Test: Science and Technology- 1 Free Online Test 2026

Genetically modified crops (GM crops) are plants used in agriculture, the DNA of which has been modified using genetic engineering techniques. In the late 1990s, German scientists developed a genetically modified and biofortified crop variety of rice called Golden Rice.
The Golden rice was created by transforming rice with two beta-carotene biosynthesis genes:

• psy (phytoene synthase) from daffodil ('Narcissus pseudonarcissus'), which is a variety of maize.

Hence statement 1 is not correct.

• crtI (phytoene desaturase) from the soil bacterium Erwinia uredovora.

Thus, genetic modification of the rice resulted into in the greatest accumulation of total carotenoids and beta‐carotene which is collectively termed provitamin A. Therefore, golden rice is rich source of Vitamin A. It will help to fight against Vitamin A deficiency, which is the leading cause of blindness among children and can also lead to death due to infectious diseases such as measles.

Hence statement 2 is correct.
Indian government has not allowed any GM crops for the consumption. For the time being, Bt cotton is the only genetically modified crop that is under cultivation in India. It is Philippines government that approved Golden Rice for direct use 2019. Currently, Bangladesh government is thinking about approving the cultivation of golden rice.

Hence statement 3 is not correct.

What is 3D Bioprinting?

• 3D Bioprinting is a form of additive manufacturing that uses cells and other biocompatible materials as ―inks‖, also known as bioinks, to print living structures layer-by-layer which mimic the behavior of natural living systems. Hence both statements are correct.
• Bioprinted structures, such as an organ-on-a-chip, can be used to study functions of a human body outside the body (in vitro), in 3D. The geometry of a 3D bioprinted structure is more similar to that of a naturally occurring biological system than an in vitro study performed in 2D and can be more biologically relevant. It‘s used most commonly in the fields of tissue engineering and bioengineering, and materials science. 3D bioprinting is also increasingly used for pharmaceutical development and drug validation, and in the future will be used for medical applications in clinical settings – 3D printed skin grafts, bone grafts, implants, biomedical devices, and even full 3d printed organs are all active topics of bioprinting research.

How does 3D bioprinting work?

• 3D bioprinting starts with a model of a structure, which is recreated layer-by-layer out of a bio-ink either mixed with living cells or seeded with cells after the print is complete. These starting models can come from anywhere – a CT or MRI scan, a computer-generated design (CAD) program, or a file downloaded from the internet.
• That 3D model file is then fed into a slicer – a specialized kind of computer program which analyzes the geometry of the model and generates a series of thin layers, or slices, which form the shape of the original model when stacked vertically. Cura and slic3r are examples of slicers commonly used in 3D printing. Allevi also has a specialized slicer, optimized specifically for bioprinting, built into our Allevi Bioprint software.
• Once a model is sliced, the slices are transformed into path data, stored as a g-code file, which can be sent to a 3D bioprinter for printing. The bioprinter follows instructions in the g-code file in order, including instructions to control for temperature of the extruders, extrusion pressure, bed plate temperature, crosslinking intensity and frequency, and, of course, the 3D movement path generated by the slicer. Once all of the g-code commands are completed, the print is done and can be cultured or seeded with cells as part of a biostudy.

The p-Block Elements comprise those belonging to Group 13 to 18 and these together with the s-Block Elements are called the Representative Elements or Main Group Elements.
At the end of each period in a periodic table is a noble gas element with a closed valence shell. All the orbitals in the valence shell of the noble gases are completely filled by electrons and it is very difficult to alter this stable arrangement by the addition or removal of electrons. The noble gases thus exhibit very low chemical reactivity.
Noble gases have uses that are derived from their other chemical properties. The very low boiling points and melting points of the noble gases make them useful in the study of matter at extremely low temperatures. Therefore often used for specific industrial processes.

