Examkin

General Science and Technology

222 soru

Tüm türler222Çoktan seçmeli117Çoklu seçim40Doğru / Yanlış8Eşleştirme44Sıralama13
Soru 61Soru →

Consider the following statements regarding common human communicable diseases:

1. Typhoid fever is a bacterial infection caused by *Salmonella typhi*, primarily spread through contaminated food and water.
2. Ringworm is a contagious dermatological condition caused by a protozoan parasite.
3. Hepatitis B is a viral infection targeting the liver, primarily transmitted through exposure to infective blood and body fluids.

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.
Statements 1 and 3 are accurate. Typhoid fever is a bacterial disease caused by *Salmonella typhi* spread via contaminated water/food. Hepatitis B is a viral disease caused by HBV transmitted through contact with infected blood or body fluids. Statement 2 is incorrect because Ringworm is caused by dermatophytic fungi (such as *Trichophyton*), not by a protozoan parasite.

Adım Adım Çözüm

1
Evaluate Statement 1 regarding Typhoid fever etiology and transmission.
Statement 1 is correct.
Typhoid fever is a systemic bacterial infection caused by Salmonella enterica serotype Typhi (*Salmonella typhi*), transmitted via the fecal-oral route through contaminated water and food.
2
Evaluate Statement 2 regarding Ringworm pathogen type.
Statement 2 is incorrect.
Ringworm (tinea) is a fungal skin infection caused by dermatophyte fungi such as *Trichophyton*, *Microsporum*, or *Epidermophyton*, not a protozoan parasite.
3
Evaluate Statement 3 regarding Hepatitis B infection.
Statement 3 is correct.
Hepatitis B is an infectious liver disease caused by the Hepatitis B virus (HBV), transmitted through percutaneous or mucosal exposure to infectious blood or body fluids.

Anahtar Kavram

Classification of human infectious diseases based on causative pathogens (Bacterial, Fungal, Viral, Protozoan)
Soru 62Soru →

Which of the following statements correctly describe the physics principles governing everyday light and optical phenomena?

Geçerli olan tümünü seçin

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Cevap: The formation of a primary rainbow involves a combination of refraction, internal reflection, and dispersion of sunlight within falling raindrops.; An optical fiber transmits light signals over long distances with minimal signal loss primarily through continuous total internal reflection.

Cevap

The correct statements are those identifying that rainbow formation involves refraction, internal reflection, and dispersion within raindrops, and that optical fibers transmit light via continuous total internal reflection.
Rainbow formation accurately combines refraction, dispersion, and internal reflection inside water droplets. Optical fibers operate on the principle of total internal reflection, keeping light guided within the high-index core over long distances.

Adım Adım Çözüm

1
Evaluate the mechanism of rainbow formation
Sunlight refracts upon entering a raindrop, separates into component colors (dispersion), reflects internally from the back surface, and refracts again upon leaving the droplet. Thus, the statement regarding rainbow formation is correct.
Raindrops act as natural prisms and spherical mirrors combining refraction, reflection, and dispersion.
2
Evaluate the mechanism of mirage formation
Sunlight traveling through hot air near the ground bends continuously due to varying refractive indices (refraction) until it undergoes total internal reflection toward the observer's eye, creating an inverted image that resembles water. Attributing this to diffraction in uniform air is incorrect.
Diffraction involves bending around obstacles, whereas mirages depend on density gradients and refraction/reflection.
3
Evaluate light propagation in optical fibers
Optical fibers consist of a high-refractive-index core surrounded by lower-index cladding. Light signals strike the core-cladding boundary at angles exceeding the critical angle, causing continuous total internal reflection. Thus, this statement is correct.
Total internal reflection traps light within the fiber core with negligible intensity loss.
4
Evaluate the cause of the blue sky
Molecules of nitrogen and oxygen in the atmosphere scatter shorter wavelengths (blue light) much more effectively than longer wavelengths (red light), a phenomenon known as Rayleigh scattering. Attributing the blue sky to total internal reflection off water droplets is incorrect.
Scattering intensity is inversely proportional to the fourth power of wavelength (I∝1/λ4I \propto 1/\lambda^4).

Anahtar Kavram

Everyday Applications of Optical Phenomena (Refraction, Dispersion, Rayleigh Scattering, and Total Internal Reflection)
Soru 63Soru →

Sodium bicarbonate is a chemical compound widely used in household baking, fire extinguishers, and antacids. Which of the following chemical formulas correctly represents sodium bicarbonate?

Cevabı ve açıklamayı göster

Cevap: NaHCO3\text{NaHCO}_3

Cevap

The chemical formula representing sodium bicarbonate (baking soda) is NaHCO3\text{NaHCO}_3.
The chemical formula NaHCO3\text{NaHCO}_3 represents sodium bicarbonate (also called sodium hydrogen carbonate), commonly known as baking soda.

Adım Adım Çözüm

1
Identify the chemical name and constituent ions
Sodium bicarbonate is composed of sodium ions (Na+\text{Na}^+) and hydrogen carbonate/bicarbonate ions (HCO3−\text{HCO}_3^-).
Chemical names directly correspond to the constituent cations and anions.
2
Combine the ions to write the neutral chemical formula
Combining Na+\text{Na}^+ and HCO3−\text{HCO}_3^- gives NaHCO3\text{NaHCO}_3.
The charges +1+1 and −1-1 balance directly in a 1:1 ratio.

