Examkin

General Science and Technology

222 soru

Tüm türler222Çoktan seçmeli117Çoklu seçim40Doğru / Yanlış8Eşleştirme44Sıralama13
Soru 201Soru →

In the study of human physiology, health, and epidemiology, identifying the exact biological classification of disease-causing organisms is essential for selecting appropriate medical interventions. Which of the following human diseases is correctly matched with its primary causative pathogen?

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Cevap: Kala-azar (Visceral Leishmaniasis) — Protozoan parasite

Cevap

Kala-azar (Visceral Leishmaniasis) is correctly matched as a disease caused by a protozoan parasite (Leishmania donovani).
The pairing of Kala-azar (Visceral Leishmaniasis) with a protozoan parasite is correct. Kala-azar is caused by protozoan parasites of the genus Leishmania (primarily Leishmania donovani in the Indian subcontinent), which target the reticuloendothelial system including the liver, spleen, and bone marrow.

Adım Adım Çözüm

1
Analyze the pathogen classification for Kala-azar
Kala-azar (Visceral Leishmaniasis) is caused by Leishmania donovani, a flagellated protozoan parasite, and transmitted to humans via the phlebotomine sandfly vector.
This establishes that the pairing of Kala-azar with a protozoan parasite is scientifically accurate.
2
Evaluate the pathogen classifications of the remaining options
Chikungunya is viral (Chikungunya alphavirus), Anthrax is bacterial (Bacillus anthracis), and Candidiasis is fungal (Candida species).
Identifying the correct biological kingdoms/types for each pathogen reveals that these three pairings incorrectly misclassify the causative agents.

Anahtar Kavram

Classification of Human Infectious Pathogens (Protozoan vs. Viral vs. Bacterial vs. Fungal Etiology)
Soru 202Soru →

Consider the following statements regarding human cardiac physiology and blood circulation:

1. The Sinoatrial (SA) node functions as the primary pacemaker of the heart because it generates impulse discharges at the highest intrinsic frequency.
2. The Atrioventricular (AV) node introduces a slight physiological delay in signal transmission, ensuring atria contract completely before ventricular systole begins.
3. The coronary sinus collects deoxygenated blood from the myocardium and empties directly into the left atrium.

Which of the statements given above are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 2 only

Cevap

1 and 2 only
Statements 1 and 2 accurately describe cardiac physiology. The Sinoatrial (SA) node acts as the natural pacemaker because it generates action potentials at the highest frequency. The Atrioventricular (AV) node introduces a essential physiological delay (~0.1 s) to allow the ventricles to fill completely before contracting. Statement 3 is incorrect because the coronary sinus drains deoxygenated blood from the heart wall into the right atrium, not the left atrium.

Adım Adım Çözüm

1
Evaluate Statement 1 regarding cardiac pacemaking.
Statement 1 is correct. Located in the right atrium, the SA node exhibits the highest rhythmicity (70-80 impulses per minute) and paces the heart.
The intrinsic depolarization rate of the SA node overrides slower secondary pacemakers in the conduction system.
2
Evaluate Statement 2 regarding conduction delay at the AV node.
Statement 2 is correct. Impulse propagation slows down significantly (approx. 0.1 second delay) at the AV node.
This delay ensures complete atrial emptying and optimal ventricular filling prior to ventricular contraction.
3
Evaluate Statement 3 regarding myocardial venous drainage.
Statement 3 is incorrect. The coronary sinus collects deoxygenated blood from the cardiac veins and opens into the right atrium.
All systemic deoxygenated venous return, including coronary venous drainage, enters the right atrium, while the left atrium exclusively receives oxygenated blood from the lungs.

Anahtar Kavram

Cardiac Conduction System and Coronary Circulation
Soru 203Soru →

Regarding human infectious diseases, their causative pathogens, and primary modes of transmission, which of the following statements are correct?

Geçerli olan tümünü seçin

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Cevap: Tuberculosis is a bacterial disease caused by Mycobacterium tuberculosis, primarily affecting the lungs.; Malaria is a protozoan disease caused by Plasmodium species, transmitted through female Anopheles mosquito bites.; Athlete's foot is a fungal infection of the skin commonly caused by dermatophytes.

Cevap

The correct statements are those identifying Tuberculosis as a bacterial infection of the lungs, Malaria as a protozoan infection transmitted by female Anopheles mosquitoes, and Athlete's foot as a fungal skin infection caused by dermatophytes.
The correct options accurately pair infectious diseases with their true pathogen categories and transmission routes: Tuberculosis is bacterial (Mycobacterium tuberculosis), Malaria is protozoan (Plasmodium spp.) transmitted by female Anopheles mosquitoes, and Athlete's foot is a fungal infection (dermatophytes).

Adım Adım Çözüm

1
Evaluate the pathogen and organ targeting for Tuberculosis
Tuberculosis is correctly identified as a bacterial infection caused by Mycobacterium tuberculosis.
Mycobacterium tuberculosis is a bacterium that primarily causes pulmonary disease.
2
Evaluate the causative agent and vector for Malaria
Malaria is correctly identified as a protozoan disease transmitted by female Anopheles mosquitoes.
Plasmodium is a protozoan parasite, and female Anopheles mosquitoes serve as the biological vector.
3
Analyze the etiology and transmission route of Typhoid fever
The statement describing Typhoid fever as a respiratory virus is incorrect.
Typhoid fever is caused by the bacterium Salmonella typhi and is spread through the fecal-oral route (contaminated food/water), not airborne viruses.
4
Assess the biological nature of Athlete's foot
Athlete's foot is correctly recognized as a fungal infection.
Tinea pedis is caused by dermatophytes, a group of parasitic fungi.

