<font color="#111111"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font face="Verdana, Arial, Helvetica, sans-serif"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font size="3"><font style="margin: 0px; padding: 0px; box-sizing: inherit;">Diffusion:</font></font></font></font></font></font>

<font color="#111111"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font face="Verdana, Arial, Helvetica, sans-serif"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font size="3"><font style="margin: 0px; padding: 0px; box-sizing: inherit;">Diffusion is nothing but the movement of molecules from it's higher concentration to loyer concentration.</font></font></font></font></font></font>

<font color="#111111"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font face="Verdana, Arial, Helvetica, sans-serif"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font size="3"><font style="margin: 0px; padding: 0px; box-sizing: inherit;">Or</font></font></font></font></font></font>

<font color="#111111"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font face="Verdana, Arial, Helvetica, sans-serif"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font size="3"><font style="margin: 0px; padding: 0px; box-sizing: inherit;">The sreading out and mixing of aone substance into another substance due to the motion of its particles is called diffusion.</font></font></font></font></font></font>

<font color="#111111"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font face="Verdana, Arial, Helvetica, sans-serif"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font size="3"><font style="margin: 0px; padding: 0px; box-sizing: inherit;">Brownian motion :</font></font></font></font></font></font>

<font color="#111111"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font face="Verdana, Arial, Helvetica, sans-serif"><font style="margin: 0px; padding: 0px; box-sizing: inherit;"><font size="3"><font style="margin: 0px; padding: 0px; box-sizing: inherit;">The zig-zag movement of small particles suspended in a liquid or a gads is called Brownian motion.Brownian motion tells us that the particles are tiny nature and the particles of a matter are constantly moving.</font></font></font></font></font></font>

The average speed of a body in a certain time interval is the distance covered by the body in that time interval divided by time. So if a particle covers a certain distance s in a time t1 to t2, then the average speed of the body is:

vav = s/t₂–t₁

In general, the average speed formula is:

Average Speed = Total Distance/Total Time

When an object is immersed in a liquid it experiences an upward force known as Buoyant Force.

Buoyancy

The upward force exerted by fluids (liquid and gas) on objects when they are immersed in them is called buoyant force and the phenomenon is called buoyancy.

 Now to keep the object immersed we have to apply external force from upward direction to overcome buoyant force.

In 1897, a British physicist, J. J. Thomson did a series of experiments, the conclusions of which led to a new atomic theory.

Thomson proposed a model of the atom that was like a watermelon.

In a watermelon there is a red edible part in which black seeds are embedded.

Thomson said that the atom is a spherical mass like the red part of the watermelon. This is the positively charged part of the atom.

He further compared the seeds embedded in the red part to negatively charged particles, which he called electrons.

He proposed that the positive and negative charges are equal in magnitude and so the atom as a whole is neutral.

The greatest contribution made by Thomson was the experimental proof for the existence of electrons, the negatively charged particles in the atom. For this discovery of electrons, Thomson was awarded the Nobel Prize in the year 1906.

But, his model could not explain the results of experiments carried out by other scientists like Rutherford and Bohr.

Division of labour refers to the method of organising production where the work required to produce a product is divided into different specialized tasks with different workers specializing in each task.
The four ways in which division of labour will influence production in an economy are as follows:
i. Quality of production improves - Division of labour leads to an increase in the efficiency of labour which further leads not only to an increase in the quantity of output but also to an improvement in the quality of the produced goods and services.
ii. Large scale production - Division of labour makes large scale production possible. Indeed, scale production requires division of labour. If a car manufacturing company, for instance wishes to make 10000 cars in a year but does not introduce division of labour in its factory, it will have to employ so many workers that it will not be an economically viable company. It is by virtue of division of labour that the company can produce 10000 cars per year with a reasonable number of workers.
iii. Reduced average cost - Since division of labour increases total output, even with an unchanged number of labourers, the average cost of producing a commodity falls. This is a social advantage. Society can produce goods by incurring lower average cost of production.
iv. Lower prices of output - The reduced average cost of the products leads to reduced prices of the outputs in the market. As a result, consumers are benefitted.

• In 1665, Robert Hooke first discovered and named the cells.
• Depending on the presence or absence of membrane bound cell organelles and nucleus, cells may be prokaryotic or eukaryotic.
• The three major functional regions of the cell are: plasma membrane, nucleus and cytoplasm.
• Plasma membrane is a thin, selectively permeable membrane, covering the cell and is made up of lipids and proteins.
• Plasma membrane separates the contents of a cell from its outside environment and regulates the flow of substances to and from the cell through diffusion, facilitated diffusion, active transport and endocytosis.
• Cells of Plants, fungi and bacteria contain both plasma membrane & cell wall.
• The nucleus of a dividing cell shows rod-shaped chromosomes, made up of DNA and proteins. In a non-dividing cell, the chromosomes elongate and take the form of thread-like structures called chromatin fibres.
• Cytoplasm is the fluid content of the cell, occurring between nucleus and plasma membrane. It stores several vital chemicals and is the site of certain important metabolic pathways. Several specialized cell organelles are present in the cytoplasm.
• The various cell organelles include endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, plastids, vacuoles and centrosome.
• Mitochondria are the ‘powerhouses of the cell’, as they provide energy for various metabolic activities.
• Plastids occur in most plant cells. They are of three types: Chromoplasts, chloroplasts and leucoplasts.
• Chromoplasts are coloured plastids (except green colour), chloroplasts are green coloured containing chlorophyll and carry out photosynthesis in plants. Leucoplasts are colourless plastids that store starch, oil and protein granules.
• The large central vacuole of mature plant cells provides turgidity to the cell and also stores important substances.
• Centrosome is found only in animal cells and consists of two centrioles. It helps in cell division.

The basic difference between uniform linear motion & uniform circular motion is. Uniform Linear Motion: Velocity is constant & thus it is a uniform motion. Acceleration is zero. Uniform Circular Motion: Velocity is not constant due to continuous change in Direction & thus it is not a uniform motion. An object is said to move in uniform linear motion , if it travels in straight line and covers equal distance in equal time interval. Uniform circular motion: 1. When a body moves in circular path with uniform speed , it's motion is called uniform circular motion.

ATP plays a critical role in the transport of macromolecules such as proteins and lipids into and out of the cell. The hydrolysis of ATP provides the required energy for active transport mechanisms to carry such molecules across a concentration gradient.

Plasmolysis is when plant cells lose water after being placed in a solution that has a higher concentration of solutes than the cell does. This is known as a hypertonic solution. This causes the protoplasm, all the material on the inside of the cell, to shrink away from the cell wall. Plasmolysis is the process where a cell's contents shrink away from the cell wall when placed in a hypertonic solution. An example is if red blood cells are placed in a strong salt solution. The process in which water moves out of the cell, and the cell membrane of a plant cell shrinks away from its cell wall, is called plasmolysis. If the external solution balances the osmotic pressure of the cytoplasm, it is said to be isotonic.

Plant cells have a cell wall, a large central vacuole, and plastids such as chloroplasts. The cell wall is a rigid layer that is found outside the cell membrane and surrounds the cell, providing structural support and protection. The central vacuole maintains turgor pressure against the cell wall. Cells carry out all the processes of the body including producing and storing energy, making proteins, replicating the DNA, and transportation of molecules through the body. Cells are highly specialized to carry out specific tasks.