocytic hyphae– Hyphae that lack septa (non-septate) , resulting in a multinucleate, continuous cytoplasmic mass.
• Found in Zygomycetes(e.g., Rhizopus, Mucor) and Oomycetes (e.g., Phytophthora).
• Septate hyphae– Divided by cross-walls (septa) into individual cells, which may be uninucleate or multinucleate.

 

 

Question 17

Black tip of mango is caused due to the deficiency of:

1. Zinc
2. Iron
3. Boron
4. Oxygen

Correct Answer: 3

 

Explanation:

• Black tip of mangois a physiological disorder caused by boron deficiency.
• Symptoms include blackening and necrosis of the tip of the fruit.
• It is commonly observed in calcareous soils where boron availability is low.
• Zinc deficiency– Little leaf, rosetting.
• Iron deficiency– Interveinal chlorosis.
• Oxygen deficiency– Not a specific nutrient deficiency.

 

 

Question 18

Which is the best breeding method to transfer disease resistance genes from unadapted germplasm?

1. Bulk method
2. Pedigree method
3. Back cross method
4. Mass selection

Correct Answer: 3

 

Explanation:

• Backcross method– The most effective method for transferring one or a few genes (e.g., disease resistance) from an unadapted donor parent into an elite adapted recurrent parent.
• It involves repeated crossing to the recurrent parent, selecting for the desired trait at each generation.
• Bulk method– For population improvement and natural selection.
• Pedigree method– For selecting superior segregants from crosses between adapted parents.
• Mass selection– For improving populations in cross-pollinated crops.

 

 

Question 19

Pigeon pea sterility mosaic virus is transmitted by:

1. Aphid
2. Mite
3. White fly
4. Plant hopper

Correct Answer: 2

 

Explanation:

• Pigeon pea sterility mosaic virus (PPSMV)is transmitted by the eriophyid mite, Aceria cajani (persistent transmission).
• The disease causes sterility, mosaic, and stunting in pigeon pea.
• Aphid– Transmits many viruses (e.g., potyviruses).
• Whitefly– Transmits begomoviruses.
• Plant hopper– Transmits rice viruses.

 

 

Question 20

The bacterial cells are peritrichously flagellated in:

1. Agrobacterium
2. Erwinia
3. Xanthomonas
4. Pseudomonas

Correct Answer: 2

 

Explanation:

• Peritrichous flagellation– Flagella distributed all over the bacterial cell surface.
• Erwinia– Many species are peritrichous (e.g., Erwinia amylovora).
• Agrobacterium– Usually peritrichous or subpolar (1-4 flagella).
• Xanthomonas– Monotrichous (single polar flagellum).
• Pseudomonas– Lophotrichous or monotrichous (polar flagella).

 

 

Question 21

The perfect stage of Rhizoctonia solani is:

1. Glomerella tucumanensis
2. Thanatephorus cucumeris
3. Magnaporthe grisea
4. Cochliobolus miyabeanus

Correct Answer: 2

 

Explanation:

• Rhizoctonia solaniis an anamorph (asexual stage) of the basidiomycete fungus Thanatephorus cucumeris.
• It is a soilborne pathogen causing damping-off, root rot, sheath blight of rice, and other diseases.
• Glomerella tucumanensis– Perfect stage of Colletotrichum (red rot of sugarcane).
• Magnaporthe grisea– Perfect stage of Pyricularia oryzae (rice blast).
• Cochliobolus miyabeanus– Perfect stage of Bipolaris oryzae (brown spot of rice).

 

 

Question 22

Who proved that virus could pass through filters with pores small enough to retain bacteria?

1. Stanley
2. Ivanowski
3. Mayer
4. Beijerinck

Correct Answer: 4

 

Explanation:

• Martinus Beijerinck (1898)– Demonstrated that the causative agent of tobacco mosaic disease could pass through bacteria-retaining filters and called it “contagium vivum fluidum” (living fluid infectious agent).
• Ivanowski (1892)– First reported that the infectious agent passed through filters but did not propose the virus concept.
• Stanley (1935)– Crystallized tobacco mosaic virus.
• Mayer (1886)– Showed that tobacco mosaic disease was infectious but did not filter it.

 

 

Question 23

Application of potash increases:

1. Disease resistance in plants
2. Resistance to water logging
3. Frost resistance in plants
4. All of the above

Correct Answer: 1

 

Explanation:

• Potassium (K)plays a key role in disease resistance by improving cell wall strength, stomatal regulation, and activating defense enzymes.
• It does not significantly increase resistance to waterlogging or frost (these are influenced by other factors).
• Therefore, the correct answer is Disease resistance in plants→ Option 1.