Anahtar Kavram

Classification of human diseases by biological pathogen type (bacterium, protozoan, fungus, virus) and transmission pathway.
Soru 204Soru →

Consider the following statements regarding Blockchain technology and cryptographic mechanisms in cybersecurity:

1. Cryptographic hash functions used in blockchain exhibit the 'avalanche effect', where a minor modification to input data yields a significantly different hash output.
2. Immutability in a public blockchain ledger is secured because altering historical data requires recalculating the hashes of all subsequent blocks and achieving consensus across the network.
3. Asymmetric cryptography is implemented in blockchain systems primarily for compressing transaction data volume rather than managing digital keys and authentication.

Which of the statements given above are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 2 only

Cevap

The statement combination '1 and 2 only' is correct.
The combination consisting of the first and second statements is correct. Cryptographic hash functions ensure that any slight modification in input radically alters the output hash (avalanche effect). Furthermore, because blocks are cryptographically chained, modifying any past transaction invalidates all subsequent block headers, making the ledger tamper-resistant. Conversely, asymmetric encryption generates public and private key pairs for wallet identity and digital signatures, not for data compression.

Adım Adım Çözüm

1
Analyze Statement 1 regarding cryptographic hash functions.
Statement 1 is correct.
Cryptographic hash functions (such as SHA-256) feature the avalanche effect, meaning even a single bit change in the input produces a drastically altered and unpredictable hash output.
2
Analyze Statement 2 regarding ledger immutability.
Statement 2 is correct.
Each block contains the cryptographic hash of the preceding block. Changing past block data breaks the hash chain, requiring an attacker to recompute all subsequent hashes and override majority network consensus.
3
Analyze Statement 3 regarding asymmetric cryptography.
Statement 3 is incorrect.
Asymmetric cryptography (public-private key pairs) is used for digital signatures, ownership verification, and secure transaction signing, not for data compression.

Anahtar Kavram

Cryptographic Hash Functions and Asymmetric Encryption in Blockchain Security
Soru 205Soru →

Safety matches rely on specific chemical formulations on both the match head and the striking surface to ensure controlled ignition. Which of the following statements regarding the chemical composition and functions of components in safety matches are correct?

Geçerli olan tümünü seçin

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Cevap: Potassium chlorate (KClO3KClO_3) is present in the match head to serve as an oxidizing agent that decomposes to supply oxygen during friction.; The striking surface of a safety matchbox contains red phosphorus, which undergoes friction-induced conversion to ignite the match.; Antimony trisulfide (Sb2S3Sb_2S_3) is incorporated into the match head to function as a combustible fuel.

Cevap

The correct statements are those identifying potassium chlorate as the oxidizing agent in the match head, red phosphorus on the striking strip as the ignition initiator, and antimony trisulfide as the fuel in the match head.
The statements correctly identify that potassium chlorate acts as an oxidizing agent in the match head, antimony trisulfide functions as the fuel in the head, and red phosphorus on the striking surface initiates combustion via friction-induced heat.

Adım Adım Çözüm

1
Analyze the chemical composition of the match head.
The match head contains potassium chlorate (KClO3KClO_3) as an oxidizing agent, antimony trisulfide (Sb2S3Sb_2S_3) as a fuel, and a binder/glue.
Potassium chlorate decomposes to yield oxygen, which rapidly oxidizes antimony trisulfide to sustain the flame.
2
Examine the composition and reaction of the striking surface.
The striking surface contains red phosphorus, powdered glass (an abrasive/friction agent), and adhesive.
Striking generates frictional heat, transforming a minute portion of stable red phosphorus into reactive white phosphorus vapor that ignites.
3
Evaluate the safety hazard associated with white phosphorus.
White phosphorus (P4P_4) is poisonous and ignites spontaneously in air at room temperature.
It was banned internationally under the Berne Convention of 1906 due to severe occupational toxicity ('phossy jaw') and spontaneous combustion hazards.

Anahtar Kavram

Chemical Composition and Reaction Dynamics of Safety Matches
Soru 206Soru →

In the context of computer networking and cybersecurity, match the security protocols listed in List-I with their primary functions and architectural characteristics described in List-II.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Kerberos
IPsec
PGP (Pretty Good Privacy)
RADIUS

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Kerberos matches with ticket-granting identity authentication over insecure networks; IPsec matches with Layer 3 Network Layer encryption for VPN tunnels; PGP matches with hybrid cryptography for email and file privacy; and RADIUS matches with centralized AAA network administration.
The correct mapping pairs each protocol with its exact operational domain: Kerberos provides ticket-granting authentication over non-secure networks, IPsec secures communications at the Network Layer (Layer 3) for VPNs, PGP provides end-to-end cryptographic security for emails and files, and RADIUS provides centralized Authentication, Authorization, and Accounting (AAA) management.

Adım Adım Çözüm

1
Analyze Kerberos authentication mechanism.
Kerberos is designed around symmetric-key cryptography and ticket-granting service (TGS) authentication.
It verifies user and service identities across non-secure networks using time-stamped tickets.
2
Determine the OSI operating layer for IPsec.
IPsec operates transparently at the Network Layer (Layer 3).
It encapsulates and encrypts IP packets using AH and ESP protocols to form secure VPN connections.
3
Identify the primary application domain of PGP.
PGP secures emails and files via hybrid cryptography.
It encrypts message payloads using symmetric keys and encrypts those session keys using public-key infrastructure (PKI).
4
Evaluate the function of RADIUS in network access control.
RADIUS provides centralized AAA infrastructure.
It acts as a centralized server system managing user authentication, access policy enforcement, and usage accounting for network gateways.

