Biology

221. An elderly person while trying to read a book at about 25 cm from the

An elderly person while trying to read a book at about 25 cm from the eyes finds the image appears blurred because of the decreasing effectiveness of the ciliary muscles and the loss of flexibility of the lens. This defect of the eyes is called

[amp_mcq option1=”myopia” option2=”astigmatism” option3=”hypermetropia” option4=”presbyopia” correct=”option4″]

This question was previously asked in
UPSC CAPF – 2011
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The described eye defect is called presbyopia.
Presbyopia is a common age-related condition that reduces the eye’s ability to focus on close objects. It occurs because the lens of the eye hardens and loses flexibility, and the muscles surrounding the lens become less effective at changing the lens’s shape for focusing on near vision (a process called accommodation). This results in blurred vision when reading or doing other close-up tasks.
Myopia (nearsightedness) is difficulty seeing distant objects clearly. Astigmatism is a refractive error causing blurred vision at all distances due to an irregularly shaped cornea or lens. Hypermetropia (farsightedness) is difficulty seeing near objects clearly, often due to the eyeball being too short or the cornea being too flat, but presbyopia is specifically the age-related loss of accommodation.

222. Statement I : In forensic investigations, DNA fingerprinting tests are

Statement I : In forensic investigations, DNA fingerprinting tests are carried out.
Statement II : In DNA fingerprinting technique, DNA is isolated and subjected to Northern Blotting.

[amp_mcq option1=”Both the statements are individually true and statement II is the correct explanation of statement I” option2=”Both the statements are individually true but statement II is not the correct explanation of statement I” option3=”Statement I is true but statement II is false” option4=”Statement I is false but statement II is true” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2011
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Statement I is true, but Statement II is false.
DNA fingerprinting is a valid forensic technique, but the method of analysis involves DNA-specific techniques, not RNA analysis methods.
Statement I is true; DNA fingerprinting (or profiling) is widely used in forensic investigations for identification purposes, such as matching samples from a crime scene to a suspect. Statement II is false; Northern Blotting is a technique used to detect specific sequences of *RNA*. DNA fingerprinting techniques involve analyzing DNA, using methods such as Southern Blotting (historically) or more commonly PCR amplification of variable regions (like STRs) followed by electrophoresis or sequencing.

223. Plants that behave as a Xerophyte in one season and as hydrophyte in a

Plants that behave as a Xerophyte in one season and as hydrophyte in another season is known as :

[amp_mcq option1=”Saprophytes” option2=”Tropophytes” option3=”Heliotrophytes” option4=”Virotophytes” correct=”option2″]

This question was previously asked in
UPSC CAPF – 2010
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The correct option is B) Tropophytes.
Tropophytes are plants adapted to tropical climates with distinct alternating wet and dry seasons. They exhibit characteristics that allow them to survive during the dry period (e.g., shedding leaves) and thrive during the wet period, effectively behaving as xerophytes in one season and hydrophytes in another in terms of their physiological and morphological adaptations to water availability.
Saprophytes obtain nutrients from dead organic matter. Heliotropism is the growth or movement of a plant in response to sunlight. Xerophytes are plants adapted to very dry environments, and Hydrophytes are plants adapted to grow in water or very wet conditions.

224. Which of the following is/are the methods of prevention from HIV infec

Which of the following is/are the methods of prevention from HIV infection ?

  • 1. Use of condoms.
  • 2. Use of intra-uterine devices like Copper-T.
  • 3. Staying away from HIV infected person.
  • 4. Using a face mask when in company of HIV infected person.