• The low solubility of helium in fluids leads to its admixture with oxygen for breathing by deep-sea divers: because helium does not dissolve in the blood, it does not form bubbles upon decompression (as nitrogen does, leading to the condition known as decompression sickness, or the bends).
• Xenon has been used as an anesthetic; although it is costly, it is non-flammable and readily eliminated from the body.
• Radon is highly radioactive; its only uses have been those that exploit this property (e.g., radiation therapy). (Oganesson is also radioactive, but, since only a few atoms of this element have thus far been observed, its physical and chemical properties cannot be documented.).
• Krypton is used in fluorescent bulbs, flashbulbs, and lasers. Lamps filled with krypton are used at some airports as approach lights since their light can penetrate dense fog unusually well.
• Neon is also used as fog lights. Hence option (d) is the correct answer.

Chloroplasts: They are green-colored plastids, which comprise green-colored pigments within the plant
cell and are called chlorophyll. Hence, statement 1 is correct.
Chloroplast is an organelle that contains the photosynthetic pigment chlorophyll that captures sunlight and
converts it into useful energy, thereby, releasing oxygen from water.
Chloroplasts are found in all green plants and algae. They are the food producers of plants. These are found in the guard cells located in the leaves of the plants. They contain a high concentration of chlorophyll that traps sunlight. This cell organelle is not present in animal cells. Hence, statement 2 is correct.
Chloroplast has its own DNA and can reproduce independently, from the rest of the cell. They also produce amino acids and lipids required for the production of chloroplast membrane.
Functions of Chloroplast: Following are the important chloroplast function:

• The most important function of the chloroplast is to synthesize food by the process of photosynthesis.
• Absorbs light energy and converts it into chemical energy.
• Chloroplast has a structure called chlorophyll which functions by trapping the solar energy and used for the synthesis of food in all green plants.
• Produces NADPH and molecular oxygen (O2) by photolysis of water.
• Produces ATP – Adenosine triphosphate by the process of photosynthesis.
• The carbon dioxide (CO2) obtained from the air is used to generate carbon and sugar during the Calvin Cycle or dark reaction of photosynthesis.
• Where does the photosynthesis process occur in the plant cell?
• In all green plants, photosynthesis takes place within the thylakoid membrane of the Chloroplast.
   

Statement 1 is correct: A fuel cell uses the chemical energy of hydrogen or other fuels to cleanly  and efficiently produce electricity. 
Statement 2 is not correct: They can provide power for systems as large as a utility power station  and as small as a laptop computer.

Convention on International Liability for Damage Caused by Space Objects

1. This convention is one of the several international agreements that complement the Outer Space Treaty, the overarching framework guiding the behaviour of countries in space.
2. The Liability Convention came into force in 1972 and deals mainly with damage caused by space objects to other space assets, but it also applies to damage caused by falling objects on earth. Hence, Statement 1 is not correct.
3. The Convention makes the launching country “absolutely liable” to pay compensation for any  damage caused by its space object on the earth or to a flight in air. Hence, Statement 2 is  correct.

 The country where the junk falls can stake a claim for compensation if it has been damaged by the falling object.
 The amount of compensation is to be decided “in accordance with international law and  the principles of justice and equity”.

• This provision of the Convention has resulted in compensation payment only once so far — when Canada sought damages from the then Soviet Union, for a satellite with radioactive substance that fell into an uninhabited region in its northern territory in 1978. The Soviet Union is reported to have paid 3 million Canadian dollars. Hence, Statement 3 is not correct.

Named after two scientists, Lee and Kim, and the year of its discovery — 1999 — LK-99 is a 
compound which is a room-temperature superconductor working at ambient pressure.

Intermolecular forces tend to keep the molecules together but the thermal energy of the molecules tends to keep them apart. Three states of matter are the result of a balance between intermolecular forces and the thermal energy of the molecules. Hence the correct option is (c)
When molecular interactions are very weak, molecules do not cling together to make liquid or solid unless thermal energy is reduced by lowering the temperature.
Gases do not liquify on compression-only, although molecules come very close to each other and intermolecular forces operate to the maximum. However, when the thermal energy of molecules is reduced by lowering the temperature; the gases can be very easily liquified.