Anahtar Kavram

Cybersecurity Protocols and Authentication Architecture
Soru 207Soru →

Consider the following statements regarding the raw materials and chemical compounds involved in the manufacture and setting of Portland cement:

1. Gypsum (CaSO4⋅2H2OCaSO_4 \cdot 2H_2O) is added to cement clinker during final grinding to retard the rate of setting.
2. Dicalcium silicate (2CaO⋅SiO22CaO \cdot SiO_2) hydrates rapidly with water and is primarily responsible for the early strength development of cement within the first 24 hours.
3. Tricalcium aluminate (3CaO⋅Al2O33CaO \cdot Al_2O_3) undergoes rapid hydration and causes flash setting if setting retarders are omitted.

Which of the statements given above is/are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 3 only

Cevap

Statements 1 and 3 are correct.
Gypsum is added to cement clinker to prevent rapid flash setting caused by tricalcium aluminate (C3AC_3A). Tricalcium silicate (C3SC_3S), not dicalcium silicate (C2SC_2S), is responsible for early strength development.

Adım Adım Çözüm

1
Analyze Statement 1 regarding Gypsum.
Gypsum (CaSO4⋅2H2OCaSO_4 \cdot 2H_2O) is interground with cement clinker (around 2–3%) specifically to control and retard the rate of setting, allowing sufficient time for mixing, transporting, and placing concrete. Thus, Statement 1 is correct.
Gypsum reacts with tricalcium aluminate to form calcium sulfoaluminate (ettringite), which coats aluminate grains and retards early hydration.
2
Analyze Statement 2 regarding Dicalcium Silicate (C2SC_2S).
Tricalcium silicate (3CaO⋅SiO23CaO \cdot SiO_2 or C3SC_3S) hydrates rapidly and is responsible for early strength development (7 to 14 days). Dicalcium silicate (C2SC_2S) hydrates slowly and contributes to long-term progressive strength (beyond 28 days). Thus, Statement 2 is incorrect.
Confusing the hydration rates and strength contribution timelines of C3SC_3S and C2SC_2S is a common error in industrial chemistry.
3
Analyze Statement 3 regarding Tricalcium Aluminate (C3AC_3A).
Tricalcium aluminate (C3AC_3A) reacts violently and instantaneously with water, generating a high heat of hydration and leading to immediate hardening known as 'flash set'. Thus, Statement 3 is correct.
Without gypsum, C3AC_3A leads to premature flash setting, rendering the cement unworkable.

Anahtar Kavram

Chemical Composition and Hydration Reactions of Portland Cement
Soru 208Soru →

Match List-I (Plant Biotechnology Techniques) with List-II (Primary Biological Objective or Application) and select the correct matching pairs.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Meristem tip culture
Anther culture
Protoplast fusion
Embryo rescue

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Meristem tip culture matches with eradication of systemic plant viruses; Anther culture matches with development of haploid plants and immediate homozygous lines; Protoplast fusion matches with generation of somatic hybrids between sexually incompatible crop species; Embryo rescue matches with overcoming post-zygotic seed abortion in wide interspecific hybridization.
Each plant biotechnology technique targets a specific physiological barrier or breeding objective: Meristem tip culture leverages virus-free apical cells; Anther culture utilizes haploid gametocytes for rapid homozygosity; Protoplast fusion bypasses sexual hybridization barriers via somatic cell fusion; Embryo rescue prevents hybrid embryo breakdown due to endosperm incompatibility.

Adım Adım Çözüm

1
Analyze Meristem tip culture
Meristematic cells divide faster than viral replication rates and lack functional vascular connection (phloem), making them ideal for virus eradication.
Identify the primary agronomic benefit of shoot apical meristem culture.
2
Analyze Anther culture
Microspores contained in anthers are haploid (nn). Culturing them produces haploid plants which can be doubled to produce dihaploid homozygous lines.
Link male gametophytic tissue culture with rapid haploid breeding.
3
Analyze Protoplast fusion
Removing cell walls produces naked protoplasts that can be fused chemically (PEG) or electrically to form somatic hybrids.
Bypass sexual incompatibility barriers at the somatic cell level.
4
Analyze Embryo rescue
In interspecific crosses, endosperm often fails to develop, causing embryo breakdown. Excision and in vitro culture saves the hybrid embryo.
Resolve post-zygotic barriers in wide hybridization.

Anahtar Kavram

Plant tissue culture techniques and their biotechnological applications in crop improvement
Soru 209Soru →

With reference to cybersecurity protocols and network vulnerability vectors, consider the following statements:

1. DNS Cache Poisoning involves corrupting a Domain Name System resolver's cache so that requests for a legitimate domain redirect network traffic to an unauthorized server.
2. Domain Name System Security Extensions (DNSSEC) prevent spoofing by encrypting the data payload transferred between DNS clients and servers to ensure privacy.
3. Address Resolution Protocol (ARP) spoofing operates at Layer 2 (Data Link Layer) of the OSI model by broadcasting forged messages to associate an IP address with a malicious MAC address.

