Have you seen a cow chew continuously and ever wondered why they do so? Actually, cows and some other plant-eating animals swallow their food after chewing once. Later, they bring back the swallowed food into the mouth and chew it again. A plant-eating animal that brings back swallowedfood into the mouth to chew it again is called a ruminant and the process is called rumination. This habit of plant-eating animals makes their digestive system different from ours and thus the need to study them separately.
Ingestion
The food is ingested with the help of the tongue and chewed. Ruminants have sharp incisors and large molars to bite and chew grass. They also have powerful jaw muscles.
Digestion
After being chewed once, the food passes down the 2 to 3 feet long oesophagus. The oesophagus leads into the stomach. The stomach of ruminants has four chambers: rumen, reticulum, omasum, and abomasum. Rumen: The rumen helps in storing the large quantities of food that has been quickly consumed. The food is partially digested here and is now called the cud. The cud is then brought back to the mouth, re-chewed, and re-swallowed in a process called cud-chewing. The rumen has billions of bacteria and protozoa, which break down the carbohydrate called cellulose found in hay and grass. Reticulum: The reticulum helps in moving the swallowed food back into the mouth for thorough chewing. The reticulum opens into the omasum. Omasum: The omasum absorbs excess water. Abomasum: The walls of the abomasum secrete digestive juices.
Absorption
Absorption begins in the four-chambered stomach, but the main absorptive organs are the intestines. The food from the abomasum passes into the small intestine, where it mixes with secretions from the pancreas and liver. Most of the digestion of- carbohydrates, proteins, and fats takes place here. Several villi are present here, which help in increasing the surface area for absorption. The small intestine leads into the large intestine. The main function of the large intestine is to absorb water and eliminate the undigested food as faeces.
There are four different types of teeth. They are incisors, canines, premolars, and molars.
Types of teeth
Incisors: They are also called biting teeth. They are flat, blade-like teeth. The incisors are the front teeth and are so-called because they help to incise (cut) food. Canines: They are also called tearing teeth. They have very sharp edges and help to tear the food. Premolars: They have broader surfaces and, therefore, help to chew and grind the food. Molars: These are large back teeth. They have a wide grinding surface and are used primarily to chew food.
Humans develop two sets of teeth in their lifetime: the temporary set and the permanent set. The temporary set has twenty teeth, which are ‘ also called the milk teeth. Around the age of six, the milk teeth start falling out, giving way to the permanent teeth.
Permanent set of teeth
In the permanent set, there are thirty-two teeth, sixteen in each jaw. There are 4 incisors, 2 canines, 4 premolars, and 6 molars in each jaw.
Taking care of our teeth Bacteria are present all around us, even in our mouths. But all bacteria are not harmful to us. However, when we do not clean our teeth properly, some harmful bacteria start growing in the mouth. These bacteria, food particles, and the saliva together form a thin sticky layer called plaque on the surface of the teeth. Plaque that is not removed by brushing, produces acid. The acid dissolves the hard tooth enamel. Tiny holes appear on the surface of the enamel, which slowly get bigger until one large hole appears. This is called a cavity.
Heterotrophic Nutrition – Types Of Heterotrophic Nutrition With Examples
Types Of Heterotrophic Nutrition
Heterotrophic Nutrition: It is a mode of nutrition in which the organisms obtain readymade organic food from outside sources. The organisms that depend upon outside sources for obtaining organic nutritens are called heterotrophs. Heterotrophic nutrition is of three types – saprophytic, parasitic and holozoic.
Saprophytic or Saprotrophic Nutrition: It is a mode of heterotrophic nutrition in which food is obtained from organic remains like dead organisms, excreta, fallen leaves, broken twigs, food articles, etc. Organisms performing saprophytic nutrition are called saprophytes.
Parasitic Nutrition: It is a mode of hetrotrophic nutrition in which a living organisms flourishes by obtaining food from another living organism. The lving organisms which obtains food and shelter from another organism is called parasite. The organism which provides food and shelter to a parasite is known as host. An external plant parasite is Cuscuta (Amarbel). It is a non-green plant that sends haustroria or sucking roots into host plant for obtaining food and water.
