January 2023

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

By |2022-09-15T12:34:17+02:00January 24th, 2023|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 |2022-09-15T12:34:17+02:00January 24th, 2023|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 |2022-09-15T12:34:19+02:00January 24th, 2023|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 |2022-09-15T12:34:18+02:00January 24th, 2023|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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Biology Notes: Chemicals of Life: Carbohydrates

By |2022-09-15T12:32:51+02:00January 24th, 2023|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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Biology Notes: The test for carbohydrates: Starch

By |2022-09-15T12:32:45+02:00January 24th, 2023|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Chemicals of Life: Carbohydrates: Test for Starch

  • We have already looked at the structure, properties and use of carbohydrates here
  • We will now examine the test for starch in foods
  • Remember starch is a polysaccharide which are part of the carbohydrates family
  • Iodine solution is used to test for the presence of […]
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Biology Notes: Chemicals of Life: Test for Carbohydates

By |2022-09-15T12:32:44+02:00January 24th, 2023|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Chemicals of Life: Chemicals of Life: Test for Carbohydrates

  • We have already looked at the structure, properties and use of carbohydrates here
  • We will now examine the test for carbohydrates in food
  • The nature and order of tests carried out depends on whether we are dealing with a reducing sugar or non-reducing […]
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Biology Notes: Chemicals of Life: Proteins

By |2022-09-15T12:32:39+02:00January 24th, 2023|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Chemicals of Life: Proteins

  • Proteins are an essential nutrient to the human body as well as to other animals
  • They are the building blocks of body tissue
  • They also act as a fuel reserve and are used up after carbohydrates and fats stores have been exhausted
  • Proteins are thus very important for […]
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Safety in the laboratory

By |2022-09-15T12:34:21+02:00January 24th, 2023|Notes, O Level Biology Notes, Ordinary Level Notes|

A typical Biology Laboratory. Image credit ad.edu

ZIMSEC O Level Biology Notes: Safety in the Laboratory

A: Eye Protection

 

  • Wear splash goggles all the time.

B: Clothing and Personal Items

  • Closed shoes must be worn during the entire time that you are in the laboratory to protect you from splashes of chemicals, broken glass, […]
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