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General Science and Technology

222 questions

All types222Multiple choice117Multiple select40True / False8Matching44Ordering13
Question 141Question →

Which of the following cell organelles contains powerful hydrolytic enzymes capable of digesting cellular waste and is commonly referred to as the 'suicide bag' of the cell?

Show answer & explanation

Answer: Lysosome

Answer

The organelle referred to as the 'suicide bag' of the cell is the Lysosome.
Lysosomes are membrane-enclosed organelles containing hydrolytic enzymes produced by the rough endoplasmic reticulum and packaged by the Golgi apparatus. They break down cellular macromolecules, damaged organelles, and engulfed pathogens. In injured or dying cells, lysosomal membranes disintegrate, causing autolysis (self-digestion), which is why they are called 'suicide bags'.

Step-by-Step Solution

1
Identify the primary function described in the question stem
The question specifies intracellular digestion using hydrolytic enzymes and self-destruction capability.
Lysosomes store digestive enzymes like lipases, proteases, and nucleases working at acidic pH.
2
Match the organelle function with known biological terminology
Lysosomes perform autolysis when the cell is damaged, earning the terminology 'suicide bags'.
Bursting of lysosomes releases hydrolytic enzymes that digest their own cellular components.

Key Concept

Cell Organelles and their Functions (Lysosomes as digestive compartments)
Question 142Question →

With reference to India's national cybersecurity framework and the Information Technology Act, 2000 (as amended), consider the following statements:

1. The Indian Computer Emergency Response Team (CERT-In) is designated under Section 70B of the Information Technology Act as the national nodal agency for responding to computer security incidents.
2. The National Critical Information Infrastructure Protection Centre (NCIIPC) is created under Section 70A of the Information Technology Act and functions as a unit of the National Technical Research Organisation (NTRO).
3. Section 66F of the Information Technology Act explicitly deals with offences related to cyber terrorism and prescribes punishment extending up to life imprisonment.

Which of the statements given above are correct?

Show answer & explanation

Answer: 1, 2 and 3

Answer

All three statements (1, 2, and 3) are correct.
The option stating '1, 2 and 3' is correct because all three statements accurately describe key statutory provisions of India's Information Technology Act, 2000. Section 70B empowers CERT-In as the national incident response agency; Section 70A establishes NCIIPC under NTRO for critical infrastructure protection; and Section 66F prescribes life imprisonment for cyber terrorism.

Step-by-Step Solution

1
Analyze Statement 1 regarding CERT-In's statutory basis.
CERT-In was designated as the national nodal agency for incident response under Section 70B of the IT (Amendment) Act, 2008.
Verify statutory mandate under the Information Technology Act.
2
Analyze Statement 2 regarding NCIIPC's statutory basis and organization.
NCIIPC was established under Section 70A of the IT Act, 2000, operating under the National Technical Research Organisation (NTRO) to protect critical information infrastructure.
Verify legal origin and administrative agency of NCIIPC.
3
Analyze Statement 3 regarding cyber terrorism provisions.
Section 66F of the IT Act penalizes acts of cyber terrorism against the unity, integrity, security, or sovereignty of India with imprisonment extending up to life imprisonment.
Verify penal provisions for cyber offenses under the IT Act.

Key Concept

Statutory Cybersecurity Architecture of India under the IT Act, 2000
Question 143Question →

Match List-I (Plant Physiological Phenomena and Agricultural Technologies) with List-II (Biological Mechanisms and Agronomic Applications) and select the correct sequence of matching pairs:

Click a left item, then click its matching right item

Items

Guttation
Apomixis
Parthenocarpy
Micropropagation

Matches

Show answer & explanation

Answer

Guttation pairs with liquid xylem sap exudation through hydathodes via root pressure; Apomixis pairs with asexual seed formation preserving hybrid vigor; Parthenocarpy pairs with seedless fruit development without fertilization; Micropropagation pairs with in vitro tissue culture producing disease-free clones.
Guttation corresponds to the exudation of xylem sap via hydathodes under positive root pressure. Apomixis represents asexual seed development without fertilization that preserves hybrid traits. Parthenocarpy corresponds to the formation of seedless fruits without ovule fertilization. Micropropagation refers to in vitro clonal propagation using tissue explants.

Step-by-Step Solution

1
Analyze Guttation
Guttation is driven by positive root pressure during periods of low transpiration, causing sap loss through hydathodes.
Differentiates guttation from transpiration (gas phase water loss through stomata).
2
Analyze Apomixis
Apomixis yields asexual seed formation without syngamy.
Key biotechnological target for maintaining hybrid vigor in successive seed generations.
3
Analyze Parthenocarpy
Parthenocarpy leads to fruit development without seed formation.
Distinguishes seedless fruit development from parthenogenesis (embryo creation).
4
Analyze Micropropagation
Micropropagation relies on in vitro culture of tissue explants to generate elite clones.
Core technique in modern plant tissue culture and clean planting material production.