Which of the statements given above are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 3 only

Cevap

Statements 1 and 3 are correct.
The statement specifying '1 and 3 only' is correct. Statement 1 accurately defines DNS cache poisoning as a mechanism to hijack DNS lookups. Statement 3 correctly identifies that ARP spoofing functions at Layer 2 (Data Link Layer) of the OSI model. Statement 2 is incorrect because DNSSEC provides cryptographic authentication and integrity verification through digital signatures; it does not provide encryption or payload confidentiality.

Adım Adım Çözüm

1
Evaluate Statement 1 regarding DNS Cache Poisoning
Statement 1 is correct.
DNS cache poisoning introduces false address records into a DNS resolver's cache, causing it to return an incorrect IP address and diverting traffic to a malicious website.
2
Evaluate Statement 2 regarding DNSSEC functionality
Statement 2 is incorrect.
DNSSEC adds cryptographic signatures to existing DNS records to verify data origin and integrity. It does NOT encrypt the data payload or provide confidentiality/privacy for DNS queries (which is handled by DNS over HTTPS or DNS over TLS).
3
Evaluate Statement 3 regarding ARP Spoofing OSI layer and mechanism
Statement 3 is correct.
Address Resolution Protocol (ARP) works at the Data Link Layer (Layer 2) to resolve IP addresses to MAC addresses on local area networks. ARP spoofing sends forged ARP responses to map a legitimate IP to an attacker's MAC address.

Anahtar Kavram

Cybersecurity Threats and Protocol Vulnerabilities (DNS Cache Poisoning, DNSSEC authentication vs encryption, ARP Spoofing)
Tahmini Süre:1m 30s
Soru 210Soru →

With reference to the applications of nanotechnology in modern agriculture, consider the following statements:

1. Nano-encapsulated pesticides allow targeted, controlled release of active chemical ingredients, thereby minimizing runoff and environmental contamination.
2. Nano-fertilizers increase nutrient uptake efficiency in crops by facilitating enhanced penetration through plant stomata and root membranes.
3. Nano-silver particles are widely incorporated into bio-fertilizers because they specifically promote the growth and colonization of beneficial nitrogen-fixing soil bacteria and mycorrhizal fungi.

Which of the statements given above is/are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 2 only

Cevap

1 and 2 only
The correct response identifies Statements 1 and 2 as accurate applications of agri-nanotechnology. Controlled release via nano-capsules prevents environmental pollution, and small particle size boosts plant cellular transport. Statement 3 is false because silver nanoparticles exert toxic antimicrobial effects on symbiotic soil bacteria and fungi.

Adım Adım Çözüm

1
Evaluate Statement 1 on nano-encapsulated pesticides
Statement 1 is correct.
Polymeric or lipid-based nano-encapsulation shields active pesticide molecules from premature chemical degradation (via UV or hydrolysis), enabling slow, site-specific delivery and reducing pesticide leaching.
2
Evaluate Statement 2 on nano-fertilizers nutrient uptake
Statement 2 is correct.
Due to their ultra-small size (<100 nm) and high surface area, nano-fertilizers pass through plant cuticle micro-pores and stomatal openings more efficiently than conventional macromolecular chemical fertilizers.
3
Evaluate Statement 3 on nano-silver interaction with beneficial soil microbes
Statement 3 is incorrect.
Nano-silver (AgNPs) releases silver ions (Ag+Ag^+) that disrupt bacterial cell walls and metabolic enzymes. Consequently, nano-silver exhibits non-selective bactericidal and fungicidal activity, which can inhibit beneficial soil bacteria (like Rhizobium and Azotobacter) and mycorrhizal fungi rather than promoting them.

Anahtar Kavram

Applications and ecotoxicology of agricultural nanotechnology (nano-fertilizers, nano-pesticides, and antimicrobial silver nanoparticles).
Soru 211Soru →

In culinary and food chemistry, baking powder is prepared by mixing baking soda (NaHCO3\text{NaHCO}_3) with a mild edible organic acid such as tartaric acid. What is the primary purpose of incorporating this edible acid into the formulation?

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Cevap: To neutralize the alkaline sodium carbonate formed upon heating and prevent a bitter taste

Cevap

The primary purpose is to neutralize the alkaline sodium carbonate formed upon heating and prevent a bitter taste in the finished food product.
When baking soda (NaHCO3 \text{NaHCO}_3 ) is heated during baking, it undergoes thermal decomposition to release carbon dioxide gas along with sodium carbonate (Na2CO3 \text{Na}_2\text{CO}_3 ). Sodium carbonate is an alkaline compound that imparts an unpleasant bitter taste and yellowish hue to baked items. Adding an edible acid, such as tartaric acid or cream of tartar, supplies hydrogen ions that neutralize the basic sodium carbonate to form harmless, neutral sodium salts, thereby eliminating bitterness and facilitating smooth dough rising.

Adım Adım Çözüm

1
Analyze the thermal decomposition reaction of pure baking soda (NaHCO3 \text{NaHCO}_3 )
Heating baking soda alone yields sodium carbonate, water, and carbon dioxide: 2NaHCO3→ΔNa2CO3+H2O+CO2↑2\text{NaHCO}_3 \xrightarrow{\Delta} \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2 \uparrow
Understanding the byproduct of unneutralized baking soda reveals the chemical challenge in baking.
2
Determine the chemical properties of the reaction byproduct (Na2CO3 \text{Na}_2\text{CO}_3 )
Sodium carbonate (Na2CO3 \text{Na}_2\text{CO}_3 ) is a basic/alkaline salt that imparts an unpalatable bitter taste and a yellowish tinge to bread and cakes.
Alkaline compounds possess an inherently bitter flavor and affect food texture and aesthetics.
3
Evaluate the neutralizing role of the added edible acid (tartaric acid / C4H6O6 \text{C}_4\text{H}_6\text{O}_6 )
The acid provides H+ \text{H}^+ ions that react with Na2CO3 \text{Na}_2\text{CO}_3 (or directly with NaHCO3 \text{NaHCO}_3 in the presence of moisture), producing sodium tartrate, water, and extra CO2 \text{CO}_2 gas: NaHCO3+H+→Na++H2O+CO2↑\text{NaHCO}_3 + \text{H}^+ \rightarrow \text{Na}^+ + \text{H}_2\text{O} + \text{CO}_2 \uparrow
Neutralization eliminates the alkaline residue, removing bitterness while ensuring maximum leavening action.

