Onboarding Pilot Course

Different Parts of a Dissecting Microscope:
There are four main parts of a dissecting microscope: the base, the arm, the head, and the stage. The base is the bottom part of the microscope that sits on your work surface.

It houses mechanical components, such as the focus knobs and stage clips. The arm is the part that attaches the head to the base. It contains the optics of the microscope, such as the lenses. The head is the part of the microscope that you look through.

It contains the eyepieces and the ocular lens. The stage is the platform where you place your specimen. It is usually made of glass and has a hole in the center so that light can pass through to the objective lens.

Furthermore, the stage is usually adjustable so that you can move the specimen around. This is important because it allows you to view different parts of the specimen.

A group of cells having common origin, similar structure and performing a definite function is called a tissue. Tissues are found in plants and animals. Plant tissues can be grouped into two basic types: meristematic and permanent tissues. Parenchyma and Sclerenchyma are permanenrt tissues. Animal tissues can be grouped into four basic types: epithelial, muscular, connective and nervous tissues. Different tissues have distinctive architecture best suited for what they do.

Mosquito Life Cycle
Although all mosquitoes need standing water to reproduce, in different environments, different types of mosquitoes are found. Some mosquitoes are considered to be floodwater species that reproduce in temporary water environments. While other species are considered to be permanent water mosquitoes and to reproduce in long-lasting water bodies. Other species have grown in such a particular way that only their eggs are laid in natural or artificial containers.

The mosquito life cycle will also determine “How many days mosquitoes live?”

All mosquitoes experience the same four-stage life cycle, no matter what their chosen breeding habitat:

Mosquito Eggs

The larval stage (Aquatic)

Pupal stage (Aquatic)

Adult Mosquitos

The life cycle of mosquito diagrams gives the pictorial representation of mosquito growth and development.

Let Us Discuss in Detail the Mosquito Life Cycle.
Mosquito Eggs

The female mosquito lays her eggs either individually or in attached groups called rafts, depending on the specific species.

Eggs are put either directly on the surface of still water, around its margins, in tree holes, or in other areas vulnerable to rain, irrigation, or flood flooding.

In some species, with the exact amount of time depending on temperature, the eggs may hatch within a few days of laying. But if the egg is laid out of the water and is subjected to occasional flooding, before the ideal natural hatching conditions are met, the embryo may lay dormant for several years.

Larval Stage:-
The larval stage starts once the egg hatches. As they need oxygen to breathe, the larvae of most mosquito species hang suspended from the water surface.

An air tube, called a syphon, travels to the water surface from the posterior of the larva and serves as a snorkel.

Filter larvae feed on aquatic microorganisms at the surface of the water. When frightened, the larvae will plunge deeper into the water as a defensive mechanism by swimming in a characteristic 'S' action, which has gained them the nickname 'wigglers' or 'wrigglers.'

Larvae outgrow their external covering and form a new exoskeleton as they eat, throwing off the old ones.

The phases are called instars between these moults. There are 4 instars in the larval process. The period of the larval stage varies from 4 to 14 days, varying according to the species, temperature of the water, and availability of food.

Pupal Stage:-
There is no feeding in the pupal process, but the pupa still has to breathe air on the surface of the water and is sensitive to light, shadows, and other disturbances.

Pupae are also physically active to escape to deeper water by rolling or tumbling action, which is why they are commonly referred to as tumblers.

The pupal stage lasts from 112 to 4 days, during which the skin of the pupa splits along the back, allowing the newly formed adult to emerge slowly and rest on the water surface.

Adult Mosquitos :-
Generally, the male adult mosquito will first emerge and linger near the breeding site, waiting for the females.

Due to high adult mortality rates, mating happens rapidly after emergence.

As much as 30% of the adult population can die on a daily basis.

By laying large numbers of eggs to assure the continuation of the species, the females compensate for this high rate.

On average, male mosquitoes live for only 6 or 7 days, feeding primarily on plant nectar and not taking blood meals.

Females with an adequate food supply can live up to 5 months or longer, with about 6 weeks being the average female life span.

In addition to plant nectar, the female usually has to take a blood meal to nourish and develop the eggs.

Female mosquitoes locate victims through the carbon dioxide and other trace chemicals exhaled and the temperature patterns they produce.

Mosquitoes are highly sensitive to carbon dioxide, amino acids, octanol, and several chemicals.

The average flight range of the female mosquito is between 1 and 10 miles, but some species can travel up to 40 miles before a blood meal is taken.

The female will oviposit (lay) its eggs after each blood meal, completing the life cycle. While some species oviposit only once, others in the course of their lives may lay eggs several times.