Anahtar Kavram

Chemical Nomenclature and Daily Life Applications of Sodium Compounds
Soru 64Soru →

With reference to everyday chemical compounds and their industrial applications, consider the following statements:

1. Bleaching powder (CaOCl2CaOCl_2) acts as a strong oxidizing agent and liberates chlorine gas when reacting with atmospheric carbon dioxide.
2. Baking soda (NaHCO3NaHCO_3) decomposes thermally during cooking to produce oxygen gas, which causes dough to expand and rise.
3. Plaster of Paris (CaSO4⋅12H2OCaSO_4 \cdot \frac{1}{2}H_2O) is manufactured by heating gypsum at 373 K373\text{ K}, and sets into a hard solid mass of gypsum upon addition of water.

Which of the statements given above is/are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 3 only

Cevap

Statements 1 and 3 only are correct.
The correct response identifies statements 1 and 3 as true while recognizing statement 2 as false. Bleaching powder (CaOCl2CaOCl_2) reacts with atmospheric CO2CO_2 to release chlorine gas, acting as a strong oxidant. Plaster of Paris is produced by controlled heating of gypsum at 373 K373\text{ K} and hardens back into gypsum upon hydration. Baking soda releases carbon dioxide gas upon heating, not oxygen.

Adım Adım Çözüm

1
Analyze Statement 1 regarding bleaching powder (CaOCl2CaOCl_2).
Bleaching powder acts as a bleaching and oxidizing agent in various chemical industries. When exposed to atmospheric carbon dioxide, it reacts according to CaOCl2+CO2→CaCO3+Cl2↑CaOCl_2 + CO_2 \rightarrow CaCO_3 + Cl_2 \uparrow, releasing chlorine gas.
This confirms statement 1 is scientifically accurate.
2
Analyze Statement 2 regarding baking soda (NaHCO3NaHCO_3).
When heated during cooking, sodium hydrogen carbonate undergoes thermal decomposition: 2NaHCO3→ΔNa2CO3+H2O+CO2↑2 NaHCO_3 \xrightarrow{\Delta} Na_2CO_3 + H_2O + CO_2 \uparrow. The evolved gas is carbon dioxide (CO2CO_2), not oxygen (O2O_2).
Carbon dioxide bubbles trap in the dough, causing bread/cakes to rise and become soft and spongy. Therefore, statement 2 is incorrect.
3
Analyze Statement 3 regarding Plaster of Paris (CaSO4⋅12H2OCaSO_4 \cdot \frac{1}{2}H_2O).
Gypsum (CaSO4⋅2H2OCaSO_4 \cdot 2H_2O) loses three-fourths of its crystallization water when heated carefully at 373 K373\text{ K} (100∘C100^\circ\text{C}) to form calcium sulfate hemihydrate (Plaster of Paris). When mixed with water, it rehydrates to form hard crystalline gypsum.
This confirms statement 3 is scientifically accurate.

Anahtar Kavram

Chemical formulas, preparation methods, and everyday reactions of industrial salts (Bleaching powder, Baking soda, and Plaster of Paris).
Tahmini Süre:1m 30s
Soru 65Soru →

Scrub Typhus is an acute febrile infectious disease of significant public health concern in several regions of India. Which of the following statements correctly identifies the causative pathogen and primary vector responsible for transmitting this disease to humans?

Cevabı ve açıklamayı göster

Cevap: It is caused by the obligate intracellular bacterium Orientia tsutsugamushi and transmitted to humans by the larval stage of trombiculid mites.

Cevap

Scrub Typhus is caused by the obligate intracellular bacterium Orientia tsutsugamushi and is transmitted to humans by the larval stage of trombiculid mites (chiggers).
Scrub Typhus is a zoonotic rickettsial infection caused by Orientia tsutsugamushi. The disease is transmitted to humans when larval trombiculid mites (chiggers), belonging mainly to the genus Leptotrombidium, bite humans while feeding. A characteristic black eschar often forms at the bite site.

Adım Adım Çözüm

1
Identify the biological nature of the causative pathogen for Scrub Typhus
Orientia tsutsugamushi (formerly Rickettsia tsutsugamushi) is an obligate intracellular Gram-negative bacterium.
Establishing pathogen type differentiates bacterial rickettsial infections from viral and protozoan tropical diseases.
2
Identify the transmission vector and life cycle stage responsible for human infection
Human infection occurs via the bite of the larval stage ('chigger') of trombiculid mites (Leptotrombidium species).
Only the larval mites feed on tissue fluids of vertebrates; adult and nymphal mites live freely in the soil feeding on plant debris.
3
Distinguish Scrub Typhus etiology from other common endemic vector-borne diseases in India
Culex mosquitoes transmit Japanese Encephalitis virus; sandflies transmit Leishmania donovani; Salmonella Typhi spreads via contaminated water without a vector.
Systematically eliminates distractors presenting mismatched pathogen-vector pairs.