Select the correct answer using the code given below :

[amp_mcq option1=”1 and 2 only” option2=”3 and 4″ option3=”1, 2 and 4″ option4=”1 only” correct=”option4″]

This question was previously asked in
UPSC CAPF – 2010
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Among the given options, the use of condoms is a method of prevention from HIV infection.
Using condoms correctly and consistently during sexual activity significantly reduces the risk of HIV transmission. Intra-uterine devices (like Copper-T) are contraceptives and do not prevent HIV or other sexually transmitted infections (STIs). Staying away from an HIV-infected person is not necessary for prevention as HIV is not transmitted through casual contact. Using a face mask is irrelevant as HIV is not an airborne virus.
Other effective methods for preventing HIV transmission include abstinence, reducing the number of sexual partners, consistent and correct use of condoms, pre-exposure prophylaxis (PrEP), post-exposure prophylaxis (PEP), using sterile needles for injection, and safe blood transfusion practices. Antiretroviral therapy (ART) can also reduce the viral load in infected individuals to undetectable levels, effectively preventing sexual transmission (Undetectable = Untransmittable, U=U).

225. Which of the following are the risk factors in the transmission of the

Which of the following are the risk factors in the transmission of the HIV infection ?

  • 1. Smoking and drinking alcohol
  • 2. Observing bad hygiene
  • 3. Blood transfusion
  • 4. Unprotected sex

Select the correct answer using the code given below :

[amp_mcq option1=”1 and 3 only” option2=”3 and 4 only” option3=”1, 3 and 4″ option4=”1, 2 and 4″ correct=”option2″]

This question was previously asked in
UPSC CAPF – 2010
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The risk factors in the transmission of the HIV infection among the given options are Blood transfusion and Unprotected sex.
HIV is transmitted through specific bodily fluids: blood, semen, vaginal secretions, rectal fluids, and breast milk. Transmission routes primarily involve unprotected sexual contact (vaginal, anal, oral), sharing of needles or syringes, blood transfusions (rare in countries with screening), and from mother to child during pregnancy, childbirth, or breastfeeding. Smoking, drinking alcohol, and general bad hygiene are not direct routes of HIV transmission.
HIV is not transmitted through casual contact like touching, hugging, kissing, sharing utensils, using the same toilet, or mosquito bites. Understanding the actual transmission routes is crucial for prevention.

226. Which one of the following statements is not correct about “Flavr Savr

Which one of the following statements is not correct about “Flavr Savr” tomatoes ?

[amp_mcq option1=”It is genetically engineered” option2=”Its ripening process is slow” option3=”The fruit cannot be left on the plant for a long period” option4=”They have increased yield and better flavour” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2009
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The statement “The fruit cannot be left on the plant for a long period” is not correct about “Flavr Savr” tomatoes.
The Flavr Savr tomato was genetically engineered to slow down the ripening process by inhibiting the enzyme polygalacturonase. This characteristic allowed the tomato to stay on the vine longer, enabling it to develop more flavour before being harvested, and also extended its shelf life. Therefore, the fruit *could* be left on the plant for a longer period compared to conventional tomatoes picked green for transport.
A) It is genetically engineered: This is correct. Flavr Savr was the first commercially grown genetically engineered food.
B) Its ripening process is slow: This is correct. The genetic modification specifically targeted slowing down the ripening process.
D) They have increased yield and better flavour: The primary goal was better shelf life and allowing vine ripening for potentially better flavour. Increased yield was not a direct outcome of this specific modification. While allowing longer vine ripening might contribute to better flavour compared to artificially ripened tomatoes, claiming “increased yield and better flavour” as a definitive characteristic is debatable, but statement C is clearly and definitively incorrect based on the technology’s purpose.

227. Aquatic animals breathe much faster than terrestrial animals because o

Aquatic animals breathe much faster than terrestrial animals because of :

[amp_mcq option1=”low amount of dissolved oxygen in water” option2=”low amount of hemoglobin in their blood” option3=”high metabolic rate of aquatic animals” option4=”large amount of dissolved nitrogen in water” correct=”option1″]

This question was previously asked in
UPSC CAPF – 2009
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Aquatic animals breathe dissolved oxygen from water using gills or other specialized structures. The concentration of dissolved oxygen in water is significantly lower (only about 5-10 ml per litre, or 5-10 parts per million) and fluctuates more compared to the concentration of oxygen in air (about 210 ml per litre, or 210 parts per million). To extract sufficient oxygen from this lower concentration, aquatic animals need to process a much larger volume of water, resulting in faster breathing rates compared to terrestrial animals which breathe air with a much higher oxygen concentration.
– Dissolved oxygen levels in water are much lower than oxygen levels in the air.
– Aquatic animals breathe faster to compensate for the lower oxygen concentration in their environment.
Temperature and salinity affect the solubility of oxygen in water; higher temperatures and salinity generally lead to lower dissolved oxygen levels. This can further impact the breathing rates of aquatic animals.

