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.
The small intestine contains a number of receptive cells which detect the presence of macronutrients and secrete hormones which instructs the pancreas on how much insulin and glucagon to release.

Salts are the ionic compounds generally formed by neutralisation of an acid with base. They can be acidic, basic as well as neutral. Example acidic salts: sodium bicarbonate, basic salts: magnesium chloride, neutral salt: sodium chloride.

• A compound is a pure substance composed of two or more elements combined chemically in a fixed proportion by mass.

Rhizobium   is the nitrogen fixing bacteria present mainly in the soil. The Rhizobia chemically convert the nitrogen from the air to make it available for the plant.These bacteria live in symbiotic relationship with leguminous plants. The Rhizobia live in nodules in the roots of the plant. These bacteria convert atmospheric nitrogen to nitrates and nitrites which can be used by the plants directly. Nitrogen fertilizers are not required.

When an object changes its position with elapse of time in respect to a stationary object, such as a building, electric pole, etc., the object is said to be in motion.

Rectilinear Motion: Motion along a straight line is known as RECTILINEAR MOTION OR MOTION ALONG A STRAIGHT LINE. For example: Motion of a car along a straight line.

Curvilinear Motion: Motion along a curve line is known as CURVILINEAR MOTION. For example: Motion of car or any moving object along a curve line.

Circular Motion: Motion along a circle is known as CIRCULAR MOTION. For example: Motion of cyclist along a circular park.

• The highest temperature reached during a day is called the maximum temperature.
• The lowest temperature reached during a day is called the minimum temperature.

Air pressure or atmospheric pressure is the weight of air acting on a unit are of surface.Air exerts pressure in all directions.

Experiment to demonstrate Air pressure

Apparatus Required:Glass tumbler, water and card board.

Procedure :
Fill the glass tumbler completely with water.
Cover it with card board.
Note : There should not be air between water and card board.

Support the card board with you hand and invert the tumbler.Holding the glass tumbler gently, remove the hand.

Observation:
Cardboard does not fall because the air pressure is acting from all the direction.

The reaction of an acid with a base to give salt, water and heat is called neutralisation. 
Example: Hydrochloric Acid + Sodium Hydroxide → Sodium Chloride + Water + Heat
                HCl + NaOH → NaCl + H₂O + Heat
The heat evolved in the neutralisation reaction raises the temperature of the reaction mixture.
Example: During the mixing of dilute sulphuric acid with potassium hydroxide, the test tube heats up.

• The day to day condition of the atmosphere at a place and time with respect to the temperature, pressure, humidity, wind speed and wind direction, sunshine, clouds, rainfall etc. is called weather at that place.
• The highest temperature reached during a day is called the maximum temperature.
• The lowest temperature reached during a day is called the minimum temperature.
• Rainfall is measured by an instrument called the rain gauge.
• Humidity is defined as a measure of water vapour in air.

Steps Involved in Balancing a Chemical Equation:

Consider  the  chemical  reaction  between  magnesium  and  oxygen  to  understand  the  steps  involved  in balancing a chemical equation.

Step 1:

Let us first write the word equation for this reaction.

Magnesium + Oxygen → Magnesium oxide

Step 2:

Write the chemical equation for the reaction between magnesium and oxygen.

Mg + O₂ → MgO

Step 3:

Count the number of atoms of an element occurring on both L.H.S. and R.H.S. in this equation.

Mg + O₂ → MgO

Step 4:

To balance a chemical equation, first draw boxes around each formula. Do not change anything inside the boxes while balancing the equation. 

Choose  a  reactant  or  a  product which has  the  maximum  number  of  atoms  in  it. 

In that compound, select the element which has the maximum number of atoms. In this equation we shall select MgO i.e. magnesium oxide and the element oxygen in it.

To balance the oxygen atoms, let us multiply magnesium oxide molecule by 2 on the right hand side.

Step 5:

There  are  two  oxygen  atoms  on  either  side  of  the  equation  but  one  magnesium  atom  on  the  reactant's side and two on the product's side. Therefore, multiply the magnesium atom by 2 on the left hand side.

Therefore, the number of atoms of each element of reactants = The number of atoms of each element of products.

Step 6: Writing Specific Conditions on the Arrow

The reaction is carried out in the presence of ‘Heat’. On heating, magnesium combines with oxygen present in air to form magnesium oxide.

Step 7: Writing Symbols of Physical States

The various ways in which a chemical equation can be made more informative are : (i) By indicating the physical states of the reactants and products. Example: Solid state is indicated by the symbol (s).