Anahtar Kavram

Disease Etiology and Vector Transmission of Scrub Typhus
Soru 66Soru →

Consider the following statements regarding major infectious human diseases, their causative pathogens, and vectors of public health importance:

1. Scrub Typhus is a bacterial disease caused by *Orientia tsutsugamushi* and is transmitted to humans through the bite of infected larval trombiculid mites (chiggers).
2. Japanese Encephalitis is a viral disease caused by a Flavivirus and is transmitted primarily by mosquitoes of the *Culex* genus, with pigs and wading birds acting as amplifying hosts.
3. Lymphatic Filariasis is a protozoan disease caused by *Wuchereria bancrofti* and is transmitted primarily by the bite of female *Phlebotomus* sandflies.

Which of the statements given above is/are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 2 only

Cevap

Statements 1 and 2 are correct, whereas Statement 3 is incorrect.
Scrub Typhus is caused by the bacterium Orientia tsutsugamushi and is transmitted by chigger mites. Japanese Encephalitis is caused by a mosquito-borne Flavivirus with pigs and ardeid birds serving as key amplifying hosts. Both Statements 1 and 2 are completely accurate. Statement 3 is false because Wuchereria bancrofti is a filarial nematode (helminth), not a protozoan, and its primary vector in India is the Culex quinquefasciatus mosquito rather than the sandfly.

Adım Adım Çözüm

1
Evaluate Statement 1 regarding Scrub Typhus.
Scrub Typhus is caused by Orientia tsutsugamushi (an obligate intracellular bacterium) and transmitted by larval trombiculid mites (chiggers). Statement 1 is factually correct.
Verify the pathogen category (bacterium) and vector (chigger mite) for Scrub Typhus.
2
Evaluate Statement 2 regarding Japanese Encephalitis.
Japanese Encephalitis is caused by the Japanese Encephalitis Virus (a single-stranded RNA virus of the genus Flavivirus) and transmitted principally by Culex tritaeniorhynchus mosquitoes, with pigs and water birds serving as amplifying reservoirs. Statement 2 is factually correct.
Verify the viral nature, mosquito vector family, and host reservoirs of Japanese Encephalitis.
3
Evaluate Statement 3 regarding Lymphatic Filariasis.
Lymphatic Filariasis is caused by parasitic filarial nematodes (roundworms/helminths) such as Wuchereria bancrofti and Brugia malayi. In India, its principal vector is the Culex quinquefasciatus mosquito. Sandflies (Phlebotomus species) transmit Visceral Leishmaniasis (Kala-azar), not filariasis. Thus, Statement 3 is incorrect.
Identify taxonomic misclassifications of the pathogen (helminth vs protozoan) and vector misattribution (mosquito vs sandfly).
4
Synthesize the statement evaluations to select the correct choice.
Only Statements 1 and 2 are correct.
Combine verified truth values of all three statements.

Anahtar Kavram

Classification of infectious human diseases by pathogen type (bacterial, viral, helminthic) and specific vector-host transmission dynamics.
Tahmini Süre:2m 0s
Soru 67Soru →

Match the essential vitamins listed in List-I with their corresponding deficiency disorders listed in List-II, and identify the correct pairs:

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Öğeler

Vitamin B1 (Thiamine)
Vitamin B3 (Niacin)
Vitamin C (Ascorbic Acid)
Vitamin D (Calciferol)

Eşleşmeler

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Cevap

Vitamin B1 (Thiamine) pairs with Beriberi; Vitamin B3 (Niacin) pairs with Pellagra; Vitamin C (Ascorbic Acid) pairs with Scurvy; Vitamin D (Calciferol) pairs with Rickets.
Each vitamin plays a specific biochemical role: Thiamine (B1) deficiency produces Beriberi; Niacin (B3) deficiency causes Pellagra; Ascorbic Acid (Vitamin C) deficiency causes Scurvy; and Calciferol (Vitamin D) deficiency leads to Rickets due to defective mineralization of bone matrix.

Adım Adım Çözüm

1
Analyze Vitamin B1 (Thiamine) function and deficiency.
Thiamine is critical for carbohydrate metabolism and nerve function. Deficiency causes Beriberi.
Matches Vitamin B1 to Beriberi.
2
Analyze Vitamin B3 (Niacin) function and deficiency.
Niacin is required for cellular respiration. Deficiency causes Pellagra.
Matches Vitamin B3 to Pellagra.
3
Analyze Vitamin C (Ascorbic Acid) function and deficiency.
Ascorbic acid is necessary for collagen formation and tissue repair. Deficiency causes Scurvy.
Matches Vitamin C to Scurvy.
4
Analyze Vitamin D (Calciferol) function and deficiency.
Calciferol regulates intestinal calcium uptake. Deficiency leads to Rickets in growing children.
Matches Vitamin D to Rickets.

Anahtar Kavram

Vitamin Deficiency Disorders and Human Nutritional Physiology
Soru 68Soru →

Vitamins are essential organic micronutrients required for key physiological functions in the human body. Which of the following statements regarding vitamins and deficiency disorders are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Vitamin A deficiency is associated with night blindness (nyctalopia) and xerophthalmia.; Vitamin C deficiency causes scurvy, characterized by bleeding gums and delayed wound healing.