Key Concept

Plant Physiology and Agricultural Biotechnology Mechanisms
Question 144Question →

Which of the following statements regarding human infectious diseases, their causative pathogens, and transmission mechanisms are correct?

Select all that apply

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Answer: Cholera is an acute diarrheal disease caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae.; Hepatitis B is a viral infection that primarily targets and causes inflammation of the human liver.; Ringworm is a contagious dermatological infection caused by microscopic dermatophytic fungi.

Answer

The correct statements are those identifying Cholera as a bacterial infection, Hepatitis B as a viral liver disease, and Ringworm as a fungal skin infection.
The statements confirming Cholera as a bacterial illness, Hepatitis B as a viral liver infection, and Ringworm as a fungal dermatological condition are scientifically accurate. The assertion regarding Malaria is false because female Anopheles mosquitoes serve as the biological vector for Malaria transmission, whereas Aedes mosquitoes transmit viral infections like Dengue and Yellow Fever.

Step-by-Step Solution

1
Analyze the statement regarding Cholera etiology.
Cholera is caused by the bacterium Vibrio cholerae. The statement is correct.
Vibrio cholerae is an established bacterial pathogen causing severe watery diarrhea.
2
Evaluate the statement regarding Hepatitis B pathobiology.
Hepatitis B is caused by HBV, a virus attacking hepatic tissue. The statement is correct.
Hepatitis B is classified as a viral hepatitis strain infecting hepatocytes.
3
Examine the vector mechanism described for Malaria transmission.
Malaria parasite Plasmodium is carried by female Anopheles mosquitoes, not Aedes. The statement is incorrect.
Confusing Anopheles and Aedes mosquito vectors is a common epidemiological error; Aedes transmits arboviruses.
4
Assess the causative agent for Ringworm.
Ringworm (tinea) is caused by fungal dermatophytes. The statement is correct.
The name ringworm is a misnomer for fungal skin lesions.

Key Concept

Classification of Human Infectious Pathogens and Biological Vectors
Question 145Question →

Which type of satellite orbit has an orbital period that matches Earth's rotational period of approximately 24 hours, causing the satellite to appear stationary relative to a fixed location on Earth's equator?

Show answer & explanation

Answer: Geostationary Orbit

Answer

Geostationary Orbit
A geostationary orbit is a circular orbit situated at an altitude of approximately 35,786 km directly above Earth's equator. Because its orbital period matches Earth's rotational period (~24 hours) and it revolves in the same direction as Earth's rotation (west to east), the satellite remains stationary relative to a point on Earth's surface.

Step-by-Step Solution

1
Identify the relationship between satellite orbital period and Earth's rotation period given in the prompt.
The satellite completes one full orbit around Earth in approximately 24 hours, matching Earth's rotational rate.
When a satellite's angular velocity equals Earth's angular velocity of rotation, its relative motion with respect to the ground is zero.
2
Classify the specific orbit located over the equator with this matching 24-hour period.
A circular equatorial orbit at ~35,786 km altitude with a 24-hour period is defined as a Geostationary Orbit (GEO).
This specific orbital configuration ensures constant line-of-sight communication over a fixed region of the Earth.

Key Concept

Geostationary Orbit Characteristics
Estimated Time:45s
Question 146Question →

State whether the following statement regarding Internet infrastructure security is True or False: Domain Name System Security Extensions (DNSSEC) mitigate DNS spoofing and cache poisoning by encrypting DNS query payloads to ensure data confidentiality during transmission between client resolvers and authoritative servers.

Show answer & explanation

Answer: False

Answer

False. DNSSEC provides origin authentication and data integrity using digital signatures, but it does not encrypt DNS transactions or guarantee payload confidentiality.
The statement is false because DNSSEC introduces cryptographic signatures to validate the authenticity and integrity of DNS resource records to prevent cache poisoning, but it does not encrypt DNS traffic. Privacy and confidentiality require transport-layer encryption protocols like DNS over HTTPS (DoH) or DNS over TLS (DoT).

Step-by-Step Solution

1
Analyze the functional objectives of Domain Name System Security Extensions (DNSSEC).
DNSSEC attaches public-key digital signatures (such as RRSIG records) to DNS data to verify that the response originates from the correct server and has not been altered.
Defining the primary security goal of DNSSEC is essential to evaluate the statement.
2
Distinguish between data integrity/authentication and data confidentiality in network security.
DNSSEC responses are cryptographically signed but transmitted in plain text, meaning DNS queries remain visible to intermediate network observers.
Authenticating the source of data (integrity) does not conceal the contents of the data (confidentiality).
3
Identify the protocols that explicitly address DNS confidentiality.
Protocols like DNS over TLS (DoT) and DNS over HTTPS (DoH) encrypt DNS queries for confidentiality, whereas DNSSEC focuses exclusively on authenticity and tamper resistance.
This confirms that attributing payload encryption and data confidentiality to DNSSEC is technically false.