(ii) By indicating the heat changes taking place in the reaction. For Example: An exothermic reaction is indicated by writing “+Heat” or “+Heat energy” or “+Energy” on the products side of an equation.

(iii) By indicating the “conditions” under which the reaction takes place.

Example: Delta stands for heat which is written on the arrow sign in the equation.

The structure used by amoeba to get food is Pseudopodia.

Explanation: The Pseudopodia is a vacuole. These vacuoles do not have any definite shape. Amoeba is an organism which is single celled and is seen at aquatic habitats. Pseudopodium is the structure utilized by amoebas to accumulate food for it. Pseudopodium is an extension from cytoplasm which is like a finger and encourages the movement in the organism which in turn aides in getting the food and engulfing it.

Calcium carbonate is one of the most popular chemicals which is first encountered in school classrooms, where the use of chalk (a form of CaCO₃) is found. It is found in the earth’s crust.  It is also found in many forms such as marble, limestone, etc.

A change can be defined as an alteration in the physical and chemical properties of matter due to the effect of some kind of energy. E.g. cooking, digestion of food.

How the ice is converted into water? did you got this doubt?

Here ice get energy from the surroundings and get converted into water. means here energy is involved in changing the state of ice to liquid.

You mom cook rice. where she cooks the rice on a stove. here stove supplies heat energy to for cooking.

From the above 2 examples you can understand that change involves energy.

• HCl makes the medium acidic so that digestive enzymes can perform their functions.
• Mainly protein digestion occurs in stomach.
• HCl also kills the bacteria that may have enter along with the food we eat.
• The digestive juices break down proteins into smaller substances.

Sandy soil is less fertile and it can be increased by adding humus to it in the form of manure.

Laterite soil is found in regions of high temperature and very high rainfall. The rains will wash all the nutrients from the soil, leaving it infertile. The leaching process will leave behind iron-rich soil, absent of silicon. The humus composition is also affected by bacteria and fungi that thrive in high temperatures.

Such soils are found in the hot and humid regions of Western Ghats, Eastern Ghats, Malwa Plateau, Tamil Nadu, Kerala etc.

Winds or wind currents are generated by two factors:

1. Uneven heating between Poles and Equator

• Centre of the earth is called Equator and the two extreme positions are Poles.
• Poles are cooler than equator as highest intensity of the sun’s heat and light falls on the equator and it reduces as we go either side of equator towards the poles.
• Cooler air from surrounding areas of the equator comes towards the equator to fill the place of warm air which rises up due to sun’s heating.
• Similarly, cooler air from poles comes towards the surrounding areas as the surrounding areas have air warmer than the poles.
• These winds from north to equator and south to equator are not straight as their direction change due to earth’s rotation on its axis.

1. Uneven heating between Land and Water

• This occurs in the coastal areas.
• Sea Breeze: This causes the wind to move from Sea towards Land and the process continues during the day. These are also called Monsoon winds.
• Land Breeze:This causes the wind to move from Land towards Sea and the process continues during the night.

A new quilt has air spaces between the layers of the woollen or cotton batting. These air spaces trap air and act as insulators. They do not allow the body heat to escape and keep us warm. When the quilt gets old, the layers of batting press against each other reducing the air spaces between them. Because of this, much air is not trapped and we do not feel warm as before.

Nutrition: The sum total of processes by which living organisms obtain food materials and prepare them for use in the growth, repair and providing energy is termed nutrition.
Nutrition is of two types: 1) Autotrophic nutrition, 2) Heterotrophic nutrition.
1) Autotrophic nutrition: The mode of nutrition in which an organism prepares its own food is called autotrophic nutrition. Mostly green plants have the ability to manufacture their own organic food due to the presence of chlorophyll. They take up CO₂ and H₂O and manufacture carbohydrates in the presence of sunlight process called as photosynthesis. Such organisms are called autotrophs and their mode of nutrition is called autotrophic.
2) Heterotrophic nutrition:  The mode of nutrition in which an organism takes food from another organism is called heterotrophic nutrition. In this type of nutrition, the animals derive organic food materials by consuming bodies or products of other living or dead plants or animals.

• Electromagnetic waves are nothing but changing magnetic and electric fields.
• Electromagnetic waves are solutions of Maxwell’s equations, which are the fundamental equations of electrodynamics. He described that the magnetic field can be produced by changing electric field.

Overcurrent or excess current is a situation where a larger than intended electric current exists through a conductor, leading to excessivegeneration of heat, and the risk of fire or damage to equipment. Possiblecauses for overcurrent include short circuits, excessive load, and incorrect design.