👉Symbiotic Relationship –

Chapter 2 | Nutrition in Animals

👉Animals take directly or indirectly plants’ food. Plants prepare complex food that converts into simpler forms by the process of digestion.
👉Nutrition in Animals is done by different steps – Ingestion, Digestion, Absorption, Assimilation and Egestion.
👉Starfish pop out its stomach through its mouth to eat its food.

👉Digestion in Human –

• The human digestive system called the alimentary canal is divided into various compartments – the buccal cavity, food pipe or oesophagus, stomach, small intestine, large intestine, rectum and anus.
• The process of taking food into the mouth is called ingestion.
• In the mouth, the breakdown of food begins with the help of sets of teeth, tongue and saliva.
• The Saliva breaks down the starch into sugars.
• Now, the swallowed food passes into the food pipe or oesophagus. It opens into the stomach.
• The inner lining of the stomach secretes mucus, hydrochloric acid and digestive juices.
• The mucus protects the lining of the stomach.
• The acid kills many bacteria that enter along with the food and makes the medium in the stomach acidic.
• The digestive juices break down the proteins into simpler substances.
• The length of the small intestine is about 7.5 meters long.
• The small intestine receives secretions from the liver called bile. This bile juice is stored in a sac called the gallbladder. It plays an important role in the digestion of fat.
• The liver is the largest gland in the body, situated in the upper part of the abdomen on the right side.
• The pancreas secretes pancreatic juice that acts on carbohydrates and proteins.
• In the small intestine, carbohydrates get broken down into simple sugars such as glucose, fats into fatty acids and glycerol and proteins into amino acids.
• The digested food can now pass into the blood vessels in the wall of the intestine. This process is called absorption.
• The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi (singular villus). The villi increase the surface area for absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials. 
• The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body. This is called assimilation.
• The large intestine is about 1.5 metres in length. Its function is to absorb water and some salts from the undigested food materials.
• The remaining waste passes into the rectum and remains there as semi-solid faeces. The faecal matter is removed through the anus from time to time. This is called egestion.

👉Milk Teeth & Permanent teeth:

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 is the permanent teeth. It may last throughout life or fall off during old age.

👉Set of teeths: Molar, Premolar, Canine & Incisor.

👉Grass eating animals like Cows, Buffaloes etc. quickly swallow the grass and store it in a separate part of the stomach called the rumen. Here the food gets partially digested and is called Cud. But later the cud returns to the mouth in small lumps and the animal chews it. This process is called rumination and these animals are called ruminants.

👉The grass is rich in cellulose which is not digested by humans but digested by grass-eating animals (Ruminants) because of certain bacteria present in a sac-like structure between the small intestine and large intestine.

👉Amoeba, a single-celled organism pushes out one or more finger-like projections on their body called pseudopodia or false feet for movement and capture of food. The food becomes trapped in a food vacuole. Digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances. Gradually the digested food is absorbed. The undigested residue of the food is expelled outside by the vacuole.

Chapter 3 | Fibre to Fabric

👉The process of selecting parents for obtaining special characters in their offspring, such as soft under hair in sheep, is termed as “Selective breeding”.

👉Wool derives from the fleece or fine hair or fibres of animals like sheep, yak, Angora goat, camels.

👉Some Indian breeds of sheep –

👉Processing fibres into wool

Step 1

The fleece of the sheep along with a thin layer of skin is removed from its body. This process is called shearing.

Step 2

The sheared skin with hair is thoroughly washed to remove dust. This is called Scouring.

Step 3

Hair of different textures is separated or sorted in a factory. It is called Sorting.

Step 4

The small fluffy fibres called burrs are picked out from the hair. The fibres are scoured again and dried. This is the wool ready to be drawn into fibres.

Step 5

The fibres can be dyed in various colours, as the natural fleece of sheep and goats is black, brown or white.

Step 6

The fibres are straightened, combed and rolled into yarn. The longer fibres are made into wool for sweaters and the shorter fibres are spun and woven into woollen cloth.

👉Sorter’s disease – workers in the wool industry may get infected by a bacterium called anthrax which causes a fatal blood disease called shorter’s disease.

👉The rearing of silkworms for obtaining silk is called sericulture.

👉Life history of silk moth:

Different stages of a silk moth are – eggs, larva, pupa and adult. The larval stage is called caterpillars or silkworms. The caterpillar secretes fibre made of a protein that hardens on exposure to air and becomes silk fibre. Before entering into pupa stage, the caterpillars weave a net to hold themselves. Then it swings its head from side to side and soon it is covered with itself by the moth inside the cocoon. Silk fibres are used for weaving silk cloth.

👉The silk yarn is obtained from the cocoon of the silk moths. The most common silk moth is the mulberry silk moth.

👉It takes about 25 to 30 days from the caterpillar stage to go into the pupa stage of a silkworm.

👉Processing silk: the cocoons are kept under the sun or boiled or exposed to steam. The silk fibres separate out. The process of taking out threads from the cocoon for use as silk is called reeling the silk. Reeling is done in special machines, which unwind the threads or fibres of silk from the cocoon.

Chapter 4 | Heat

👉A reliable measure of the hotness of an object is its temperature. Temperature is measured by a device called a thermometer.

👉A clinical thermometer reads temperature from 35 degrees C to 42 degrees C.

👉The normal temperature of the human body is 37 degrees C.

👉The range of a laboratory thermometer is generally from –10 degrees C to 110 degrees C.

👉Transfer of Heat: Conduction Convection and Radiation.

👉Conduction – the process by which heat is transferred from the hotter end to the colder end of an object is known as conduction. In solid, generally, the heat is transferred by the process of conduction.

👉Convection is the transfer of heat by circulating it through air or liquids. Unlike conduction, in which there must be direct or indirect contact between the two objects for heat transfer to take place, convection relies on the circulating motion of the molecules in order to transfer heat. Also unlike conduction, which relies on the microscopic movement of particles to transfer heat, convection is a bulk transfer of a lot of mass at the same time.

👉Radiation is another method of transfer of heat that does not require any medium. 

👉Woollen clothes keep us warm in winter as they have air trapped in between the wool fibres. This air prevents the flow of heat from our body to cold surroundings because air is a bad conductor of heat.

Chapter 5 | Acids, Bases and Salts

👉Substances & contain Acid/Base List:

👉Physical Change