The substances that taste bitter are called base and their nature is basic. They are slippery to touch. Example: baking soda containing sodium hydrogen carbonate, Milk of magnesia, Soaps, Lime water containing calcium hydroxide, Household cleaners.

The definition of sour is something with an acidic taste, or someone who is resentful or angry. Milk that has gone bad is an example of something that would be described as sour. The unsweetened juice of a lemon is an example of something that would be described as sour. A person with a grumpy and rude personality who is angry all the time is an example of someone who would be described as having a sour personality.

Autotrophic nutrition is that mode of nutrition in which an organism makes its own food from the simple inorganic materials like carbon dioxide and water present in the surroundings (with the help of sunlight energy).
Example: Green plants obtain food by autotrophic nutrition.

Carbon and energy requirements of the autotrophic organism are fulfilled by photosynthesis. The process by which green plants make their own food (like glucose) from carbon dioxide and water by using sunlight energy in the presence of chlorophyll is called photosynthesis.

The raw materials for photosynthesis are carbon dioxide and water. The green plants take carbon dioxide from air for photosynthesis. The carbon dioxide gas enters the leaves of the plants through the stomata present on their surface. The water required by the plants for photosynthesis is absorbed by the roots of the plants from the soil through the process of osmosis. The water absorbed by the roots is transported upwards through the xylem vessels to the leaves where it reaches the photosynthetic cells and utilized in photosynthesis.

The conditions for photosynthesis are sunlight, chlorophyll, carbon dioxide and water.

Factors affecting the rate of photosynthesis are (i) Light (ii) Carbon dioxide (iii) Water (iv) Temperature (v) Mineral elements.

The process of photosynthesis takes place in the green leaves of a plant. The carbon dioxide gas required for making food is taken by the plant leaves from the air which enters the leaves through tiny pores called stomata. Water required for making food is taken from the soil which is transported to the leaves from the soil through the roots and the stem. The sunlight provides energy required to carry out the chemical reactions involved in the preparation of food. The green pigment called chlorophyll absorbs sunlight energy.

Electrical symbols are required to do the electrical drawing and without the help of electrical symbols, we won't be able to do the electrical drawing. Electrical circuits are represented by electrical drawings. Symbols and number combinations are used to represent electrical circuits. An electronic symbol is a pictogram used to represent various electrical and electronic devices or functions, such as wires, batteries, resistors, and transistors, in a schematic diagram of an electrical or electronic circuit.

Structure of Cyclone The structure of cyclone contains:

• Eye – Low pressure and area of sinking air. Its diameter ranges from 10-100 kms.
• Eye Wall – Dense cloud surrounding eye having maximum wind speed. It causes maximum destruction.

Spiral rain bands – Band of clouds spiraling into eye wall and it contains heavy rains

Monsoons always blow from cold to warm regions. The summer monsoon and the winter monsoon determine the climate for most of India and Southeast Asia. The summer monsoon is associated with heavy rainfall. It usually happens between April and September. India actually has two monsoons –- the southwest monsoon and the northeast monsoon. The southwest monsoon, which is the main monsoon, comes in from the sea and starts making its way up India's west coast in early June. By mid-July, most of the country is covered in rain.

• Do not lie on the ground or take shelter under an isolated tree.
• If you are in water, move out of it.
• Do not take shelter under an umbrella with a metallic rod.

Acrylic is a strong, lightweight and warm synthetic fibre that resembles wool. It is available in a number of colours and is more durable and affordable than natural wool.

Quartz is a compound called silicon dioxide. A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time, this crystal oscillator creates a signal with very precise frequency , so that the quartz clocks are at least an order of magnitude more accurate than mechanical clocks.The first quartz clock was built in 1927 by Warren Marrison and J.W. Horton at Bell Telephone Laboratories

Dilute acids contain a large amount of water. A concentrated acid can be diluted with the addition of water.

A dilute acid is that in which the concentration of the water mixed in the acid is higher than the concentration of the acid itself. For instance, 5% sulfuric acid is a dilute acid.

The inner walls of the stomach and small intestine and the various glands  such secrete  digestive juices as salivary glands, various other glands and liver and pancreas. Salivary glands secrete salivary amylase enzyme. The liver is essentially an exocrine gland, secreting bile into the intestine. But, the liver is also an endocrine gland and a blood filter. The liver has a diversity of functions not typically associated with glands. The liver is a metabolic factory, synthesizing and breaking down a variety of substances. The pancreas is a glandular organ in the digestive system and endocrine system of vertebrates. In humans, it is located in the abdominal cavity behind the stomach. It is an endocrine gland producing several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide which circulate in the blood. 

Atom is the basic unit of matter. It constitutes the smallest particle of an element. In 1808, John Dalton proposed the Atomic theory which states that: Matter is made up of tiny particles called atoms. Atoms are indivisible and cannot be created or destroyed.

Protein rich food such as mixture of corn, pulses, jowar and oil cakes should be given to the sheep for good growth of curly and shiny hair.

 Because black colour absorbs heat and gets really hot when sunlight hits it which helps it in cook the food better.

Quantities that can be measured such as length, weight, time, temperature, speed,etc. are called physical quantities.

The blue litmus paper turns red in acidic solution whereas the red litmus paper remains unaffected. The red litmus paper turns blue in basic solution whereas the blue litmus paper will remain unaffected. When both the papers remain unaffected, the solution is said to be neutral.

The digestive system is the parts of the body that digest food; it is also called the gastrointestinal system. It breaks down food into simple chemicals that can be absorbed into the blood stream. From the blood stream, nutrients go first to the liver, which is a kind of chemical factory for the body.

1. Autotrophs or Autotrophic: - Plants that have chlorophyll trap the energy from the sun and prepare their own food. Such nutrition wherein the food is prepared by the organisms itself is called autotrophic nutrition. The organisms capable of preparing their own food are called autotrophs. All green plants are Autotrophs (Auto means self and trophos means nourishment). They prepare their own food by a process called photosynthesis.
2. Heterotrophs or heterophobic: - Heterotrophic organisms are those who obtain food from other organisms. Since these organisms depend on other organisms for their food, they are called consumers. All animals and non-green plants like fungi come under this category.Organisms that follow the heterotrophic mode of nutrition are called heterotrophs.

Those non-green plants which obtain their food (or nutrition) from dead and decaying organic matter are called saprophytes. The non-green plants called fungi derive their food from dead and decaying organic matter, so fungi are saprophytes. Some of the common fungi are mushroom, bread mould and yeast.

Rotatory motion is the motion that occurs when a body rotates on its own axis.  A few examples of the rotatory motion are as follows:

• The motion of the earth about its own axis around the sun is an example of rotary motion.
• While driving a car, the motion of wheels and the steering wheel about its own axis is an example of rotatory motion.