At a glance : Chapter 2 Nutrition in Animals Living organisms are bundles of cells that carry out specialized functions. 1. Life is uncertain because Organic Matter is born, it Organic / Biotic Matter grows, and it dies or comes to an end in its physical form. 2. All forms of life : plant, animal, birds, insects, humans, are Living or Organic matter on Earth. 3. Organism have movement or locomotion, and the ability to re-create its own kind. Animals and human bring up their young ones. 4. When a form of life will end or how it will react in various situations is uncertain. This is a basic feature of life. 3 Characteristics of living organism Respirat ion movement Growth and repair Life span and death Sensitivit y Nutrition Reproducti on Excretion Organis m Shape and size Maintaining internal conditions Cellular organizati on 9 10 x 10 Learning TM Page 1
Internal Growth Growth in Living Organisms Cellular organisation is internal Cells increase in size and number to cause internal growth Differential Growth Substances in food causes different parts of the body to grow in different proportions Food is converted into protoplasm to enable cells to absorb it easily Growth is Irreversible Growth in living organism cannot be reversed. The movement of growth is always forward and never backward. 10 Living organisms are bundles of cells carrying out specialized functions Feeding and Nutrition result From many steps In the cell activity Movement of The body is due Ability of the cells To contract and Expand back to Original shape Obtain energy from food and respire ( have oxidation) Show movement through internal life force Review : In Chapter 1 it was learnt that : Born, grow, reproduce, and die Through production of more Body substance and more Cell substance. Can self repair and self clean Made of cell structures Blood cells transport Oxygen and nutrition From digested food, Protect the body from diseases, absorb water, regulate body heat, and reproduce their own kind. Repair of cells Due to cell division 11 10 x 10 Learning TM Page 2
1. Nutrition is the energy required to carry out the activities of life. All living organisms get this energy from Food. 2. Plants with leaves are the only organisms that make their own food. They need soil water, air, and sunlight for making their own food. 3. All other forms of living organisms depend on plants for their food. Now: Chapter 2 deals with Nutrition in Animals 1. What is included in Animal nutrition? 3. How is the food digested? Digestion means breaking down the food into simpler units. 3. Utilisatio n of food by the body 1. Nutritient requireme nt Animal Nutrition includes 1. WHAT? Points 2 and 3 = HOW? 2. Mode of intake of food 2. The process of Nutrition involves the following steps : a) Ingestion or taking the food into the body. b) Digestion, or breaking down the food in simpler substances c) Absorption or making the soluble food a part of the blood stream to be carried to all parts. d) Assimilation converting food into energy for use. e) Egestion transporting of waste material for throwing out of the body 3. What is digestion and why is it needed? 1. What does the animal eat? a) Herbivorous eat: Grass, shrub leaves, berries, plants, roots, tree leaves, fruits. b) Carnivorous eat other animals that they hunt. c) Scavengers eat dead animals and decaying matter and other small animals they can hunt. 2. How does it eat? By : Cutting, chewing, and swallowing; Capturing and swallowing, sucking, sponging, scrapping, picking, piercing and sucking. 10 x 10 Learning TM Page 3
Answer. The process of breaking down of complex food components, into simpler soluble forms, that are easier to be absorbed by the living organism, is called digestion. Digestion is needed to convert food into energy. Why the Digestive System is needed? 1. The food that is eaten, needs to be converted into soluble form that can be absorbed by the blood, for distribution as energy throughout the body. 2. The process of digestion includes any chemical change involving breaking down of food into simpler, soluble forms. This enables the soluble form of food to be absorbed through the living membranes of other systems in the body. Enzymes play an important role in digestion. 2 Main parts of the Human Digestive System 5. Egestion 4. Intestinal juices are added in the lower part of the Small intestines. 3. Pancreas is a gland that secretes pancreatic juices. These help to digest carbohydrates, proteins, mineral salts. 4. Small Intestines 5. Large Intestines 6. Anus. 3. Stomach 1. Buccal cavity in the mouth 2. Oesophagus or gullet linking throat to stomach Salivary Glands in the mouth, discharge saliva that is mixed with each morsel of food while chewing. 2. Liver is the largest gland that secretes a digestive juice called bile into the stomach. Bile is needed mainly for digesting fats. 10 x 10 Learning TM Page 4
