Class 10 Absorption by Roots Mock Test (ICSE)

Topics in Absorption by Roots

• Diffusion and osmosis
• Plasmolysis and deplasmolysis
• Turgidity and flaccidity
• Root pressure and ascent of sap
• Imbibition

Absorption by Roots practice questions with answers

1. Q1Multiple choice·1 mark
   Which of the following phenomena is primarily responsible for pushing up sap to small heights in herbaceous plants?

   1. (a)Capillarity
   2. (b)Imbibition
   3. (c)Transpiration pull
   4. (d)Root pressure
   Show answer and step marks

   1. Correct option: (d)+1

   Answer: (d)
2. Q2Multiple choice·1 mark
   The swelling of dry wooden doors and windows during the rainy season is primarily due to:

   1. (a)Imbibition
   2. (b)Diffusion
   3. (c)Osmosis
   4. (d)Active transport
   Show answer and step marks

   1. Correct option: (a)+1

   Answer: (a)
3. Q3Multiple choice·1 mark
   The movement of molecules from a region of higher concentration to a region of lower concentration without the involvement of a semi-permeable membrane is called:

   1. (a)Osmosis
   2. (b)Active transport
   3. (c)Turgidity
   4. (d)Diffusion
   Show answer and step marks

   1. Correct option: (d)+1

   Answer: (d)
4. Q4Multiple choice·1 mark
   Plasmolysis in a plant cell occurs when it is placed in a:

   1. (a)Hypotonic solution
   2. (b)Pure water
   3. (c)Isotonic solution
   4. (d)Hypertonic solution
   Show answer and step marks

   1. Correct option: (d)+1

   Answer: (d)
5. Q5Long answer·4 marks
   (a) Define root pressure. (b) When a healthy herbaceous plant is cut a few centimetres above the soil surface, sap is often observed oozing out of the cut end. What does this observation demonstrate? (c) State two reasons why root pressure alone is insufficient to lift water to the top of tall trees like redwoods or eucalyptus. (d) Name the major force responsible for the ascent of sap in tall trees.
   Show answer and step marks

   1. (a) Root pressure is the positive pressure that builds up in the root xylem as water continuously enters the root cells by osmosis, pushing sap upward.+1
   2. (b) It demonstrates root pressure: water absorbed by the roots is pushed up the xylem with enough force to ooze out of the cut stem.+1
   3. (c) First reason, any one of: root pressure is small and can push water up only a few metres; it is low or absent when transpiration is high, as on hot sunny days; it is rarely shown by tall trees such as conifers; or any other valid reason.+0.5
   4. (c) Second reason, a different one from the same list.+0.5
   5. (d) Transpiration pull (the cohesion-tension pull created by transpiration from the leaves).+1

   Answer: (a) The positive pressure developed in the root xylem by the osmotic entry of water into the roots, which pushes sap upward. (b) The existence of root pressure. (c) Any two of: it can push water only a few metres; it is low or absent when transpiration is high; it is rarely shown by tall trees such as conifers. (d) Transpiration pull.

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