Cevap

The statements highlighting that Vitamin A deficiency causes night blindness/xerophthalmia and Vitamin C deficiency leads to scurvy are correct. Rickets and scurvy are non-communicable nutritional deficiencies, not infectious diseases caused by viruses, protozoa, or vectors.
The statements asserting that Vitamin A deficiency leads to night blindness and Vitamin C deficiency causes scurvy are anatomically and physiologically accurate.

Adım Adım Çözüm

1
Analyze the physiological role of Vitamin A
Vitamin A is required for visual pigment formation in rod cells. Severe deficiency causes night blindness and xerophthalmia.
Establishes correct link between Vitamin A and its clinical deficiency manifestations.
2
Analyze the physiological role of Vitamin C
Vitamin C serves as a essential co-factor for collagen hydroxylases. Deficiency results in weak blood vessel walls, bleeding gums, and scurvy.
Establishes correct link between Vitamin C and collagen tissue integrity.
3
Evaluate statements regarding etiology of Rickets and Scurvy
Both conditions stem from nutritional deficiencies (Vitamin D/calcium and Vitamin C respectively). They are not infectious diseases transmitted by pathogens or vectors.
Differentiates non-communicable nutritional deficits from pathogen-driven infectious diseases.

Anahtar Kavram

Nutritional Deficiencies vs. Pathogenic Infectious Diseases
Soru 69Soru →

Consider the following physical observations commonly seen in daily life:

1. A straight pencil partially immersed in a glass of water appears bent at the air-water boundary.
2. Stars twinkle in the night sky when observed from the ground, whereas planets shine with a steady brightness.
3. The Sun appears slightly flattened (oval-shaped) near the horizon during sunrise and sunset.

Which of the following optical phenomena is primarily responsible for all three of these observations?

Cevabı ve açıklamayı göster

Cevap: Boundary and atmospheric refraction of light rays

Cevap

Boundary and atmospheric refraction of light rays is primarily responsible for all three observations.
The correct answer highlights boundary and atmospheric refraction of light rays. Refraction occurs when light alters its speed and direction upon moving through media of different optical densities. The apparent displacement of a submerged pencil, the scintillation (twinkling) of point-like starlight through turbulent air layers, and the vertical foreshortening (flattening) of the solar disk near the horizon are all classical manifestations of optical refraction.

Adım Adım Çözüm

1
Analyze Observation 1 (submerged pencil bending)
Light rays traveling from the submerged portion of the pencil pass from water (denser medium) into air (rarer medium), bending away from the normal. The eye traces these rays back in straight lines, making the pencil appear elevated and bent at the boundary.
This is a direct application of Snell's law of refraction at a sharp interface.
2
Analyze Observation 2 (twinkling of stars vs. steady planets)
Starlight traverses atmospheric layers of constantly fluctuating temperature and density, continuously changing its refractive index and causing the apparent position and brightness of the point-like star to fluctuate rapidly. Planets, being larger extended sources, average out these atmospheric refraction fluctuations.
Atmospheric refraction acting on point sources causes scintillation (twinkling).
3
Analyze Observation 3 (flattening of the Sun near the horizon)
Light from the lower edge of the Sun passes through a thicker and denser atmospheric layer than light from the upper edge, undergoing greater upward refraction. This vertical compression makes the circular solar disk appear flattened into an ellipse.
Differential atmospheric refraction causes unequal displacement between the top and bottom of the solar disk.
4
Synthesize the underlying unifying physical law
All three phenomena stem from the bending of light caused by variations in the refractive index of optical media, which is defined as refraction.
Identifying refraction as the common mechanism resolves the question.

Anahtar Kavram

Refraction of Light and Atmospheric Refraction
Tahmini Süre:1m 30s
Soru 70Soru →

Which of the following statements regarding polymers and their daily life or industrial applications are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Teflon (polytetrafluoroethylene) is used as a non-stick coating on cookware due to its high thermal stability and chemical inertness.; Bakelite is a thermosetting plastic used to make electrical switches and utensil handles because it is a poor conductor of electricity and heat.; Vulcanization of natural rubber involves heating raw rubber with elemental sulfur to improve its elasticity and tensile strength.

Cevap

The correct statements are those describing Teflon as a non-stick coating, Bakelite as a thermosetting plastic for electrical switches, and vulcanization of natural rubber using sulfur.
Teflon is resistant to heat and chemicals, making it ideal for non-stick cookware coatings. Bakelite is a thermosetting polymer used in heat-resistant handles and electrical appliances. Vulcanization cross-links rubber molecules with sulfur to make it stronger and more elastic. In contrast, PVC is a thermoplastic that can be repeatedly softened and reshaped upon heating.

Adım Adım Çözüm

1
Evaluate the properties of Teflon
Teflon (PTFE) is chemically inert and withstands high temperatures, so its application in non-stick cookware is correct.
Verify the household application of polytetrafluoroethylene.
2
Evaluate the classification and use of Bakelite
Bakelite is a phenol-formaldehyde resin classified as a thermosetting plastic, making it ideal for electrical fittings and cookware handles.
Confirm thermal and electrical conductivity characteristics.
3
Evaluate the classification of Polyvinyl chloride (PVC)
PVC is a thermoplastic, not a thermosetting plastic. It softens upon heating and can be recycled/reshaped.
Differentiate between thermoplastics and thermosetting plastics.
4
Evaluate the vulcanization process of rubber
Vulcanization uses sulfur to create disulfide bonds across polymer chains, enhancing elasticity and durability.
Verify the chemical process of rubber strengthening.