Holozoic Nutrition: It is a mode of heterotrophic nutrition which involves intake of solid pieces of food. Since solid food is taken in, holozoic nutrition is also called ingestive nutrition. The food may consist of another animal, plant or its parts. Depending upon the source of food, holozoic organisms are of three types – Herbivores, carnivores, omnivores. Herbivores: (L.herba-plant, vorare-to eat). They are holozoic organisms which feed on plants or plant parts, e.g., Cow, Buffalo, Deer, Goat, Rabbit, Grasshopper, Elephant, Squirrel, Hippopotamus. Carnivores: They are animals which feed on other animals. Carnivores are also called predators they hunt, kill and feed on their preys, e.g. Lion, Tiger, Leopard, Snake, Hawk. Omnivores: (L.omnis-all, vorare-to eat). They are holozoic organisms which feed on both plant and animal materials, e.g. Cockroach, Ant, Pig, Crow, Rat, Bear, Dog, Humans.
Heterotrophic plants are of the following types:
Parasitic Plants
A parasitic plant is one that partially or completely depends on another plant (called host) for nutrition. Usually, parasitic plants develop special roots, which penetrate into the tissues of the host plant. The prepared food is generally absorbed from the root or the stem of the host plant. Some examples are Cuscuta (dodder) and mistletoe.
mistletoeCuscuta
Mistletoe has leathery, green leaves, and so it can make its own food. But it depends on the host for minerals and water. Cuscuta (Dodder) has a short root and a long, thread like stem. It twines around the host stem and sends branches around neighbouring stems.
In a parasitic relationship, only the parasitic plant benefits. The parasitic plant harms the host plant to some extent by slowing down its growth and sometimes causing heavy damage. However, a parasitic plant rarely kills the host plant.
Saprophytic Plants
A saprophytic plant is one that obtains its nutrients from dead and decaying plant and animal matter (sapros, rotting; phyton, plant). It is usually whitish, but some plants can have brightly coloured flowers. These plants often have no leaves at all. They often grow in deep shade in tropical forests. Some examples are Indian Pipe and coral root.
Indian PipeCoral Root
Indian Pipe is found commonly in Asia and North America. Coral roots are found in forests around the world. The roots of saprophytic plants contain organisms called fungi. The fungi convert the dead and decaying matter into nutrients that can then be used as food like sugar by these plants. Fungi are also called saprotrophs.
Insectivorous Plants
Insectivorous plants are plants that derive some or most of their nutrients by trapping and consuming animals, mainly insects. These plants mostly grow in places where either the soil is deficient in certain nutrients (e.g., nitrogen) or too little light is available to carry out photosynthesis. Hence, these plants need to obtain the required nutrients from other sources. Some examples are the pitcher plant, Drosera (sundew), bladderwort, and the Venus flytrap.
The leaf of the pitcher plant is modified to form a tubular pitcher-like structure. The inside of the pitcher is lined with downward pointing hair that do not allow any trapped insect to climb up and escape. The fluid at the bottom of the pitcher contains digestive juices that digest the insect.
Pitcher Plant
The slender leaves of bladderworts bear a large number of very small, pear-shaped bladder structures, which act like trapdoors and suck in small insects in less than a second.
Bladderwort
The leaves of the sundew plant have long, thin structures called tentacles, which have drops of a sticky substance called mucilage at their ends. Once an insect touches the tentacles, it gets stuck in the mucilage and is unable to escape. It is then digested.
Sundew
The Venus flytrap has leaves that are modified to trap insects. The inner surface of the leaves have short, stiff hair. When an insect touches the hair, the leaves snap shut in less than a second. The insect is then digested.
Venus Fly Trap (Dionaea muscipula)
Symbiotic Plants
Certain plants live in association with other organisms, share food and other resources. Both the types mutually gain from each other. Such plants are called symbiotic plants and the relationship is called symbiotic. A good example is lichens.
Lichens
Activity
Aim: To grow fungi. Materials required: A piece of bread, water, and box. Method: Moisten the bread with water and keep it in the closed box for a few days. Observation: You will see some grey patches on the bread. Conclusion: The patches are due to the growth of fungi.
Selina Concise Biology Class 9 ICSE Solutions Nutrition
APlusTopper.com provides step by step solutions for Selina Concise ICSE Solutions for Class 9 Biology Chapter 10 Nutrition. You can download the Selina Concise Biology ICSE Solutions for Class 9 with Free PDF download option. Selina Publishers Concise Biology for Class 9 ICSE Solutions all questions are solved and explained by expert teachers as per ICSE board guidelines.
Selina ICSE Solutions for Class 9 Biology Chapter 10 Nutrition
Exercise 1
Solution A.
(c) Fructose and glucose
(d) Potassium – Banana
(b) and (c). (Note: Marasmus is mainly caused due to the deficiency of proteins, but as per the options provided, the right answer would be both carbohydrates and fats.)