Key Concept

DNSSEC security guarantees (Origin Authentication and Integrity vs Payload Confidentiality)
Estimated Time:1m 30s
Question 147Question →

With reference to principles of genetics and cell division, consider the following statements:
1. In incomplete dominance, the phenotypic ratio in the F2F_2 generation is identical to its genotypic ratio (1:2:11:2:1).
2. Recombination nodules appear during the Pachytene substage of Prophase I in meiosis, where crossing over occurs via the enzyme recombinase.
3. Haemophilia is an X-linked recessive genetic trait that is transmitted directly from an affected father to his sons.

Which of the statements given above are correct?

Show answer & explanation

Answer: 1 and 2 only

Answer

The statement option asserting that 1 and 2 only are correct represents the accurate answer.
Incomplete dominance alters the standard 3:1 Mendelian phenotypic ratio to 1:2:1, making it identical to the genotypic ratio. Furthermore, recombination occurs during Pachytene of Meiosis I facilitated by recombinase. Haemophilia is X-linked, making direct father-to-son transmission genetically impossible because sons inherit only the father's Y chromosome.

Step-by-Step Solution

1
Analyze Statement 1 regarding Mendelian inheritance exceptions
In incomplete dominance (e.g., Snapdragon flowers), monohybrid crosses yield red (RRRR), pink (RrRr), and white (rrrr) phenotypes in a 1:2:11:2:1 ratio, which mirrors the genotypic ratio 1RR:2Rr:1rr1RR : 2Rr : 1rr. Thus, Statement 1 is correct.
Verify phenotypic vs genotypic ratio equivalence in non-Mendelian traits.
2
Analyze Statement 2 regarding meiotic prophase events
Crossing over occurs between non-sister chromatids of homologous chromosomes during Pachytene stage, mediated by recombination nodules containing recombinase. Thus, Statement 2 is correct.
Identify the precise substage of Prophase I responsible for genetic variation.
3
Analyze Statement 3 regarding pedigree and sex-linked inheritance
Haemophilia genes reside on the X chromosome. A father contributes his Y chromosome to male offspring and X chromosome to female offspring. Therefore, male-to-male transmission of X-linked traits does not occur. Statement 3 is incorrect.
Determine sex-chromosome transmission dynamics in human inheritance.

Key Concept

Non-Mendelian Inheritance, Meiotic Crossing Over, and Sex-Linked Inheritance Patterns
Estimated Time:2m 0s
Question 148Question →

With reference to transgenic Bt (*Bacillus thuringiensis*) technology used in agricultural crop protection, consider the following statements:

1. The crystalline insecticidal proteins produced by *Bacillus thuringiensis* are inactive protoxins that require the alkaline pH environment of the insect midgut for solubilization and activation.
2. Transgenic crops expressing *Cry1Ac* genes provide broad-spectrum protection primarily against sap-sucking insect pests such as aphids and whiteflies.
3. The mandatory planting of non-Bt 'refuge' crops surrounding Bt crop fields is an agronomic management strategy intended to delay the development of insect resistance to Bt toxins.

Which of the statements given above is/are correct?

Show answer & explanation

Answer: 1 and 3 only

Answer

1 and 3 only
The correct response identifies statements 1 and 3 as true. The Bt crystal protoxin requires an alkaline midgut pH for conversion into an active toxin that disrupts gut cell membrane integrity. Furthermore, non-Bt refuge planting is a established IPM strategy designed to preserve susceptible alleles within target pest populations, slowing down natural selection for resistance.

Step-by-Step Solution

1
Analyze Statement 1 regarding the mechanism of action of Bt endotoxins.
Bt bacteria produce inactive crystal proteins (protoxins). Upon ingestion by susceptible insects, these protoxins are solubilized in the alkaline environment of the insect midgut and cleaved by proteases into active toxins, which bind to midgut epithelial cells and create pores. Thus, statement 1 is correct.
Understanding the biochemical trigger for Bt toxin activation is essential for evaluating plant biotechnology applications.
2
Analyze Statement 2 regarding the target pest spectrum of Cry1Ac gene products.
The Cry1Ac gene specifically encodes toxins active against lepidopteran pests (such as the American bollworm, Pink bollworm, and tobacco budworm). Sucking pests (order Hemiptera, such as aphids, jassids, and whiteflies) are not susceptible to Cry1Ac toxins. Thus, statement 2 is incorrect.
Distinguishing between pest orders and their specific susceptibility to Cry protein sub-classes is key to agronomic crop protection analysis.
3
Analyze Statement 3 regarding the agronomic purpose of refuge crop strategies.
Planting non-Bt refuge crops ensures a localized population of susceptible insects that mate with any rare homozygous resistant insects emerging from Bt fields. This dilutes resistance genes in the pest population and significantly delays resistance development. Thus, statement 3 is correct.
Insect resistance management (IRM) strategies are vital components of sustainable agricultural biotechnology policy.