A nuclear reactor coolant is a coolant in a nuclear reactor used to remove heat from the nuclear reactor core and transfer it to electrical generators and the environment. Frequently, a chain of two coolant loops is used because the primary coolant loop takes on short-term radioactivity from the reactor. Hence statement 1 is correct.

Molten salts share with metals the advantage of low vapour pressure even at high temperatures, and are less chemically reactive than sodium. Salts containing light elements like FLiBe {a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2)} can also provide moderation. In the Molten Salt Reactor Experiment, it served as a solvent carrying nuclear fuel.

Gases have also been used as a coolant. Helium is extremely inert both chemically and with respect to nuclear reactions but has a low heat capacity. But India‘s first Prototype Fast Breeder Reactor which will be commissioned in December 2021 at Kalpakkam marking the second of the three-stage nuclear power programme will use liquid sodium as a coolant. Hence statement 2 is not correct.

Aqua regia, (Latin for 'royal water') is a freshly prepared mixture of concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1. Hence statement 1 is correct.

It can dissolve gold, even though neither of these acids can do so alone. Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that are able to dissolve gold and platinum. Hence statement 2 is correct.

Reverse Osmosis is a technology that is used to remove a large majority of contaminants from water by pushing the water under pressure through a semi-permeable membrane.

Total Dissolved Solids (TDS) in water are some organic and inorganic materials, which include minerals and ions that are dissolved in a particular quantity in water. When water passes through stones, pipes or different surfaces, the particles are absorbed into the water. TDS in water can come from different sources such as minerals in chemicals used for treating water, runoff from the road salts and chemicals or fertilizers from the farms.

Water that has a TDS level of more than 1000mg/L is unfit for consumption. A high level of TDS in water can lead to a number of health problems. The presence of potassium, sodium, chlorides increases the TDS level in the water. However, the presence of toxic ions such as lead, nitrate, cadmium, and arsenic present in water can lead to a number of serious health problems. This is especially important for children because they are much more sensitive to contaminants because their defence systems have not fully developed. Hence statement 1 is correct.

Several types of devices are used to improve the aesthetic qualities of drinking water and to remove chemicals. Activated carbon filters are the most common, they are more effective in removing organic chemicals. They are often used to improve taste, smell and appearance. Hence statement 2 is not correct.

The desalinated water that is demineralized or deionized, is called permeate (or product) water. The water stream that carries the concentrated contaminants that did not pass through the RO membrane is called the reject (or concentrate) stream.

Statement 1 is not correct: Homo indicates the genus of human beings.

Statement 2 is correct: Human beings belong to the species sapiens.

Statement 3 is correct: All human beings belong to kingdom Animalia. All animals belonging to various phyla are assigned to the highest category called Kingdom Animalia in the classification system of animals.

Lamarckism (or Lamarckian inheritance) is the idea that an organism can pass one characteristic that it acquired during its lifetime to its offspring (also known as the inheritance of acquired character). Hence, statement 1 is correct.
Lamarck incorporated the following two ideas into his theory of evolution:

• Use and disuse of organs- Individuals lose characteristics which they do not require (or use) and develop characteristics which they do not require (or use) and develop characteristics that are useful. Hence, statement 2 is correct.
• Inheritance acquired traits- Individuals inherit the traits of their ancestors. Darwin's theory (Natural selection) has been supported by a lot of evidence. Lamarck's Theory of Inheritance of Acquired Characteristics has been disproved. This was done in two major ways. The first is by experiment. We have seen through many real examples and observations that changes that occur in an animal during life are not passed on to the animal's offspring. If a dog's ears are cropped short, its puppies are stillborn with long ears. If someone exercises every day, runs marathons, eats well, and is generally very healthy, the fitness is not passed on and the person's children still have to work just as hard to get that fit and healthy. These and other examples show that Lamarck's theory does not explain how life formed and became the way it is. Hence, statement 3 is not correct.

