11th Class

The substance used for nutrition are called nutrients. Nutreology is the study of food and their use in diet and therapy. Types of nutrition (1) Autotrophic / Holophytic : The individuals, which synthesizes their own food. It can be grouped into two following categories – (i) Photoautotrophs : The individual, which synthesizes their own food from \[C{{O}_{2}}\] and \[{{H}_{2}}O\] in presence of sunlight. Examples – Green plants, euglena, green sulphur bacteria, chlorobium. (ii) Chemoautotrophs : The individuals which synthesizes their food with the help of chemical. Examples – Sulphur bacteria, nitrite bacteria, nitrate bacteria, nitrosomonas, nitrifying bacteria– nitrosomonas, nitrobacter etc. (2) Heterotrophic : The animals derive organic food materials by consuming bodies or products of other living or dead plants or animals. Heterotrophs are of following three types on the basis of their mode of feeding. (i) Holotrophic or Holozoic : These individuals ingest mostly solid food. Example – Animals.         more...

Digestion in vertebrates occurs in the digestive tract or alimentary canal. The various parts involved in digestion can be broadly grouped in two groups – (1) Digestive tract or alimentary canal (2) Digestive glands (3) Digestive tract or alimentary canal On the basis of the embryonic origin, the alimentary canal of vertebrates can be divided into three parts – (1) Fore gut / Stomodaeum : Ectodermal. It includes buccal cavity / oral cavity, pharynx, oesophagus, stomach and small part of duodenum. (2) Mid gut / Mesodaeum : Endodermal. It includes small intestine, and large intestine. (3) Hind gut / Proctodaeum : Ectodermal. It includes anal canal and anus. Parts of alimentary canal and its histology Mouth The mouth is a transverse slit bounded by two movable lips or labia, upper lip and lower lip. Upper lip has small ridges on the sides, a tubercle in the middle and a vertical more...

The process by which complex food is converted into simplest food with the help of digestive enzymes (Hydrolytic enzymes) is called digestion. Hence process of digestion is a hydrolytic process. Types of digestion (1) Intracellular : When the process of digestion occurs within the cell in the food vacuole. Examples : Protozoa, Porifera, Coelenterata and free living platyhelminthes. (2) Extracellular : When the process of digestion occurs outside the cell. Examples : Coelenterates and phylum platyhelminthes to phylum chordata.

Organism can be grouped into following four classes on the basis of their respiratory habit. (1) Obligate aerobes : These organisms can respire only in the presence of oxygen. Thus oxygen is essential for their survival. (2) Facultative anaerobes : Such organisms usually respire aerobically (i.e., in the presence of oxygen) but under certain condition may also respire anaerobically (e.g., Yeast, parasites of the alimentary canal). (3) Obligate anaerobes : These organisms normally respire anaerobically which is their major ATP- yielding process. Such organisms are in fact killed in the presence of substantial amounts of oxygen (e.g., Clostridium botulinum  and C. tetani). (4) Facultative aerobes : These are primarily anaerobic organisms but under certain condition may also respire aerobically.

On the basis of the availability of oxygen and the complete or incomplete oxidation of respiratory substrate. The respiration may be either of the following two types : Aerobic respiration and Anaerobic respiration Aerobic respiration It uses oxygen and completely oxidises the organic food mainly carbohydrate (Sugars) to carbon dioxide and water. It therefore, releases the entire energy available in glucose. \[{{C}_{6}}{{H}_{12}}{{O}_{6}}+6{{O}_{2}}\xrightarrow{enzymes}6C{{O}_{2}}+6{{H}_{2}}O+energy\,\,(686Kcal)\] It is divided into two phases : Glycolysis, Aerobic oxidation of pyruvic acid. Glycolysis / EMP pathway (1) Discovery : It was given by Embden, Meyerhof and Parnas in 1930. It is the first stage of breakdown of glucose in the cell. (2) Definition : Glycolysis ( Gr. glykys= sweet, sugar; lysis= breaking) is a stepped process by which one molecule of glucose (6c) breaks into two molecules of pyruvic acid (3c). (3) Site of occurrence : Glycolysis takes place in the cytoplasm and does not use oxygen. more...

In respiration many types of high energy compounds are oxidised. These are called respiratory substrate or respiratory fuel and may include carbohydrates, fats and protein. (1) Carbohydrate : Carbohydrates such as glucose, fructose (hexoses), sucrose (disaccharide) or starch, insulin, hemicellulose (polysaccharide) etc; are the main substrates. Glucose are the first energy rich compounds to be oxidised during respiration. Brain cells of mammals utilized only glucose as respiratory substrate. Complex carbohydrates are hydrolysed into hexose sugars before being utilized as respiratory substrates. The energy present in one gram carbohydrate is 4.4 Kcal or 18.4 kJ. (2) Fats : Under certain conditions (mainly when carbohydrate reserves have been exhausted) fats are also oxidised. Fat are used as respiratory substrate after their hydrolysis to fatty acids and glycerol by lipase and their subsequent conversion to hexose sugars. The energy present in one gram of fats is 9.8 Kcal or 41kJ, which is maximum more...