Biology

Human Excretory system * The human excretory system consists of a pair of kidneys, a pair of kidneys, a pair of ureters, a urinary bladder and the urethra. * The kidneys are compact, bean- shaped organs on either side of the spinal cord in the lower back. * Nephrons are the functional units of a ... Read more

Life Processes * The circulatory system consists of the heart and blood vessels. * Plasma contains suspended red blood cells, white blood cells and Platelets. * Red blood cells contain a pigment called haemoglobin. * In newborn babies, 17 to 22 gm/dl of haemoglobin should be present in the blood. For children, the normal range ... Read more

Control and Coordination - Coordination in Plants * Plants show two different types of movement- One independent of growth and the other dependent on growth. * Plants growth in the direction of stimulus is defined as tropic movement. * The movement of a plant part is response to light is called phototropism. * The movement ... Read more

Natural Resources - Biogeochemical Cycles * The continual cycle of water between the land, the ocean and the atmosphere is called the water cycle. * The interaction of biotic and a biotic component between the biological and geological world is called Biogeochemical Cycle. * In the carbon cycle, green plants use carbon dioxide from the ... Read more

Transpiration * Transpiration is the loss of water due to evaporation that occurs through pores in leaves called stomata. * The opening and closing of stomata is directly impacted by the turgidity of guard cells. * The transport pull for the ascent of water in Xylem cells is made possible by three physical properties of ... Read more

Means of Transport * Diffusion, facilitated diffusion and active transport are three means of transport in plants. * Diffusion is a passive process; it requires no expenditure of energy. * Diffusion facilitated by proteins without any energy expenditure is referred to as facilitated transport. * Unlike diffusion, active transport requires energy to move molecules against ... Read more

First and Second Laws of Inheritance * Gregor Johann Mendal carried out several hybridisation experiments with truebreeding pea lines which had sharply contrasting characters. * A monohybrid cross is the study of inheritance of one pair of contrasting characters. * The law of Dominance states that a monohybrid, pure line cross between parents with contrasting ... Read more

Nucleus * The nucleus is surrounded by a nuclear envelope or nuclear membrane. * The nuclear envelope consists of the outer membrane and inner membrane. * At a number of places, the two membrane fuse and give rise to minute pores called nuclear pores. * Present inside the nuclear envelope is the nucleoplasm, the nuclear ... Read more