Transport in Plants

Free sample questions

Transport in Plants — sample Biology questions with answers

1. Question 1

   The main function of xylem in plants is to transport:

   • AWater and mineral salts from roots to leaves
   • BPhotosynthetic products from leaves to the rest of the plant
   • CWater and mineral salts from leaves to roots
   • DHormones from roots to shoots

   Answer: A. Water and mineral salts from roots to leaves

   Xylem transports water and mineral salts unidirectionally from roots to the upper parts of the plant. Phloem transports photosynthetic products. Therefore, answer A is correct.

2. Question 2

   The process of water loss in the form of vapour from the leaf surface is known as:

   • AGuttation
   • BTranspiration
   • CRespiration
   • DPhotolysis

   Answer: B. Transpiration

   Transpiration is the process of water loss in vapour form from stomatal pores, cuticle, and lenticels. Guttation is water loss in liquid form from leaf tips. So B is correct.

3. Question 3

   Which of the following is a factor that increases the rate of transpiration?

   • AHigh air humidity
   • BLow temperature ($10^{\circ }\text{C}$)
   • CModerate air movement (wind)
   • DHigh concentration of carbon dioxide in the air

   Answer: C. Moderate air movement (wind)

   Wind increases transpiration rate because it removes water vapour from around the stomata, maintaining a humidity gradient. High humidity and low temperature reduce transpiration. High CO2 causes stomata to close, reducing transpiration.

4. Question 4

   The theory that explains the upward movement of water in xylem is:

   • ARoot pressure theory
   • BCohesion-tension theory
   • CPressure flow theory
   • DOsmosis theory

   Answer: B. Cohesion-tension theory

   The cohesion-tension theory describes the upward movement of water in xylem through cohesive forces between water molecules and adhesive forces on xylem walls, along with transpiration that generates tension.

5. Question 5

   What is meant by cuticular transpiration?

   • AWater loss through the leaf cuticle
   • BWater loss through stomata
   • CWater loss through stem lenticels
   • DWater loss through roots

   Answer: A. Water loss through the leaf cuticle

   Cuticular transpiration is water loss through the thin cuticle layer on the leaf surface. Although the cuticle is waterproof, a small amount of water can still diffuse through it.