Your Answer : (Not Answered)

Correct Answer : C

Among the options, the answer is Heinrich Anton de Bary.

In 1861 de Bary inoculated healthy potato plants with spores of the late blight fungus and reproduced the disease, which proved that the fungus was its cause and not a result of decay. This settled the long debate after the Irish potato famine.

Earlier, in 1807, Benedict Prevost had shown that wheat bunt was caused by a fungus, and some texts credit him with the first demonstration; he is not among the options, so the paper takes de Bary, whose proof was the decisive one. Louis Pasteur worked on fermentation and animal disease, E. J. Butler on Indian plant diseases in the twentieth century, and M. S. Swaminathan on wheat and rice breeding.

Your Answer : (Not Answered)

Correct Answer : B

Phytoplasmas move through the phloem sieve tubes.

Phytoplasmas, the wall-less organisms formerly called mycoplasma-like organisms (MLOs), live only in the phloem of the plant. They are introduced by phloem-feeding insects such as leafhoppers and planthoppers and are carried through the sieve tubes with the flow of sugars, which is why they cause yellowing, stunting, little leaf and phyllody throughout the plant.

The xylem is the home of other pathogens such as the ratoon stunting bacterium. Phytoplasmas do not move through cambium tissue, and they are too large to pass along the plasmodesmata between ordinary cells, which is how plant viruses spread.

Your Answer : (Not Answered)

Correct Answer : D

The answer is All of these.

Leaf crinkle of black gram (urdbean) is a virus disease that makes leaves large, crinkled and rough, with stunted plants and malformed flowers. Studies have recorded its spread by mechanical sap inoculation, through infected seed, which carries it into new fields, and by insect vectors, with whitefly among those reported.

Because the disease is transmitted in each of the named ways, no single option is complete. Using virus-free seed and rogueing infected plants are the main controls.

Your Answer : (Not Answered)

Correct Answer : B

Bunchy top of banana is transmitted by Pentalonia nigronervosa.

Banana bunchy top, caused by the banana bunchy top virus, is spread from plant to plant by the banana aphid, Pentalonia nigronervosa, and over long distances by infected suckers. Affected plants have narrow, upright, bunched leaves with dark green streaks along the veins, and rarely bear fruit.

Myzus persicae (green peach aphid) transmits potato and many other viruses, Aphis nerii is the oleander aphid, and Lipaphis erysimi is the mustard aphid; none of them is the vector of bunchy top.

Your Answer : (Not Answered)

Correct Answer : D

Such outgrowths are called Enations.

Enations are outgrowths of hypertrophied (overgrown) tissue that arise from the veins, usually on the lower surface of leaves, often shaped like small ear lobes or cups. They are a typical symptom of some virus diseases, such as pea enation mosaic and tobacco leaf curl.

Puckering is a raised, blistered wrinkling of the leaf blade, witches' broom is a dense cluster of thin shoots, and shoestring describes leaves reduced to narrow strips, as in tomato infected by cucumber mosaic virus. None of them is an outgrowth from the veins.

Your Answer : (Not Answered)

Correct Answer : B

The bacterial disease of wheat is Pink seed.

Pink seed (pink grain) of wheat is caused by the bacterium Erwinia rhapontici, which enters through injuries and stains the grain pink. Another bacterial disease of wheat is tundu, or yellow ear rot, caused by Rathayibacter tritici together with the nematode Anguina tritici.

The other options are not bacterial. Powdery mildew is caused by the fungus Blumeria graminis, wheat yellow mosaic by a virus, and smuts are fungal diseases.

Your Answer : (Not Answered)

Correct Answer : B

The Great Bengal famine of 1943 was caused mainly by Brown leaf spot of rice.

Brown spot, caused by the fungus Helminthosporium oryzae (now Bipolaris oryzae, sexual stage Cochliobolus miyabeanus), spread severely in the 1942 aman rice crop after a cyclone and heavy rain, on crops weakened by poor soil nutrition. The loss of yield was a major factor in the food shortage, along with wartime conditions, and the outbreak is the standard example of a plant disease behind a famine.

