The correct option is (c) 2 and 3 only.
Explanation
Stomata are minute pores found primarily on the epidermis of leaves and young stems. They are bordered by specialized guard cells that regulate the opening and closing of the pore. The primary functions of stomata are to facilitate gas exchange for metabolic processes and to regulate water loss through transpiration.
Statement-wise Analysis:
- Statement 1 is Incorrect: Plants cannot directly utilize atmospheric nitrogen ($N_2$) through their leaves or stomata. Nitrogen is an essential macronutrient, but it is primarily absorbed from the soil by the roots in the form of nitrate ($NO_3^-$) or ammonium ($NH_4^+$) ions. Atmospheric nitrogen is converted into usable forms through biological nitrogen fixation (by bacteria in root nodules or soil) or industrial processes, not via direct intake through stomata.
- Statement 2 is Correct: Stomata are the main site for the exchange of gases between the plant and the atmosphere. During photosynthesis, plants take in carbon dioxide ($CO_2$) and produce oxygen ($O_2$) as a by-product. This oxygen is released into the atmosphere through the stomatal pores.
- Statement 3 is Correct: Stomata facilitate transpiration, which is the loss of water in the form of vapour from the aerial parts of the plant. While this process results in water loss, it creates a transpirational pull that is essential for the upward movement of water and dissolved minerals from the roots to the leaves.
Key Takeaway:
Stomata serve as the gateway for gas exchange (intake of $CO_2$, release of $O_2$) and transpiration (water vapour loss). However, nutrient uptake, specifically nitrogen, occurs through the root system, not the stomata.