Knowledge to be still

 Mechanical and Chemical Digestion in the Oral cavity The gastrointestinal tract starts in the oral cavity where your teeth grind and chew food, breaking it into small manageable pieces. This chewing process, known as mastication, is temporalis dependent upon powerful muscles muscle (masseter and temporalis), as well as smaller muscles that permit fine control; they move the mandible (lower jawbone) against the upper jaw and enable crushing of relatively hard food. muscle. Mastication causes exocrine glands under the tongue and in the back called saliva which performs two essential functions. It moistens and compacts the chewed food so your tongue can roll it into a ball (bolus) and push it masseter to the back of your mouth for swallowing and easy passage through the pharynx and In addition, saliva contains digestive enzymes (e.g. salivary amylase) which begin the breakdown of carbohydrates. Mastication and saliva secretion work in harmony:chewing increases the surface area of ...

 Food in the Small Intestine As the contents of the stomach become thoroughly liquefied, they pass into the duodenum, the first segment (about 10 of the small intestine. Food typically takes 4-5 hours to pass through the stomach into the duodenum, the first part of the small intestine. After being churned and mixed with digestive juices in the stomach, food chyme moves slowly into the folds of the small intestine through the pyloric sphincter or valve. The small intestine (or small bowel) is the longest section of the digestive tract (approx 17 feet) and is divided into three segments: the duodenum, jejunum and ileum, each of which performs different digestive functions. Chyme from the stomach is propelled through the small intestine by peristalsis.  Functions of the Small Intestine The small intestine is where most chemical digestion takes place; peptides (complex chains of protein molecules) are broken down into amino acids; lipids (fats) are broken down into fatty acids and...

 Distinguishing Characteristics of Birds They are homoiothermic i.e. warm blooded animals because they can maintain their body temperature. The body is covered by different coloured feathers which are epidermal exoskeleton. Body is fusiform (streamlined) to allow better movement in air with less resistance. Fore limbs are modified into wings for flight.They have adapted a bipedal life and hind limbs are used for walking on land. The aquatic birds posses webbed feet. Skin is without epidermal glands except for uropygial gland present at the base of tail. Bones of the birds are hollow having air spaces which make them light in weight. Sternum is well developed in to a keel which not only helps in cutting the air during flight but also provide additional area for the attachment of muscles. Jaws are without tecth and are modified in the form of a beak. Digestive system has a crop to store the food and a gizzard to grindit. Heart is four chambered with two auricles and two ventricles. A...

Life Cycle of Angiosperms The angiospermic plant is a diploid sporophyte which is composedo f root, stem, leaves and flowers. Flower is the reproductive organ, whiles tamens and the carpels are its reproductive parts. Stamens are maler eproductive parts while the carpels are the female reproductive parts. Eachs tamen consists of an anther with four pollen sacs. A large number of microspores are produced by meiosis in each pollen sac. The wall of microspore becomes thick and is known as pollen grain.  During pollination the pollen grains are transferred to the stigma of the carpels. The pollen grain germinates and develops into male gametophyte or microgametophyte. The nucleus of the pollen grain divides into a generative nucleus and vegetative or tube nucleus. The generative nucleus divides into two male gametes. The pollen grain sends down a tube called the pollen tube which contains two male gametes and tube nucleus. The pollen tube together with the two male gametes and a tube n...

 Water Movement in Xylem through TACT Mechanism.  Four important forces combine to transport water solutions from the roots, through the xylem elements in the stem, and into the leaves. These TACT forces are: transpiration, adhesion, cohesion and tension. a. Transpiration Involves the pulling of water up through the xylem of a plant utilizing the energy of evaporation and the tensile strength of water. b. Adhesion  Is the attractive force between water molecules and other substances. Because both water and cellulose are polar molecules there is a strong attraction for water within the hollow capillaries of the xylem. c. Cohesion  is the attractive force between molecules of the same substance. Water has an unusually high cohesive force due to the hydrogen bonding. It is estimated that water's cohesive force within xylem give it a tensile strength equivalent to that of a steel wire of similar diameter. A combination of adhesion, cohesion, and surface tension allow wat...

  Kingdom Fungi Fungi were regarded as plants because of the presence of certain characters since the last many decades, but detailed studies have revealed a set of characteristics that distinguish fungi from plants. Fungi lack chlorophyll, while the plants have this pigment; wall of a fungal cell is made up of a carbohydrate called chitin not found in plant cell walls; though generally filamentous, fungi are not truly multicellular like plants, because the cytoplasm of one fungal cell is continuous through pores with the cytoplasm of adjacent cells; and fungi are heterotrophic eukaryotes, while plants are autotrophic. It is mainly because of these reasons that fungi are placed in their own kingdom fungi. Fungi are generally saprophytes and are the most important decomposers in terrestrial ecosystem. Many fungi are also known as parasites of animals and plants. They are found everywhere. They also develop symbiotic association with other organism. Recent finding are that fungi ar...

 Respiratory Electron transport Chain The last step in aerobic respiration is the oxidation of reduced co enzymes NADH and FADH, produced in glycolysis and Krebs cycle by molecular oxygen. The pairs of hydrogen atoms released from glucose during glycolysis and Krebs cycle of aerobic respiration are not received directly by oxygen but pass along a series of electron carriers called coenzymes and cytochromes. This series of electron carriers constitute respiratory electron transport chain. The final electron acceptor at the end of the electron transport chain is oxygen forming water. Various molecules involved in the electron transport are NADH,,FADH.coenzyme Q. cytochrome b (Cyt.b), cytochrome c(Cyt.c). cytochrome a (Cyt.a) and Cytochrome a, (Cyt.a, ). The coenzyme Q and cytochromes are alternately reduced and oxidized. Electrons are passed along a series of carriers as they lose energy at each transfer. Some of this energy is used in the formation of ATP from ADP and inorganic ph...