NEET UG - Plant-water relations - water potential transpiration ascent of sap Online Test (MCQ Quiz)

1. What is the symbol commonly used to represent water potential?

A) Ψ B) Ω C) Δ D) Σ

2. Which component of water potential is always zero or negative in a plant cell?

A) Pressure potential (Ψp) B) Solute potential (Ψs) C) Gravity potential (Ψg) D) Matrix potential (Ψm)

3. In a turgid plant cell, which component of water potential is significantly positive?

A) Solute potential (Ψs) B) Pressure potential (Ψp) C) Gravity potential (Ψg) D) Osmotic potential (Ψo)

4. Water moves from a region of higher water potential to a region of lower water potential. This statement describes:

A) Active transport B) Facilitated diffusion C) Osmosis D) Bulk flow

5. What is the term for the pressure exerted by the cell wall against the protoplast of a plant cell?

A) Turgor pressure B) Osmotic pressure C) Wall pressure D) Suction pressure

6. If a plant cell is placed in a hypertonic solution, water will move:

A) Into the cell B) Out of the cell C) No net movement D) Across the cell wall only

7. The process by which water moves into a plant root from the soil is primarily driven by:

A) Active transport of ions B) A difference in water potential C) High atmospheric pressure D) Capillary action in the soil

8. Which term describes the outward movement of water in liquid form from plant surfaces, mainly through stomata?

A) Guttation B) Transpiration C) Evaporation D) Secretion

9. Stomata are pores that regulate gas exchange and transpiration. They are typically found on:

A) Roots and stems B) Leaves and stems C) Flowers and fruits D) Only on the upper epidermis of leaves

10. The primary driving force for transpiration is:

A) Root pressure B) Capillary action C) Atmospheric humidity and temperature D) Photosynthesis

11. Which of the following factors does NOT significantly affect the rate of transpiration?

A) Wind speed B) Light intensity C) Soil moisture content D) Oxygen concentration in the atmosphere

12. When stomata close, transpiration rate decreases, but this also affects:

A) Water absorption by roots B) Oxygen uptake for respiration C) Carbon dioxide uptake for photosynthesis D) All of the above

13. The 'Cohesion-Tension Theory' explains the mechanism of:

A) Nutrient uptake B) Photosynthesis C) Transpiration D) Ascent of sap

14. Cohesion refers to the attraction between water molecules due to:

A) Ionic bonds B) Covalent bonds C) Hydrogen bonds D) Van der Waals forces

15. Adhesion, in the context of water transport in plants, refers to the attraction between water molecules and:

A) Other water molecules B) The walls of the xylem vessels C) The atmosphere D) The soil particles

16. What is the role of tension in the ascent of sap according to the Cohesion-Tension Theory?

A) It pushes water up from the roots. B) It pulls water up from the leaves. C) It creates pressure in the xylem. D) It facilitates water entry into root hairs.

17. Root pressure can contribute to the ascent of sap, especially under conditions of:

A) High transpiration rate B) Low soil temperature C) High humidity and low transpiration D) Abundant sunlight

18. The upward movement of water in the xylem is a process of:

A) Active transport B) Diffusion C) Bulk flow D) Osmosis

19. Guttation is the loss of water in liquid form from plant parts, often seen as droplets on leaf margins. It occurs when:

A) Transpiration rate is very high B) Root pressure exceeds transpiration pull C) Atmospheric humidity is very low D) Stomata are wide open at night

20. The water potential of pure water at standard temperature and pressure is defined as:

A) Zero B) One C) Negative infinity D) Positive infinity

21. Adding a solute to pure water will cause the solute potential (Ψs) to become:

A) More positive B) Zero C) More negative D) Unchanged

22. A plant cell with a negative solute potential and a positive pressure potential indicates:

A) It is flaccid B) It is turgid C) It is plasmolysed D) It has no water

23. Plasmolysis occurs when a plant cell is placed in a solution that is:

A) Hypotonic B) Isotonic C) Hypertonic D) Neutral

24. The potential difference that drives water movement across a semipermeable membrane is the difference in:

A) Solute concentration B) Pressure C) Water potential D) Temperature

25. Which of the following structures in the root is primarily responsible for water absorption from the soil?

A) Root cap cells B) Root hairs C) Vascular cambium D) Root cortex parenchyma

26. The movement of water from the soil into the root xylem can occur via the symplast and apoplast pathways. Which pathway involves movement through the cytoplasm of cells?

