Question

Chlorosis occurs when plants are grown in
A. Shade
B. Strong sunlight
C. Fe-free medium
D. Dark

Answer 1

Hint: Plants are made up of multicellular cells i.e. multicellular organisms; they fall in the kingdom Plantae. Plants prepare their food by the process of photosynthesis. Plants play an important role in maintaining the world's ecosystem as they produce the oxygen and are important in the food chain.

Complete answer:
Plants are mainly autotrophs; they prepare their own food with the process of photosynthesis. Photosynthesis occurs in the chloroplast, which contain chlorophyll and carotenoids, molecules of these enzymes absorb light energy and help in the formation of food. Some plants are heterotrophic and parasitic in nature and depend upon the other living organism for their survival.
The main source of the nutrition and minerals for the plants is soil. If the soil contains the entire essential nutrient leads to the proper growth and development of the plant or a tree. Very acidic or very alkaline nature of the soil also affects the plant growth.
The plants uptake micro and macro nutrients from the soil;
> Macronutrients: nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Some macro nutrients are also derived from the air like oxygen, hydrogen, carbon.
> Micronutrients: iron, manganese, boron, molybdenum, copper, zinc, chlorine, and cobalt.
Mostly the soil conditions across the world can provide plants with proper climate and soil with sufficient nutrition for a complete life cycle and development, without the addition of nutrients as fertilizer. If the soil doesn't have sufficient amounts of nutrients so it is necessary to artificially modify soil fertility through the addition of fertilizer to promote vigorous growth and increase or sustain yield.
Chlorosis is normally a symptom of the plant disease in which the plant gets pale or yellow in color from green color. It is the failure of the green pigment chlorophyll because of the lack of nutrients or oxygen in the plan leaves. Chlorosis is mainly caused by the deficiency of the iron in the plant leaves. The leaves turn yellow with the dark green network of the veins.

Thus, the correct answer is option (C).

Note: Study of plants is termed as Botany and the study of plant disease is known as plant pathology.
Other than the Iron deficiencies there are some more:
Nitrogen deficiency: Spindly yellow plants or yellow leaves, sometimes with pink tints.
Potassium deficiency: Brown leaf edge with Yellow or purple leaf with poor flowering or fruiting.
Phosphorus deficiency: Dull yellow foliage and show slow growth
Magnesium deficiency: Early leaf falls with Yellowing between the leaf veins. Mostly in tomatoes, apples, grape vines, raspberries, roses and rhododendrons.
Boron deficiency: Stunted growth with tip dieback on lettuce, cause dimples in pears with brown patches underneath.
Molybdenum deficiency: In cauliflower elongated twisted leaves and brassicas growing in alkaline soil.