Stroma vs Stoma
In plants, gaseous exchange occurs through the stomata and light independent reaction of the photosynthesis takes place in the stroma.
What is Stoma?
A stoma is a microscopic pore surrounded by two specialized guard cells found in the leaves and stems. Its main function is gaseous exchange. In all dicots and some monocots, the guard cells are kidney shaped or bean seed shaped. They may be or may not be surrounded by 2 or 3 subsidiary cells, which are different from other epidermal cells. The wall of the guard cells surrounding the pore is thicker than the other parts. The 2 guard cells are firmly held together at the 2 ends. The guard cells bear chloroplasts. In grasses and hedges, the guard cells are dumb bell shaped. There are two triangular shaped accessory cells on either side. These stomata are arranged in a regular pattern. They are linearly arranged parallel to each other while, in dicots, they are irregularly scattered. Normally the stomata open during day time and close at night. That is diurnal habit. The time of the day when stomata open may be different in each plant species. Opening and closing due to change of turgidity of guard cells. Quick changes of water potential inside guard cells cause them to absorb or lose water from or to the neighboring epidermal cells. There are cellulose microfibrils in the guard cell walls that are arranged around the circumference as though they are radiating from the centre of stomata; they are called radial micellations. When water enters the guard cells the guard cells expand that they cannot increase much in diameter due to radial micellations. The guard cells increase in length especially along their thinner outer wall because the inner walls are thicker. As they swell outwards, the microfibrils pull the inner wall with them, thus opening stomata.
What is Stroma?
Chloroplasts are surrounded by two membranes. These membranes form the chloroplast envelope. Chloroplasts contain chlorophyll and other photosynthetic pigments, which are located on a system of membranes. The membranes run through a ground substance or stroma. The stroma is the site of the light independent reactions of photosynthesis. The structure is gel like containing soluble enzymes particularly those of the Calvin cycle and other chemicals such as sugars and organic acids.
What is the difference between Stroma and Stoma?
• A stoma is a microscopic pore surrounded by two specialized guard cells found in the leaves and stems. Its main function is gaseous exchange.
• The site of the light independent reactions of photosynthesis is the stroma. The structure is gel like containing soluble enzymes particularly those of the Calvin cycle and other chemicals such as sugars and organic acids.