A) Apoplast pathway B) Symplast pathway C) Transmembrane pathway D) Vacuolar pathway

27. The Casparian strip in the endodermis forces water entering via the apoplast pathway to switch to the symplast pathway. What is its function?

A) To increase water absorption B) To prevent water loss C) To regulate the entry of solutes into the xylem D) To provide structural support to the root

28. What is the primary function of xylem in plants?

A) Transport of sugars B) Transport of water and minerals C) Storage of food D) Photosynthesis

29. The loss of water vapour from aerial parts of plants, primarily through stomata, is known as:

A) Evaporation B) Transpiration C) Condensation D) Sublimation

30. Which of the following is NOT a mechanism that aids in the ascent of sap?

A) Transpiration pull B) Root pressure C) Capillary action D) Active pumping by xylem vessels

31. A decrease in turgor pressure in a plant cell leads to:

A) Increased growth B) Wilting C) Increased photosynthesis D) Enhanced water uptake

32. The water potential of a cell is determined by the sum of its:

A) Solute potential and gravity potential B) Pressure potential and solute potential C) Matrix potential and osmotic potential D) Atmospheric potential and soil potential

33. When a plant is under water stress, stomata tend to:

A) Open wider B) Close C) Remain unaffected D) Open only at night

34. The phenomenon where water moves across a semipermeable membrane from a region of lower solute concentration to a region of higher solute concentration is called:

A) Diffusion B) Active transport C) Osmosis D) Imbibition

35. Xylem vessels are composed of dead cells and are essentially hollow tubes. This structural feature facilitates:

A) Active transport of water B) Storage of water C) Unimpeded bulk flow of water D) Regulation of water entry

36. The main driving force for the movement of water into root hairs from the soil is:

A) Higher solute concentration in root hair cells B) Lower solute concentration in root hair cells C) Higher water potential in root hair cells D) Lower water potential in the soil

37. What is the role of guard cells in transpiration?

A) They absorb water from the soil. B) They regulate the opening and closing of stomata. C) They transport water to the leaves. D) They store photosynthetic products.

38. If a plant cell has a water potential of -0.5 MPa and its surrounding solution has a water potential of -0.2 MPa, water will move:

A) Into the cell B) Out of the cell C) No net movement D) Across the cell wall only

39. Which phenomenon is responsible for the 'negative pressure' or 'pull' in the xylem that draws water upwards?

A) Root pressure B) Capillary action C) Transpiration D) Evaporation from root surface

40. The pressure potential (Ψp) in a turgid plant cell is typically:

A) Zero B) Negative C) Positive D) Equal to solute potential

41. Which of the following is a consequence of excessive transpiration?

A) Increased turgor pressure B) Wilting C) Reduced solute concentration in cells D) Enhanced nutrient uptake

42. The movement of water from one cell to another through plasmodesmata is part of the:

A) Apoplast pathway B) Symplast pathway C) Transcellular pathway D) Cuticular pathway

43. What is the term for the potential energy of water per unit volume due to pressure?

A) Solute potential B) Osmotic potential C) Pressure potential D) Matrix potential

44. During heavy rainfall, the water potential of the soil generally:

A) Decreases significantly B) Increases significantly C) Remains constant D) Becomes negative

45. The phenomenon of guttation is most likely to occur:

A) During a hot, dry afternoon B) At night or early morning when transpiration is low C) When the plant is severely dehydrated D) Under strong sunlight

46. Which of the following is a characteristic of xylem tissue that aids in water transport?

A) Presence of sieve plates B) Living parenchyma cells C) Lignified, hollow vessels and tracheids D) Sieve tubes

47. If the solute potential (Ψs) of a cell is -0.7 MPa and the pressure potential (Ψp) is +0.4 MPa, what is the water potential (Ψw) of the cell?

A) -1.1 MPa B) -0.3 MPa C) +0.3 MPa D) +1.1 MPa

48. The rate of transpiration is directly proportional to:

A) Atmospheric humidity B) Wind speed C) Leaf surface area D) Number of stomata

49. Which of the following is a major component of the apoplast pathway?

A) Cytoplasm B) Vacuoles C) Cell walls and intercellular spaces D) Plasmodesmata

50. The movement of water into a plant cell from a hypotonic solution is driven by:

A) A lower water potential inside the cell B) A higher water potential inside the cell C) Active transport of water molecules D) High solute concentration inside the cell

Plant-water relations - water potential transpiration ascent of sap - Online Test

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