A small metallic bob suspended by a light inextensible string from a rigid support, such that it is free to oscillate without friction about a point, is called a simple pendulum.

Terms Related to Simple Pendulum:-
Mean Position: When a freely suspended pendulum is at rest, then this position of the bob is called mean position or rest position.
Extreme Position: The position of the bob at the maximum distance from the mean position is called extreme position. There are two extreme positions on either side of the mean position.
Length of the Pendulum: The distance between the point of suspension to the centre of gravity of the bob is called the length of the pendulum.
Oscillatory Motion: The bob of the pendulum moves to and fro along the same path and passes through the mean position. This type of motion is called oscillatory motion.
Oscillation: The complete to and fro motion of the pendulum constitutes one complete oscillation.
Amplitude: The maximum displacement of the pendulum, i.e., the displacement between the mean position and the extreme position, is called its amplitude.
Time Period: The time taken by an oscillating pendulum to make one complete oscillation is called its time period.
Frequency: The number of oscillations made by the pendulum in one second is called its frequency of oscillation. The unit for frequency in the SI system is the hertz (Hz).

Laws of Simple Pendulum:-
There are three laws that govern the time period of a simple pendulum.
1. The first law states that the period of oscillation of a simple pendulum of constant length is independent of its amplitude, provided the amplitude is small.
2. The second law states that the period of oscillation of a simple pendulum of constant length is independent of the size, shape, mass and material of the bob, provided it is not very light.
3. The third law states that the time period of oscillation of a simple pendulum is directly proportional to the square root of the length of the pendulum, for a given place.

An electromagnet is a temporary strong magnet made from a piece of soft iron when current flows in the coil wound around it. It is an artificial magnet.

The strength of magnetic field of an electromagnet depends on:-
Number of turns: The strength of magnetic increases on increasing the number of turns of the winding.
Current: The strength of magnetic field increases on increasing the current through the solenoid.

Newton’s Third Law of Motion states, “There is an equal and opposite reaction to every action.” Newton’s third law distinguishes between two sorts of forces: action forces and reaction forces. These two forces have the same magnitude but act in different directions.

Newton’s third is so clear and lovely that it has become commonplace in our language. As a result, there are several misunderstandings. Here are some key points about Third’s law of motion:

1. The phrase’s action and reaction used in the third law indicate nothing else except ‘force’. Using several names to describe the same physical notion caused some misunderstanding. As a result, the forces occur in pairs and are applied in opposite directions.
2. The phrases action and reaction in Newton’s third law may give the erroneous impression that action precedes response, i.e. the action is the cause and reaction is the effect. However, there is no cause-and-effect relationship. As a result, the forces imparted are instantaneous. According to the same logic, one of them may be termed action and the other response.
3. Different bodies are affected by action and reaction forces, but not the same body. Summing up the two forces and asserting that the net force is zero is a mistake.

In solid solutions, solute and solvent are in the solid-state. For example ceramics and polymer blends.
In liquid solutions, solid, gas or liquid is mixed in a liquid state.
Gaseous solutions are usually homogenous mixtures of gases like air.
Depending upon the number of solutions and solutes, it can be classified into dilute and concentrated solutions.

Different Types of Solutions
Depending upon the dissolution of the solute in the solvent, solutions can be categorized into supersaturated solution, unsaturated and saturated solutions.

A supersaturated solution comprises a large amount of solute at a temperature wherein it will be reduced, as a result the extra solute will crystallize quickly.
An unsaturated solution is a solution in which a solvent is capable of dissolving any more solute at a given temperature.
A saturated solution can be defined as a solution in which a solvent is not capable of dissolving any more solute at a given temperature.
The solutions are of two forms, depending on whether the solvent is water or not.

Aqueous solution – When a solute is dissolved in water the solution is called an aqueous solution. Eg, salt in water, sugar in water and copper sulfate in water.
Non-aqueous solution – When a solute is dissolved in a solvent other than water, it is called a non-aqueous solution. Eg, iodine in carbon tetrachloride, sulphur in carbon disulfide, phosphorus in ethyl alcohol.
Solutions are spoken of as having two components, the solvent and the solute. Another classification of the solution depends on the amount of solute added to the solvent.

A dilute solution contains a small amount of solute in a large amount of solvent.
A concentrated solution contains a large amount of solute dissolved in a small amount of solvent.

Boiling point:-
The temperature at which a liquid boils and turns to vapor i.e. changes its state at atmospheric pressure is called the boiling point of the liquid.
Boiling is a bulk phenomenon.
The boiling point of water is 100°C.
The boiling point of water varies with atmospheric pressure.