Wheat rust, blast and bacterial leaf blight are serious diseases, but none of them is linked with the 1943 famine.

Your Answer : (Not Answered)

Correct Answer : B

Pineapple black rot is a Fungal disease.

Black rot of pineapple, also called water blister or soft rot, is caused by the fungus Ceratocystis paradoxa (anamorph Thielaviopsis paradoxa), the same fungus that causes base rot of planting material. It enters the fruit through wounds at harvest and in transit, turning the flesh soft, watery and dark.

It is managed by careful handling, cool storage and treating cut stalks with fungicide, measures aimed at a fungus, not a virus or bacterium.

Your Answer : (Not Answered)

Correct Answer : C

The structure in the drawing is an acervulus.

An acervulus is a flat or cushion-shaped bed of short conidiophores that forms under the cuticle or epidermis of the host and then breaks through to release its conidia. The drawing shows exactly this: a cushion of cells with short upright stalks bearing oval spores, and long bristle-like hairs (setae) among them. It is typical of the anthracnose fungi such as Colletotrichum.

A pycnidium is a rounded or flask-shaped body with a pore through which spores escape, not an open cushion. A sclerotium is a hard, compact resting mass of hyphae with no spore-bearing stalks. A sorus is a heap or pustule of spores, as in rusts and smuts, without stalked conidia and bristles.

Your Answer : (Not Answered)

Correct Answer : A

The famine was caused by Late blight, in 1845-49.

The Irish Potato Famine, the Great Hunger, followed the arrival in Ireland of late blight, caused by the water mould Phytophthora infestans. From 1845 the disease destroyed the potato crop, on which most of the rural poor depended, for several years running. About a million people died and a similar number emigrated.

Early blight, caused by the fungus Alternaria solani, is a less destructive disease and was not involved. The 1740s dates are a century too early; the famine is dated 1845-49 (some accounts close it in 1852).

Your Answer : (Not Answered)

Correct Answer : C

Insecticides usually act upon the nervous system.

Most widely used insecticides are nerve poisons. Organophosphates and carbamates block the enzyme acetylcholinesterase, so nerve signals do not switch off; organochlorines such as DDT and the pyrethroids keep the sodium channels of nerve cells open; neonicotinoids act on the receptors for acetylcholine. The insect suffers tremors, paralysis and death.

Some products act in other ways, such as stomach poisons or growth regulators, but the main group works on the nervous system rather than on the muscles, digestion or circulation.

Your Answer : (Not Answered)

Correct Answer : B

The nematode is Globodera.

Globodera species, the potato cyst nematodes (golden nematode), are cyst-forming nematodes. The females swell into round bodies that break through the root surface (the paper's "roof surface" is a misprint for root). They are first white, turn golden yellow and then die and harden into brown cysts full of eggs, which can survive in soil for many years.

Meloidogyne, the root-knot nematode, causes galls inside the root rather than cysts on it. Longidorus and Trichodorus are ectoparasites that feed from outside the root and form no cysts.

Your Answer : (Not Answered)

Correct Answer : B

Thrips mouthparts are asymmetrical because the right mandible is absent.

Thrips have rasping-sucking mouthparts in a cone. Only the left mandible develops, as a stylet used to pierce the plant surface; the right mandible is reduced or lost during development. The paired maxillary stylets then suck up the sap from the damaged cells, which gives the silvery streaks typical of thrips damage.

It is the left mandible that is present, so 'Left mandible' is wrong, and since one mandible remains, 'Both' is also wrong. 'None of these' does not apply because the absence of the right mandible is the reason.

Your Answer : (Not Answered)

Correct Answer : B

The paper's answer is Malphigian tubules (Malpighian tubules).

