Gravitational potential at any point in a gravitational field is the work done in bringing a unit mass from infinity to that point. .Gravitational potential determines the direction of motion of a body in the gravitational field of another body. 

Gravitational potential energy of a particle at a point in a gravitational field due to a body is measured by the work done in moving the particle from infinity to that point. It is equal to the product of potential at the point due to the body and the mass of the particle.

We can say that gravitational potential at a point is equal to the potential energy of the unit mass kept at that point.

The conditions when average speed and average velocity will be equal are

1. When the distance and displacement of the particular object are equal or you can say that when the object is moving in a straight line, because when an object is moving in a straight line the distance and displacement are equal.

2. Either the speed or velocity should be constant during the motion of the object i.e in straight line.

Average velocity would be equal to average speed when the total distance travelled equals the net displacement of a particle. This happens when a particle moves along a straight line in a fixed direction.

When a battery lights a bulb, first energy transformation takes place in the battery and then in the bulb. In the battery, the chemical energy gets converted into electrical energy. In the bulb, the electrical energy from the bulb gets converted into heat energy and then into light energy.

The animal cells are grouped together to form animal tissues. These tissues vary in their structure, function, and origin.The animal tissues are divided into epithelial, connective, muscular and nervous tissues. 
 

Animal tissues are of four types, viz. epithelial tissue, connective tissue, muscular tissue and nervous tissue.

Epithelial Tissue:

The epithelial tissue forms the covering or lining of most of the organs. The cells of epithelial tissue are tightly packed and form a continuous sheet. There is small amount of cementing materials between the cells and no intercellular space is present. Permeability of the epithelial tissue plays a great role in exchange of materials among various organs it also plays an important role in osmoregulation. All epithelial tissues are separated by the underlying tissue by an extracellular fibrous basement membrane. 

Connective Tissue:

The cells of a connective tissue are loosely scattered in a matrix. The matrix can be a fluid, jelly like, dense or rigid. The nature of matrix depends on the function a connective tissue serves.

Muscular Tissue:

Muscular tissue is composed of muscle cells. Muscle cells are specialized cells which have the capability to contract and expand. Due to contraction and expansion, muscles facilitate various kinds of movements in the body.  

A liquid solution is a liquid in which a substance has been completely dissolved. The substance can be either solid, gas, or another liquid.

For instance, when you dissolve salt in water, the Sodium and Chlorine ions are completely separated, surrounded on all sides by water molecules.

Water and ethanol are both liquids at room temperature. When the two are mixed together we get a homogeneous mixture which is a solution of alcohol in water or even the other way round.

• Lysosomes are electron microscopic, vesicular structures of the cytoplasm, bounded by a single membrane (lipoproteinous) which are involved in intracellular digestive activities, contains hydrolytic enzymes, so called lysosomes.

• These were first discovered by a Belgian biochemist, Christian de Duve (1955) in the liver cells and were earlier named pericanalicular dense bodies

Electromagnetic radiation can be defined as a form of energy that is produced by the movement of electrically charged particles traveling through a matter or vacuum or by oscillating magnetic and electric disturbance. The magnetic and the electric fields come at 90° to each other and the combined waves move perpendicular to both electric and magnetic oscillating fields occurring the disturbance.

Given :

Initial odometer reading=2000km
Final odometer reading=2400km
Total distance= Final distance- Initial distance
=2400-200=400km
Total time=8h
Average speed =?

Formula to be used :
Average speed= Total Distance/Total time

Average speed in Km/hr:
Average speed=400/8
=50 km/hr

Average Speed in m/s:
1km/hr=5/18 m/s
∴50km/hr=50x5/18=250/18=13.88m/s

Initial odometer reading=2000km
Final odometer reading=2400km
Total distance= Final distance- Initial distance
=2400-200=400km
Total time=8h
Average speed =?

Formula to be used :
Average speed= Total Distance/Total time

Average speed in Km/hr:
Average speed=400/8
=50 km/hr

Average Speed in m/s:
1km/hr=5/18 m/s
∴50km/hr=50x5/18=250/18=13.88m/s

The amount of water required prepare 500 g of 2.5% solution of sugar is 487.5 g

Explanation:

Mass percent : It is defined as the mass of the given component present in the total mass of the compound.

Formula used :

Mass of solution  = 500 g

Mass of sugar  = ?

Mass of sugar = 12.5 g

Thus mass of water = mass of solution - mass of sugar = (500 - 12.5) g = 487.5 g

Mass of the solution = mass of solute + mass of solvent
Given that the mass percent of sodium sulphate solution is 20%.
Let the mass of sodium sulphate which is required to prepare this solution be x grams.
Given that the mass of water is 100 g.
So,
20 = [x/(x + 100)] * 100
20/100 = [x/x + 100]
1/5 = x/x + 100
x + 100/5 = x
x + 100 = 5x
5x - x = 100
4x = 100
x = 100/4
x = 25
Thus, 25g of sodium sulphate is required. 

Unicellular organisms refer to living entities that have only one cell, and the cell is responsible for performing all the functions. Some examples are amoeba, paramecium, bacteria, and cyanobacteria.

