Question – 02
A. Describe different methods to estimate the age of the Universe.
Answer:
Universe
The totality of everything that exists or has existed both in space and time,
including all matter and energy, planets, stars, and galaxies, is known as the
Universe.
Methods to measure
the age of the universe
There are two methods scientists rely on for calculating the age of the
universe which are the following
1- Calculating the expansion rate of the universe:
According to scientists, the universe is approximately 14 billion years old. It
is the age of the universe that is estimated from the big bang. According
to this method, we assume that the universe is expanding at a constant rate by
using Hubble’s constant (Ho).
Hubble noted that the distance of a galaxy is directly proportional to its
speed, and means. The further the galaxy was, it was moving away.
d=vt
t=d/v
where, v= Hod
t=d/ Hod
t=1/H
Hence, scientists
were able to use the Hubble constant to estimate the age of the universe by
working backwards to Big Bang.
2- By determining the age of the oldest universe:
Scientists determine the age of the universe from the following
✔ Spectrum:
The star’s spectrum helps determine the age of stars because blue stars tend to
die faster than red stars.
✔ Luminosity:
A brighter star will exhaust its energy faster than a less bright star.
Therefore, the star with less luminous intensity exists for a longer time than
with a more luminous intensity
✔ Mass:
The amount of a star’s mass also helps in finding the life of a star. If a star
is dense, it tends to die quickly as compared to a less dense star. Thus, the
density factor also helps calculate a star’s life.
✔ Motion/Speed:
The brighter star tends to have more energy; in turn, its speed will be greater
than the comparatively less luminous star. Eventually, the brighter star will
consume its energy quickly and die before the other less bright star, thus,
will have a short life and vice versa.
B. Explain the formation of the Lunar Eclipse.
Answer:
Eclipse:
The eclipse means the obscuring of one astronomical object by another.
Lunar eclipse formation:
Lunar eclipse means obscuring the moon from the Sun’s light by the Earth’s
interaction between the Sun and the moon. In other words, when Earth comes
between the Sun and the moon and casts the shadow across the lunar surface.
This situation is called a lunar eclipse. It’s a common phenomenon, and about
three lunar eclipses occur yearly.
Types of lunar eclipse:
1- Complete lunar eclipse
When the entire moon comes under the Umbra part of the shadow, it is called a
complete lunar eclipse. It happens when it is a full moon, and the Sun, Earth,
and Moon are aligned in a straight line.
2- Partial lunar eclipse
When the moon passes through the part of the Earth’s Umbra region, it is called
a partial lunar eclipse. It occurs due to the imperfect alignment of the Sun,
Earth, and moon.
3- Penumbral lunar eclipse
When the moon travels through the Earth’s penumbra, it is called a penumbral
lunar eclipse. It also occurs due to the imperfect alignment of the Sun, Earth,
and moon.
C. Explain the terms Dark Energy and Dark Matter.
Answer:
Dark Matter:
Dark matter comprises particles that do not reflect, absorb, or emit light.
Thus, they cannot be detected by observing electromagnetic radiations. It is a
material that cannot be seen directly. It is a mysterious and invisible
substance. We believe it exists because of its effects on the objects.
Moreover, the force of dark matter is always attractive. It attracts all the
particles even though light cannot move out of them. Astronomers believe that
dark matter exists because visible matter does not have enough gravitational
muster to hold galaxies together. The composition of dark matter is:
super-dense astronomical bodies called massive astrophysical compact halo
objects (MACHOs) and weakly interacting massive particles (WIMPs).
For example:
Neutron stars
Black holes
Dark energy:
Dark energy is the energy that helps in the expansion of the universe. In fact,
in 1998, astronomers studying distant supernovae were shocked to learn that the
universe began expanding faster around 7.5 billion years after the Big Bang.
That indicates some unknown force is fighting gravity’s pull, causing galaxies
to speed apart from one another. Dark energy is a repulsive force. It is the
opposite of dark matter. Dark energy repels the objects, due to which things
move far away from each other.