Anahtar Kavram

Classification and industrial applications of synthetic polymers and modified natural rubber
Soru 71Soru →

Match the chemical compounds and industrial materials in List-I with their corresponding primary application or functional property in List-II:

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Calcium Carbide (CaC2CaC_2)
Sodium Benzoate (C6H5COONaC_6H_5COONa)
Superphosphate of Lime
Bakelite Polymer

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Calcium Carbide matches with artificial fruit ripening via moisture-triggered acetylene generation; Sodium Benzoate matches with food preservation in acidic environments; Superphosphate of Lime matches with water-soluble phosphatic fertilizer production via sulfuric acid treatment of rock phosphate; and Bakelite Polymer matches with thermosetting resin used for electrical insulation and cookware handles.
Each compound is accurately matched with its primary chemical role: Calcium Carbide releases acetylene for fruit ripening; Sodium Benzoate serves as an acidic food preservative; Superphosphate of Lime provides water-soluble phosphorus for crops; and Bakelite provides heat-resistant electrical insulation as a thermosetting plastic.

Adım Adım Çözüm

1
Analyze the chemical reactivity and practical use of Calcium Carbide (CaC2CaC_2).
Calcium carbide undergoes hydrolysis upon contact with water to produce acetylene gas (C2H2C_2H_2) according to the reaction: CaC2+2H2O→Ca(OH)2+C2H2CaC_2 + 2H_2O \rightarrow Ca(OH)_2 + C_2H_2.
Acetylene gas acts as an analogue to ethylene, inducing artificial ripening in fruits like mangoes and bananas.
2
Determine the mode of action of Sodium Benzoate (C6H5COONaC_6H_5COONa).
In acidic media (such as fruit juices and carbonated beverages), sodium benzoate converts into undissociated benzoic acid.
The undissociated acid readily diffuses across microbial cell walls to disrupt glucose fermentation, acting as an effective preservative.
3
Evaluate the industrial synthesis of Superphosphate of Lime fertilizer.
Insoluble calcium phosphate mineral in rock phosphate is treated with sulfuric acid: Ca3(PO4)2+2H2SO4→Ca(H2PO4)2+2CaSO4Ca_3(PO_4)_2 + 2H_2SO_4 \rightarrow Ca(H_2PO_4)_2 + 2CaSO_4.
The resulting monocalcium phosphate is water-soluble, allowing plant roots to readily absorb bioavailable phosphate nutrients.
4
Identify the polymer structure and physical properties of Bakelite.
Bakelite is produced by step-growth condensation polymerization of phenol with formaldehyde in the presence of an acid or base catalyst.
Extensive 3D covalent cross-linking makes Bakelite a thermosetting plastic that does not melt upon heating, making it suitable for electrical switches and appliance handles.

Anahtar Kavram

Chemical compounds in daily life and industrial applications
Tahmini Süre:2m 0s
Soru 72Soru →

Consider the following statements regarding human infectious diseases and their etiology:

1. Kala-azar (Visceral Leishmaniasis) is caused by a protozoan parasite transmitted to humans through the bite of infected sandflies.
2. Human African Trypanosomiasis (Sleeping Sickness) is a bacterial infection transmitted by the bite of tsetse flies.
3. Dengue is a viral infection transmitted to humans through the bite of infected female Aedes aegypti mosquitoes.

Which of the statements given above are correct?

Cevabı ve açıklamayı göster

Cevap: 1 and 3 only

Cevap

Statements 1 and 3 are correct, while statement 2 is incorrect.
The correct response includes statements 1 and 3. Kala-azar is indeed a parasitic protozoan disease transmitted by sandflies, and Dengue is an arboviral disease transmitted by female Aedes mosquitoes. Statement 2 is incorrect because Sleeping Sickness is caused by protozoan parasites (Trypanosoma brucei), not bacteria.

Adım Adım Çözüm

1
Analyze statement 1
Kala-azar is caused by Leishmania parasites (protozoa) and spread by phlebotomine sandflies, making statement 1 true.
Verify the pathogen and vector for Kala-azar.
2
Analyze statement 2
Sleeping Sickness is caused by microscopic protozoan parasites of the species Trypanosoma brucei, not bacteria, making statement 2 false.
Verify the pathogen classification for Human African Trypanosomiasis.
3
Analyze statement 3
Dengue is caused by the Dengue virus (FLAVIVIRIDAE family) and transmitted by Aedes mosquitoes, making statement 3 true.
Verify the pathogen and vector for Dengue.