The term  ̳black hole‘ was coined in the mid-1960s by American physicist John Archibald Wheeler. Blackhole refers to a point in space where the matter is so compressed as to create a gravity field from which even light cannot escape.

Black-holes were theorized by Albert Einstein in 1915. There is a region of space beyond the black hole
called the event horizon. Hence statement 2 is correct.

This is a "point of no return", beyond which it is impossible to escape the gravitational effects of the
black hole.

Black holes have an intense gravitational field near them because of the large amount of mass they have
which is concentrated in a very small volume. Hence statement 1 is correct.

If one defines the density of a black hole as the ratio of its mass to its volume, then the density decreases
as the size of the black hole increases. So the ―density‖ would depend on the size of the black hole. The
―density‖ of black holes left behind by stellar death is much, much higher than that of the earth.

Stars end their lives in two different ways:

• those will mass around the mass of the Sun will end their lives in a gentle way, becoming a planetary nebula and leaving behind a remnant called "white dwarf".
• Stars much more massive than the Sun explode as a supernova leaving behind either a "neutron star" or a "black hole".

So the Sun will never burst and will not become a black hole. Hence statement 3 is not correct.
 

• Statement 1 is not correct: SMRs are advanced nuclear reactors that have a power capacity of up  to 300 MW(e) per unit, which is about one-third of the generating capacity of traditional nuclear  power reactors.
• Statement 2 is not correct: SMRs are based on nuclear reaction technology, which will come under  the provisions of Atomic Energy Act, 1962.

All three statements are correct:

•  Aditya-L1 is the first space-based Indian observatory to study the Sun. It will be launched by  the PSLV-C57.
• The solar mission will not see the spacecraft actually go to the sun, it will instead create a space  observatory at a point from which the sun can be observed even during an eclipse.
• The spacecraft is planned to be placed in a halo orbit around the Lagrange point 1 (L1), around  1.5 million km from the Earth, of the Sun-Earth system.
• A satellite placed in the halo orbit around the L1 point has the major advantage of  continuously viewing the Sun without any occultation/eclipses. This will provide a greater  advantage of observing the solar activities and its effect on space weather in real time.
• It is equipped with seven payloads (instruments) on board with four of them carrying out  remote sensing of the Sun and three of them carrying in-situ observation.
• The mission will focus on study of the Solar upper atmospheric (chromosphere and corona)  dynamics. It will also study the chromospheric and coronal heating, physics of the partially  ionized plasma, initiation of the coronal mass ejections, and flares

None of the pairs are correctly matched.

•  Nebulae are enormous clouds of gas and dust in interstellar space.
•  Transients refer to astronomical phenomena with durations of fractions of a second to weeks  or years. Typically they are extreme, short-lived events associated with the total or partial destruction of an astrophysical object.
• A supernova is the colossal explosion of a star.  It happens when a star has reached the end of  its life and explodes in a brilliant burst of light

The xylem and the phloem make up the vascular tissue of a plant and transports water, sugars, and other important substances around a plant. What is commonly referred to as  ̳sap‘ is indeed the substances that are being transported around a plant by its xylem and phloem.

Phloem and xylem are closely associated and are usually found right next to one another. One xylem and one phloem are known as a  ̳vascular bundle‘ and most plants have multiple vascular bundles running the length of their leaves, stems, and roots.

Xylem tissue is used mostly for transporting water from roots to stems and leaves but also transports other dissolved compounds. Phloem is responsible for transporting food produced from photosynthesis from leaves to non-photosynthesizing parts of a plant such as roots and stems. Phloem

• The phloem carries important sugars, organic compounds, and minerals around a plant. Sap within the phloem simply travels by diffusion between cells and works its way from leaves down to the roots with help from gravity. The phloem is made from cells called  ̳sieve-tube members‘ and  ̳companion cells‘. Hence, statement 1 is not correct.