For example:
Phantom dark energy, where not only is expansion accelerating, but the
acceleration is also increasing over time-the Big Rip, where expansion becomes
infinitely fast, tearing galaxies, atoms and the fabric of space-time itself
apart.
D. Define the term Black Hole. What’s expected inside it?
Answer
Black Hole:
A black hole is a cosmic body in the centre of almost every galaxy in the
universe, including the Milky Way galaxy in which our solar system exists.
Examples:
Sagittarius A* is a supermassive black hole that exists at the centre of the
Milky Way Galaxy.
Formation of Black Hole:
A black hole is formed by the death of extremely massive stars with more than
three solar masses. At the end of a massive star’s life, the core of the star
becomes highly unstable and is collapsed. The crushing weight of constituent
matter falling in from all sides compresses the dying star to a point of zero
volume and infinite density called the singularity.
What is expected
inside the black hole?
The black hole is called a black hole because the gravity and density inside
the black hole are so strong that it attracts everything coming toward it, even
the electromagnetic radiation cannot escape. Hence, the black hole cannot be
observed directly. However, it can be observed by its gravitational influence
on nearby matter. The boundary of black holes is called the event horizon.
Question – 03
A. Describe different causes and preventions of ‘Polio’
Answer:
Polio:
Polio is the inflammation of the grey matter in the spinal cord. It is an
infectious viral disease. It can cause paralyze in the severe condition.
Mechanism:
A virus called poliovirus causes polio.
Causes:
✔ Person-to-person contact
✔ Oral route(Infected Phlegm from the nose or mouth )
✔ The faecal route, any contact with the infected faeces of the
individual
✔ Excessive use of intramuscular injections.
✔ No proper past vaccination in childhood.
Preventions:
✔ There’s no cure for polio, but the vaccines like inactivated
poliovirus vaccine (IPV) and Oral poliovirus vaccine (OPV) allow your body to
fight off the virus.
✔ The other prevention for polio includes ensuring hygiene and
encouraging good sanitation practices
✔ Further, contact with the infected person should be avoided.
B. Define the term ‘Bio-Fuel’. How is it helpful to promote clean energy??
Answer:
Definition:
Biofuel is considered to be the purest and the easiest available fuel on the
planet. It is also known as agro-fuel. They may be in solid, liquid, and
gaseous forms derived from biomass.
For example:
Biodiesel is an alternative fuel for diesel engines that is produced by
chemically reacting a vegetable oil or animal fat with an alcohol, such as
methanol and ethanol.
Bio-fuel and clean
energy:
Biofuels are very helpful in the production of pollution-free energy. It is
because, ethanol-a biofuel- can produce 48 % less carbon dioxide content than
conventional gasoline. Carbon dioxide is the major contributor to pollution.
Hence, biofuels are very helpful in reducing air pollution. Moreover, the
production of biofuels is environmentally friendly. Therefore, it does not play
a role in global warming. The reason is that it does not produce greenhouse
gases: carbon dioxide, nitrogen- chlorofluorocarbon, methane etc. in addition
to it, the agricultural waste can easily be managed, which is responsible for
the production of methane gas. Thus, biofuels play a crucial role in
pollution-free energy.
C. Define ‘Carbohydrates’. Describe different steps to digest these in the human body.
Answer:
Carbohydrates:
Carbohydrate is derived from the two words: carbo means carbon, and hydrate
means hydrogen. Hence, carbohydrates contain water and hydrogen. They are also
called ‘sugars’. They are the most abundant molecules on the surface of the
earth.
Their empirical formula is Cx (H2O)y
Formation:
Moreover, they are prepared by the photosynthesis process in plants.
Carbon dioxide+water+sunlight -> Glucose+Oxygen
The process is taken
place in the presence of sunlight and chlorophyll. Glucose is obtained as a
byproduct. It is further polymerized to form starch and cellulose.
Steps to digest the carbohydrates in the human body:
Carbohydrates start to digest as they enter the mouth.
✔ Mouth
In the first step, in the oral cavity, the salivary glands are
present that produce saliva. It provides moisturization to food particles.