Anahtar Kavram

Chemical leavening mechanism of baking powder and neutralization of alkaline residues by edible acids
Tahmini Süre:1m 0s
Soru 212Soru →

Soaps and synthetic detergents are essential cleansing agents with distinct chemical structures and behaviors in aqueous environments. Which of the following statements regarding soaps and synthetic detergents are correct? (Select all correct options)

Geçerli olan tümünü seçin

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Cevap: Soaps are sodium or potassium salts of higher fatty acids produced by the alkaline hydrolysis (saponification) of natural fats and oils.; Synthetic detergents function effectively in hard water because their calcium and magnesium salts are soluble in water.

Cevap

The statements confirming that soaps are sodium or potassium salts of higher fatty acids obtained via saponification and that synthetic detergents clean effectively in hard water due to the solubility of their calcium and magnesium salts are both correct.
Soaps are produced through alkaline saponification of esters of fatty acids (triglycerides) using sodium or potassium hydroxide. Synthetic detergents maintain cleansing efficacy in hard water because their corresponding calcium and magnesium salts do not precipitate out as scum, remaining completely soluble in aqueous solution.

Adım Adım Çözüm

1
Analyze the chemical composition and synthesis of conventional soaps.
Soaps are sodium or potassium salts of long-chain fatty acids (such as stearic, oleic, and palmitic acids) produced by heating triglycerides with alkali solutions (NaOHNaOH or KOHKOH) during saponification.
Establishing the fundamental chemical identity of soaps confirms the accuracy of the statement describing alkaline hydrolysis.
2
Evaluate the behavior of synthetic detergents versus soaps in hard water.
Hard water contains dissolved Ca2+Ca^{2+} and Mg2+Mg^{2+} ions. Soaps react with these ions to form insoluble curds (scum), whereas synthetic detergents form soluble calcium and magnesium salts, allowing uninterrupted lathering.
Assessing ionic interaction explains why synthetic detergents overcome the functional limitations of soap in hard water.
3
Differentiate between sodium/potassium soaps and anionic/cationic detergent classifications.
Potassium soaps are softer and more soluble (used in toilet soaps and shaving creams), and sodium alkyl sulfates are anionic (not cationic) detergents.
Validating physical properties and surfactant ionic charges eliminates the remaining inaccurate statements.

Anahtar Kavram

Chemical nature, saponification, surfactant classification, and hard water reactivity of soaps versus synthetic detergents.
Tahmini Süre:1m 15s
Soru 213Soru →

Consider the following statements regarding chemical compounds commonly used as therapeutic agents and food additives in daily life:

1. A 0.2%0.2\% aqueous solution of phenol acts as an antiseptic, whereas its 1.0%1.0\% solution functions as a disinfectant.
2. Aspartame is widely used as an artificial sweetener in baked confectionery due to its high thermal stability at baking temperatures.
3. Bithionol is compounded into toilet soaps to impart antiseptic and antimicrobial properties.

Which of the statements given above is/are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 3 only

Cevap

1 and 3 only
The combination stating '1 and 3 only' is correct because dilute phenol (0.2%0.2\%) serves as an antiseptic while 1.0%1.0\% phenol functions as a disinfectant, and bithionol is the standard chemical additive used to confer antiseptic qualities to cleansing soaps. Aspartame decomposes at high baking temperatures and is therefore unusable in cooked confectionery.

Adım Adım Çözüm

1
Analyze statement 1 regarding the antiseptic versus disinfectant properties of phenol
Statement 1 is valid
Phenol behaves differentially based on concentration: a dilute 0.2%0.2\% solution is safe for application on living tissues (antiseptic), while a stronger 1.0%1.0\% solution is toxic to living tissues and used for inanimate surfaces (disinfectant).
2
Analyze statement 2 regarding the thermal behavior and practical applications of aspartame
Statement 2 is invalid
Aspartame (the methyl ester of aspartic acid/phenylalanine dipeptide) is roughly 100 times sweeter than cane sugar but is thermolabile; it decomposes at cooking and baking temperatures, restricting its application strictly to cold foods and soft drinks.
3
Analyze statement 3 regarding the role of bithionol in personal care products
Statement 3 is valid
Bithionol (bithional) is a halogenated phenolic compound systematically added to toilet soaps to impart antiseptic properties and curb the bacterial degradation of sweat.

