Any one tell me some important …

Excretion in Humans: The biological process involved in the removal of various harmful metabolic wastes from the body is called excretion. The excretory system of human beings includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. Let us see this process in detail now. The basic filtration unit in the kidneys, is a cluster of blood capillaries.Each such cluster is associated with the cup-shaped end of a tube, that collects the filtered urine. These filtration units are called nephrons, and each kidney contains several such clusters.The urine forming in each kidney then enters the ureter, which connects the kidneys with the urinary bladder.Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra.

Respiration in humans: Let us now see how respiration takes place in humans. We have broken down the process in points for better understanding, which you can now see on your screen. In human beings, air is taken into the body through the nostrils and is filtered by fine hair that line the passage.The air passes through the throat where rings of cartilage are present, which ensure that the air-passage does not collapse.The air then reaches the lungs, where the passage divides into smaller and smaller tubes which finally terminate in alveoli.  These alveoli are the places where exchange of gases takes place.The blood brings carbon dioxide from the rest of the body, which is released into the alveoli, and the oxygen in the alveolar air is taken up by blood, to be transported to all the cells in the body.Now the oxygen that is taken in our body, has to be transported all parts of the body. This is done by the respiratory pigment called haemoglobin, present in red blood cells.

Nutrition of Ameoba: Amoeba takes in food using temporary finger-like extensions on the cell surface which fuse over the food particle forming a food-vacuole. Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm. Important diagram – amoeba engulfing a food vacuole

Nutrition in autotrophs: Autotrophs fulfil their food and energy requirements by the process of photosynthesis. The steps that take place during photosynthesis are: (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates. The carbon dioxide required by the plant is obtained through tiny pores present on the surface of the leaves called stomata. Note that the exchange of gases occurs across the surface of stems, roots and leaves as well. Water used in photosynthesis is taken up from the soil by the roots in terrestrial plants. Other materials like nitrogen, phosphorus, iron and magnesium are taken up from the soil. Important diagrams – from this unit, diagramatic representation of cross-section of a leaf and stomatal pores can be asked, so make sure you practice drawing them atleast once before the exam.