Saliva releases an enzyme amylase that acts on the carbohydrates-sugars- and
starts to break them down.
✔ Stomach:
In the second step, the food particles enter the stomach, and
stomach walls produce enzymes and dilute HCL to kill bacteria in the food.
✔ Small gut:
In the third, these particles enter the duodenum of the small
intestine. It activates the pancreas for the secretion of pancreatic amylase
that breakdown the chime into maltose. From here, lactase, maltase, and sucrose
form on the walls of the small intestine. These enzymes further break down the
sugars into monosaccharides or most uncomplicated sugars. The insulin hormone
released from the pancreas that breakdown the larger sugar molecules into
glucose and allow it to use as energy for the body.
✔ Colon:
In the fourth step, the breakdown material passes to the colon.
Here, further digestion is taken place by the secretion of intestinal bacteria.
Fibres are present in carbohydrates that are not soluble. Hence, they release
from the body through the bladder.
D. Describe the ‘Cell Structure. Write down at least three differences between an animal cell and a plant cell.
Answer:
Cell:
The cell is the basic structural and functional unit of life. Millions of cells
are present in the human body. The size of cells is very, thus, cannot be seen
through the naked eye. Instead, microscopes are used to see them. Robert Hook
discovered the partition in 1665.
Cell structure:
1. Cell Membrane:
The outermost layer of the animal cell and the second most outer layer of the plant
cells is called the cell membrane. The major components of the cell membrane
are carbohydrates, phospholipids, proteins, and other lipids such as
cholesterol. Together these components make up the fluid mosaic model. In plant
cells, different cell wall is present outside the cell membrane.
2. Cytoplasm:
In addition to it, cells have cytoplasm. It is fluid-like material that is
present between the cell membrane and Nucleus. All the cell organelles: Endoplasmic
Reticulum-detoxifying the harmful bacteria that enter through food along
with the preparation of protein, Ribosomes-helping in the digestion of
food, Golgi bodies-preparing the protein into the final product and
sending it to where it is needed, Mitochondria-providing energy to the
body, plastids-assisting in the photosynthesis process, Vacuoles-acting
as storehouses of water and other metabolic products, etc., are located within
the cytoplasm, each having its distinct composition for the particular
function.
3. Nucleus:
The other major component of the cells is Nucleus, being in the centre of
animal cells and at the side of the plant cells. The Nucleus of the cell consists
of the nuclear membrane, nucleolus, nucleoplasm, and chromosome that carries
the genetic information in DNA, a part of the Nucleus.
|
Features |
Plant cells |
Animal cells |
|
Nucleus |
The nucleus is present near the cell membrane |
The nucleus is in the centre of the cell |
|
Vacuole |
They have a relatively large vacuole |
They have a relatively small vacuole |
|
Cell Wall |
They have a cell wall |
They do not have cell walls |
|
Centrioles |
They do not have centrioles |
They have centrioles |
Question – 04
A. What is ‘Acid Rain’ Describe its causes and how it can be prevented?
Answer:
Acid Rain:
When the PH of the rainwater is less than 5.6, such
rainwater is called acid rain. The PH decreases because when the
rainwater passes through the atmosphere it reacts with the oxides of nitrates
and sulphate. It forms sulfuric and nitric acid, as a result.
Causes:
The causes of acid rain are given below.
1. Sulphur dioxide is released from natural disasters, especially from volcanic
eruptions, industries, and transportation.
2. Oxides of nitrogen are released from transportation, fertilizers, and
pesticides.
3. Oil refineries and power plants of fossil fuels also cause the emission of
oxides of sulfur and nitrogen.
Reactions:
Preventions:
✔ The mode of transportation should be replaced. Use public
transport instead of private transport. It is preferable to walk.
✔ The use of energy-efficient appliances, such as air conditioners
must be reduced.
✔ Non-renewable energy should be replaced by renewable energy
resources.
✔ The use of fossil fuels must be limited.