Key Concept

Bt Transgenic Technology and Insect Resistance Management
Question 149Question →

With reference to recent developments in Biotechnology and Nanotechnology, consider the following statements:

1. Quantum dots are semiconductor nanocrystals whose fluorescence wavelength decreases as the particle size increases.
2. Somatic Cell Nuclear Transfer (SCNT) produces embryonic stem cells that inherit nuclear genomic DNA primarily from the somatic cell donor rather than the egg donor.
3. Carbon nanotubes can display either metallic or semiconducting electrical conductivity depending on their chiral angle and diameter.

Which of the statements given above is/are correct?

Show answer & explanation

Answer: 2 and 3 only

Answer

Statements 2 and 3 are correct, while Statement 1 is incorrect.
The option stating '2 and 3 only' is correct because Statement 2 accurately describes how SCNT transfers nuclear DNA from the somatic cell donor, and Statement 3 accurately describes chirality-governed electrical properties of carbon nanotubes. Statement 1 is false because larger quantum dots emit longer wavelengths (red-shift), not shorter wavelengths.

Step-by-Step Solution

1
Analyze Statement 1 regarding Quantum Dots and optical emission.
Statement 1 is incorrect. In quantum dots, confinement effects broaden the band gap as particle size decreases. Smaller dots emit higher-energy, shorter-wavelength light (blue light), whereas larger dots emit lower-energy, longer-wavelength light (red light).
Quantum confinement correlates bandgap energy inversely with nanoparticle size.
2
Analyze Statement 2 regarding Somatic Cell Nuclear Transfer (SCNT).
Statement 2 is correct. SCNT transfers a somatic nucleus into an enucleated oocyte, making the nuclear DNA virtually identical to the somatic donor cell.
The recipient egg cell contributes only cytoplasm and mitochondrial DNA, while the nuclear gene payload originates entirely from the somatic donor.
3
Analyze Statement 3 regarding Carbon Nanotubes (CNTs).
Statement 3 is correct. The orientation of the graphene roll (chirality vector (n,m)(n, m)) determines whether a single-walled carbon nanotube is metallic or semiconducting.
When (n−m)(n - m) is a multiple of 3, the CNT exhibits metallic conductivity; otherwise, it behaves as a semiconductor.

Key Concept

Quantum confinement in quantum dots, nuclear donor inheritance in SCNT, and chirality-dependent conductivity of carbon nanotubes
Question 150Question →

Match the everyday physical observations in List-I with their primary underlying physics principles in List-II:

Click a left item, then click its matching right item

Items

Cooling of water stored in an earthen pot
Vacuum space in a double-walled thermos flask
Occurrence of land breeze during nighttime in coastal areas
Loosening a tight metal jar lid by running hot water over it

Matches

Show answer & explanation

Answer

Cooling of water in an earthen pot matches with absorption of latent heat during porous surface evaporation; Vacuum space in a double-walled thermos flask matches with prevention of heat transfer mechanisms that require a material medium; Occurrence of land breeze matches with convective circulation driven by differential specific heat capacities; Loosening a tight metal jar lid matches with differential expansion rates of distinct solid materials upon heating.
Each everyday observation corresponds directly to a fundamental law of thermal physics: earthen pot cooling functions via latent heat of vaporization during evaporation; a thermos vacuum jacket blocks medium-dependent heat transfer (conduction and convection); land breezes are thermal convection currents caused by specific heat differences between land and water; and loosening a glass jar lid utilizes the higher coefficient of thermal expansion of metals compared to glass.

Step-by-Step Solution

1
Analyze the cooling mechanism in an earthen pot.
Microscopic pores facilitate surface evaporation. The phase change consumes thermal energy in the form of latent heat of vaporization from the stored liquid.
Evaporative cooling directly relies on latent heat absorption from the remaining liquid.
2
Examine the role of a vacuum gap in thermal insulation.
Conduction and convection mandate atomic or molecular collisions within a medium. A vacuum evacuates matter, blocking both heat transfer paths.
Thermal energy cannot conduct or convect without physical particles.
3
Evaluate the thermal dynamics driving coastal land breezes.
Because land has a lower specific heat capacity than ocean water, land loses heat faster at night. The resulting temperature difference induces density changes and convective air circulation.
Differential cooling rates establish local atmospheric pressure gradients.
4
Determine the principle behind thermal opening of glass jars.
When exposed to hot water, both the metal lid and glass container absorb heat, but the metal lid expands to a greater degree due to its higher thermal expansion coefficient.
Different materials expand at distinct rates per unit of temperature increase.

