February 2025

Biology Notes: Water and its properties: Surface tension

By |2025-02-12T09:46:13+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: High surface tension and cohesion (adhesion and cohesion)

  • Cohesion is the force whereby individual molecules stick together.
  • Adhesion is the force whereby water molecules stick to other surfaces.

Biological role

  • Cohesion helps water to move as an unbroken column in the xylem tubes in plants.
  • Adhesion helps the water to stick […]
Read More
Comments Off on Biology Notes: Water and its properties: Surface tension

Protecting Water supplies

By |2025-02-12T09:10:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

A protected well. Image credit totallandcare.org A protected well. Image credit totallandcare.org ZIMSEC O Level Combined Science Notes: Testing the purity of water

  • Most rural areas do not have access to running tap water
  • Their water comes from various sources including dams, wells, boreholes, springs
  • Some of these sources are produce […]
Read More
Comments Off on Protecting Water supplies

Chemical building blocks of Life: Water

By |2025-02-12T09:43:19+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

Water is life

ZIMSEC O Level Biology Notes:Chemical building blocks of Life: Bio-molecules

Water

Structure of a water molecule

  • Water is essential for life.
  • Approximately 75% earth’s surface is water.
  • Life evolved in water.
  • An average adult body is 50 to 65 percent water
  • This rises to about 80% in a child
  • A water molecule is made up of 2 hydrogen atoms […]
Read More
Comments Off on Chemical building blocks of Life: Water

Biology Notes: Water and its properties: Polar solvent

By |2025-02-12T09:44:38+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: Polar solvent

  • Water is an excellent solvent for ions and polar molecules because the water molecules attract to them, collect and separate them.
  • This is what happens when a substance dissolves in water.
  • Once a chemical is in solution, it is free to move about and react with other chemicals.

    • […]

Read More
Comments Off on Biology Notes: Water and its properties: Polar solvent

Biology Notes: Water and its properties: Transparency and high heat of evapouration

By |2025-02-12T09:45:09+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Properties and Biological significance of water

Property: High heat of vaporization

  • This is a measure of the heat energy required to vaporize a liquid to overcome the attractive forces between its molecules so that they can escape as a gas.
  • A relatively large amount of energy is needed to vaporize water.
  • This is due […]
Read More
Comments Off on Biology Notes: Water and its properties: Transparency and high heat of evapouration

Biology Notes: Water and its properties: Transport medium and specific heat capacity

By |2025-02-12T09:45:21+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: Transport medium

  • Water is a neutral liquid medium because it has a pH of 7.

Biological role of this property

  • Water’s solvent properties also mean that it acts as a transport medium in the blood transporting cells, lymphatic and excretory system, the alimentary canal and in the xylem and phloem.

Property: High […]

Read More
Comments Off on Biology Notes: Water and its properties: Transport medium and specific heat capacity

Biology Notes: Water and its properties: Density and heat fusion

By |2025-02-12T09:45:59+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: High heat of fusion

  • This is a measure of the heat energy required to melt a solid (ice).
  • Liquid water must lose a large amount of heat energy to freeze.

Biological role

  • Contents of cells and their environment are therefore less likely to freeze.
  • This is an advantage for bodies of […]
Read More
Comments Off on Biology Notes: Water and its properties: Density and heat fusion
Toggle Sliding Bar Area
Go to Top