✔ Devices like scrubbers must be used to chemically remove SO2
from the gases leaving the smoke stack to use as a raw material.
B. What is ‘Water Pollution’ Discuss its causes and measurement methods. Name the countries with the highest and lowest percentage of it.
Answer:
Water Pollution
Any change in the physical and chemical properties of water that make it
unsuitable to drink and for the use of other purposes.
Causes of Water Pollution:
1. Physical Pollutants:
Physical change in water occurs due to harmful secretion of the products
from industries, municipal etc.
2. Agricultural Pollutants:
The products used in the agricultural sectors like fertilizers and pesticides
release many harmful chemicals. These chemicals are added to the water and used
by humans.
3. Hospital Pollutants:
The waste released from the hospitals like syringes, bottles, wrappers etc.
Such waste causes water pollution.
Measurement of Water Pollution:
Water pollution is particularly measured by
✔ Measuring physical factors oxygen, pH, temperature, salinity and
nutrients (nitrogen and phosphorus) can help indicate the quality of water.
✔ Measuring toxicants such as insecticides, herbicides, and metals
also help provide information on what is impacting the system.
✔ Biological indicators-measures of macro-invertebrate or fish
diversity, benthic algal growth, and benthic oxygen demand- are direct measures
of the health of the fauna and flora in the waterway.
Countries with Highest and Lowest Water Pollution:
✔ India is the country having the highest water pollution.
✔ Sweden is the country that has the lowest water pollution.
C. Write a comprehensive note on Smog?
Answer:
Define:
Smog is the combination of smoke and fog. It is air pollution that reduces
visibility.
Composition:
Fog is the cloud of droplets that are present near the surface of the earth.
The visibility in fog reduces by 1 km. It is high in density and contains large
numbers of droplets. But, these droplets are smaller in size. On the other
side, smoke contains pollutants. These pollutants come from industries,
fertilizers, pesticides, transport etc. The contaminants are NOx, SOx, CO, and
CO2. But, the main components of smoke are particulate matter-dust particles-
and ground-level ozone. Smog forms when the sunlight and its heat react with
pollutants in the atmosphere. These pollutants come from many sources. It forms
smog.
Causes of Smog:
✔ Overpopulation is a significant cause of smog. More usage of
agricultural products, industries, and transport increases pollution.
✔ Fireworks also increase the level of air pollutants in the
atmosphere. On Diwali, the big cities have a high level of smog.
✔ The use of coal as a fuel has become a prominent contributor to
the smog.
Effects of Smog:
✔ The pollutants present in the smog enter the human body through
inhalation. It causes bronchitis, lung cancer, and other respiratory disorder.
✔ The pollutants in the smog also cause skin cancer, skin rashes,
and redness of the skin can occur.
✔ Road accidents increase because the visibility sometimes decreases
by 1km.
Preventions of Smog:
Preventive measures should be taken to avoid the harmful effects of smog.
First, wearing a mask is the best to prevent the inhalation of smog pollutants
into the body. Moreover, staying at home is the best solution to prevent road
accidents.
D. Describe different causes of ‘Tsunami’. Is there any difference between a Tsunami and a tidal wave? Name the worst Tsunami ever recorded.
Answer:
Tsunami:
A series of waves that are produced due to the sudden disturbance under the
water’s surface is called a tsunami. These waves are harbour waves. These are
also called seismic sea waves.
Causes of Tsunami:
✔ Undersea Quakes:
Almost 80 per cent of Tsunamis are produced due to abrupt disturbances under
the ocean sometimes by the earthquake. It is the process, in which the tectonic
plates slide over the other plates beneath them. Due to it, these plates sink
into the earth’s mantle. As a result, harbour waves produce and lead to
tsunamis.
✔ Volcanoes:
Sometimes, tsunamis are caused by volcanic eruptions since the volcanic
eruption, on the one hand, is responsible for raising the earth’s temperature
and on the other hand for the movement of tectonic plates.
✔ Asteroids Crashing into Ocean:
It is a very rare case when these harbour waves produce due to the striking of
meteorite with the oceanic surface.