Key Concept

Thermal energy transfer mechanisms, latent heat, specific heat capacity, and thermal expansion in daily applications.
Estimated Time:1m 30s
Question 151Question →

With reference to modern biotechnology, consider the following statements regarding CRISPR-Cas9 technology:

1. It functions as a precise genome-editing tool in living organisms.
2. The Cas9 enzyme acts as molecular scissors to cut target DNA sequences.

Which of the statements given above is/are correct?

Show answer & explanation

Answer: Both 1 and 2

Answer

Both statements 1 and 2 are correct.
Both statements are correct. CRISPR-Cas9 is a major biotechnological advancement adapted from bacterial immune systems. Guide RNA leads the complex to a complementary target sequence on the DNA strand, and the Cas9 enzyme acts as molecular scissors to cut the DNA, enabling precise genomic modifications.

Step-by-Step Solution

1
Evaluate Statement 1 regarding the application of CRISPR-Cas9.
Statement 1 is correct because CRISPR-Cas9 is widely used as a gene-editing technology to add, remove, or alter genetic material in organisms.
CRISPR enables precise modification of DNA sequences within genomes.
2
Evaluate Statement 2 regarding the specific role of the Cas9 component.
Statement 2 is correct because Cas9 is an endonuclease protein that cuts double-stranded DNA at targeted sites specified by guide RNA.
The endonuclease activity of Cas9 functions analogously to molecular scissors.

Key Concept

CRISPR-Cas9 Genome Editing Mechanism
Estimated Time:45s
Question 152Question →

Consider the following statements regarding Public Key Infrastructure (PKI) and digital signature mechanisms:

1. A digital signature ensures non-repudiation and data integrity, but it does not inherently provide message confidentiality.
2. The Online Certificate Status Protocol (OCSP) allows real-time verification of a digital certificate's revocation status without requiring the download of complete Certificate Revocation Lists (CRLs).
3. In asymmetric cryptography, a sender encrypts a message with their own private key to ensure confidentiality for the intended recipient.

Which of the statements given above is/are correct?

Show answer & explanation

Answer: 1 and 2 only

Answer

The statements asserting that digital signatures provide non-repudiation and integrity without inherent confidentiality (Statement 1) and that OCSP enables real-time certificate status verification compared to CRLs (Statement 2) are correct. The statement regarding private key encryption for confidentiality (Statement 3) is incorrect.
Statements 1 and 2 are accurate. A digital signature verifies origin and prevents tampering but does not hide the content from third parties. OCSP provides live, real-time revocation checks per certificate, improving on CRL download overhead. Statement 3 is wrong because recipient confidentiality requires encryption using the recipient's public key.

Step-by-Step Solution

1
Analyze Statement 1 regarding digital signature security services.
Digital signatures are created by hashing data and encrypting the hash with the sender's private key. This guarantees integrity and non-repudiation. However, the plaintext payload remains unencrypted unless symmetric/asymmetric encryption is added.
Verify if confidentiality is an inherent property of digital signatures.
2
Analyze Statement 2 regarding PKI certificate revocation protocols.
CRL requires downloading complete, potentially large lists of revoked certificates periodically. OCSP sends a lightweight request for a single certificate status directly to an OCSP responder in real time, making it faster and less bandwidth-intensive.
Compare CRL and OCSP certificate revocation checking mechanisms.
3
Analyze Statement 3 regarding asymmetric key cryptography for confidentiality.
To achieve confidentiality, data must be encrypted using the recipient's public key, ensuring only the recipient holding the corresponding private key can decrypt it. Encrypting with a sender's private key provides authentication/signature, not confidentiality.
Identify the proper key selection for message encryption.

Key Concept

Public Key Infrastructure, Asymmetric Cryptography Key Usage, and Certificate Revocation Protocols
Question 153Question →

In public health and epidemiology, infectious human diseases are categorized by the biological nature of their causative agents to determine appropriate clinical treatments and preventive measures. Which of the following human diseases is caused by a bacterial pathogen?

Show answer & explanation

Answer: Diphtheria

Answer

Diphtheria is caused by a bacterial pathogen (Corynebacterium diphtheriae).
Diphtheria is a serious contagious infection of the upper respiratory tract caused by the bacterium Corynebacterium diphtheriae, which produces an exotoxin responsible for forming a characteristic pseudomembrane in the throat.