(a) A, D and E
(c) Carrot
(a) C
Solution B.1.
(a) T (True) (b) F (False). Kwashiorkor is a severe protein deficiency disease. (c) F (False). Iodine is required for the proper working of thyroid. (d) F (False). Antibodies are proteins produced by the immune system of the body, when it detects harmful substances called antigens. (e) T (True)
Solution B.2.
(i) Fluorine (ii) Iodine (iii) Iron
Solution C.1.
CARBOHYDRATES
EXAMPLES
USES
(i) Monosaccharides
1.Glucose
Provides an instant source of energy
2.Fructose
Needed for maintaining a healthy body
(ii) Disaccharides
1.Sucrose
Needed for good health
2.Maltose
Further broken down to produce glucose molecule which provides energy to the body
(iii) Polysaccharides
1.Cellulose
Acts as roughage which prevents constipation
2. Glycogen
Reserve carbohydrate in humans and stored in liver and muscles
Solution C.2.
Balanced diet is defined as the one which contains all the principal constituents of food in proper quantity. Balanced diet is the one that provides at least 50% of energy from carbohydrate, 35% from fat, and 15% from protein. The precise optimal quantities of each nutrient will vary with age, sex and activity.
Solution C.3.
Bones are generally made of calcium and iron. Milk and milk products are rich in calcium and Vitamin A. That is why, a doctor advises a bone patient to include more of milk and milk products in his everyday food to make his bones and teeth strong. Milk also prevents oxidation of Vitamin A. Calcium present in milk even helps in clotting of blood. Milk, is therefore a wholesome food.
Solution D.1.
Need for food by the body:
Growth: Food is necessary for building new protoplasm or cells. This helps in the growth of an organism.
Repair: Food provides materials for the repair of worn out or damaged cells and tissues.
Energy: We obtain energy from food. This energy is required for carrying out various life functions.
Maintenance: Nutrients obtained through food help to maintain the chemical composition of cells.
Provision of raw materials: Raw materials required for the synthesis of products such as enzymes, hormones, sweat, milk, etc. are obtained through food.
Protection: Food provides protection from diseases and infection.
Solution D.2.
Proteins are the body building foods. They provide the chemical material for the growth and repair of body cells and tissues. At the time of emergency, proteins can also be oxidized in the body to release energy. Protein deficiency disease of young children: Kwashiorkor
Solution D.3.
Whole grain atta, fruits and green leafy vegetables are the chief sources of roughage.
Roughage does not provide any nutrients to our body. It still has nutritive value and is essential for the proper functioning of the gut.
It absorbs a lot of water and retains it. In this way, it keeps faecal matter soft preventing constipation.
It combines with intestinal waste and makes it bulky.
It helps in the formation of stools and helps our body to expel the undigested waste food.
Roughage expands the intestinal lumen and helps in slow and smooth movement of food through the gastrointestinal tract. This movement is required for proper and complete digestion of food and for the elimination of intestinal waste.
Roughage stimulates secretion from the digestive tract and also helps in removal of cholesterol, fatty secretory substances and toxins from the body.
Solution E.1.
VITAMIN
RICH SOURCE
DEFICIENCY DISEASE
(i) Thiamine
Whole grain
Beri-beri
Niacin
Milk
(ii) Pellagra
(iii) Ascorbic acid
(iv) Citrus fruit
Scurvy
Calciferol
(v) Fish liver oil
(vi) Rickets
(vii) Retinol
Carrot, yellow fruit
(viii) Night blindness
Solution E.2.
Mineral
Function
Rich Source
Iodine
Promotes the secretion of thyroxine by the thyroid gland
Iodised salt, sea foods
Iron
Formation of haemoglobin
Whole cereals, fish
Calcium
Allows muscle contraction and clotting of blood
Dairy foods, beans
Potassium
Controls nerve and muscle activity, fluid balance, secretion of neurotransmitter
Banana, potato
More Resources for Selina Concise Class 9 ICSE Solutions
Photosynthesis: Photosynthesis is the primary mode of food production in green plant. ” The process by which green plants synthesize food from simple substances carbon dioxide and water in the presence of sunlight is called Photosynthesis” The process of photosynthesis can be represented in the form of chemical reaction, as given below : 6CO2 + 12H2O → C6H12O6 + 6H2O + 6O2 Carbon Water Glucose Water Oxygen dioxide
Photosynthesis
Conditions Necessary for Photosynthesis The general conditions necessary for photosynthesis are: • The presence of a green pigment called chlorophyll. • The presence of light. • The availability of carbon dioxide. • The availability of water.
