Answer: Option A. -> Both A & R are true and R explains A
:
A
Sulphur forms disulphide bridges between sulphur containing amino acids and stabilizes protein structure.

Answer: Option A. -> A & C
:
A
The plant is fixed in the soil with the root system. The soil holds water and supplies air to roots. The soil is the reservoir of water and minerals. Soil also harbors nitrogen-fixing bacteria and other microbes which supply atmospheric nitrogen in utilizable organic form to plants.

Answer: Option B. -> A - Infection thread containing bacteria B - Inner cortical and pericycle cells under division
:
B
Rhizobia infects the root hair and forms infection thread. It causes inner cortical cells and pericycle cells to divide rapidly.

Answer: Option A. -> The element is relatively immobile. 
:
A
Some deficiency symptoms tend to appear first in the young tissues whenever the elements are relatively immobile and are not transported out of the mature organs. Calcium is a part of thestructural component of the cell and because of that it is not easily degraded and released for use by the younger growing regions of the plants. This causes the younger leaves to show the symptoms of the deficiency.

Answer: Option B. -> Carbon
:
B
Carbon is the most abundant element found in plants. Plantsusecarbondioxide during photosynthesis. Theytake in carbon dioxide and convert it to energy for growth. When the plant dies, carbon dioxide is given off from the decomposition of the plant.

Answer: Option A. -> Chlorine
:
A
Chlorine is involvedin osmosis. It is also involved in maintaining the ionic balance that is necessary for plants to take up mineral elements during photosynthesis.

Answer: Option D. -> Cu
:
D
Trace elements arenutrients that are utilized by the plants in small quantities. They arealso called micronutrients. Fe, Mg, Zn, Cu are some examples of trace elements.

Answer: Option C. -> Manganese
:
C
Manganese is a micronutrient.

Answer: Option D. -> Sodium and Iodine
:
D
Sodium and Iodine are not needed by the majority of plants but very much needed by almost all animals. Deficiency of iodine causes the thyroid gland to swell up and cause problems. Sodium is essential in transferring nerve impulses across neurons.

Answer: Option C. -> Zinc  
:
C
Leaf malformations like little leaf and leaf rosettes are caused due to the deficiency of Zinc.