Step-by-Step Solution

1
Identify the causative organism for each disease option listed.
Diphtheria is caused by Corynebacterium diphtheriae (bacterium); Rabies is caused by Rabies virus (virus); Sleeping sickness is caused by Trypanosoma brucei (protozoan); Athlete's foot is caused by Trichophyton species (fungus).
Classifying pathogens by biological kingdom/type determines the mechanism of infection and appropriate medical intervention.
2
Select the disease that corresponds strictly to a bacterial etiology.
Diphtheria is the only disease in the list caused by a bacterium.
Antibiotics are effective against bacterial pathogens like Corynebacterium diphtheriae, whereas viral, protozoan, and fungal infections require distinct therapeutic agents.

Key Concept

Pathogen Etiology of Infectious Human Diseases
Estimated Time:1m 0s
Question 154Question →

Satellite orbits around Earth are designated according to their altitude above the Earth's surface. Arrange the following satellite orbits in increasing order of their average altitude from the surface of Earth (from lowest altitude to highest altitude).

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence from lowest to highest altitude is Low Earth Orbit (LEO), followed by Medium Earth Orbit (MEO), and finally Geostationary Earth Orbit (GEO).
Low Earth Orbit (LEO) is closest to Earth at 160–2,000 km160\text{--}2,000\text{ km}, followed by Medium Earth Orbit (MEO) extending from 2,000 km2,000\text{ km} up to 35,786 km35,786\text{ km}, and Geostationary Earth Orbit (GEO) positioned at a high altitude of 35,786 km35,786\text{ km}.

Step-by-Step Solution

1
Identify the altitude range for Low Earth Orbit (LEO).
LEO ranges from approximately 160 km160\text{ km} to 2,000 km2,000\text{ km} altitude.
It is the closest orbit to Earth.
2
Identify the altitude range for Medium Earth Orbit (MEO).
MEO ranges from approximately 2,000 km2,000\text{ km} up to 35,786 km35,786\text{ km} altitude.
It lies between Low Earth Orbit and Geostationary Earth Orbit.
3
Identify the altitude for Geostationary Earth Orbit (GEO).
GEO is positioned at a fixed altitude of approximately 35,786 km35,786\text{ km}.
This specific altitude matches Earth's rotational period of approximately 24 hours.
4
Arrange the orbits in increasing order of altitude.
Sequence: LEO (160–2,000 km160\text{--}2,000\text{ km}) →\rightarrow MEO (2,000–35,786 km2,000\text{--}35,786\text{ km}) →\rightarrow GEO (35,786 km35,786\text{ km}).
Ordering from lowest numeric altitude to highest altitude.

Key Concept

Classification of satellite orbits by altitude (LEO, MEO, GEO)
Question 155Question →

When a thin film of oil floating on water is exposed to white sunlight, vibrant multicolored bands are observed across its surface. Which physical phenomenon is primarily responsible for the formation of these colors?

Show answer & explanation

Answer: Interference between light waves reflecting from the upper and lower surfaces of the oil film

Answer

Interference between light waves reflecting from the upper and lower surfaces of the oil film
The brilliant colors seen on an oil slick or soap bubble are caused by thin-film interference. When white light falls on the film, a portion reflects from the top surface and another portion reflects from the lower surface. Because the light reflecting from the bottom surface travels a slightly longer path through the oil, the two reflected light waves superimpose. Depending on the film's thickness and the wavelength of light, certain colors interfere constructively (appearing bright) while others interfere destructively, generating bright color patterns.

Step-by-Step Solution

1
Identify the optical boundary interaction
Sunlight striking the thin oil layer on water encounters two interfaces: the air-oil top interface and the oil-water bottom interface.
Light is partially reflected at the top boundary and partially transmitted into the oil layer before reflecting off the bottom boundary.
2
Analyze the phase shift and path difference
The wave reflecting from the bottom interface travels an extra distance equal to twice the thickness of the film.
The optical path difference between the two reflected rays determines whether specific colors undergo constructive or destructive interference.
3
Determine the cause of the observed color spectrum
Varying thickness across the oil film leads to constructive interference of different spectral colors at different locations, creating brilliant multicolored bands.
This behavior is a classic manifestation of thin-film wave interference.

Key Concept

Thin-film interference of light waves
Estimated Time:1m 0s
Question 156Question →

In recombinant DNA technology, specific enzymes are utilized to precisely cut DNA strands at designated nucleotide recognition sites. Which of the following enzymes acts as 'molecular scissors' in genetic engineering?