 

 

Question 24

Systemic fungicides were first discovered by:

1. Knoll and Ruska
2. Von Schmelling and M. Kulka
3. Leeuwenhoek
4. Biffen

Correct Answer: 2

 

Explanation:

• Von Schmelling and M. Kulka– Discovered the first systemic fungicides (oxathiin derivatives like carboxin) in the 1960s.
• Knoll and Ruska– Invented electron microscope.
• Leeuwenhoek– Developed microscopes.
• Biffen– Worked on plant breeding (yellow rust resistance in wheat).

 

 

Question 25

Berberis vulgaris is the alternate host of:

1. Yellow rust of wheat
2. Brown rust of wheat
3. Black rust of wheat
4. None of the above

Correct Answer: 3

 

Explanation:

• Berberis vulgaris(common barberry) is the alternate host for black rust of wheat (Puccinia graminis sp. tritici).
• The fungus completes its life cycle on barberry (pycnial and aecial stages).
• Yellow rust(Puccinia striiformis) – No alternate host (microcyclic).
• Brown rust(Puccinia recondita) – Alternate host is Thalictrum (meadow rue).

 

 

Question 26

Loose smut of wheat can be controlled by:

1. Seed treatment with Vitavax
2. Spraying of Vitavax
3. Soil application of Vitavax
4. All of the above

Correct Answer: 1

 

Explanation:

• Loose smut of wheat(Ustilago nuda tritici) is a seedborne disease. The mycelium is present inside the embryo.
• Seed treatment with Vitavax (carboxin)– A systemic fungicide that penetrates the seed and eradicates the internal mycelium.
• Spraying or soil application– Not effective because the pathogen is internal to the seed.
• Therefore, the correct answer is Seed treatment with Vitavax→ Option 1.

 

 

Question 27

Ug 99 is a race of which of the following rust pathogen?

1. Puccinia graminis tritici
2. Puccinia recondita
3. Puccinia striiformis
4. Melampsora lini

Correct Answer: 1

 

Explanation:

• Ug99(TTKSK) is a highly virulent race of stem rust (black rust) of wheat caused by Puccinia graminis sp. tritici.
• It was first identified in Uganda in 1999(hence Ug99).
• It poses a major threat to global wheat production due to its ability to overcome many resistance genes (e.g., Sr31).
• Puccinia recondita– Leaf rust (brown rust).
• Puccinia striiformis– Yellow rust (stripe rust).
• Melampsora lini– Flax rust.

 

 

Question 28

Leaf curl of cotton can be managed by:

1. Control of insect vector
2. Use of resistant varieties
3. Follow clean cultivation
4. All of the above

Correct Answer: 4

 

Explanation:

• Cotton leaf curl disease(caused by begomoviruses, transmitted by whitefly Bemisia tabaci) can be managed by:
  • Control of insect vector– Insecticide application, yellow sticky traps.
  • Use of resistant varieties– Growing resistant cotton cultivars (e.g., varieties with CLCuV resistance).
  • Clean cultivation– Removing weed hosts and crop residues that harbor the virus or vector.
• Therefore, All of the above→ Option 4.

 

 

Question 29

Whip smut of sugarcane is caused by:

1. Ustilago nuda
2. Ustilago hordei
3. Urocystis agropyri
4. Ustilago scitaminea

Correct Answer: 4

 

Explanation:

• Whip smut of sugarcaneis caused by Ustilago scitaminea (syn. Sporisorium scitamineum).
• It produces a long, black, whip-like structure from the central shoot.
• Ustilago nuda– Loose smut of wheat and barley.
• Ustilago hordei– Covered smut of barley.
• Urocystis agropyri– Flag smut of wheat.

 

 

Question 30

Who discovered Bordeaux Mixture?

1. A. de Bary
2. M.A. Millardet
3. J. Butler
4. Biffen

Correct Answer: 2

 

Explanation:

• Bordeaux mixture(copper sulfate + lime) was discovered by M.A. Millardet (1885) for controlling downy mildew of grapevine.
• A. de Bary– Father of plant pathology; studied late blight of potato.
• J. Butler– Imperial Mycologist (India); father of Indian plant pathology.
• Biffen– Plant breeder (yellow rust resistance in wheat).

 

 

 

Question 31

“Fungi and Disease in Plants” was written by:

1. B. Mundkur
2. C. Mehta
3. J. Butler
4. S. Singh

Correct Answer: 3

 

Explanation:

• Fungi and Disease in Plantswas written by Sir Edwin John Butler (Imperial Mycologist in India).
• Butler is known as the Father of Indian Plant Pathology.
• B. Mundkur– Worked on smut diseases.
• C. Mehta– Worked on wheat rust epidemiology in India.
• S. Singh– Wrote books on plant diseases but not this specific one.