Xylem

• The xylem is responsible for keeping a plant hydrated. Xylem sap travels upwards and has to overcome serious gravitational forces to deliver water to a plant‘s upper extremities, especially in tall trees. Hence, statement 2 is not correct.

What is DNA? DNA, or deoxyribonucleic acid, is the fundamental building block for an individual's entire genetic makeup. It is a component of virtually every cell in the human body. Further, a person's DNA is the same in every cell. For example, the DNA in a man's blood is the same as the DNA in his skin cells, semen, and saliva.

DNA is a powerful tool because each person's DNA is different from every other individual's, except for identical twins. Because of that difference, DNA collected from a crime scene can either link a suspect to the evidence or eliminate a suspect, similar to the use of fingerprints. It also can identify a victim through DNA from relatives, even when nobody can be found. And when evidence from one crime scene is compared with evidence from another, those crime scenes can be linked to the same perpetrator locally, statewide, and across the Nation.

Where is DNA contained in the Human body?
DNA is contained in blood, semen, skin cells, tissue, organs, muscle, brain cells, bone, teeth, hair, saliva, mucus, perspiration, fingernails, urine, feces, etc. Hence option (d) is the correct answer.

 Both the statements are not correct.

•  India’s first 3D printed Post Office was inaugurated in Bengaluru’s Cambridge Layout.
•  3D Printing is a process that uses computer-created design to make three-dimensional objects  layer by layer.
• 3D Printing was invented in the 1980s by Charles W. Hull. 
• 3D printers construct the desired object by using a layering method, opposite of the subtractive  manufacturing processes. 

 Here layers of a material like plastic, composites or bio-materials are built up to construct  objects that range in shape, size, rigidity and color

Statements 1 and 2 are not correct.

• Tritium (T) is a hydrogen atom that has two neutrons in the nucleus and one proton. 
• It is produced naturally in the upper atmosphere when cosmic rays strike nitrogen molecules  in the air. It is also produced during nuclear weapons explosions, and as a byproduct in nuclear reactors.
• Tritium is a radiogenic and radioactive isotope of hydrogen with a half-life of 12.3 years. 

Hence, Statement 3 is correct.

India has consciously proceeded to explore the possibility of tapping nuclear energy for the purpose of
power generation. As result, India has planned three stage nuclear programme.

• STAGE 1 : Pressurised Heavy Water Reactor (PHWR) Pressurised Heavy Water Reactor using Natural UO2 as fuel matrix to produce electricity while generating plutonium-239 as by-product. Heavy water as moderator and coolant India achieved complete self- reliance in this technology and this stage of the programme is in the industrial domain
• STAGE 2 (FBR): Fast Breeder Reactor is India‘s second stage of nuclear power generation. FBR is a nuclear reactor that uses fast neutron to generate more nuclear fuels than they consume while generating power.

In the second stage, it envisages the use of Pu-239 obtained from the first stage reactor operation. As the fuel core in FBR, a blanket of U-238 surrounding the fuel core will undergo nuclear transmutation to produce fresh Pu239 as more and more Pu-239 is consumed during the operation.

Besides a blanket of Th-232 around the FBR core also undergoes neutron capture reactions leading to the formation of U-233. U-233 is the nuclear reactor fuel for the third stage of India‘s Nuclear Power Programme. FBR is known as fast breeder because it doesn‘t use moderator while liquid sodium is used as coolant. India‘s first Prototype Fast Breeder Reactor is a 500 MWe fast breeder nuclear reactor presently being constructed at the Madras Atomic Power Station in Kalpakkam (Tamil Nadu).