Anahtar Kavram

Chemical Classification and Everyday Applications of Antiseptics, Disinfectants, and Artificial Sweeteners
Tahmini Süre:1m 0s
Soru 214Soru →

Synthetic polymers and resins serve specialized functions in household items and engineering materials due to their distinct thermal and mechanical properties. Match each polymer listed in List I with its primary daily life or industrial application in List II:

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Öğeler

Teflon (Polytetrafluoroethylene)
Bakelite (Phenol-Formaldehyde Resin)
Melamine (Melamine-Formaldehyde Resin)
Kevlar (Poly-para-phenylene terephthalamide)

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Teflon matches with non-stick cookware coatings; Bakelite matches with electrical switches and heat-resistant handles; Melamine matches with shatter-resistant dinnerware; Kevlar matches with bulletproof protective gear.
Teflon is chemically inert and non-adhesive, making it the premier coating for non-stick cookware. Bakelite is an electrical insulator and heat-resistant thermoset suited for switches and cookware handles. Melamine provides a hard, glossy, shatter-proof finish ideal for dinnerware. Kevlar possesses ultra-high tensile strength essential for ballistic armor.

Adım Adım Çözüm

1
Determine the primary application of Teflon
Teflon (polytetrafluoroethylene) is characterized by carbon-fluorine bonds providing non-stick and hydrophobic properties, matching non-stick cookware coating.
Its non-reactivity and low surface energy prevent adhesion of oils and foods.
2
Determine the primary application of Bakelite
Bakelite is an early synthetic thermoset used for electrical fittings and cookware handles.
It does not soften upon heating and is a non-conductor of electricity.
3
Determine the primary application of Melamine
Melamine resin matches unbreakable crockery and dinnerware.
The condensation polymer of melamine and formaldehyde yields high surface hardness and fracture resistance.
4
Determine the primary application of Kevlar
Kevlar matches bulletproof vests and high-tensile armor.
Aromatic polyamide chains align in parallel crystalline arrays, yielding extreme tensile strength per unit weight.

Anahtar Kavram

Structure-property relationships and industrial applications of commercial polymers and thermosetting resins
Tahmini Süre:1m 0s
Soru 215Soru →

In chemical industry and metallurgy, gaseous fuels synthesized from carbonaceous feedstocks are categorized based on their manufacturing process and chemical composition. Which of the following statements correctly distinguishes Water Gas from Producer Gas?

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Cevap: Water gas is an industrial fuel mixture of carbon monoxide and hydrogen (CO+H2\text{CO} + \text{H}_2) produced by passing steam over red-hot coke, whereas producer gas is a mixture of carbon monoxide and nitrogen (CO+N2\text{CO} + \text{N}_2) produced by passing air over incandescent coke.

Cevap

Water gas is a mixture of carbon monoxide and hydrogen (CO+H2\text{CO} + \text{H}_2) produced by passing steam over red-hot coke, whereas producer gas is a mixture of carbon monoxide and nitrogen (CO+N2\text{CO} + \text{N}_2) produced by passing air over incandescent coke.
The correct option accurately outlines the chemical definitions of both fuel gases. Water gas is prepared industrially by blowing steam through a bed of red-hot carbon/coke (C+H2O→CO+H2\text{C} + \text{H}_2\text{O} \rightarrow \text{CO} + \text{H}_2), yielding carbon monoxide and hydrogen. Producer gas is produced when air is passed over incandescent carbon (2C+O2+4N2→2CO+4N22\text{C} + \text{O}_2 + 4\text{N}_2 \rightarrow 2\text{CO} + 4\text{N}_2), resulting in a fuel gas dominated by carbon monoxide and atmospheric nitrogen.

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1
Identify the industrial synthesis and composition of Water Gas (Synthesis Gas / Syngas)
Water gas is manufactured by passing superheated steam over red-hot incandescent coke at approximately 1000∘C1000^\circ\text{C} according to the endothermic reaction: C(s)+H2O(g)→CO(g)+H2(g)\text{C(s)} + \text{H}_2\text{O(g)} \rightarrow \text{CO(g)} + \text{H}_2\text{(g)}. Its major combustible constituents are carbon monoxide and hydrogen in approximately equimolar proportion.
Establishing the precise chemical equation confirms that water gas consists essentially of CO\text{CO} and H2\text{H}_2.
2
Identify the industrial synthesis and composition of Producer Gas
Producer gas is manufactured by blowing a controlled stream of dry air over incandescent coke or coal in a furnace producer: 2C(s)+O2(g)+4N2(g)→2CO(g)+4N2(g)2\text{C(s)} + \text{O}_2\text{(g)} + 4\text{N}_2\text{(g)} \rightarrow 2\text{CO(g)} + 4\text{N}_2\text{(g)}. Because atmospheric air contains nearly 78%78\% nitrogen by volume, the resulting gas consists mainly of combustible carbon monoxide (∼30%\sim 30\%) and non-combustible nitrogen gas (∼60%\sim 60\%).
Air-blown gasification introduces atmospheric nitrogen, differentiating producer gas from steam-blown water gas.
3
Evaluate the choices to select the accurate distinction
The option defining water gas as CO+H2\text{CO} + \text{H}_2 (from steam and coke) and producer gas as CO+N2\text{CO} + \text{N}_2 (from air and coke) provides the exact chemical and technological distinction.
Matches established chemical metallurgy and industrial gas standards tested in State PSC examinations.

Anahtar Kavram

Industrial Fuel Gases: Composition and Synthesis of Water Gas vs Producer Gas
Tahmini Süre:1m 0s
Soru 216Soru →

Consider the following statements regarding chemical fertilizers and their industrial applications in agriculture:

1. Urea (NH2CONH2\text{NH}_2\text{CONH}_2) has the highest nitrogen content (approximately 46%46\%) among all solid commercial nitrogenous fertilizers, supplying nitrogen in the amide form.
2. Single Superphosphate (SSP) is manufactured industrially by digesting ground rock phosphate with concentrated nitric acid.
3. Neem-coating of urea retards the activity of nitrifying bacteria in the soil, thereby decreasing nitrogen loss via leaching and volatilization.

