Plant Pathology - Study Mode

[#306] Rate of transpiration is related to
Correct Answer

(D) Light, temperature, atmospheric humidity and wind

Explanation

Solution: The rate of transpiration is related to Light, temperature, atmospheric humidity and wind. Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. The rate of transpiration is controlled by the stomatal aperture, and these small pores open especially for photosynthesis, a light supply will encourage open stomata. Temperature affects the rate of transpiration in two ways, an increased rate of evaporation due to a temperature rise will hasten the loss of water. Relative humidity affects drier surroundings giving a steeper water potential gradient, and so increasing the rate of transpiration. In still air, water lost due to transpiration can accumulate in the form of vapour close to the leaf surface. This will reduce the rate of water loss, as the water potential gradient from inside to outside of the leaf is then slightly less.

[#307] Phenyl mercuric acetate
Correct Answer

(A) Reduces transpiration

Explanation

Solution: Phenyl mercuric acetate Reduces transpiration. Phenyl mercuric acetate (PMA) induced stomatal closure and decreased transpiration. Stomata of leaves treated with any of the 3 PMA concentrations closed earlier and at a higher relative water content than did stomata of untreated leaves.

[#308] In flowering plants archesporium gives rise to
Correct Answer

(C) Wall and tapetum

Explanation

Solution: In flowering plants, archesporium gives rise to Wall and tapetum. The cell or group of cells from which spore mother cells develop (as those from which the microspores develop in the pollen sac or the megaspore in the ovule). A two-lobed anther develops four pollen sacs that situate at four corners of the anther. Development of pollen sacs begins with the differentiation of archesporial cells in the hypodermal region below the epidermis at four corners of the young anther. The archesporial cells divide by periclinal division to give a subepidermal primary parietal layer and a primary sporogenous layer.

[#309] Yellow mosaic virus disease of moong spreads by
Correct Answer

(A) Bemisia tabaci

Explanation

Solution: Yellow mosaic virus disease of moong, also known as mung bean yellow mosaic virus (MYMV), is primarily transmitted by the insect vector Bemisia tabaci . Bemisia tabaci, commonly known as the whitefly, is a notorious vector for various plant viruses, including yellow mosaic viruses. It feeds on the sap of infected plants and transmits the virus to healthy plants as it moves between them. B. Aphir crassivora: Aphir crassivora is not known to be a vector for the yellow mosaic virus disease of moong. It is not associated with the transmission of this particular virus. C. Nephotettix viruscens: Nephotettix viruscens is not known to be a vector for the yellow mosaic virus disease of moong. It is associated with the transmission of rice viruses, not the yellow mosaic virus of moong. D. None of these: This option is incorrect since the correct answer is A. Bemisia tabaci , which is known to spread the yellow mosaic virus disease of moong. Therefore, the correct answer is: A. Bemisia tabaci

[#310] The active compound in mineral gypsum and phosphogysum is
Correct Answer

(A) Calcium sulphate

Explanation

Solution: The active compound in mineral gypsum and phosphogypsum is Calcium sulphate. Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ยท2H 2 O. Phosphogypsum (PG) is the calcium sulfate hydrate formed as a by-product of the production of fertilizer from phosphate rock. It is mainly composed of gypsum. Although gypsum is a widely used material in the construction industry, phosphogypsum is usually not used but is stored indefinitely because of its weak radioactivity.