• STAGE 3: (Breeder Reactor). A Stage III reactor or an Advanced nuclear power system involves a self-sustaining series of thorium-232-uranium-233 fuelled reactors. U-233, obtained from second stage will be used as fuel in nuclear reactor.

Besides, U-233 fuelled breeder reactors will have a Th-232 blanket around the U-233 reactor core which will generate more U-233 as the reactor goes operational thus resulting in the production of more and more U-233 fuel from the Th-232 blanket as more of the U-233 in the fuel core is consumed helping to sustain the long term power generation fuel requirement.

Hence all the statements are correct.

Electric Fuse is a current interrupting device that protects the electrical circuit. The principle behind the operation of the fuse is the heating effect of the electrical current. If the current passes through a conductor with a certain resistance, the loss due to the conductor's resistance is dissipated in the form of heat. Under normal operating conditions, the heat produced in the fuse element is easily dissipated into the environment due to the flow of current through it. As a result, the fuse part remains at a temperature below its melting point. Hence statement 1 is correct.

Whenever some faults, such as short circuits, occur, the current flow through the fuse element exceeds the prescribed limits. This creates an excess of heat that melts the fuse part and breaks the circuit. So if the electrical current passing through the fuse goes beyond what the device can handle, the fuse link is melted and the circuit is opened to prevent damage to the electrical component. Fuses are always connected in series with the component to be protected from overcurrent, so that when the fuse blows (opens) it will open the entire circuit and stop current through the component. Hence statement 2 is not correct.

Proton, neutron, and electron are tiny particles that makeup atoms. The neutrino is also a tiny elementary particle, but it is not part of the atom. Such particles are also found to exist in nature. Hence statement 1 is correct.
Neutrino has a very tiny mass and no charge. It interacts very weakly with other matter particles. So weakly that every second trillion of neutrinos fall on us and pass through our bodies unnoticed. Neutrinos come from the sun (solar neutrinos) and other stars, cosmic rays that come from beyond the solar system, and from the Big Bang from which our Universe originated. They can also be produced in the lab. Hence statement 3 is correct.

The INO (India based Neutrino Observatory) will study atmospheric neutrinos only. Solar neutrinos have much lower energy than the detector can detect. INO Project is aimed at building a world-class underground laboratory with a rock cover to conduct basic research on the neutrino. The Tata Institute of Fundamental Research is the nodal institution. The observatory is to be built jointly with the Department of Atomic Energy and the Department of Science and Technology. The observatory will be located underground so as to provide adequate shielding to the neutrino detector from cosmic background radiation.

The operation of INO will have no release of radioactive or toxic substances. It is not a weapons laboratory and will have no strategic or defence applications.

They are the second most abundant particle in the universe after particles of light called photons. Hence statement 2 is not correct.

Both statements are correct: Green hydrogen is hydrogen produced using renewable energy sources such as wind, solar, or hydropower, through a method known as electrolysis.

• Electrolysis involves the process of splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂) by applying an electric current.
• When the electricity used in this process comes from renewable sources, the hydrogen produced is termed “green” because the entire process has minimal environmental impact.
• Benefit: Green hydrogen is a clean fuel that can help decarbonize various sectors, including iron and steel, chemicals, and transportation.
  • Additionally, hydrogen can be stored for extended periods and used to generate electricity through fuel cells.

DNA fingerprinting is a chemical test that shows the genetic makeup of a person or other living things.
It‘s used as evidence in courts, to identify bodies, track down blood relatives, and to look for cures for
disease.
Uses:
DNA fingerprinting most often has been used in court cases and legal matters. It can:

• Physically connect a piece of evidence to a person or rule out someone as a suspect.
• Show who your parents, siblings, and other relatives may be.
• Identify a dead body that‘s too old or damaged to be recognizable.
• DNA fingerprinting is extremely accurate. Most countries now keep DNA records on file in much the same way police keep copies of actual fingerprints.
• For criminal identification. Hence, option1 is correct.
• To resolve disputes of maternity/paternity. Hence, option 2 is correct.
• To identify mutilated remains. Hence, option 3 is correct.
• In cases of exchange of babies in a hospital ward. Hence, option 4 is correct.
• In forensic wildlife. Hence, option 5 is correct.