✔ Undersea landslide:
When the land under the ocean slides the way it does above- at the earth’s
surface- it causes irregular horrible changes in the movement of water leading
to tsunamis.
It is observed that an earthquake on the Richter scale greater than 7.0 can
cause a disastrous and horrible tsunami.
Difference between tsunami and tidal waves:
|
Tsunami |
Tidal waves |
|
These waves produce only due to geographical events: earthquakes,
volcanoes etc. |
These waves produce only due to the gravitational pull of the
moon and sun. |
|
Tsunamis only occur under the oceanic surface |
Tidal waves occur in rivers, lakes, and other water bodies. |
|
The blow of air across the surface of the ocean does not cause a
tsunami. |
A blow of air can cause the production of tidal waves often
called wind waves. |
The worst tsunami
ever recorded:
The worst tsunami was recorded in Indian ocean-Sumatra, Indonesia in 2004.
300,000 people died in this disaster.
Question – 05
A. Write a note, on how data is stored on a ‘Hard Disk’?
Answer:
Hard Disk:
A hard disk is a device used to store data permanently. It is a magnetic
storage medium. The data can be read and written on it. A hard disk is also
called a hard drive, fixed drive, and hard disk drive. A hard disk can store
data in trillions of bytes.
Data stores on hard
disk:
A hard disk is a disk that can store data even when no electrical power is
supplied to it. The magnetic property of a hard disk enables it to store data. In
computers, binary language is used: 0 or 1. A hard disk consists of a circular
disk called a platter. It is made up of Aluminium that is coated with nickel,
cobalt, and platinum. It becomes a magnet. Over it, the coating of carbon is
made to make the surface of the disk smooth to avoid the deterioration of the
data.
The platter is
divided into many small circular sectors. These areas are to specify where to
store the data. Moreover, there is an arm like the read and write head, which
remains on the platter but does not touch it. The distance between the platter
and head is in nanometers. It is to prevent scratches on the platter. The
sectors on the platter give information about their storage capacity. The more
circular sectors the more capacity to store data. To read and write the data of
the whole platter the upper and below heads are placed. Electromagnet generates
a magnetic field and through the coil, the impulse of electric current is
received. This magnetic property helps hard disks store data.
B. How an ‘Optical Fiber’ is constructed? How is it helpful in transmitting electromagnetic radiations?
Answer:
Define:
Fibre optics is a bundle of thin strands made of glass or plastic, which uses
light (photon particles) to transmit signals. Therefore, the transmission
capacity of fibre optic is far greater than other modes of communication, such
as copper wire and metallic wires. As a result, it is used in the form of
different cables and is being utilized in numerous fields of life.
The basic structure
of Optical Fibers:
✔ Optical fibre consists of four layers
✔ Core made up of glass
✔ Cladding is a reflective layer made up of glass or plastic
✔ Coating cover as a protective layer
✔ Jacket to bundle all fibres in one cable.
Types of Optical
Fiber:
There are many types of optical fibres. However, the most significant types are
1. Single-mode Optical Fiber:
A fibre that is designed to carry a single signal at a time
2. Multi-mode Optical Fiber:
A fibre that is designed to carry more than one signal at a time
Working of Optical
Fiber:
The propagation of light in an optical fibre requires that light should be
totally confined within the fibre and not escape from it. This can be done by
1. Total internal reflection
2. Continuous Refraction
In a fibre-optic system, a machine called a transmitter turns information into
the light. Then the transmitter sends the light through optical fibres. As the
light moves at a high speed through the core, it bounces off the cladding
either by the phenomenon of total internal reflection or continuous refraction.
If the fibre has a bend in it, the light can bounce off the cladding and turn
the corner to follow the bend. At the end of the fibres, a machine called a
receiver accepts the light. The receiver turns the light back into sound,
pictures, or computer codes.