Show answer & explanation

Answer: Restriction enzymes

Answer

Restriction enzymes act as the 'molecular scissors' in recombinant DNA technology by cleaving DNA molecules at specific recognition sequences.
Restriction enzymes, also known as restriction endonucleases, cut double-stranded DNA molecules at specific palindromic recognition sites. Because of this precise cutting action, they are universally termed 'molecular scissors' in biotechnology and genetic engineering.

Step-by-Step Solution

1
Identify the primary function of each enzyme listed in genetic engineering.
Restriction enzymes cut DNA, DNA ligase joins DNA, DNA polymerase synthesizes DNA strands, and reverse transcriptase synthesizes cDNA from RNA.
Matching each biological enzyme to its catalytic role clarifies which enzyme performs sequence-specific cleavage.
2
Select the enzyme corresponding to the 'molecular scissors' terminology.
Restriction endonucleases (restriction enzymes) fit this definition precisely.
The term 'molecular scissors' refers to enzymes that break phosphodiester bonds at specific target sequences within DNA.

Key Concept

Restriction Endonucleases in Biotechnology
Question 157Question →

Which of the following space missions represents India's first dedicated multi-wavelength space observatory launched by the Indian Space Research Organisation (ISRO)?

Show answer & explanation

Answer: AstroSat

Answer

AstroSat is India's first dedicated multi-wavelength space observatory mission launched by ISRO.
AstroSat is India's pioneer multi-wavelength space astronomy mission. It enables simultaneous multi-wavelength observations of various astronomical bodies and cosmic sources across optical, ultraviolet, and low to high-energy X-ray bands.

Step-by-Step Solution

1
Identify the designated primary mission objective of India's astronomical satellites.
AstroSat was launched in 2015 carrying five payloads capable of studying astronomical objects across optical, UV, and X-ray wavebands simultaneously.
Differentiating between lunar probes, solar observatories, polarimetry missions, and broad multi-wavelength telescopes clarifies the unique role of AstroSat.

Key Concept

ISRO Space Astronomy Observatories
Estimated Time:45s
Question 158Question →

Consider the following statements regarding certain communicable human diseases, their causative organisms, and transmission pathways:

1. Scrub typhus is a bacterial infection caused by Orientia tsutsugamushi and transmitted to humans through the bites of larval trombiculid mites.
2. Chagas disease is a viral infection transmitted primarily through the bite of the female Anopheles mosquito.
3. Leptospirosis is a bacterial zoonosis caused by spirochetes of the genus Leptospira, commonly contracted through contact with water or soil contaminated by animal urine.

Which of the statements given above are correct?

Show answer & explanation

Answer: 1 and 3 only

Answer

Statements 1 and 3 only are correct.
The correct response identifies statements 1 and 3 as scientifically accurate. Scrub typhus is an obligate intracellular bacterial zoonosis transmitted by trombiculid mites, and Leptospirosis is a spirochetal bacterial infection transmitted via water contaminated with urine from host reservoirs.

Step-by-Step Solution

1
Evaluate Statement 1 regarding Scrub typhus.
Scrub typhus is indeed caused by the intracellular bacterium Orientia tsutsugamushi and transmitted by larval trombiculid mites (chiggers). Statement 1 is correct.
Accurate biological classification of pathogen and vector for Scrub typhus.
2
Evaluate Statement 2 regarding Chagas disease.
Chagas disease (American trypanosomiasis) is caused by the flagellate protozoan parasite Trypanosoma cruzi, not a virus. It is transmitted mainly by triatomine bugs ('kissing bugs'), not Anopheles mosquitoes. Statement 2 is incorrect.
Identification of pathogen and vector misattribution.
3
Evaluate Statement 3 regarding Leptospirosis.
Leptospirosis is caused by pathogenic spirochetes (bacteria) belonging to the genus Leptospira, shedding in the urine of infected animal hosts (e.g., rodents) into soil and water bodies. Statement 3 is correct.
Accurate characterization of zoonotic bacterial pathology.

Key Concept

ETIOLOGY AND VECTOR DYNAMICS OF COMMUNICABLE HUMAN DISEASES
Question 159Question →

Consider the following statements regarding plant growth regulators and their technological applications in agriculture and tissue culture:

1. In plant tissue culture micropropagation, a high ratio of auxin to cytokinin promotes root organogenesis (rhizogenesis), whereas a high ratio of cytokinin to auxin promotes shoot bud differentiation (caulogenesis).
2. Synthetic auxins such as 2,4-Dichlorophenoxyacetic acid (2,4-D) act as selective herbicides by inducing lethal abnormal growth in broad-leaved dicotyledonous weeds while leaving monocotyledonous cereal crops unaffected.
3. Ethephon hydrolyzes within plant cells to release ethylene gas, which is applied in commercial agriculture to synchronize fruit ripening and induce female flower development in cucurbit crops.

