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Lessons
- Chapter 1 – Nutrients in plants
- Chapter 2 – Nutrition in Animals
- Chapter 3 – Fibre to Fabric
- Chapter 4 – Heat
- Chapter 5 – Acids bases and salts
- Chapter 6 – Physical and Chemical Changes
- Chapter 7 – Weather, Climate and Adaptations of Animals to Climate
- Chapter 8 – Winds, Storms and Cyclone
- Chapter 9 – Soil
- Chapter 10 – Respiration in Organisms
- Chapter 11 – Transportation in Animals and Plants
- Chapter 12 – Reproduction in Plants
- Chapter 13 – Motion and Time
- Chapter 14 – Electric Current and its Effects
- Chapter 15 – Light
- Chapter 16 – Water: A Precious Resource
- Chapter 17 – Forests: Our Lifeline
- Chapter 18 – Waste water Story
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Question Bank
- Question Bank – Chapter 1 – Nutrients in Plants
- Question Bank – Chapter 2 – Nutrition in Animals
- Question Bank – Chapter 3 – Fibre to Fabric
- Question Bank – Chapter 4 – Heat
- Question Bank – Chapter 5 – Acids, Bases and Salts
- Question Bank – Chapter 6 – Physical & Chemical Changes
- Question Bank – Chapter 7 – Weather, Climate & Adaptations of Animals to Climate
- Question Bank – Chapter 8 – Winds, Storms and Cyclones
- Question Bank – Chapter 9 – Soil
- Question Bank – Chapter 10 – Respiration in Organisms
- Question Bank – Chapter 11 – Transportation in Animals and Plants
- Question Bank – Chapter 12 – Reproduction in Plants
- Question Bank – Chapter 13 – Motion and Time
- Question Bank – Chapter 14 – Electric Current & Its Effects
- Question Bank – Chapter 15 – Light
- Question Bank – Chapter 16 – Water: A Precious Resoure
- Question Bank – Chatper 17 – Forest: Our Life Line
- Question Bank – Chapter 18 – Waste Water Story
Chapter 2 – Nutrition in Animals
CHAPTER 2
Nutrition in Animals
- Plants can prepare their own food by photosynthesis but Animals
- All organisms including humans require food for growth, repair and functioning of the body.
- Animals nutrition includes nutrient requirement, mode of intake of food and its utilisation in the body.
- The breakdown of complex components of food like carbohydrates into simpler substances is called
- For digestion in humans, the food passes through a continuous canal consisting of several digestive organs and glands.
- The digestive tract and the associated glands together constitute the digestive system.
- Glands secrete digestive juice which converts complex substance of food into simpler ones.
- The canal can be divided into various compartments as – buccal cavity, food pipe or oesophagus, stomach, small intestine, large intestine, rectum and anus.
- Food is taken into the body through the mouth.
- The process of taking food into the body is called ingestion.
- The swallowed food passes into food pipe.
- Food pipe runs along the neck and chest.
- Food is pushed down by movement of the wall of food pipe.
- Stomach is a thick-walled flattened U shaped bag.
- The inner lining of stomach secretes mucous, hydrochloric acid and digestive juices.
- Small intestine is highly coiled and is about 7.5 m long.
- Small intestine receives secretions from liver and the pancreas.
- Here, carbohydrates get broken into simple sugars such as glucose, fats into fatty acids and glycerol and proteins into amino acids.
- The absorption of digested food into blood vessels takes place through thousands of fingers like outgrowth called villi.
- LIVER– It is situated in upper part of the abdomen. It is the largest gland in the body.
- It secretes bile juice which is stored in a sac called gall bladder.
- Bile plays an important role in digestion of fats.
- The food that remains undigested enters into large intestine.
- Its function is to absorb water and some salts from undigested food material.
- The remaining waste passes into the rectum and remains there as semi-solid faeces.
- The faecal matter is removed through the anus. This is called egestion.
- The grazing animals like cows, buffaloes and deer are known as Ruminants.
- They quickly swallow the grass and store it in part of stomach called Rumen.
- The swallowed food returns to mouth and the animal chews it. This process is called Rumination.
- Amoeba is a microscopic single-celled organism.
- It moves and captures the food by pushing out one or more finger like projections called Pseudopodia or False feet.
- The food becomes trapped in the food vacuole.
- Absorbed foods are used for growth, maintenance and multiplication.
- The undigested food is expelled outside by the vacuole.
- Animal nutrition includes nutrient requirement, mode of intake of food and its utilization in the body.
- Human digestive system consists of alimentary canals and secretory glands. It consists of buccal cavity, oesophagus, stomach, small intestine and large intestine ending in rectum and anus.
- The main digestive glands which secrete digestive juices are salivary glands, liver and pancreas.
- Nutrition is a complex process involving ingestion, digestion, absorption, assimilation and egestion.
- The absorbed substances are transported to different parts of the body and the undigested residues are expelled out of the body as faeces through the anus.
- Starfish feeds on animals covered by hard shells of calcium carbonate.
- After opening the shell, the starfish pops out its stomach through its mouth to eat the soft animal inside the shell.
- The stomach then goes back into the body and the food is slowly digested.
- The first set of teeth grows during infancy and they fall off at the age between six to eight years.
- These are termed milk teeth. The second set that replaces them are the permanent teeth.
- The permanent teeth may last throughout life or fall off during old age or due to some dental disease.
- Normally bacteria are present in our mouth but they are not harmful to us.
- However, if we do not clean our teeth and mouth after eating, many harmful bacteria also begin to live and grow in it.
- These bacteria break down the sugars present from the leftover food and release acids (see Chapter 5 to know what an acid is).
- The acids gradually damage the teeth This is called tooth decay.
- If it is not treated in time, it causes severe toothache and in extreme cases results in tooth loss.
- Chocolates, sweets, soft drinks and other sugar products are the major culprits of tooth decay.
- Therefore, one should clean the teeth with a brush or datun and dental floss (a special strong thread which is moved between two teeth to take out trapped food particles) at least twice a day and rinse the mouth after every meal.
- Also, one should not put dirty fingers or any unwashed object in the mouth.