Request a call back

Join NOW to get access to exclusive study material for best results

CBSE Class 10 Answered

Explain about adhesion cohesion theory   
Asked by amulyasavataikar | 10 Apr, 2023, 04:41: PM
answered-by-expert Expert Answer
The cohesion–tension theory is also known as the water column theory or the cohesive force theory. This theory was proposed by Dixon and Jolly.
The cohesion–tension theory is based on the following facts:
i. Transpiration Pull:
  • Because of the continuous loss of water from the leaves due to transpiration, the diffusion pressure deficit always remains higher in the mesophyll cells.
  • As a result, the mesophyll cells absorb water from the adjacent internal mesophyll cells and compensate for the loss of water. This loss causes a water deficit in the xylem.
  • Rapid transpiration develops a pull or tension in the xylem called the transpiration pull. It is about 20 atm.
  • Transpiration pull is called negative pressure because it develops from the aerial parts and progresses to the underground parts of plants.
ii. Cohesion Force:
  • A force of mutual attraction present between the water molecules is called cohesive force.
  • Water molecules are held together continuously by a cohesive force to form a continuous water column. This cohesive force is up to 45–270 atm.
iii. Adhesive Force:
  • Water molecules are also attached with the walls of the vessels and tracheids through a force called adhesive force.
  • Cohesive and adhesive forces work together to maintain the continuity in between water and the cell wall.
  • The forces are responsible for maintaining unbroken continuity of the water column from the roots to the leaves.
  • This water column is pulled upwards continuously without breaking, from the roots to the leaves by transpiration.
Answered by Sheetal Kolte | 11 Apr, 2023, 11:40: AM

Application Videos

CBSE 10 - Biology
Asked by amulyasavataikar | 10 Apr, 2023, 04:41: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by rgiri4857 | 19 Apr, 2022, 07:30: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by ps8843899 | 08 Mar, 2022, 10:07: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by Trisha Gupta | 27 Jun, 2021, 07:43: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by Trisha Gupta | 12 Jun, 2021, 04:51: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by deepakgnildh | 14 Feb, 2021, 07:13: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by sattusatyamm | 05 Jun, 2020, 10:06: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by queenwara949 | 02 Jun, 2020, 07:05: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by reshmasouza2010 | 11 Mar, 2019, 08:58: PM
ANSWERED BY EXPERT ANSWERED BY EXPERT
CBSE 10 - Biology
Asked by arti.aggarwal17 | 13 Feb, 2019, 08:01: AM
ANSWERED BY EXPERT ANSWERED BY EXPERT
Get Latest Study Material for Academic year 24-25 Click here
×