228. Adulteration of mustard oil has led to several outbreaks of Epidemic D

Adulteration of mustard oil has led to several outbreaks of Epidemic Dropsy in India. Which one of the following contaminant is responsible for it ?

[amp_mcq option1=”Automobile oil” option2=”Linseed oil” option3=”Argemone oil” option4=”Rapeseed oil” correct=”option3″]

This question was previously asked in
UPSC CAPF – 2009
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Epidemic Dropsy is a clinical state resulting from consuming edible oils (most commonly mustard oil) that have been contaminated with Argemone oil. Argemone oil contains the toxic alkaloid sanguinarine, which is responsible for the symptoms of epidemic dropsy, including edema (swelling), skin lesions, gastrointestinal symptoms, and even heart failure. The contamination occurs when seeds of the Argemone mexicana plant, which visually resemble mustard seeds, are accidentally or intentionally mixed with mustard seeds.
– Epidemic Dropsy is caused by the consumption of edible oil contaminated with Argemone oil.
– The toxic substance in Argemone oil is sanguinarine.
Argemone mexicana is also known as Mexican poppy or prickly poppy. The seeds are small, black, and round, similar to mustard seeds, making accidental contamination during harvesting or processing possible.

229. Organisms of which of the following phylum are called sponges ?

Organisms of which of the following phylum are called sponges ?

[amp_mcq option1=”Coelenterata” option2=”Platyhelminthes” option3=”Porifera” option4=”Echinodermata” correct=”option3″]

This question was previously asked in
UPSC NDA-2 – 2024
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Organisms belonging to the phylum Porifera are commonly known as sponges. The name “Porifera” means “pore-bearers,” which describes the characteristic feature of sponges having a body permeated by pores.
Porifera are the simplest multicellular animals, typically sessile aquatic organisms. They lack true tissues and organs and filter feed water that passes through their porous bodies.
Coelenterata (now more commonly called Cnidaria) includes jellyfish, sea anemones, and corals, characterized by a radial symmetry and stinging cells (cnidocytes). Platyhelminthes are flatworms (e.g., tapeworms, flukes), known for their flattened body shape and bilateral symmetry. Echinodermata includes marine animals like starfish, sea urchins, and sea cucumbers, characterized by radial symmetry (often pentaradial) and a water vascular system.

230. Which part of nephron of the human kidney is responsible for filtratio

Which part of nephron of the human kidney is responsible for filtration of blood for excretion ?

[amp_mcq option1=”Collecting duct” option2=”Renal vein” option3=”Ureter” option4=”Bowman’s capsule” correct=”option4″]

This question was previously asked in
UPSC NDA-2 – 2024
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Filtration of blood in the human kidney for the purpose of excretion occurs in the renal corpuscle, specifically within the structure known as Bowman’s capsule. Blood is filtered from the glomerulus (a network of capillaries) into the space within Bowman’s capsule.
The nephron is the functional unit of the kidney. It consists of the renal corpuscle (Glomerulus and Bowman’s capsule) and the renal tubule. The renal corpuscle is where the initial step of urine formation, glomerular filtration, takes place.
After filtration in Bowman’s capsule, the filtrate passes through the renal tubule (proximal convoluted tubule, loop of Henle, distal convoluted tubule), where essential substances are reabsorbed back into the blood, and waste products are further secreted into the tubule. The collecting duct collects urine from multiple nephrons before it travels to the renal pelvis and out via the ureter. The renal vein carries purified blood away from the kidney.
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