Which of the statements given above are correct?

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Cevap: 1 and 3 only

Cevap

Statements 1 and 3 only are correct.
The correct selection includes statements 1 and 3. Urea contains 46%46\% nitrogen by mass in amide form, representing the highest concentration among solid nitrogenous fertilizers. Neem coating provides natural triterpenoids that function as nitrification inhibitors, slowing the transformation of ammonium to nitrate and mitigating leaching and denitrification losses. The second statement is incorrect because Single Superphosphate is industrially manufactured using concentrated sulfuric acid rather than nitric acid.

Adım Adım Çözüm

1
Evaluate the composition and nitrogen delivery mechanism of urea (Statement 1).
Urea (NH2CONH2\text{NH}_2\text{CONH}_2) has a molar mass of 60 g/mol60\text{ g/mol} with two nitrogen atoms contributing 28 g/mol28\text{ g/mol} (2860×100≈46.6%\frac{28}{60} \times 100 \approx 46.6\%). It delivers nitrogen in amide form which is converted to ammoniacal and nitrate forms in soil.
Confirming the exact chemical formulation and percentage composition validates the first statement.
2
Analyze the industrial synthesis of Single Superphosphate (Statement 2).
Single Superphosphate (SSP) is produced by reacting insoluble fluorapatite/rock phosphate (Ca3(PO4)2\text{Ca}_3(\text{PO}_4)_2) with concentrated sulfuric acid (H2SO4\text{H}_2\text{SO}_4) to form water-soluble monocalcium phosphate (Ca(H2PO4)2\text{Ca}(\text{H}_2\text{PO}_4)_2) and gypsum (CaSO4⋅2H2O\text{CaSO}_4\cdot2\text{H}_2\text{O}). Treatment with nitric acid produces nitrophosphate instead.
Identifying the specific mineral acid used in industrial phosphorus fertilizer manufacture shows the second statement is false.
3
Assess the chemical and biological function of neem-coated urea (Statement 3).
Neem oil contains bioactive triterpenoids that inhibit *Nitrosomonas* and *Nitrobacter* soil bacteria, slowing the oxidative conversion of ammonium into highly leachable nitrate.
Verifying the nitrification inhibition property confirms that the third statement is correct.

Anahtar Kavram

Chemical composition, industrial synthesis, and biochemical efficiency mechanisms of nitrogenous and phosphatic fertilizers.
Tahmini Süre:1m 15s
Soru 217Soru →

Match the evolutionary theories and biological principles in List-I with their primary explanatory mechanisms in List-II:

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Lamarckism
Darwinism
Mutation Theory
Germplasm Theory

Eşleşmeler

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Cevap

Lamarckism corresponds to the inheritance of acquired traits via use and disuse; Darwinism corresponds to differential survival and reproductive success driving adaptation; Mutation Theory corresponds to sudden discontinuous variations; and Germplasm Theory corresponds to genetic transmission occurring strictly through germ cells.
Each evolutionary concept is correctly paired with its foundational principle: Lamarckism with the inheritance of acquired characteristics through use and disuse; Darwinism with natural selection via differential reproduction; Mutation Theory with sudden, discontinuous saltatory changes; and Germplasm Theory with the strict segregation and heritability of germline cells.

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1
Identify the foundational mechanism of Lamarckism
Lamarckism matches with phenotypic modifications developed through use and disuse being inherited.
Jean-Baptiste Lamarck proposed that environmental needs induce physiological changes in somatic organs which are then transmitted to subsequent generations.
2
Identify the foundational mechanism of Darwinism
Darwinism matches with differential survival and reproductive success of organisms with favorable traits.
Charles Darwin established natural selection as the mechanism whereby organisms possessing beneficial variations survive and reproduce at higher rates.
3
Identify the core principle of Hugo de Vries's Mutation Theory
Mutation Theory matches with evolution proceeding through sudden, discontinuous single-step large variations.
Hugo de Vries posited that speciation is caused by sudden, discrete genetic alterations (saltations) rather than gradual continuous variations.
4
Identify the core concept of August Weismann's Germplasm Theory
Germplasm Theory matches with inheritance operating exclusively through reproductive germ cells.
August Weismann experimentally showed that changes in the somatoplasm cannot reach the germplasm, precluding the inheritance of acquired somatic traits.

Anahtar Kavram

Foundational Theories and Mechanisms of Biological Evolution
Tahmini Süre:1m 15s
Soru 218Soru →

In the study of molecular genetics and evolutionary biology, sickle-cell anemia serves as a classic model of interaction between genetic mutations and natural selection. Which of the following statements correctly describes the genetic basis of sickle-cell anemia and its evolutionary significance in human populations?

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Cevap: It is caused by a point mutation in the beta-globin gene, and heterozygous individuals exhibit higher survival rates in malaria-endemic regions due to balancing selection.

Cevap

It is caused by a point mutation in the beta-globin gene, and heterozygous individuals exhibit higher survival rates in malaria-endemic regions due to balancing selection.
The choice stating that sickle-cell anemia is caused by a point mutation in the beta-globin gene and maintained by balancing selection due to malaria resistance is correct. A point mutation at the sixth codon of the beta-globin gene (HBBHBB) substitutes glutamic acid with valine. In malaria-endemic geographical zones, heterozygous individuals (HbA/HbSHb^A/Hb^S) possess a distinct survival advantage against severe *Plasmodium falciparum* malaria while avoiding the fatal complications of homozygous sickle-cell anemia (HbS/HbSHb^S/Hb^S), exemplifying heterozygote advantage under balancing natural selection.