Which of the statements given above are correct?

Show answer & explanation

Answer: 1, 2 and 3

Answer

All three statements (1, 2, and 3) are correct.
The correct answer includes all three statements because each accurately describes a established biological and technological application of plant hormones. Statement 1 correctly reflects the Skoog-Miller model of organogenesis in micropropagation, Statement 2 accurately describes the selective action of synthetic auxin 2,4-D on broad-leaved dicot weeds in cereal fields, and Statement 3 correctly details the ethylene-releasing mechanism of ethephon in horticultural crop management.

Step-by-Step Solution

1
Evaluate Statement 1 on hormonal balance in tissue culture organogenesis.
Skoog and Miller established that morphogenesis in callus cultures is controlled by the ratio of auxin to cytokinin: a high auxin:cytokinin ratio promotes rhizogenesis (root formation), a high cytokinin:auxin ratio promotes caulogenesis (shoot formation), and an intermediate ratio promotes callus proliferation. Statement 1 is correct.
Verify physiological principles of plant tissue culture micropropagation.
2
Evaluate Statement 2 on synthetic auxin selectivity as a herbicide.
2,4-D is a synthetic auxin that acts as a selective herbicide. Dicotyledonous plants absorb and translocate it rapidly, causing unsustainable metabolic strain, vascular collapse, and uncontrolled stem elongation, whereas monocotyledonous crops (like wheat, rice, and corn) metabolize and inactivate it rapidly or have resistant vascular anatomy. Statement 2 is correct.
Verify chemical weed management mechanisms in agricultural science.
3
Evaluate Statement 3 on ethephon and ethylene action in horticulture.
Ethephon (2-chloroethylphosphonic acid) breaks down into ethylene, phosphate, and chloride ions at plant physiological pH. Ethylene triggers climacteric fruit ripening and alters floral development towards female flower production in cucurbits. Statement 3 is correct.
Verify post-harvest and developmental applications of plant growth regulators.

Key Concept

Plant Growth Regulators and Agronomic Applications
Estimated Time:2m 0s
Question 160Question →

With reference to RNA interference (RNAi) technology and its applications in crop protection and plant biotechnology, which of the following statements are correct?

Select all that apply

Show answer & explanation

Answer: In-planta expression of long double-stranded RNA (dsRNA) triggers the host or pest Dicer enzyme to generate small interfering RNAs (siRNAs) that target matching messenger RNA (mRNA) for degradation.; Host-Delivered RNAi (HDRNi) enables transgenic crops to synthesize specific double-stranded RNA molecules that induce lethal gene knockdown when ingested by targeted herbivorous insects.

Answer

The correct statements are that double-stranded RNA (dsRNA) is processed by Dicer enzymes into small interfering RNAs (siRNAs) to target mRNA for degradation, and Host-Delivered RNAi (HDRNi) allows transgenic crops to synthesize target dsRNA that causes lethal gene knockdown upon ingestion by pests.
The correct statements accurately describe RNA interference as a post-transcriptional gene silencing mechanism. Double-stranded precursor RNA is cleaved by Dicer into functional siRNAs that bind to the RNA-induced silencing complex (RISC) to degrade complementary messenger RNA. Furthermore, Host-Delivered RNAi (HDRNi) leverages this by enabling crop plants to express specific dsRNAs that, upon ingestion by target insect pests, disrupt vital pest physiological pathways.

Step-by-Step Solution

1
Analyze the biochemical mechanism of RNA interference in plants.
RNAi is a natural post-transcriptional gene silencing pathway wherein long double-stranded RNA (dsRNA) is recognized and cleaved by the Dicer ribonuclease enzyme into short 21-24 nucleotide duplexes called small interfering RNAs (siRNAs).
Understanding the fundamental pathway confirms the role of Dicer and siRNAs in degrading target complementary mRNA.
2
Evaluate the mechanism of Host-Delivered RNAi (HDRNi) in agricultural pest control.
Crops engineered with transgenic constructs produce insect-specific dsRNA. When pests ingest plant tissues, the dsRNA enters insect cells and triggers sequence-specific mRNA destruction of essential survival genes.
This confirms that crop protection via HDRNi is a functional biotechnology application.
3
Differentiate RNAi post-transcriptional silencing from genomic DNA alteration and transcriptional initiation blockade.
RNAi targets existing transcript molecules (mRNA) in the cytoplasm and does not insert foreign DNA into target pest chromosomes or act primarily by blocking promoter binding during transcription.
This identifies the conceptual flaws in statements asserting chromosomal gene insertion or exclusive transcriptional promoter blockage.

Key Concept

RNA Interference (RNAi) and Post-Transcriptional Gene Silencing in Agriculture
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