At the large intestine, where the undigested food stored. Rectum is the final section of the large intestine, terminating at the ****. In humans it is about 12 cm long. It acts as a temporary storage site for feces.

Nutrition is  the process of intake of nutrients in the surroundings. 

Grass eating animals are called ruminant animals. Example – cow. They have special stomach to digest cellulose present in the grass. Their stomach is large and is divided into four compartments.

1. Rumen:
2. Omasum 
3. Abomasum
4. Reticulum

   The bacteria present in the rumen start to digest cellulose and gets partially digested. The partially digested food/grass in the rumen of a cow is called cud. After some time, the cud is brought back into the mouth and is chewed thoroughly. That is why, a cow moves its jaws from side to side and chew continuously even when it is not eating grass.

   The process by which the cud is brought back from the stomach to the mouth of the animal and chewed again is called rumination. The animals which chew the cud are called ruminants. When the cud is thoroughly chewed in the mouth of the cow, it is swallowed and goes into the other compartments of the cow’s stomach and then into the small intestine for complete digestion and absorption.  

   However, digestion in human beings starts in the mouth. The mouth contains teeth, tongue and salivary glands. The teeth cut the food into small pieces, chew and grind it. The tongue mixes the food with saliva. The salivary glands secrete a watery liquid called saliva.

   The slightly digested food goes into the food pipe or oesophagus by peristalsis. No digestion of food takes place in the oesophagus.

   The slightly digested food reaches the stomach through oesophagus for further digestion where it is broken down into smaller pieces. The inner lining of the stomach secretes gastric juice which includes mucus, hydrochloric acid and digestive juices. Mucus protects the lining of the stomach from hydrochloric acid. Hydrochloric acid makes the medium in the stomach acidic to facilitate the digestion of proteins. The digestive juices break down the protein into simpler substances. Then the partially digested food goes into the small intestine.

   The small intestine is a very long and narrow tube where complete digestion of food takes place. It receives secretions of liver, pancreas and its own walls. Liver secretes liquid called bile which helps in the digestion of fats and converts them into small droplets. Pancreas secretes pancreatic juice which breaks down fats into fatty acids and glycerol. Pancreatic juice also breaks down carbohydrates and proteins into simpler forms. The intestinal juice secreted by the walls of small intestine breaks down the carbohydrates into glucose, proteins into amino acids. Thus, the food gets completely digested in small intestine. Humans cannot digest cellulose.

Evaporation is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. It is the opposite process of condensation. Evaporation therefore, proceeds more quickly at higher temperature, at higher flow rates between the gaseous and liquid phase and in liquids with lower surface tension (i.e. higher vapor pressure). Since only a small proportion of the molecules are located near the surface and are moving in the proper direction to escape at any given instant, the rate of evaporation is limited. Also, as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling.

Heat is the transfer of energy from a hot body. The sense of touch can be used to understand the degree of hotness or coldness of something. But the sense of touch is not reliable and cannot be always used to say how much hot anything is. Moreover, using the sense of touch can be risky in case of something being very hot. Thus, hotness of anything is measured in terms of Temperature in reliable way. To measure temperature a device called Thermometer is used. There are three units which are used to measure the temperature: Degree Celsius, Fahrenheit and Kelvin.

Food is the most important and basic thing for life. Carbohydrates, proteins, fats, vitamins and minerals are the components of food. These components are necessary for all living beings. All plants and animals require food for their growth and getting energy. The process of utilization of food by an animal to obtain energy for growth and development is known as nutrition. Plants make their food themselves but animals cannot. Hence, animals depend directly or indirectly on the plant.

Spiders : Spiders weave sticky web in which small insects get stuck. In spiders digestion of food actually takes place outside their body.  A spider weaves a sticky web in which small insects get stuck. It then injects digestive juices into the body of the insect, which digests the body part of the insects. The spider then sucks up the digested food.

Paramecium: Paramecium is  a tiny unicellular animal which lives in water.
 Ingestion: Paramecium uses its hair like structures called cilia to sweep the food particles from water and put them into mouth.  Ingestion is followed by other steps such as digestion, absorption, assimilation and egestion which are same as in Amoeba.

In an electrical circuit, electric potential between two points is defined as the amount of work done by an external agent in moving a unit charge from one point to another.
Mathematically,    E = WQ
Where, E = electrical potential difference between two points
W = Work done in moving a change from one point to another
Q = the quantity of charge in coulombs
The potential difference is measured by an instrument called voltmeter. The two terminals of a voltmeter are always connected parallel across the points whose potential is to be measured.

Cell: The basic structural unit of a living organism is called cell. All living beings are made up of cells. Some organisms are made up of a single cell or of a few numbers of cells. Some other organisms are made up of numerous cells.
Cell Membrane: Cell membrane is also called plasma membrane. It makes the boundary of a cell. It is composed of protein and lipid. It is porous and allows various materials to pass through it.
Cytoplasm: A jelly-like substance is present between the cell and nucleus. It is called cytoplasm. Different cell organelles are present in the cytoplasm. Examples of cell organelles are; mitochondria, Golgi body, ribosomes, lysosomes, chloroplast, etc.
Nucleus: This is a spherical structure which is present inside the cell; usually at the centre of the cell. Nucleus is surrounded by a double membrane called nuclear membrane. A dot-like structure; called nucleolus is present inside the nucleus. Nucleus contains chromosomes which are thread-like structures. Genes are present on chromosome. They are responsible for transferring characters from parents to their offspring.

photosynthesis is a process by which green plants use sunlight to synthesize foods from carbon dioxide and water

Amoeba is a unicellular organism and is categorised under protozoa.Amoeba reproduces by binary fission by dividing its body into two parts.