The melting point is defined as the temperature at which a substance changes from the solid state into the liquid state at atmospheric pressure.

The melting point of ice is 273 K (or zero degree Celsius).

When two or more elements or compounds mix together, not necessarily in a definite ratio and do not interact chemically, then the resulting substance is known as a mixture. The components of the mixture have their own physical properties. For example a mixture of sand and water maintains the properties of both sand water. There are two types of mixtures: Homogenous and Heterogeneous. A homogenous mixture is a type of mixture in which the components mixed are uniformly distributed throughout the mixture and heterogeneous mixture is a type of mixture in which all the components are unevenly mixed. In this section we shall learn about the separation of mixtures.
Methods of separation of mixtures:-
The process of separating the inorganic substances present in the mixture or the constituents of the mixture by physical methods is known as separation of mixtures.
1. Chromatography:-
Chromatography is a method used to separate the different components in a liquid mixture. This method is based on the different properties of compounds in two phases: stationary and mobile phase. Based on this, chromatography can be classified into:

Paper chromatography
Column chromatography
Thin layer chromatography
Gas chromatography
Example: Separation of colours in dye
2. Centrifugation:-
This method is used to separate out tiny solid particles that usually pass through a filter paper and hence the separation of these insoluble particles is carried out with the help of centrifugation. The centrifugation process is based on the shape and size of particles, viscosity of the medium and speed of rotation. With the help of this process we can separate butter from cream. We use an apparatus known as centrifuge and this contains a centrifuge tube holder which contains equal amount of solid-liquid mixture. On rotating the rotor, due to the centrifugal force the denser insoluble particles separate from the liquid and ends up at the bottom of the tube and the liquid gets collected at the top.

Sunlight is necessary for photosynthesis, the sun provides the initial energy that starts the cycle of photosynthesis The energy from the light causes a chemical reaction that breaks down the molecules of carbon dioxide and water and reorganizes them to make the sugar (glucose) and oxygen gas.

Photosynthesis:
Photosynthesis is the process of conversion of light energy (sunlight) into chemical energy (food) by using carbon dioxide, water and chlorophyll.
6 CO2 + 12 H2O → Glucose (C6H12O6) + 6 H2O + 6 O2
Oxygen is released from the plant as a by-product of photosynthesis.
Therefore, carbon dioxide is used as a raw material and gets utilized in the process.

Unicellular organisms, have relatively simple organisations. So, the asexual mode of reproduction is common in them. It is so because by asexual reproduction unicellular organisms can multiply very fast. In Amoeba it occurs by binary and in yeast by budding to be described first.
In the sexual reproduction, both male and female gametes have to fuse, while in asexual reproduction, cell division takes place.
Heterotrophic organisms (humans, animals and decomposers) can reproduce either asexually or sexually, e.g., in bacteria sexual reproduction occurs via conjugation and asexual reproduction occurs via binary fission.
Uninucleate organisms, like Ulva (algae) reproduce asexually by zoospores and sexually by the fusion of gametes.

The equivalent resistance is where the aggregate resistance connected either in parallel or series is calculated. Essentially, the circuit is designed either in Series or Parallel. Electrical resistance shows how much energy one needs when you move the charges/current through your devices. If you require lots of energy, then the resistance necessary is also high. The equivalent resistance of a network is that single resistor that could replace the entire network in such a way that for a certain applied voltage V you get the same current I as you were getting for a network.
Equivalent resistance formula for series resistance is given by,
Req=R1 ​ +R 2 ​ +… +R n

The equivalent resistance is where the aggregate resistance connected either in parallel or series is calculated. Essentially, the circuit is designed either in Series or Parallel. Electrical resistance shows how much energy one needs when you move the charges/current through your devices. If you require lots of energy, then the resistance necessary is also high. The equivalent resistance of a network is that single resistor that could replace the entire network in such a way that for a certain applied voltage V you get the same current I as you were getting for a network.

Equivalent resistance formula for parallel resistance is given by,
1/Req ​ = 1/R 1 ​ ​ + 1/R 2 ​ ​ +… + 1/R n

“Alcohols are a group of compounds containing one, two or more hydroxyl (-OH) groups that are attached to the alkane of a single bond. These compounds have a general formula -of ROH.”
The alcohols are converted to aldehydes and ketones by the process of oxidation.

Acids are chemical substances which are characterized by a sour taste in an aqueous medium. They have the tendency to turn blue litmus red. On the other hand, bases are chemical substances which are characterized by a bitter taste and are slippery to touch. Some bases are soluble in water, while others are not.