 

 

Question 32

Agrobacterium is a:

1. Gram negative bacterium
2. Gram positive bacterium
3. Bacteria lacking cell wall
4. None of these

Correct Answer: 1

 

Explanation:

• Agrobacterium(e.g.,  tumefaciens) is a Gram-negative, rod-shaped bacterium.
• It causes crown gall disease by transferring a segment of its Ti plasmid (T-DNA) into plant cells.
• Gram-positive– Clavibacter, Streptomyces.
• Bacteria lacking cell wall– Mycoplasma.

 

 

Question 33

Exobasidium vexans belongs to:

1. Basidiomycetes
2. Ascomycetes
3. Zygomycetes
4. Oomycetes

Correct Answer: 1

 

Explanation:

• Exobasidium vexansis a Basidiomycete fungus that causes blister blight of tea.
• It produces basidiospores on the underside of infected leaves.
• Ascomycetes– Erysiphe, Claviceps.
• Zygomycetes– Rhizopus, Mucor.
• Oomycetes– Phytophthora, Plasmopara (not true fungi).

 

 

Question 34

Rice tungro disease is transmitted by:

1. Aphid
2. White fly
3. Green leaf hopper
4. Nematode

Correct Answer: 3

 

Explanation:

• Rice tungro diseaseis caused by a combination of Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV) .
• It is transmitted by the green leafhopper, Nephotettix virescens(and other Nephotettix species) in a semi-persistent manner.
• Aphid– Transmits rice yellow dwarf, etc.
• Whitefly– Transmits cotton leaf curl, tomato leaf curl.
• Nematode– Transmits some soilborne viruses.

 

 

Question 35

Phyllody is the:

1. Development of floral organs into leaf-like structures
2. Development of organs in an unexpected location
3. Over development of colour
4. Under development of colour

Correct Answer: 1

 

Explanation:

• Phyllody– A plant disease symptom where floral organs (sepals, petals, carpels, stamens) are transformed into leaf-like structures.
• It is often caused by phytoplasmas(e.g., sesame phyllody, brinjal little leaf).
• Development of organs in an unexpected location– Ectopic development.
• Over/under development of colour– Not related to phyllody.

 

 

Question 36

Normally spherical viruses contain:

1. Higher nucleic acid percentage and lower protein
2. Higher protein percentage and lower nucleic acid
3. Lipids
4. None of the above

Correct Answer: 2

 

Explanation:

• Spherical (icosahedral) virusestypically have a higher protein percentage and lower nucleic acid content compared to filamentous viruses.
• The protein capsid makes up the majority of the virion mass, while nucleic acid (RNA or DNA) is a smaller component.
• Lipids– Found in enveloped viruses, but not in all spherical viruses.

 

 

Question 37

Indian Phytopathological Society was established by:

1. C. Mehta
2. F. Dastur
3. B. Mundkur
4. J. Butler

Correct Answer: 2

 

Explanation:

• The Indian Phytopathological Society (IPS)was established in 1947 by  J.F. Dastur.
• C. Mehta– Known for wheat rust research.
• B. Mundkur– Worked on smut diseases.
• J. Butler– Father of Indian plant pathology.

 

 

Question 38

The fungi included in order Peronosporales cause the plant diseases known as:

1. Smut
2. Damping off
3. Powdery mildew
4. Downy mildew

Correct Answer: 4

 

Explanation:

• Peronosporales(Oomycetes) include fungi-like organisms that cause downy mildew diseases (e.g., Plasmopara viticola on grape, Sclerospora graminicola on pearl millet).
• Smut– Caused by Ustilaginales (Basidiomycetes).
• Damping off– Caused by Pythium, Rhizoctonia (not specific to Peronosporales).
• Powdery mildew– Caused by Erysiphales (Ascomycetes).

 

 

Question 39

Wheat streak mosaic virus is transmitted by:

1. Aphids
2. Leafhopper
3. Whiteflies
4. Mites

Correct Answer: 4

 

Explanation:

• Wheat streak mosaic virus (WSMV)is transmitted by the eriophyid mite, Aceria tosichella (wheat curl mite).
• Transmission is persistent and the virus is also seedborne at low levels.
• Aphids– Transmit barley yellow dwarf virus, etc.
• Leafhopper– Transmit rice tungro, etc.
• Whiteflies– Transmit begomoviruses.

 

 

Question 40

Cauliflower mosaic virus is an:

1. dsDNA
2. ssRNA
3. dsRNA
4. ssDNA

Correct Answer: 1

 

Explanation:

• Cauliflower mosaic virus (CaMV)is a double-stranded DNA (dsDNA) virus, belonging to the family Caulimoviridae.
• It is one of the few plant viruses with a dsDNA genome (most plant viruses have ssRNA genomes).
• ssRNA– Most plant viruses (e.g., TMV, potyviruses).
• dsRNA– Reoviruses (e.g., rice dwarf virus).
• ssDNA– Geminiviruses (e.g., cotton leaf curl virus).