This set of Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Effects of Air Pollutants on Vegetation”.
1. Which of part of the plants are most susceptible to the harmful effects of air pollutants?
a) The leaf
b) The root
c) The trunk
d) The branches
View Answer
Explanation: The leaf is the most susceptible to the effects of air pollutants. The pollutants get deposited on the leaves where they remain and block the stomata of the leaves. Their deposition causes multiple health issues.
2. What is meant by necrosis of the leaf?
a) Yellowing of leaf
b) Dead areas on leaf
c) Weighing down of leaf
d) Falling of leaf
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Explanation: Dead areas are formed on the leaves as the cells die. This phenomenon is called necrosis of leaves. Pollutants like hydrogen fluoride and nitrogen dioxide cause necrosis. Other listed symptoms have other names.
3. What is meant by chlorosis of the leaf?
a) Death of cells
b) Falling off of the leaf
c) Yellowing of leaf
d) Weighing down of the leaf
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Explanation: Reduction in chlorophyll levels is the chlorosis of the leaves. The effects of chlorosis can spread to other parts of the plant. Pollutants like sulphur dioxide cause chlorosis of leaves. Other symptoms have other names.
4. What is meant by abscission of the leaf?
a) Death of the leaf cells
b) Yellowing of the leaf
c) Weighing down of the leaf
d) Falling off of the leaf
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Explanation: Abscission means the falling off of the leaves. This condition is the side-effect of epinasty. In epinasty, pollutants deposit on the surface of leaves and weigh them down. The leaves fall off over time, causing abscission.
5. Which kind of particulates causes incrustations on the leaves?
a) Cement dust
b) Volcanic dust
c) Fumes
d) Sulphates
View Answer
Explanation: Cement dust, along with mist and rain, gets deposited on the surface of the leaf. The layer formed on top of the leaves due to the deposition is called incrustation. The full effects of all particulates are unknown because of several reasons.
6. Which kind of plants are affected by sulphur dioxide?
a) Root vegetables
b) Green leafy vegetables
c) Fruits
d) Starchy vegetables
View Answer
Explanation: Green leafy vegetables, especially spinach, are affected by pollutants like sulphur dioxide. This is because sulphur dioxide causes the bleaching and even chlorosis, leading to the loss of chlorophyll in the leaf.
7. Sulphur dioxide causes chlorosis of the leaf. Which of the following is another effect of sulphur dioxide?
a) Necrosis
b) Abscission
c) Bleaching
d) Epinasty
View Answer
Explanation: Sulphur dioxide causes both chlorosis and bleaching of the leaf. Such effects occur due to the acidic nature of sulphur dioxide. The effects manifest at the exposure of very low concentrations (less than 1 ppm), for several days.
8. Which of the following crops are not affected by nitrogen dioxide?
a) Tomato
b) Citrus plants
c) Cotton
d) Spinach
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Explanation: Tomato plants (stunted growth), citrus plants (abscission) and cotton plants (necrosis) are all affected by exposure to nitrogen dioxide. These effects manifest after exposure to different concentrations and exposure periods. Spinach is adversely affected by exposure to sulphur dioxide.
9. Which of the following concentration to nitrogen dioxide cause acute leaf injury?
a) 25 ppm for 1 hour
b) 0.25 ppm for 1 hour
c) 2.5 ppm for 1 hour
d) 0.1 ppm for 1 hour
View Answer
Explanation: The exposure of 25 ppm of nitrogen for an hour can cause acute leaf injury. Different effects occur due to various exposure periods and concentrations. Low concentration of less than 1 ppm for several months may cause necrosis.
10. The effects of ozone are accelerated when sulphur dioxide is present.
a) True
b) False
View Answer
Explanation: The effects of ozone get sped up in the presence of sulphur dioxide. Tobacco leaves show this accelerated effect, on which the effects manifest after about 2 hours of combined exposure. Ozone is a strong oxidising agent whose effects include necrosis and bleaching.
11. What are the effects of hydrogen fluoride?
a) Abscission
b) Epinasty
c) Necrosis
d) Chlorosis
View Answer
Explanation: Hydrogen fluoride causes the necrosis of the leaf tip. Necrosis means the death of the leaf cells due to exposure to pollutants. Plants like grapes are especially susceptible to the effects of hydrogen fluoride.
12. Which of the following is an effect on the plant leaf upon exposure to ethylene?
a) Necrosis
b) Bleaching
c) Chlorosis
d) Epinasty
View Answer
Explanation: Epinasty is an effect of ethylene; the leaves get weighed down due to pollutant deposition. This condition leads to abscission of the leaves. Very low concentrations of exposure for several weeks can lead to the manifestation of these effects.
13. Discolouration of the underside of the leaf is the effect of which of the following pollutants?
a) Sulphur dioxide
b) PAN
c) Ethylene
d) Particulates
View Answer
Explanation: The exposure to PAN causes the browning of the underside of leaves. PAN formation occurs in photochemical smog, and even concentrations of less than 0.1 ppm for a few hours can cause such effects.
Sanfoundry Global Education & Learning Series – Pollution Control.
To practice all areas of Pollution Control, here is complete set of 1000+ Multiple Choice Questions and Answers.
