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Question 3377

Oxygen liberated during photosynthesis comes from:

Awater

Bcarbon dioxide

Cglucose

DBoth carbon dioxide and glucose.

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A. waterExplanation: During photosynthesis, green plants use sunlight to convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂). The oxygen gas released in this process comes specifically from the splitting of water molecules — a reaction known as photolysis of water, which occurs in the light-dependent reaction inside the chloroplasts. Chemical equation: 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O The oxygen atoms in the released O₂ come entirely from the original water molecules, as demonstrated by isotopic experiments using heavy oxygen (O¹⁸) tracers.

Question 3374

Which quantity remains constant in parallel connection of resistance?

AElectric current flow rate

BPotential difference

CAmount of electricity

DBoth the potential difference and amount of electricity

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B. Potential differenceExplanation: In a parallel connection of resistances, the potential difference (voltage) across each resistor remains the same, while the current divides among the different branches according to their resistances. This property makes parallel circuits widely used in household electrical wiring.

Question 3372

Under critical temperature, on compressing gases turn to liquid, because:

Amolecules are of finite size.

Bmolecules have random motion.

Cmolecules have inter-molecular forces.

Dmolecules are spherical.

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C. molecules have inter-molecular forces.Explanation: Below the critical temperature, gases can be liquefied by applying pressure because the intermolecular forces of attraction between gas molecules become effective. These forces pull the molecules closer together, resulting in the formation of a liquid state.

Question 3371

Number of spinal nerves in human are:

A11 pairs

B27 pairs

C32 pairs

D31 pairs

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D. 31 pairsExplanation: In humans, the spinal cord gives rise to 31 pairs of spinal nerves. Each spinal nerve is a mixed nerve containing both sensory and motor fibers. They are divided into groups based on the region of the vertebral column from which they originate: 8 pairs — Cervical nerves 12 pairs — Thoracic nerves 5 pairs — Lumbar nerves 5 pairs — Sacral nerves 1 pair — Coccygeal nerve These spinal nerves connect the central nervous system (CNS) to different parts of the body, transmitting sensory information to the brain and motor commands to muscles.

Question 3125

Which pigment gives pale yellow color to urine?

AErithromycin

BAmoxylin

CUrochronie

DUnicom

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C. UrochronieExplanation: The pale yellow color of normal human urine is due to the presence of a pigment called Urochrome. It is produced from the breakdown of hemoglobin in red blood cells. The intensity of the color depends on the concentration of the urine — darker yellow indicates concentrated urine, while very pale or colorless urine suggests dilution due to high water intake.

Question 3120

Which is the respiratory organ of fish?

AEars

BGills

CSkin

DLungs

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B. GillsExplanation: Fish respire through specialized organs called gills, located on either side of their head. Gills contain thin filaments with a large surface area and rich blood supply that allow exchange of gases. When water passes over the gill membranes, oxygen diffuses into the blood and carbon dioxide diffuses out. This process enables aquatic respiration and supports survival underwater.

Question 3119

Which of the following branch deals with the various principles that govern the relationship between organisms and their environment?

AHistology

BEcology

CEntomology

DAnthropology

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B. EcologyExplanation: Ecology is a branch of biology that deals with the relationships of living organisms with one another and with their physical surroundings. It examines how organisms adapt to their environment, how energy flows through ecosystems, and how matter cycles within the biosphere. The term “Ecology” was first coined by Ernst Haeckel in 1866.

Question 3117

The waves which can propagate even through the vacuum,are called __________.

AMechanical waves

BReverse waves

CInverted waves

DElectromagnetic waves

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D. Electromagnetic wavesExplanation: Electromagnetic waves can propagate even through a vacuum because they do not require any material medium for transmission. Examples include light waves, radio waves, X-rays, and microwaves. In contrast, mechanical waves like sound require a medium such as air, water, or solids to travel.

Question 3114

Sound waves having frequency less than 20 Hz are called __________ waves.

AIntelligent

BInferior

CInfrasonic

DInstrumental

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C. InfrasonicExplanation: Sound waves with frequencies below 20 Hz are called infrasonic waves. These waves are inaudible to the human ear but can be produced by natural phenomena such as earthquakes, volcanic eruptions, and ocean waves.

Question 3113

The mixture of flammable gases (carbon monoxide and hydrogen) and nonflammable gases (nitrogen and carbon dioxide) is called by what name?

ALaser Star Gas

BBreathing Gas

CProducer Gas

DLaughing Gas

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C. Producer GasExplanation: Producer gas is a mixture of flammable gases such as carbon monoxide (CO) and hydrogen (H₂), along with nonflammable gases like nitrogen (N₂) and carbon dioxide (CO₂). It is produced by the partial combustion of carbon-containing fuels (like coal or coke) with air and steam, and is used as a fuel in industrial furnaces.

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Science

Oxygen liberated during photosynthesis comes from:

Which quantity remains constant in parallel connection of resistance?

Under critical temperature, on compressing gases turn to liquid, because:

Number of spinal nerves in human are:

Which pigment gives pale yellow color to urine?

Which is the respiratory organ of fish?

Which of the following branch deals with the various principles that govern the relationship between organisms and their environment?

The waves which can propagate even through the vacuum,are called __________.

Sound waves having frequency less than 20 Hz are called __________ waves.

The mixture of flammable gases (carbon monoxide and hydrogen) and nonflammable gases (nitrogen and carbon dioxide) is called by what name?

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