O Level Biology Notes

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April 2018

Biology Notes: Chemicals of Life: Test for Proteins

By |2018-04-16T08:35:30+02:00April 16th, 2018|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Chemicals of Life: Proteins

  • We have already looked at the properties and importance of proteins here
  • Here we will now look at the test for proteins in foods
  • Generally the Biuret’s test is used to test whether proteins are present in food
  • The Biuret’s reagent is made up by adding sodium hydroxide […]

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Biology Notes: Chemicals of Life: Proteins

By |2018-04-15T05:30:14+02:00April 14th, 2018|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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March 2018

Biology Notes: Chemicals of Life: Test for Carbohydates

By |2018-03-10T08:47:03+02:00March 10th, 2018|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: The test for carbohydrates: Starch

By |2018-04-16T07:36:48+02:00March 10th, 2018|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: Carbohydrates

By |2018-03-03T12:05:44+02:00March 3rd, 2018|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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June 2017

Marketing:Introduction

By |2017-06-07T12:48:08+02:00June 7th, 2017|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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March 2017

Chemical building blocks of Life: Water

By |2018-03-03T10:59:46+02:00March 30th, 2017|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 […]

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

By |2018-03-03T12:06:15+02:00March 30th, 2017|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 |2018-03-03T10:44:39+02:00March 30th, 2017|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: Polar solvent

By |2018-03-03T10:34:23+02:00March 30th, 2017|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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