The digestive system 2.2 Liver is the largest gland in the body, located in upper right side of abdomen. It secretes Bile into the stomach through the bile duct. 2.3 Pancreas is another digestive gland located to the left side of the liver. It secretes pancreatic juice. This juice has three enzymes Amylopsin, Trypsin, Steapsin. 1.1 Mouth: lips, tongue and salivary glands. 2. 1.2 Teeth: Incisors, Canine, Premolars, Molars. 20 milk teeth; 28 till 30years of age. 32 thereafter. (1) Alimentary canal is 9 metres long, highly coiled in small intestines. (2) Digestive glands 2.1.1 Saliva: is a solvent that stimulates the taste buds, and moistens and lubricates food to help in swallowing Food particles are formed as bolus for swallowing in a mass Stomach is the muscular bag part of the Alimentary canal, at the end of the oesophagus tube, and opens below in to the small intestines.. Enzyme ptyalin converts starch into Maltos 1.3 Oesophagus is the tube connecting the mouth to the stomach. Peristalisis is a wave of constriction caused by the circular muscles of the gut pushing the food along the Oesophagus. 2.1 Three salivary glands : (a) parotid below each ear; (b sub mandibular in lower jaw; (c) sublingual : below the tongue. 1.2.1 Structure of tooth: a) Crown above the gum and neck. Crown is made of Enamel, and neck and below is made of Dentine. Cement fixes the tooth, and Pulp is the central space in the tooth. 4 Exercises at the end of Chapter 2 1. Fill in the blanks: 1.1 The main steps of nutrition in humans are ingestion, digestion, absorption, assimilation and egestion. 1.2 The largest gland in the human body is the Liver. 1.3 The stomach releases hydrochloric acid and digestive juices which act on food. 1.4 The inner wall of the small intestine has many finger like outgrowths called villi. 1.5 Amoeba digests its food in the food vocuole. 2. Mark T if the statement is true and F if it is false: (a) Digestion of starch starts in the stomach. (False) (b) The tongue helps in mixing food with saliva. (True) (c) The gall bladder temporarily stores bile. (True) (d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (True ) 10 x 10 Learning TM Page 5
3. Tick mark the correct answer in each of the following: Here the correct answer is indicated in colour a) Fat is completely digested in the (i) stomach (ii) mouth (iii) small intestine (iv) large intestine b) Water from the undigested food is absorbed mainly in the (i) stomach (ii) food pipe (iii) small intestine (iv) large intestine 4. Match the items of Column I with those given in Column II: Answer: The correct match is as follows: Column I Food components Carbohydrates Proteins Fats Column II Product(s) of digestion Sugar Amino acids Fatty acids and glycerol 5. What are villi? What is their location and function? Answer: Villi are finger like outgrowth in the inner lining of the small intestines. Their function is to increase the surface area of intestines, and to absorb the digested food into the blood stream. 6. Where is the bile produced? Which component of the food does it help to digest? Answer. The bile is produced in the liver. It helps in the digestion of fats in the food. 7. Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also. Answer. Cellulose is a type of carbohydrate found only in grass. Humans cannot digest it as their digestive system does not have the special bacteria that helps to digest cellulose. 10 x 10 Learning TM Page 6
Only ruminants have the bacteria and the special sac like structure called Rumen. The grass grazed by the ruminants is partially chewed. It gets collected in the rumen. There digested further by the special bacteria and turned into cud. Later the cud returns to the mouth and is chewed further by the ruminant. Then it goes to the small intestine to be absorbed. 8. Why do we get instant energy from glucose? Answer. Glucose is similar to fruit sugar found in fruits. It is absorbed quickly in to the blood stream after very little digestion, because it is in simple form and needs no breaking up into simpler units. Therefore, it is able to provide instant energy. 9. Which part of the digestive canal is involved in: a) absorption of food = Small intestines. b) chewing of food = bucca cavity. c) killing of bacteria = stomach. d) complete digestion of food = Small intestines. e) formation of faeces = Large intestines. 10. Write one similarity and one difference between the nutrition in amoeba and human beings. Answer. The nutrition in amoeba and human beings is similar in the process that the food is broken into simpler form and absorbed, and the undigested residue is egested. One difference is that humans have a formal structure of glands and body parts that are involved in the process of nutrition. The amoeba has no such structure. Whenever a food particle comes near it, it extends out a pseudopodia around the particle to engulf it. Therefore, it is informal in its nutrition structure. 11. Match the items of Column I with suitable items in Column II Column I Column II Salivary gland Stomach Saliva secretion Acid release 10 x 10 Learning TM Page 7
Liver Rectum Small intestine Large intestine Bile juice secretion Release of faeces Digestion is completed Storage of undigested food 10 x 10 Learning TM Page 8