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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87 questions · page 2 of 5
- A. Temperature
- B. pH
- C. Light
- D. None of these
Explanation: Light directly stimulates guard cells to accumulate solutes, causing water to enter and increasing their turgor, which opens the stomatal…
Correct answer: Light- A. Lenticels
- B. Guard cells
- C. Hydathods
- D. All of these
Explanation: Guard cells surround each stomatal pore and act as a turgor-controlled hydraulic valve, opening or closing the pore as water enters or…
Correct answer: Guard cells- A. 90%
- B. 91%
- C. 93%
- D. 95%
Explanation: Stomata are the main pathway for water vapour leaving a leaf, so stomatal transpiration is commonly estimated at about 90% of total…
Correct answer: 90%- A. Transpiration pull
- B. Root pressure
- C. Osmotic pressure.
- D. None of these
Explanation: Root pressure develops when root cells actively accumulate salts in the xylem, lowering the xylem water potential and drawing water into…
Correct answer: Root pressure- A. A big pore
- B. Stoma
- C. Sponge
- D. Cars or small protusions
Explanation: Lenticels are small, raised or slightly protruding porous areas in the bark that permit gas exchange.
Correct answer: Cars or small protusions- A. Hydathods
- B. Stomata
- C. Lenticels
- D. None of these
Explanation: Lenticels are aerating pores in the bark that allow oxygen and carbon dioxide exchange and permit some water loss as vapour.
Correct answer: Lenticels- A. 2-3%
- B. 1-3%
- C. 1-4%
- D. 1-2%
Explanation: Lenticular transpiration through bark lenticels is usually about 1% to 2% of total transpiration, so option d gives the standard…
Correct answer: 1-2%- A. 6-8%
- B. 5-7%
- C. 7-9%
- D. 4-6%
Explanation: Cuticular transpiration is commonly estimated at about 5% to 7% of total transpiration, giving option b.
Correct answer: 5-7%- A. 600 Kpa
- B. 800 Kpa
- C. 1000 Kpa
- D. 900 Kpa
Explanation: Exceptional root pressure is commonly stated to reach about 800 kPa, meaning a positive pressure of 800 kPa in the xylem.
Correct answer: 800 Kpa- A. 8mh-1
- B. 1 mh-1
- C. 7 mh-1
- D. 4 mh-1
Explanation: In many plants other than very tall trees, the upward movement of water is commonly given as about 1 m h^-1.
Correct answer: 1 mh-1- A. Osmotic
- B. Pressure
- C. Both of these
- D. None of these
Explanation: Osmotic or solute potential measures the change in water potential caused by dissolved solute particles, which lower the water potential…
Correct answer: Osmotic- A. Deffusion
- B. Osmosis
- C. Active transport
- D. None of these
Explanation: Osmosis is the net movement of water through a selectively permeable membrane from higher water potential to lower water potential.
Correct answer: Osmosis33. The pressure generated when water enters & inflates plant cells is called ___________ potential?
- A. Water
- B. Osmotic
- C. Pressure
- D. Solute
Explanation: When water enters a plant cell, it pushes the plasma membrane against the cell wall and produces turgor pressure, represented as pressure…
Correct answer: Pressure- A. Three
- B. Four
- C. Two
- D. Five
Explanation: The two major components used for plant water potential are solute potential and pressure potential, expressed as Ψw = Ψs + Ψp.
Correct answer: Two- A. Tonoplast
- B. Apoplast
- C. Symplast
- D. Vacuolar.
Explanation: The apoplast is the continuous pathway through cell walls and intercellular spaces, but the Casparian strip blocks it at the endodermis.
Correct answer: Apoplast36. The diffusion of ions along with water also takes place by mass flow system along the ________ path?
- A. Tonoplast
- B. Apoplast
- C. Symplast
- D. Vacuolar
Explanation: Mass flow through cell walls and intercellular spaces occurs along the apoplast pathway, which does not require water to cross plasma…
Correct answer: Apoplast- A. Root hairs
- B. Root cells
- C. Underground stem
- D. All of these
Explanation: Root hairs greatly increase the surface area in contact with the soil and have thin walls, making them the main sites for water and…
Correct answer: Root hairs38. There are __________ types of nutrients needed by plants besides light to carry out photosynthesis
- A. Two
- B. Three
- C. Four
- D. Five
Explanation: In the usual school-level description, photosynthesis requires three materials besides light: water, carbon dioxide and chlorophyll, which…
Correct answer: Three- A. Large number of vacoules in a plant cell.
- B. Higher ionic concentration inside vacuoles resulting from active pumping of ions at their tonoplastic membrane
- C. Higher osmotic pressure of the cell vacuole
- D. both b and c
Explanation: Active pumping of ions into the vacuole increases its solute concentration and therefore its osmotic pressure, drawing in water and…
Correct answer: both b and c- A. Vitamin B and C
- B. Vitamin B and D
- C. Vitamin C and B
- D. Vitamin A and B
Explanation: Scurvy results from vitamin C deficiency, while beri-beri results from vitamin B1, or thiamine, deficiency.
Correct answer: Vitamin C and B