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1
Identify the molecular and genetic basis of sickle-cell anemia
Sickle-cell disease is caused by a single nucleotide substitution (point mutation/transversion of A to T) in the sixth codon of the beta-globin (HBBHBB) gene on chromosome 11, replacing hydrophilic glutamic acid with hydrophobic valine (GAG→GTGGAG \rightarrow GTG).
Establishes that the condition is a monogenic point mutation rather than a chromosomal anomaly or mitochondrial inheritance.
2
Analyze the physiological phenotype and evolutionary pressure in malaria-endemic areas
Heterozygous carriers (HbA/HbSHb^A/Hb^S) produce both normal and abnormal hemoglobin, causing red blood cells infected with *Plasmodium falciparum* to sickle prematurely and be cleared by the spleen before the parasite completes its intraerythrocytic cycle.
Identifies the specific biological mechanism granting resistance to severe falciparum malaria without causing full sickle-cell disease.
3
Apply the principles of population genetics and natural selection
Heterozygote advantage (overdominance) leads to balancing selection, which actively maintains both the normal HbAHb^A and mutant HbSHb^S alleles in human populations where malaria is endemic.
Connects molecular genetics to evolutionary mechanisms.

Anahtar Kavram

Molecular point mutation in hemoglobin beta chain and balancing selection via heterozygote advantage against falciparum malaria
Tahmini Süre:1m 0s
Soru 219Soru →

In evolutionary biology, comparative anatomy provides evidence of common ancestry and evolutionary adaptation through homologous and analogous organs. Which of the following pairs of anatomical structures represents homologous organs resulting from divergent evolution?

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Cevap: Forelimbs of cheetahs and wings of bats

Cevap

Forelimbs of cheetahs and wings of bats
The forelimbs of cheetahs and the wings of bats are homologous organs because they share a common basic anatomical framework—the vertebrate pentadactyl limb—inherited from a common ancestor. Divergent evolution led these structures to adapt to distinct functional demands, such as rapid terrestrial running in cheetahs and powered flight in bats.

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1
Define homologous structures and divergent evolution in the context of comparative anatomy
Homologous organs are structures in different organisms that share a common embryonic origin and basic anatomical architecture derived from a common ancestor, but have evolved different functions (divergent evolution).
Establishing the defining criteria differentiates homology from analogy.
2
Evaluate the anatomical composition and lineage of the forelimbs of cheetahs and the wings of bats
Both cheetah forelimbs (adapted for running) and bat wings (adapted for flying) possess the fundamental vertebrate pentadactyl plan consisting of the humerus, radius, ulna, carpals, metacarpals, and phalanges.
Shared structural plan despite divergent functional adaptation confirms homology.
3
Contrast with analogous structures formed by convergent evolution
Pairs such as butterfly wings/bird wings, octopus eyes/mammal eyes, and shark fins/dolphin flippers do not share a common structural origin and represent convergent adaptations (analogy).
Eliminates distractors that represent convergent evolutionary adaptations.

Anahtar Kavram

Homologous Organs and Divergent Evolution
Tahmini Süre:1m 0s
Soru 220Soru →

With reference to meiotic cell division in sexually reproducing organisms, arrange the following events occurring during Prophase I in their correct chronological sequence from earliest to latest:

Öğeleri doğru sıraya koymak için sürükleyin

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Cevap

Pairing of homologous chromosomes (synapsis) → Exchange of genetic material (crossing over) → Dissolution of synaptonemal complex with visible chiasmata → Terminalization of chiasmata and nuclear envelope breakdown
Prophase I of meiosis comprises five distinct chronological sub-stages: Leptotene (compaction of chromosomes), Zygotene (synapsis and formation of synaptonemal complex), Pachytene (crossing over between non-sister chromatids), Diplotene (dissolution of the synaptonemal complex and visibility of chiasmata), and Diakinesis (terminalization of chiasmata and breakdown of the nuclear envelope). Therefore, synapsis precedes crossing over, followed by chiasmata emergence and subsequent terminalization.

Adım Adım Çözüm

1
Identify the stage associated with chromosome pairing and synapsis
Synapsis occurs during Zygotene, where homologous chromosomes align and form the synaptonemal complex.
Physical pairing of homologues must precede any coordinated reciprocal genetic exchange.
2
Identify the stage associated with genetic recombination
Crossing over occurs during Pachytene, facilitated by the recombinase enzyme complex at recombination nodules.
Recombination takes place between aligned non-sister chromatids within the established bivalent.
3
Identify the stage characterized by synaptonemal complex dissolution and chiasmata formation
During Diplotene, the synaptonemal complex dissolves, and homologous chromosomes separate except at crossover sites (chiasmata).
The structural dissolution reveals the physical crossing points between non-sister chromatids.
4
Identify the final sub-stage of Prophase I
During Diakinesis, chiasmata shift to chromosome ends (terminalization), the spindle apparatus forms, and the nuclear envelope and nucleolus disappear.
This completes Prophase I and prepares the cell for Metaphase I alignment.

Anahtar Kavram

Sequential sub-stages of Prophase I in Meiosis: Leptotene → Zygotene → Pachytene → Diplotene → Diakinesis
Tahmini Süre:1m 15s
ÖncekiSayfa 11 / 12Sonraki
General Science and Technology Alıştırma Soruları — State PSC Exam — Sayfa 11 | Examkin