Search Previous Year Questions

The correct answer is Typhoid.

Key Points

• Typhoid is a bacterial infection that can lead to a high fever, diarrhea, and vomiting and can be fatal.
• It is caused by the bacteria Salmonella typhi.
• Typhoid fever is a type of enteric fever, along with paratyphoid fever
• The infection is often passed on through contaminated food and drinking water.
• It is more prevalent in places where handwashing is less frequent.
• Typhoid fever is uncommon in the UK, with an estimated 500 cases occurring each year.
• Two typhoid vaccines are licensed for use for the prevention of typhoid: 
• Oral Ty21a vaccine  and the injectable typhoid polysaccharide vaccine

​ Additional Information

• Bacteria are found even inside the human body, on our skin, in our hairs, and on all other surfaces.
• Bacteria inside our gut or stomach are good bacteria and we must have them to lead a healthy life.

List of Bacterial Diseases in Humans

• Hepatitis A : 
• Hepatitis A is an inflammation of the liver caused by the hepatitis A virus (HAV).
• The virus is primarily spread when an uninfected person ingests food or water that is contaminated with the feces of an infected person.
• Measles :
• Measles is caused by morbillivirus, which is mostly seen in the winter and spring.
• It is a highly contagious illness caused by a virus that replicates in the nose and throat of an infected child or adult.
• it is spread through airborne droplets from an infected child.
• Polio :
• Polio is a disease caused by the poliovirus.
• ​The virus enters the body through the mouth or nose, getting into the digestive and respiratory systems.
• It multiplies in the throat and intestines.
• It can also attack the nervous system, the nerve network that helps the brain communicate with the rest of the body.
• It happens mostly in children younger than 5.
• The World Health Organization (WHO) continues to work to eliminate polio.

The correct answer is Vitamin K.

Key Points

• Vitamin K is a fat-soluble vitamin.
• Vitamin K is required for the liver to make factors that are necessary for blood clotting.
• Hemorrhage is a deficiency disease of Vitamin K.

Additional Information

• Vitamin C is essential for the healing of wounds, repair, and maintenance of cartilage, bone, and teeth.
• Ascorbic acid is the chemical name of vitamin C.
• Vitamin C is the first artificially synthesized vitamin.
• Vitamin A is also called Retinol.
• It helps for good vision and maintains healthy eyes.
• Xerophthalmia and night blindness are deficiency diseases of Vitamin A.
• Thiamine is the chemical name of VItamin B1.
• Vitamin B1 helps the body cells to convert carbohydrates into energy.

The correct answer is Option 4.

A normal adult has 32 teeth: incisors (8), Canines (4), premolars (8) and molars (12). Normal adult's 32 teeth is an upgrade form of a 20 piece "milk teeth" version.

The correct answer is Chitin.

Key Points

• The cell wall of fungi is made from a compound known as 'chitin'.
• The cell wall of plant cells is made from 'cellulose'.
• The cell wall is a tough, rigid layer that surrounds some types of cells.
• The cell wall is the very basic component of the cell of a plant, bacteria, fungi, etc.
• The cell wall is located just outside of the cell membrane.
• Protozoans and animal cells do not have a cell wall.

​

Additional Information

• Cellulose is a fibrous material of plant origin that can be obtained from the bark, wood, the leaves of plants, or other plant-based materials.
• The principal constituent of mucus is a mucopolysaccharide called mucin.
• Mucus is a protective substance that’s excreted from multiple areas of the body, such as the mouth, sinuses, throat, lungs, stomach, and intestines.
• Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria.

The correct answer is Cerebrospinal Fluid.

Key Points

Cerebrospinal fluid (CSF)

• Cerebrospinal fluid (CSF), clear, colorless liquid that fills and surrounds the brain and the spinal cord and provides a mechanical barrier against shock.
• Formed primarily in the ventricles of the brain, the cerebrospinal fluid supports the brain and provides lubrication between surrounding bones and the brain and spinal cord.
• The Choroid Plexus of the Brain secretes  Cerebrospinal Fluid.

Additional Information 

Formation of CSF

• Formed from the choroid plexus situated in the ventricles.
• The choroid plexus is the tuft of capillary projections presents inside the ventricle.
• The choroid plexus is covered by the pia matter and ependymal covering.
• The active transport mechanism is involved in the secretion of CSF.

Properties of CSF

• The volume is around 150 ml.
• Rate of formation around 0.3ml/minute.
• Specific gravity: 1.005
• The reaction is alkaline.

Absorption of CSF

• Mostly absorbed by the arachnoid villi into the dural sinus and spinal veins.
• 500ml of CSF is formed every day and an equal amount is absorbed.

The correct answer is Both chemical and physical change.