Water soluble bases are known as alkalis. They have the tendency to turn red litmus blue. Acids and bases react with a wide range of chemical compounds to form salts.

there is a device known as the pH meter, which is used to determine the pH level of a substance. This electronic device has a special electronic bulb that is sensitive to hydrogen ions. The ones that are present in the solution. The bulb produces a signal which is then amplified by and is shown in a meter format in the electronic meter attached. The meter displays the pH level and in which category does the substance belong. For very precise measurement, the pH meter should be calibrated before each measurement.

A soap is a water-soluble compound which is made via a process called saponification by the reaction between sodium hydroxide or potassium hydroxide with vegetable or animal oil (fats).
In the study of comparative cleaning capacity of soap in soft and hard water, H2O, in its normal form, sometimes fails to remove dirt and grime from the clothes even after several washes. This is because the dirt or stain present on the clothes has oil content or has a greasy nature. Soaps are one of the commonly used cleaning agents that are used for removing all types of stains and dirt. It reacts with water to extract the oil content and make the cloth clean. Soaps are either formed from animals or plants. They contain potassium salts of water-soluble sodium with higher fatty acids like palmitic acids, stearic acids, or oleic acids. Most fatty acids are available in oils and fats. When oil or fat is mixed alkali like caustic potash soap or caustic soda and glycerin, the cleaning abilities are developed.

Determining Soft Water

Soft water is free from harsh minerals that tend to damage our body and things on which it has been used. Soft water is gentle for our home and body. Soft water does not have much content like calcium and magnesium and, thus, helps in the prevention of scale buildup around the house, including pipelines and appliances. Soft water helps in increasing the effectiveness of soap when compared to hard water. Hard water has a higher chance of inactivating the cleaning quality of soap's ingredients. In terms of health, soft water helps in treating dryness and preventing stickiness caused by cool weather, hard water, and low humidity. Soft water ensures silkier & softer skin and hair after every wash.

Determining Hard Water

Hard water is water that is rich in magnesium and calcium contents. These are two naturally available minerals in the water. These two minerals are essential for health but not appreciable in terms of general water usage. Hardness in water can cause damage to your home. While using hard water for daily works, you can notice a film of residue on the dishes, or the formation of spots in shower or clothes. Sometimes it is possible to discover fine particles inside the appliances, especially when it comes to dishwasher or laundry machines. Heating hard water can leave deposits of calcium in the beaker. A daily accumulation of calcium deposits can damage the lifespan and performance of any appliance. To make it worse, the heating expenses will skyrocket, and the appliance's efficiencies will certainly plunge. Hardness in water also causes ill effects on personal hygiene. It may give you a feel of residual hair and skin after washing. This makes our skin and hair more dry and brittle.

Urine is produced by the kidney. It is a liquid waste that needs to be eliminated from the body. The kidneys eliminate the wastes from the bloodstream. In humans, urine is a yellowish liquid containing water and several other chemical components such as uric acid, urea, traces of enzymes, hormones, and carbohydrates.
Production of Urea:-
It is produced naturally by the body while the proteins are disintegrated during which amino groups are eliminated from the amino acids that are in the proteins. The eliminated amino groups are converted into extremely toxic ammonia and furthermore into urea by the liver. The urea moves into the kidneys, where it is finally eliminated from the body.

Detecting urea:-
For detection of urea in the urine sample, urease tests are performed. Urease is an enzyme that carries out the decomposition of urea into carbon dioxide and ammonia. Addition of an alkaline substance such as ammonium carbonate causes it to turn into an alkaline solution from slightly acidic urine.

Osmosis is the process in which solvent molecules moves through a semi-permeable membrane from a region of higher concentration to a region of lower concentration until the amount of fluid is equalised on both sides of the semipermeable membrane. The fluid that passes through the semipermeable membrane is known as the solvent, while the dissolved substance in the fluid is known as the solute. A solution that is separated from another solution by a semi-permeable membrane can have three osmotic states: isotonic, hypotonic and hypertonic. In an isotonic solution is the pressure at both sides of the membrane the same. A hypotonic solution has a lesser number of solute particles than the solution to which it is compared. A hypertonic solution has a higher number of solute particles. At equilibrium is a solution always isotonic.

This video explains how to study osmosis using a potato osmometer.

Chromatography is used to separate mixtures of substances into their components. All forms of chromatography work on the same principle. They all have a stationary phase (a solid, or a liquid supported on a solid) and a mobile phase (a liquid or a gas). The mobile phase flows through the stationary phase and carries the components of the mixture with it. Different components travel at different rates.