Unicellular organisms refer to living entities that have only one cell, and the cell is responsible for performing all the functions. Some examples are amoeba, paramecium, bacteria, and cyanobacteria.

When a few drops of ink is added to the water, it evenly spreads throughout the water, thereby turning it into a blue coloured solution.

This happens due to the principle of diffusion.

• According to the principle of diffusion, substances move from a region of higher concentration to a region of lower concentration.

• The ink starts diffusing in the water and continues until it reaches an equilibrium state with respect to the concentration of the solute( in this case, ink).

When drops of ink are added to water, the water molecules make random movement and collide with the ink molecules. Now, the ink molecules also make random movement and move from area of higher to lower concentration of molecules. Thus, it forms a colloidal solution of ink and water.

Temperature is the degree of heat of a person or an object. Celsius scale is commonly used to represent temperature scale. Originally centigrade is the name of the Celsius temperature scale and renamed after the Swedish astronomer Anders Celsius.

Schleiden (1838) and Schwann (1839) proposed the Cell Theory. Virchow (1855) made further addition to the cell theory.

HISTORY OF DISCOVERY OF CELLS

• Robert Hooke was the first to discover cell (1665).

• Leeuwenhoek was the first to discover free living cells in pond water (1674).

• Robert Brown discovered the nucleus (1831).

• Purkinje coined the term ‘protoplasm (1839).

• Schleiden (1838) and Schwann (1839) proposed the Cell Theory. Virchow (1855) made further addition to the cell theory.

• The discovery of electron microscope (1940) made it possible to study the structures of cell organelles.

The temperature remains constant because -

• The liquid water turns into gaseous vapour    during the boiling process. So,in this scenario,a change of the physical state is taking place.

• Now, for the above mentioned change of the physical state,a certain amount of energy is necessary which is known as the latent heat of evaporation.

• All the supplied heat during the boiling process is the latent heat of evaporation which is only capable to change the state of the substance. Changing the temperature of the substance is not a role of the latent heat of evaporation.

• That's why,the temperature remains constant throughout the whole boiling process.

The temperature of a substances remains constant during melting and boiling even when heat is being supplied to it continuously because the heat that is supplied is being used up in changing a state of matter by overcoming intermolecular force of attraction.This heat is known as latent heat of fusion for melting and latent heat of vaporisation for boiling.therefore the temperature remains same. 

Membrane biogenesis is a process in which number of proteins and lipids produced in the endoplasmic reticulum help in the synthesis of cell membrane in a cell.

Significance:-

Membrane biogenesis are most helpful in agricultural industries and the genetic engineering of plants and crops. Like if we know the pathway of membrane biogenesis we ca alter that pathway using genetic engineering and simultaneously altering the formation of membrane which can be useful in some situations. If we know the pathway we can inhibit that pathway to inhibit the membrane formation in a cell due to which they die simultaneously. this technique can be used for killing harmful or useless cells.

Membrane biogenesis is the process that involves cell membrane development with the aid of proteins and lipids. The production of these membranes is driven by the endoplasmic reticulum. Membranes synthesized by the membrane biogenesis process help to divide the cell into functional and structural compartments. Entire cell membranes are called endomembranes. The endomembrane network contains different membranes suspended in the cytoplasm and the plasma membrane.

The cytoskeleton is the network of fibres forming the eukaryotic cells, prokaryotic cells and archaeans. These fibres in the eukaryotic cells contain a complex mesh of protein filaments and motor proteins that help in cell movement.

It provides shape and support to the cell, organizes the organelles and facilitates transport of molecules, cell division and cell signalling.

Nucleus

• The nucleus is small, round and membrane bound structure found in cell.
• The fluid inside the nucleus surrounded by nuclear membrane is called nucleoplasm.
• It controls the cell’s growth and reproduction because it contains cell's hereditary information.
• It is covered by dual layer called nuclear membrane.
• The nuclear membrane contains pores due to which materials can travel both inside the nucleus from its outer surrounding i.e. cytoplasm.
• The nucleus contains some thread like structures called chromatin. It exists during the resting stage of cell.
• The chromatin contains DNA (Deoxy-ribo nucleic acid), RNA (Ribo Nucleic acid) and proteins.
• The nucleus contains some rod shaped structures in a cell that contains the hereditary information. They are called chromosome.
• They are formed when the chromatin condenses together when the cell is about to divide.
• Chromosomes contain DNA and nuclear proteins.
• They contain the hereditary information for inheritance of features from the parents to the offspring as DNA.
• The DNA molecules contain the information for construction and organization of cells. Genes are the functional segments of DNA.
• Human body has 23 pairs of *** chromosomes. A boy has one X chromosome and one Y chromosome whereas a girl has two X chromosomes.
• The nucleus of cell divides itself to give rise to new offsprings.

1. A multi-cellular organism is made up of many different types of cells. Each cell carries out a specific function. A group of cells that carries out a specific function is called a tissue.

2. Different tissues carry out different functions. This is called the division of labour. A tissue gives the highest possible efficiency of function in multi-cellular organisms.