The Malpighian tubules are the excretory organs of insects. They take up water, salts and nitrogenous wastes from the blood and pass them into the hindgut; in the rectum most of the water and useful salts are then reabsorbed, while the nitrogen leaves as nearly dry uric acid. This tubule-and-rectum system lets insects excrete wastes while losing very little water, and in some beetles and caterpillars the tubules are fused to the rectum (the cryptonephridial system) to draw out still more water.

Rectal gills are breathing organs of dragonfly nymphs in water. The crop stores food, and the proventriculus grinds and filters it; neither has a role in conserving water.

Your Answer : (Not Answered)

Correct Answer : C

Epiricania melanoleuca is an ectoparasitoid of Pyrilla perpusilla.

Pyrilla, the sugarcane leafhopper, sucks sap and causes heavy losses in north India. Epiricania melanoleuca is a moth whose larvae live attached to the outside of Pyrilla nymphs and adults, feeding on them under a white waxy covering and killing them. Releasing its egg masses and cocoons in the field is the standard biological control of Pyrilla, and it can bring outbreaks down without insecticides.

The other insects are different sugarcane pests: Chilo sacchariphagus indicus is the internode borer, Ceratovacuna lanigera the woolly aphid, and Scirpophaga nivella the top borer. Each has its own natural enemies.

Your Answer : (Not Answered)

Correct Answer : D

The paper's answer is Charles Valentine Riley.

Riley, the American entomologist, organised the introduction of the vedalia beetle (Rodolia cardinalis) from Australia into California in 1888-89. The beetle brought the cottony cushion scale, which was destroying the citrus industry, under control within a year. It was the first great success of classical biological control, and Riley is widely called the father of biological control.

That success was against an insect pest rather than a plant pathogen, so the question applies Riley's title to the whole field. None of the other three is associated with biological control: Pasteur and Koch founded the germ theory of disease, and Butler founded plant pathology in India.

Your Answer : (Not Answered)

Correct Answer : D

The headquarters is at Faridabad.

The Directorate of Plant Protection, Quarantine and Storage, under the Union Ministry of Agriculture and Farmers Welfare, is headquartered at NH-IV, Faridabad, Haryana. It deals with plant quarantine at ports and borders, integrated pest management, locust warning and the registration of pesticides under the Insecticides Act.

Hyderabad hosts the National Institute of Plant Health Management, which comes under the Directorate, but not its headquarters. Ludhiana and New Delhi are not its seat either.

Your Answer : (Not Answered)

Correct Answer : B

The beetle Zygogramma bicolorata is used for the biological control of Parthenium hysterophorus. Its larvae and adults eat the leaves of the weed.

Cactoblastis cactorum controls prickly pear and Neochetina eichhorniae controls water hyacinth.

The Mexican beetle Zygogramma bicolorata was introduced into India in 1983 for the control of parthenium and its grubs and adults feed on the leaves. The other insects named in the options are agents for other weeds.

Your Answer : (Not Answered)

Correct Answer : C

Cantharidin is produced by the blister beetle (family Meloidae). It is a toxic compound that blisters skin and is used in small doses as a medicine to remove warts.

The cochineal insect gives carmine dye, the giant fly is not a source of it, and the lac insect gives lac.

Cantharidin is made by blister beetles and by some related beetles. The substance blisters the skin, which gives the beetle its name, and it has been used in medicine for warts.

Your Answer : (Not Answered)

Correct Answer : C

The exotic bee Apis mellifera was successfully introduced in India in 1962, in Himachal Pradesh. Earlier attempts in 1880 and 1887 had failed, and the 1962 introduction established it for commercial beekeeping.

The years 1942, 1952 and 1972 are not the date of this successful introduction.

Earlier attempts to bring the European honey bee into India failed, and only the 1962 introduction in Himachal Pradesh at Nagrota Bagwan succeeded. After that, Apis mellifera spread to commercial beekeeping in Punjab, Haryana and other states.