Biology Std 10-Function and location Study notes Physiology Organ Location Function Lenticels On the surface of old, stems Exchange of photosynthetic and respiratory gases Cuticle Wax like covering on epidermis of leaves & green stems Prevent Transpiration Mesophyll Cells Between the epidermal cells of the leaf. Traps light energy with the chloroplast present in them for photosynthesis Cambium Below the bark of the tree Increases the girth of the stem of leaf, stem and leaves/ Innermost part of Vascular bundles Conducts water from the roots to the aerial parts of plant. Phloem Found in the veins of leaf, stem and leaves /Periphery of the Vascular Bundles Translocates the prepared food in the leaves to the storage organs. Hydathodes Special openings on the leaf margin Guttation Guard Cells Between the epidermal cells of the leaf/ On either side of stoma. Regulate the opening and closing of the stoma Chloroplast In the cytoplasm of green plant cells Photosynthesis Thylakoids/ Grana In the chloroplast Site of Reaction Stroma Colourless ground substance present in the chloroplast Site of light independent reaction Minute openings(surrounded by guard cells) occurring in large number on the lower surface of leaf Diffusion of photosynthetic and respiratory gases , Transpiration
Circulatory System Structure Location Function 1) Heart Situated between the two in the thoracic cavity. The apex is tilted towards the left side. Pumps oxygenated blood to the different parts of the body. 2) Pericardial fluid Found in the pericardial cavity, between the two membranes of pericardium. Protects the heart from mechanical injury and shock. Acts as a lubricant and reduces friction for the beating of the heart. Keeps the tissues of the heart moist. 3) Sino atrial node (S A node) or Pacemaker. Upper wall of right atrium. Initiates the heart beat. Regulates the contraction of the auricles. 4) Atrio Ventricular node. (AV node) Bottom of the auricle. Regulates the contraction of the ventricles. 5) Bundle of His Arises from the A V node and consists of a left and right branch which extends upto the apex of the heart. It receives an impulse from the A V node and transmits it to the Purkinje fibres. 6) Bicuspid valve or mitral valve. Between the left auricle and ventricle of the heart. Allows the blood to flow from the left auricle to the left ventricle and prevents it from going back into the auricle. 7) Tricuspid valve. Between the auricle and ventricle of the heart. Allows the blood to flow from the right auricle to the right ventricle and prevents it from going back into the auricle. 8) Chordae tendinae. Extend from the papillary muscles to the pointed ends of the cuspid valves. Keeps the tricuspid and bicuspid valves in position and prevents them from upturning. 9) Pulmonary semilunar valve. At the opening of the pulmonary artery which arises from the right ventricle. Prevents backflow of deoxygenated blood into the right ventricle. 10) Aortic semilunar At the opening of the aorta which arises from the left ventricle. Prevents backflow of oxygenated into the left ventricle. 11) Coronary artery Arises from the aortic arch, near its base as it emerges from the heart. Supply oxygenated to the walls of the heart.