Anahtar Kavram

Distinction between protozoan, bacterial, and viral pathogens in vector-borne diseases
Tahmini Süre:1m 0s
Soru 73Soru →

Which of the following optical phenomena occurring in the Earth's atmosphere are primarily caused by atmospheric refraction of light?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: The apparent early sunrise and delayed sunset relative to the geometrical position of the Sun; The apparent twinkling of stars when viewed from the Earth's surface; The apparent flattened or oval shape of the Sun at sunrise and sunset

Cevap

The optical phenomena caused by atmospheric refraction are the apparent early sunrise and delayed sunset, the twinkling of stars, and the apparent vertical flattening of the Sun's disc near the horizon. The reddish appearance of the Sun during sunrise and sunset is caused by Rayleigh scattering of light.
Atmospheric refraction occurs because Earth's atmosphere becomes progressively denser toward the surface, continuously bending incoming light rays. This bending elevates the apparent position of celestial objects, creating the illusion of early sunrise and delayed sunset, flattens the Sun's disc due to unequal refraction at its top and bottom edges, and causes stars (point sources) to twinkle as light passes through shifting air layers.

Adım Adım Çözüm

1
Identify the primary mechanism of atmospheric refraction
Light bends toward the normal as it moves from optically rarer outer atmospheric layers to denser layers near Earth's surface.
Gradual variation in atmospheric density creates a refractive index gradient.
2
Evaluate atmospheric refraction effects on solar observation
Bending of light causes the Sun to appear approximately 0.5∘0.5^\circ higher near the horizon, leading to early sunrise, delayed sunset, and vertical compression (flattening) of the solar disc.
Differential bending occurs across the vertical height of the solar disc and relative to the true horizon.
3
Evaluate starlight propagation through atmospheric turbulence
Point sources of light fluctuate in position and intensity (twinkling).
Random variations in refractive index along the light path continuously alter ray paths.
4
Distinguish refraction from scattering phenomena
The reddening of the Sun is driven by wavelength-dependent scattering (Scattering∝1λ4\text{Scattering} \propto \frac{1}{\lambda^4}), not refraction.
Rayleigh scattering removes short-wavelength blue light over long atmospheric path lengths.

Anahtar Kavram

Atmospheric Refraction vs Rayleigh Scattering
Soru 74Soru →

Which of the following human diseases is caused by a virus and transmitted primarily through the bite of an infected Aedes mosquito?

Cevabı ve açıklamayı göster

Cevap: Dengue

Cevap

Dengue is caused by a virus and transmitted primarily by the bite of an infected Aedes mosquito.
Dengue is an acute febrile viral disease caused by the dengue virus, belonging to the genus Flavivirus. It is transmitted to humans through the bites of infected female mosquitoes, predominantly Aedes aegypti.

Adım Adım Çözüm

1
Identify the biological nature of the pathogen and the vector mentioned in the stem.
The target disease requires a viral pathogen and transmission via an Aedes mosquito vector.
Different human infectious diseases are distinguished by their specific pathogen types (virus, bacterium, protozoan) and modes of transmission.
2
Evaluate Dengue against these criteria.
Dengue is caused by an RNA virus of the Flaviviridae family and transmitted by infected female Aedes mosquitoes (Aedes aegypti and Aedes albopictus).
This matches both criteria specified in the question.

Anahtar Kavram

Disease Etiology and Insect Vectors
Soru 75Soru →

Match the common chemical substances in List-I with their primary applications in daily life and industry in List-II. Which of the following options represents the correct pairing of each substance with its application?

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Quicklime (CaOCaO)
Milk of Magnesia (Mg(OH)2Mg(OH)_2)
Baking Soda (NaHCO3NaHCO_3)
Gypsum (CaSO4⋅2H2OCaSO_4 \cdot 2H_2O)

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Quicklime matches with cement manufacturing; Milk of Magnesia matches with antacid application; Baking soda matches with leavening agent and fire extinguisher; Gypsum matches with retarding cement setting time.
Each chemical substance is correctly paired with its specific real-world application based on its chemical properties: Quicklime in cement making, Milk of Magnesia as an antacid, Baking soda in food/fire safety, and Gypsum for delaying cement hardening.

Adım Adım Çözüm

1
Identify the industrial application of Quicklime (CaOCaO)
Quicklime is key to forming calcium silicates in cement manufacturing.
Understanding primary inorganic chemical raw materials.
2
Identify the medicinal role of Milk of Magnesia (Mg(OH)2Mg(OH)_2)
Milk of Magnesia neutralizes stomach acid (HClHCl) safely as an antacid.
Acid-base neutralization in household medicine.
3
Identify the household uses of Baking Soda (NaHCO3NaHCO_3)
Baking Soda releases CO2CO_2 gas when heated or mixed with acid, aiding baking dough expansion and smothering flames.
Thermal decomposition of hydrogen carbonates.
4
Identify the construction function of Gypsum (CaSO4⋅2H2OCaSO_4 \cdot 2H_2O)
Gypsum slows down the hydration rate of cement, retarding its setting time.
Modifying physical characteristics of industrial materials.

Anahtar Kavram

Everyday and industrial applications of common inorganic chemical compounds
Soru 76Soru →

Which of the following statements regarding human immunoglobulin functions, immune cell receptor interactions, and pathogen neutralization mechanisms are correct?

