Free Biological Importance of Water MCQs with Answers
87 Biological Importance of Water MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Water supports life through its polarity, hydrogen bonding and ability to dissolve ionic and polar substances. Its high specific heat, heat of vaporization, cohesion, adhesion and incompressibility help regulate temperature, transport materials and maintain structure, while hydrolysis and osmosis depend directly on water.
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- A. Its low surface tension
- B. Its high specific heat capacity
- C. Its low density in the liquid state
- D. Its inability to form hydrogen bonds
Explanation: Water has an unusually high specific heat capacity because a large amount of energy is absorbed breaking hydrogen bonds before the…
Correct answer: Its high specific heat capacity- A. non-polar
- B. polar
- C. ionised at all temperatures
- D. held together by covalent bonds between molecules
Explanation: The oxygen atom pulls the shared electrons away from the two hydrogens, leaving a partial negative charge on the oxygen and partial…
Correct answer: polar- A. about 10 per cent
- B. about 30 per cent
- C. about 50 per cent
- D. 70 to 90 per cent
Explanation: Most cells are between seventy and ninety per cent water, which is why it is treated as the medium of life rather than as one nutrient…
Correct answer: 70 to 90 per cent- A. specific heat capacity
- B. latent heat of vaporisation
- C. surface tension
- D. density
Explanation: A large amount of energy is needed to break the hydrogen bonds holding liquid water together and convert it to vapour, and that energy is…
Correct answer: latent heat of vaporisation- A. the ice layer insulates the water below, letting aquatic organisms survive the winter
- B. it allows water to evaporate faster in cold weather
- C. it increases the amount of oxygen dissolved in the lake
- D. it lowers the freezing point of the remaining water
Explanation: Water is unusual in becoming less dense as it freezes, because the hydrogen bonds lock the molecules into an open lattice, so ice forms at…
Correct answer: the ice layer insulates the water below, letting aquatic organisms survive the winter- A. the low viscosity of water
- B. the high density of water
- C. cohesion between water molecules caused by hydrogen bonding
- D. the fact that water is a poor solvent for gases
Explanation: Hydrogen bonds make water molecules stick to one another, so a column pulled by evaporation at the leaves does not break, and adhesion to…
Correct answer: cohesion between water molecules caused by hydrogen bonding- A. Low viscosity
- B. High specific heat capacity
- C. High surface tension
- D. High polarity
Explanation: A great deal of energy goes into breaking hydrogen bonds before the temperature of water rises, so oceans and lakes absorb and release…
Correct answer: High specific heat capacity- A. Concentration of water molecules inside and outside the cell
- B. Concentration of enzymes on either side of the cell membrane
- C. Rate of molecular motion on either side of the cell membrane
- D. None of these
Explanation: Osmosis is the net movement of water across a selectively permeable membrane, driven by a difference in water concentration on the two…
Correct answer: Concentration of water molecules inside and outside the cell- A. 60%
- B. 65%
- C. 70%
- D. 75%
Explanation: Water commonly makes up about 70% of the body mass of a mammal, although the exact percentage varies with age, tissue type, and species.
Correct answer: 70%- A. Vitamin A
- B. Vitamin C
- C. Vitamin D
- D. B complex
Explanation: Vitamin A is converted into retinal, a component of rhodopsin, the light-sensitive pigment in rod cells of the retina.
Correct answer: Vitamin A- A. zero
- B. one
- C. negative
- D. two
Explanation: Water potential is defined relative to pure water, which is assigned a value of 0 MPa under standard reference conditions.
Correct answer: zero- A. imbibition
- B. plasmolysis
- C. deplasmolysis
- D. adhesion
Explanation: Plasmolysis occurs when a plant cell loses water by exosmosis, causing the protoplast to shrink away from the cell wall.
Correct answer: plasmolysis- A. Cabbage
- B. Lady finger(okra)
- C. Cassava
- D. Non of these
Explanation: Lady finger, or okra, contains approximately 90% water, although the exact value varies with variety and measurement method.
Correct answer: Lady finger(okra)- A. Hydrophytes
- B. Mesophytes
- C. Xerophytes
- D. Halophytes
Explanation: Xerophytes are plants adapted to dry habitats and commonly have a thick, waxy cuticle that reduces evaporation from leaf surfaces.
Correct answer: Xerophytes- A. Hydrophytes
- B. Mesophytes
- C. Xerophytes
- D. Halophytes
Explanation: Rose grows best where water is reasonably available but not continuously abundant, so it is classified as a mesophyte.
Correct answer: Mesophytes- A. Diffusion
- B. Active transport
- C. Osmosis
- D. All of these
Explanation: Light activates ion transport mechanisms in guard cells, and K+ is accumulated from surrounding cells by active transport.
Correct answer: Active transport- A. Increases.
- B. Lowers.
- C. Doesn't effect.
- D. Maintains.
Explanation: Adding salts and other solutes makes the xylem sap more concentrated, which lowers its water potential.
Correct answer: Lowers.- A. Bacteria
- B. Viruses
- C. Fungi
- D. Cyanobacteria
Explanation: Mycorrhizal fungi form symbiotic associations with plant roots and extend fungal hyphae through the soil, increasing the area from which…
Correct answer: Fungi- A. Opening
- B. Closure
- C. Both of these
- D. None of these
Explanation: Low carbon dioxide concentration, especially inside the leaf, promotes stomatal opening so that more CO2 can enter for photosynthesis.
Correct answer: Opening- A. One
- B. Two
- C. Three
- D. Four
Explanation: The two commonly taught explanations for stomatal movement are the starch-sugar hypothesis and the potassium-ion hypothesis.
Correct answer: TwoBiological Importance of Water MCQs: common questions
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