CONCEPT:

EXPLANATION:

• Burning a candle is both physical and chemical change.
• As the candle starts burning, the wax starts melting. This is a physical change.
• The melted wax vaporizes in the flame and the wax vapours burns and gets converted into carbon dioxide, soot etc. This is a chemical change.

The correct answer is Photosynthesis in plants.

Concept:

Chemical reaction:

• A process in which one or more substances, the reactants, are converted to one or more different substances, the products.
• Substances are either chemical elements or compounds.
• A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Explanation:

Endothermic reaction:

• A chemical reaction in which the reactants absorb energy and get converted into products.

Photosynthesis in plants: 

• It occurs in green plants in the presence of sunlight and chlorophyll.
• The reactants carbon dioxide and water are converted into glucose and oxygen.
• CO₂ + H₂O + Sunlight(Heat) → C₆H₁₂O₆ + O₂
• **_​**Solar energy is converted into chemical energy.
• Since energy is being consumed in photosynthesis, it is termed an endothermic reaction.

Additional Information​ 

Exothermic reaction:

• A chemical reaction in which heat energy is released.
• Examples: 
• Burning of natural gas
• Conversion of vegetable matter into compost
• ​Burning of magnesium ribbon in the air.

The answer is By Both.

Key Points Liquefaction of gases:

• Liquefaction of gases is the process in which a gas is liquified to change its state from gas to liquid.
• A gases can be liquified by increasing pressure and reducing the temperature.

1. Effect of pressure: When we increase the pressure, the gaseous molecule come close together.
2. Effect of Temperature: When we decrease the temperature, the kinetic energy of gaseous particles decreases and they become slower.

The pressure that has to be applied as well as the temperature depends on the molecular forces of the gas molecules. Hence, a gas can be liquified by cooling or by application of pressure, or by the combining effect of both.

Explanation:-

Both increasing the pressure and decreasing the temperature can convert a gas into a liquid, a process known as condensation. This is explained by the principles of the kinetic-molecular theory and phase transitions:

• By increasing the pressure, you effectively force the gas particles closer together.
• When they are close enough to establish attractive intermolecular forces, the gas condenses into a liquid. An everyday example of this principle are pressure cookers, which use high pressure to cook food quicker.
• By decreasing the temperature, you reduce the kinetic energy of the gas particles, which means they move around less vigorously.
• When their kinetic energy drops sufficiently, the forces of attraction between the particles overcome their kinetic energy, and they get closer together to form a liquid.
• Cooling steam is an example of this process.

So, it's accurate to say that you can convert a gas into a liquid by both increasing the pressure and decreasing the temperature. However, the specifics can depend on the particular substance under consideration and the conditions it's in.

Conclusion:-

So, A gas can be converted into a liquid by both,  increasing the pressure and decreasing the temperature

The correct answer is Melting of ice.

 Key Points

• The melting of ice is a physical change.
• The change that does not lead to changes in the chemical composition of a substance is termed physical change.
• Physical changes lead to changes in physical properties and are generally reversible in nature.
• Examples of physical changes are the melting of ice, transition into gas, textural changes, changes in size, shape, color, etc.

Additional Information

• In the case of the melting of ice, only a phase transition takes place, and the chemical composition of ice does not change.
• Chemical changes lead to the transformation in the chemical composition of the substance. Either a new substance is synthesized or a substance is decomposed.
• The setting of milk into curd, the ripening of fruits, and the fermentation of grapes all are examples of chemical changes since the chemical properties of each are changed.

Concept:

Metal:

• Some materials are hard, lustrous, malleable, ductile, sonorous and good conductors of heat and electricity.
• The materials which generally possess these properties are called metals.
• Examples of metals are iron, copper, aluminium, calcium, mercury, magnesium, etc.

Explanation:

Mercury:

• A high melting point and hardness characterise the majority of metals.
• This is due to the fact that they are happy to exchange valence electrons with nearby atoms.
• The chemical element mercury has the atomic number 80 and the symbol Hg.
• Mercury is the only metal which is found in a liquid state at room temperature.
• The reason is that mercury does a terrible job of sharing its valence electrons.

Thus, mercury remains liquid at room temperature.

Additional Information

Some other metals with characteristic exceptions: 

Sodium

• Metals like sodium and potassium are soft and can be cut with a knife.

Magnesium:

• The chemical element magnesium has the atomic number 12 and the symbol Mg.
• It is a solid that has a lustrous grey colour and many of the same physical and chemical characteristics as the other five alkaline earth metals.

Lithium:

• The chemical element lithium has the symbol Li and atomic number 3.
• Lithium is a soft, silvery-white alkali metal.
• It is the least dense metal and the most solid element under normal circumstances.