In paper chromatography, the stationary phase is a very uniform absorbent paper. The mobile phase is a suitable liquid solvent or mixture of solvents.

Detection of Sulphur in an Organic Compound :-
Sulphur is a non – metallic chemical element with the symbol ‘S’. It is present in many orgnic compounds like thiol, carbon disulphide etc. The antibiotics penicillin and the artificial sweetener saccharin etc are also sulphur containing organic compounds. Upon fusion with sodium metal, the sulphur atom in the organic compound is converted to ionic sodium sulphide, which can be extracted by boiling the fused mass with distilled water and is used for the detection of sulphur.

Vernier Calipers :-
The Vernier Caliper is a precision instrument that can be used to measure internal and external distances extremely accurately. The Vernier Caliper consists of a main scale fitted with a jaw at one end. Another jaw, containing the vernier scale, moves over the main scale. When the two jaws are in contact, the zero of the main scale and the zero of the Vernier scale should coincide. If both the zeros do not coincide, there will be a positive or negative zero error.

Screw Gauge :-
The micrometer screw gauge is used to measure even smaller dimensions. The micrometer screw gauge also uses an auxiliary scale (measuring hundredths of a millimetre) which is marked on a rotary thimble. Basically it is a screw with an accurately constant pitch (the amount by which the thimble moves forward or backward for one complete revolution). The thimble passes through a frame that carries a millimetre scale. The jaws can be adjusted by rotating the thimble using the small ratchet knob. In order to measure an object, the object is placed between the jaws and the thimble is rotated using the ratchet until the object is secured.

Surface Tension :-
Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible. Surface tension allows insects (e.g. water striders), usually denser than water, to float and stride on a water surface.

At liquid-air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). The net effect is an inward force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. Thus, the surface becomes under tension from the imbalanced forces, which is called Surface tension. Surface tension has the dimension of force per unit length, or of energy per unit area. Because of the relatively high attraction of water molecules for each other through a web of hydrogen bonds, water has a higher surface tension (72.8 millinewtons per meter at 20 °C) compared to that of most other liquids. Surface tension is an important factor in the phenomenon of capillarity.

Boyle's Law :-
Gases have various properties which we can observe with our senses, including the gas pressure, temperature, mass, and the volume which contains the gas. Scientific observation has determined that these variables are related to one another, and the values of these properties determine the state of the gas.

In the mid 1600's, Robert Boyle studied the relationship between the pressure p and the volume V of a confined gas held at a constant temperature. Boyle observed that the product of the pressure and volume are observed to be nearly constant. The product of pressure and volume is exactly a constant for an ideal gas.

p * V = constant

This relationship between pressure and volume is called Boyle's Law .

Melting Point of an Organic Compound :-
A pure, nonionic, crystalline organic compound usually has a sharp and characteristic melting C range). A mixture of very small amounts of miscible impurities will produce apoint (usually 0.5-1.0 depression of the melting point and an increase in the melting point range. Consequently, the melting point of a compound is a criterion for purity as well as for identification. The melting point of an organic solid can be determined by introducing a tiny amount into a small capillary tube, attaching this to the stem of a thermometer centered in a heating bath, heating the bath slowly, and observing the temperatures at which melting begins and is complete.

Basic Laboratory Techniques :-
Laboratory experiment is an important part in chemistry which required a good observation and utilization of right laboratory technique. In a chemical laboratory we carry out some simple operations like bending or cutting a glass tube, boring a cork and studying the complex process of analyzing substances qualitatively and quantitatively.

Water covers about three-quarters of the earth's surface and it is essential for all known forms of life. Water is a habitat for a variety of plants and animals which have special adaptations to survive in their habitats. Some of the characteristics that control the quality of water are the turbidity of water, pH of water and different types of plants and animals and their density.

Turbidity is the measure of the relative clarity of a liquid. Turbidity of the water body determines the depth to which light can penetrate and thus affects the distribution and photosynthesis of phytoplankton and macrophytes. The pH is a measure of the relative amount of free hydrogen and hydroxyl ions in an aqueous solution. Solutions with a pH less than 7 are said to be acidic and with a pH greater than 7 are basic. The pH of pure water is 7 at 25°C. A productive water body has high nutrient concentrations, and has a very high density of phytoplankton per unit area. These water bodies have high amounts of nutrients and dissolved oxygen and bear large number of organisms at different trophic levels. The status of health of a water body can be determined by analyzing water samples for the number and type of organisms present in it at a given time.