Geçerli olan tümünü seçin

Cevabı ve açıklamayı göster

Cevap: Secretory Immunoglobulin A (IgA) exists predominantly as a dimeric molecule joined by a Joining (J) chain and a secretory component, providing primary mucosal immunity against respiratory and enteric pathogens.; Immunoglobulin E (IgE) binds via its Fc region to high-affinity FcεRI receptors on mast cells and basophils, triggering mediator release in type I hypersensitivity reactions and anti-helminthic immunity.; Immunoglobulin G (IgG) is the only human antibody class capable of crossing the placental barrier, a process mediated by active transport via neonatal Fc receptors (FcRn).

Cevap

The statements confirming that secretory IgA functions as a dimeric mucosal barrier, IgE binds FcεRI receptors on mast cells to mediate type I hypersensitivity and helminth defense, and IgG crosses the placenta via neonatal Fc receptors (FcRn) are correct.
The correct statements accurately detail human immunoglobulin physiology: Secretory IgA functions as a dimeric molecule linked by a J chain and secretory component for mucosal lining protection. IgE binds high-affinity FcεRI receptors on mast cells/basophils, mediating allergic degranulation and anti-helminth defense. IgG is actively transported across the placenta by neonatal Fc receptors (FcRn) to provide fetal passive immunity.

Adım Adım Çözüm

1
Evaluate the structural and functional properties of Secretory IgA.
Secretory IgA is composed of two IgA monomers linked by a J chain and wrapped by a protective secretory component derived from polymeric immunoglobulin receptors. It protects mucosal membranes in the gastrointestinal, respiratory, and urogenital tracts.
Verifies that the statement on dimeric secretory IgA structure and mucosal pathogen protection is scientifically accurate.
2
Assess the receptor binding and physiological role of Immunoglobulin E (IgE).
IgE binds with high affinity to FcεRI receptors on mast cells and basophils. Antigen cross-linking induces immediate degranulation, releasing histamine and leukotrienes central to type I hypersensitivity and parasite immunity.
Confirms the correctness of the statement detailing IgE Fc receptor interaction and allergic/helminthic immune pathways.
3
Analyze the structural organization and temporal response of Immunoglobulin M (IgM).
Serum IgM is a pentameric complex held together by disulfide bonds and a J chain, specializing in agglutination and early complement activation during primary immune responses. It is not a monomer responsible for secondary long-term memory.
Identifies the incorrect statement mischaracterizing IgM monomeric state and secondary immune memory functions.
4
Examine the mechanism of placental antibody transfer in human pregnancy.
IgG is the sole antibody isotype that crosses the placental barrier into fetal circulation. This active transcytosis is mediated by placental neonatal Fc receptors (FcRn) binding the Fc portion of IgG.
Validates that maternal-fetal IgG placental transport via FcRn confers essential passive immunity.

Anahtar Kavram

Structure, isotype-specific effector functions, and receptor interactions of human immunoglobulins in mucosal defense, passive immunity, and hypersensitivity.
Soru 77Soru →

Match the human endocrine glands listed in List-I with their primary hormones listed in List-II:

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Pancreas
Thyroid Gland
Adrenal Medulla
Pineal Gland

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Pancreas corresponds to Insulin, Thyroid Gland corresponds to Thyroxine, Adrenal Medulla corresponds to Adrenaline, and Pineal Gland corresponds to Melatonin.
Each endocrine gland matches directly with its characteristic primary hormone secretion: the pancreas produces insulin, the thyroid gland produces thyroxine, the adrenal medulla produces adrenaline, and the pineal gland produces melatonin.

Adım Adım Çözüm

1
Match the Pancreas with its hormone.
Pancreas secretes Insulin.
Insulin is synthesized by pancreatic beta cells to lower blood glucose.
2
Match the Thyroid Gland with its hormone.
Thyroid Gland secretes Thyroxine.
Thyroxine regulates general cellular metabolism and energy production.
3
Match the Adrenal Medulla with its hormone.
Adrenal Medulla secretes Adrenaline.
Adrenaline increases heart rate and blood flow during stressful acute conditions.
4
Match the Pineal Gland with its hormone.
Pineal Gland secretes Melatonin.
Melatonin secretion is modulated by light exposure to maintain diurnal rhythm.

Anahtar Kavram

Human Endocrine System and Secretory Hormones
Soru 78Soru →

Match the physical applications and everyday observations in List-I with their underlying governing physics principles in List-II, and select the correct matching combination.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

Spontaneous upward movement of ink through blotting paper and oil climbing a cotton lamp wick
Apparent shift in the perceived pitch of a train whistle as it passes a stationary observer
Silvering on the inner glass surfaces of a vacuum thermos flask to maintain liquid temperature
Operation of oceanographic SONAR systems to map seabed topography and locate submerged vessels

Eşleşmeler

Cevabı ve açıklamayı göster

Cevap

Spontaneous upward movement of ink matches Capillary action driven by surface tension; Apparent shift in train whistle pitch matches Doppler Effect; Silvering on vacuum thermos flask surfaces matches Reflection of infrared thermal radiation; and Operation of SONAR matches Reflection and echo timing of ultrasonic acoustic waves.
Each everyday observation is correctly paired with its underlying physical principle: capillary action drives fluid transport through porous media; relative wave source motion causes pitch shifts governed by the Doppler Effect; highly reflective silver coatings suppress thermal energy transfer by reflecting infrared radiation; and SONAR uses reflected ultrasonic acoustic waves for underwater object localization.