Photosynthetic Pigment: The light energy must be absorbed by a suitable pigment i.e. chlorophyll (green pigment). Chlorophyll is green colour pigment.
Mechanism of Photosynthesis: Photosynthesis is divided in 2 main steps (A) light reaction (B) dark reaction
Light reaction: It is also called Hill Reaction. It occurs in grana of thylakoids. It is named as light reaction as it occurs only in presence of light.
Inside a chloroplast
Water: The root system of plants enables them to obtain water from the soil. The root system consists of a main or primary root, rootlets or secondary roots, and root hair. Root hair increase the surface area of roots, and are found in great numbers near the tips of roots. Water and soluble nutrients travel through the root system and reach the leaves. Water and soluble nutrients are transported from roots to other parts of the plant through structures called xylem. The starch formed as a result of photosynthesis is transported to the various parts of the plant by structures called phloem.
Root system
Major Step: Absorption of light by chlorophyll. Photolysis of water. Reduction of CO2 to Carbohydrates. In this process ADP changes to ATP & inorganic phosphate. Release of oxygen into atmosphere.
Opening and Closing Stomata: The opening and closing of stomata depend upon the turgid or flaccid state of the guard cells. When guard cells are in turgid state the stomatal aperture opens and when guard cells are in flaccid state the stomatal aperture closes. The inner wall of guard cells (towards pore) is thick and outer wall (towards other epidermal cells) is thin. When the turgor pressure of the guard cells is increased the outer thinner wall of the guard cell is pushed out (towards the periphery) due to which a tension is created on the inner thicker wall thus pulling the inner thicker wall towards the periphery thus leading to the opening of stomatal aperture. On the contrary when the guard cells are in a flaccid state the outer thinner wall of guard cells returns to original position (moves towards pore) due to which tension on the inner wall is released which also returns to its original position and stomatal aperture gets closed again.
Dark Reaction: This reaction is not dependent on light. It is also known as calvin – Benson Cycle or C3 cycle as first stable product is phosphogliceric acid (PGA) a 3 carbon compound.
C4 Cycle or Hatch & Slakcycle: 4-C compound i.e. oxaloacetic acid (OAA). This cycle is found in many other tropical & subtropical monocots eg : Maize, Sorghum , Wheat, Oat, Pearl, millet etc. In dicots also many such plants are known eg : Amaranthus, Chenopodium, Atriplex, Euphorbia etc. In some families of dicots Compositae, Portulaceae, Nyctaginaceae.
Crassulacean Acid Metabolism (CAM): Certain plants, especially succulents which grow under extremely xeric (dry) condition, fix atmospheric CO2 in dark. Since the process was first observed in the plants belonging to family crassulaceae (eg. Bryophyllum, kalanchoe etc.) It was termed crassulacean acid metabolism (CAM). The most characteristic feature of these plants is that their stomata remain open at night (in dark) but closed during the day (in light). Thus, CAM is a kind of adaptation in succulents to carry out photosynthesis without much loss of water.
Activity 1
Aim: To find out if light is necessary for photosynthesis Materials needed: Green plant, black paper, scissors, and clip Method:
Cover a part of a leaf using a strip of black paper.
Place the plant in a dark corner for three days.
Pluck a leaf from the plant and test it for starch to confirm whether it is fully starch-free.
Now place the plant in sunlight for at least six hours.
Pluck the leaf covered with the strip of black paper, remove the strip, and test the leaf for starch.
Observation: The covered portion of the leaf shows no change when iodine solution is added. Conclusion: There was no starch formation in the covered part, so this part did not turn blue-black. This shows that light is necessary for photosynthesis.
Activity 2
Aim: To demonstrate that carbon dioxide is needed for photosynthesis
Materials needed: A potted plant, potassium hydroxide solution, a conical flask with a split cork, iodine solution, and a dropper Method:
Keep the potted plant inside a dark room for a few hours. Water it.
Pour potassium hydroxide solution into a conical flask. The solution absorbs carbon dioxide from the air.
Place one of the leaves (without breaking it from the plant) inside the flask and cork it.
Now, keep the entire arrangement in sunlight.
After a few hours, test the leaf in the flask and another leaf for starch, using iodine solution.
Observation: When iodine solution is added, the leaf clasped inside the conical flask shows no change, whereas the other leaf turns blue-black. Conclusion: The leaf inside the conical flask did not carry out photosynthesis because there was no carbon dioxide available to it.
