Etiolation is the response of a plant to stimuli. When plant seeds are grown in insufficient light, (either in partial or complete absence of light) the seedlings will have long, weak stems, smaller and fewer leaves because of longer internodes, and a pale yellow colour (chlorosis). This is due to a lack of chlorophyll. The increase in height helps the plant reach a possible source of light faster.

Correct Option: C

Etiolation is the response of a plant to stimuli. When plant seeds are grown in insufficient light, (either in partial or complete absence of light) the seedlings will have long, weak stems, smaller and fewer leaves because of longer internodes, and a pale yellow colour (chlorosis). This is due to a lack of chlorophyll. The increase in height helps the plant reach a possible source of light faster.

Deficiency of magnesium produces chlorosis due to breakdown of chlorophyll. Chlorosis is a condition in which plant foliage produces insufficient chlorophyll. When this happens, leaves do not have their normal green colour; they may be pale green, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates and may die unless the cause of its chlorophyll insufficiency is treated. Specific nutrient deficiencies (often aggravated by high pH) cause chlorosis, which may be corrected by supplemental feedings of iron, magnesium or nitrogen compounds in various combinations. Some pesticides, particularly herbicides, may also cause chlorosis, both to target weeds and occasionally to the crop being treated.

Correct Option: C

Deficiency of magnesium produces chlorosis due to breakdown of chlorophyll. Chlorosis is a condition in which plant foliage produces insufficient chlorophyll. When this happens, leaves do not have their normal green colour; they may be pale green, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates and may die unless the cause of its chlorophyll insufficiency is treated. Specific nutrient deficiencies (often aggravated by high pH) cause chlorosis, which may be corrected by supplemental feedings of iron, magnesium or nitrogen compounds in various combinations. Some pesticides, particularly herbicides, may also cause chlorosis, both to target weeds and occasionally to the crop being treated.

Grey spots of oat are caused by deficiency of Manganese.

Correct Option: D

Grey spots of oat are caused by deficiency of Manganese.