Adım Adım Çözüm

1
Examine the liquid transport phenomenon in blotting paper and lamp wicks (Item 1).
Correlated with Capillarity and Surface Tension (Right Item 1).
Fine interconnected pores act as narrow capillary tubes where adhesive forces between liquid molecules and porous material overcome gravitational forces.
2
Examine the pitch variation of a moving sound source (Item 2).
Correlated with the Doppler Effect (Right Item 2).
Relative velocity between a wave emitter and detector alters the observed frequency of sound waves.
3
Examine thermal loss prevention techniques in vacuum thermos flasks (Item 3).
Correlated with Thermal Radiation Reflection (Right Item 3).
A reflective silver coating lowers emissivity and reflects electromagnetic radiation in the infrared spectrum.
4
Examine underwater distance measurement via acoustic signals (Item 4).
Correlated with Ultrasonic Echo Ranging (Right Item 4).
SONAR relies on sending ultrasonic pulses through water and tracking their reflected echo return times.

Anahtar Kavram

Everyday Applications of Mechanics, Acoustics, and Thermal Physics Principles
Tahmini Süre:2m 0s
Soru 79Soru →

Polaroid sunglasses are widely used to reduce glare from horizontal reflective surfaces such as wet asphalt roads and water bodies during sunny days. Which wave property of light is primarily utilized by polaroid lenses to eliminate this reflective glare?

Cevabı ve açıklamayı göster

Cevap: Polarization by reflection, where reflected light becomes predominantly horizontally polarized and is blocked by vertically aligned polarizing filters.

Cevap

Polarization by reflection, where reflected light becomes horizontally polarized and is selectively absorbed by vertically aligned polarizing filters in the lenses.
When natural unpolarized light reflects off a flat horizontal surface, the reflected rays become polarized parallel to that surface (horizontally). Polaroid lenses feature vertically oriented transmission axes that selectively absorb this horizontally polarized glare while permitting useful ambient light to pass.

Adım Adım Çözüm

1
Analyze the nature of unpolarized sunlight and its reflection off horizontal surfaces.
Unpolarized sunlight contains electric field oscillations in all planes perpendicular to the propagation direction. When it reflects off smooth non-metallic horizontal surfaces (like water or road asphalt), the electric field components parallel to the surface (horizontal plane) are preferentially reflected.
According to Brewster's law, at specific reflection angles, the reflected light becomes strongly linearly polarized in the horizontal plane.
2
Determine the operating principle of polaroid sunglasses.
Polaroid sunglasses are manufactured with their transmission axis aligned vertically.
Vertically oriented polarizing filters absorb horizontally polarized light waves while allowing vertically polarized ambient light to pass through, effectively cutting off the glaring reflections.

Anahtar Kavram

Polarization of Light and Brewster's Law
Soru 80Soru →

Consider the following statements regarding major human infectious diseases and their modes of transmission:

1. Visceral Leishmaniasis (Kala-azar) is caused by a protozoan parasite and is transmitted to humans through the bite of infected sandflies.
2. Japanese Encephalitis is a bacterial disease transmitted to humans primarily through the bite of infected Anopheles mosquitoes.
3. Chikungunya is caused by an RNA virus and is transmitted to humans primarily by Aedes mosquitoes.

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.
Visceral Leishmaniasis (Kala-azar) is caused by the protozoan parasite Leishmania donovani and transmitted to humans via phlebotomine sandflies. Chikungunya is caused by an RNA alphavirus transmitted principally by Aedes mosquitoes. Conversely, Japanese Encephalitis is a mosquito-borne viral encephalitis caused by a flavivirus and transmitted by Culex mosquitoes (predominantly Culex tritaeniorhynchus), making statement 2 false and rendering the option specifying '1 and 3 only' the correct choice.

Adım Adım Çözüm

1
Evaluate Statement 1 regarding Visceral Leishmaniasis (Kala-azar)
Statement 1 is correct.
Visceral Leishmaniasis is caused by the protozoan parasite Leishmania donovani and is transmitted by the bite of infected female phlebotomine sandflies (Phlebotomus argentipes).
2
Evaluate Statement 2 regarding Japanese Encephalitis
Statement 2 is incorrect.
Japanese Encephalitis is caused by the Japanese Encephalitis Virus (a flavivirus, not a bacterium) and is transmitted primarily by mosquitoes of the Culex genus (mainly Culex tritaeniorhynchus), not Anopheles mosquitoes.
3
Evaluate Statement 3 regarding Chikungunya
Statement 3 is correct.
Chikungunya is an infection caused by the Chikungunya virus (an RNA virus of the Togaviridae family) transmitted to humans by Aedes mosquitoes (Aedes aegypti and Aedes albopictus).

Anahtar Kavram

Classification of infectious human diseases by pathogen type (protozoan, viral, bacterial) and their specific insect vectors
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General Science and Technology Alıştırma Soruları — State PSC Exam — Sayfa 4 | Examkin