February 2025

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.

    • […]

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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 […]
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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 […]

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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 […]
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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 […]
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Marketing:Introduction

By |2025-02-12T09:34:58+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Business Studies Notes: Marketing:Introduction

  • Is the business/organisational function concerned with identifying, anticipating and satisfying consumer needs and wants at a profit
  • The marketing process involves market research to identify consumer needs and wants
  • Once these needs are identified the organisation then satisfied by creating/providing products at the best possible price thus attaining a profit
  • Marketing also […]
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Biology Notes: Chemicals of Life: Carbohydrates

By |2025-02-12T09:17:28+02:00February 12th, 2025|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Chemicals of Life: Carbohydrates

  • In humans, mammals and a lot of other animals carbohydrates are the body’s main source of energy
  • These may be simple, soluble sugars or complex materials like starch and cellulose
  • But they all  are bio-molecules consisting of carbon (C), hydrogen (H) and oxygen (O)
  • Carbohydrates come in two main types:

    • […]

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