C. Write a comprehensive note on ‘Balanced Diet’
Answer:
Balanced Diet:
A daily intake of food by humans is called a diet. The essential nutrients that
are very necessary to our body are proteins, carbohydrates, vitamins, minerals,
lipids, and dietary fibers. These nutrients are very important to maintain the
health of the human body. If these nutrients are taken in a proper and adequate
amount, the diet is called a balanced diet.
Components of a
Balanced Diet:
The main components of a balanced diet are given below.
1. Vitamins:
Vitamins are the organic compounds that are essential for the proper growth of
the body. They are required in very small amounts. In addition to it, they
increase the absorption of essential nutrients into the body and play role in
the production of blood cells and Deoxyribonucleic acid (DNA).
2. Proteins:
Proteins are of prime importance in a balanced diet. They play a crucial role
in making protoplasm in cells and are also responsible for the production of
enzymes, hormones, and antibodies. Furthermore, proteins are very essential for
pregnant women to maintain the growth of their children.
3. Lipids:
The major constituents of lipids are fatty acids, glycerol, and sterol. Lipids
are insoluble in water and soluble in organic compounds. They are a very good
source of energy and are very essential for the formation of brain cells, and
cell membranes. Moreover, lipids produce steroids.
4. Carbohydrates:
Carbohydrates are the most abundant biomolecule on the surface of the earth.
They are the primary source of energy. Glucose is added into the bloodstream.
From here, it provides energy to the body. The major resources of carbohydrates
are cereals, grains, vegetables, and dairy products.
5. Minerals:
Minerals are essential to our body. These are not prepared by our bodies.
Hence, there is a need for the daily intake of minerals to maintain the proper
growth of the body.
Importance of a
balanced diet:
The following are the importance of a balanced diet:
✔ A well-balanced diet also ensures protects the body against
different non-communicable diseases, such as heart diseases, stroke, cancer,
and diabetes.
✔ It helps in the proper growth of the body.
✔ It increases the capacity to work.
✔ A well-balanced diet also helps reduce weight.
✔ A balanced diet increases the ability to fight or resist diseases.
✔ The deficiency of diet can cause many disorders; for example, the
deficiency of vitamins can cause scurvy, Rickets, etc.
✔ Likewise, the excess of some nutrients does more damage to the
body than good; for example, excessive lipids can lead to various storage
diseases like Gaucher disease, Sphingo-myelinase deficiency, Niemann-Pick
disease (NPD), etc.
D. What is ‘Artificial Intelligence? How is it helpful for humanity?
Answer:
Definition:
It is the study of intelligent machines capable of performing the same kinds of
functions that characterize human thoughts.
Discovery:
The term Artificial Intelligence was coined by John McCarthy in 1956 at the
Dartmouth conference, Massachusetts Institute of Technology (MIT).
Example:
WABOT-2, a robot developed by Wasefa University in Japan in the 1980s, utilized
AI programs to play keyboard instruments, read sheet music, and converse
rudimentarily with people.
Two subsets under
the term AI:
✔ Machine Learning
✔ Deep Learning
Uses of AI:
Financial institutions, scientists, psychologists, medical practitioners,
design engineers, planning authorities, and security services use AI in their
processes.
Advantages of AI:
✔ In playing games:
AI shows its intelligence in games such as chess and poker etc… In these games,
AI can suggest the probability of taking the next winning step.
✔ Natural Language Processing:
Programming natural language in computers enables computers to understand any
human language. It is only possible by AI.
✔ Expert Systems:
There is some software that is introduced for security purposes. For example,
this software only recognizes the correct user and opens the password for face
recognition, fingerprint recognition, etc. It is highly appreciable. Moreover,
medical apps have been introduced where doctors’ services can be obtained by
sitting at home.
✔ Recognition through speech:
AI has also played its role in recognition of voice. Only that person can
unlock his mobile, door, and other devices that have set this setting.
✔ Robotic technology:
Robots have been made for the services of humanity. They can perform the same
functions as humans can do. Therefore, robots have reduced the intensity of
work for humans
✔ Google:
Google is also an example of AI. People can search for anything on the search
engine just by typing. Google also displays the suggestions on the bar so
people can easily search for their desired data.