It also has medical uses. It can:

• Match tissues of organ donors with those of people who need transplants.
• Identify diseases that are passed down through your family.
• Help find cures for those diseases, called hereditary conditions.

A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapour gas-discharge lamp that uses fluorescence to produce visible light.

An electric current in the gas excites mercury vapour, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. Hence option (a) is the correct answer.

Astatine is a radioactive element of the halogen series: a decay product of uranium and thorium that occurs naturally in minute amounts and is artificially produced by bombarding bismuth with alpha particles. There are currently no uses for astatine outside of research.

Cinnabar is a toxic mercury sulfide mineral with a chemical composition of HgS. It is the only important ore of mercury. It has a bright red colour that has caused people to use it as a pigment, and carve it into jewellery and ornaments for thousands of years in many parts of the world.

Bacteria are microscopic, single-cell organisms that live on and inside plants, animals, and people. Some bacteria can infect the body of human or Plant that led to the bacterial disease. Some of the bacterial diseases are:

• Diphtheria: It is an infection caused by the bacterium Corynebacterium diphtheriae. Hence option 1 is correct.
• Tetanus: It is an infection caused by bacteria called Clostridium tetani. Hence option 2 is correct.
• Leprosy is an infectious disease caused by a bacillus, Mycobacterium leprae. The disease mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract, and the eyes. It is curable with multidrug therapy (MDT). It is likely transmitted via droplets, from the nose and mouth, during close and frequent contact with untreated cases. India officially eliminated leprosy in 2005, reducing its prevalence rate to 0.72 per 10,000 people at national level but still hosts highest patients of leprosy in the world. Hence option 3 is correct.
• Whooping cough, also called pertussis, is a serious respiratory infection caused by a type of bacteria called Bordetella pertussis. It can cause serious illness in babies, children, teens, and adults. Some other diseases which are caused by bacteria are: Cholera, typhoid, tuberculosis. Plague, and Anthrax etc. Hence option 4 is correct.

A bacteriophage is a type of virus that infects bacteria. The word "bacteriophage" literally means "bacteria eater," because bacteriophages destroy their host cells. All bacteriophages are composed of a nucleic acid molecule that is surrounded by a protein structure. A bacteriophage attaches itself to a susceptible bacterium and infects the host cell. Hence option (c) is the correct answer.

Following infection, the bacteriophage hijacks the bacterium's cellular machinery to prevent it from producing bacterial components and instead forces the cell to produce viral components. Eventually, new bacteriophages assemble and burst out of the bacterium in a process called lysis. Bacteriophages occasionally remove a portion of their host cells' bacterial DNA during the infection process and then transfer this DNA into the genome of new host cells. This process is known as transduction.

Since their discovery, bacteriophages have been considered to be potential antibacterial therapeutics for the treatment of various infectious diseases in humans. In recent times, the rapid rise of multi-drug resistant bacteria worldwide has led to a renewed interest in phage therapy as a possible alternative to antibiotics or, at least, a supplementary approach for the treatment of some bacterial infections. Furthermore, bacteriophage-based vaccination is emerging as one of the most promising preventive strategies.

Isotopes are defined as the atoms of the same element, having the same atomic number but different mass numbers. Hydrogen atom has three atomic species, namely protium (¹₁H), deuterium ( ²₁H or D) and tritium ( ³₁H or T). The atomic number of each one is 1, but the mass number is 1, 2 and 3, respectively. Hence option (b) is the correct answer.
While Isobar is defined as , atoms with identical atomic number but different atomic mass number for e.g. two elements — calcium, atomic number 20, and argon, atomic number 18 but the mass number of both these elements is 40.