Title 02_OLYMPIAD 9th CLASS BIOLOGY NEET - WS - 10 TO 20_PG - 82 TO 191.pdf ✅

IX_ OLYMPIAD 84 Narayana Group of Schools NEET BIOLOGY STUDY MATERIAL  Leaves contain microscopic cellular organelles known as chloroplasts, where photosynthesis occurs.  Each chloroplast contains a green coloured pigment called chlorophyll. Light energy is absorbed by chlorophyll molecules whereas carbon dioxide and oxygen enter through the tiny pores of stomata located in the epidermis of leaves.  These sugars are then sent to the roots, stems, leaves, fruits, flowers, and seeds.  These sugar molecules then combine with each other to form more complex carbohydrates like cellulose and starch.  The cellulose is considered as the structural material used in plant cell walls. Factors affecting Photosynthesis Photosynthesis process requires several factors such as:  Light Intensity: Increased light intensity results in a higher rate of photosynthesis low light intensity results in a lower rate of photosynthesis.  The concentration of CO2 : Higher concentration of carbon dioxide helps in increasing the rate of photosynthesis. Usually, carbon dioxide in the range of 300 – 400 PPM is adequate for photosynthesis.  Temperature: For efficient execution of photosynthesis, it is important to have a temperature range between 25°C to 35°C.  Water: As water is an important factor in photosynthesis, its deficiency can lead to problems in the intake of carbon dioxide (The scarcity of water leads to the refusal of stomatal opening to retain the amount of water they have stored inside)  Pollution: Industrial pollutants and other particulates may settle on the leaves surface. This can block the pores of stomata which makes it difficult to take in carbon dioxide. Photosynthesis Equation  Photosynthesis reaction involves two reactants, carbon dioxide and water.  These two reactants yield two products, oxygen and glucose.  Photosynthesis reaction is considered to be an endothermic reaction.
Olympiad Text Book 85 Narayana Group of Schools IX _ OLYMPIAD NEET BIOLOGY STUDY MATERIAL Structure of Chlorophyll  Chlorophyll is a green pigment found in the chloroplasts of the plant cell and in the mesosomes of cyanobacteria.  Chlorophyll plays a vital role in the process of photosynthesis by permitting plants to absorb energy from sunlight. Chlorophyll is a mixture of chlorophyll-a and chlorophyll-b.  Besides green plants, other organisms that perform photosynthesis contain various other forms of chlorophyll such as chlorophyll-c1, chlorophyll -c2, chlorophyll-d and chlorophyll-f. Process of Photosynthesis  At the cellular level, the photosynthesis process takes place in chloroplasts and chlorophyll is responsible for the characteristic green colouration of the leaves.  Leaf comprises of three parts: A petiole, epidermis and a lamina.  The lamina is used for absorption of sunlight and carbon dioxide during photosynthesis. Structure of chloroplast:  The chloroplast has an inner and outer membrane with an empty intermediate space in between the membranes.  Inside the chloroplast are stacks of thylakoids, called grana and dense fluid filled component called stroma is present in the chloroplast.  These thylakoids contain the chlorophyll.  During the process of photosynthesis, carbon dioxide enters through the stomata, water is absorbed by the root hairs from the soil and is carried to the leaves through the xylem vessels.  Chlorophyll absorbs the light energy from the sun (To split water molecules into hydrogen and oxygen)  The hydrogen from water molecules and carbon dioxide absorbed from the air are used in the production of glucose.  Oxygen is liberated out into the atmosphere through the leaves as a waste product.