February 2025

The enzyme amylase

By |2025-02-12T09:29:26+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Starch food. Image credit eurofins.com Starch food. Image credit eurofins.com ZIMSEC O Level Combined Science Notes: The enzyme amylase

  • Energy in cells is obtained by breaking down food molecules during the respiration process.
  • The chemical reactions involved are carried out by enzymes.
  • Enzyme molecules also break down food molecules in the digestive system and […]
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Changes in state

By |2025-02-12T09:08:59+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Melting ice. Image credit flemox.com Melting ice. Image credit flemox.com ZIMSEC O Level Combined Science Notes: Changes in state

When a solid item is heated the forces of attraction between the particles become weaker

as a result the particles move more quickly

  • The particles gain more kinetic energy
  • the solid item melts
  • […]

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Deficiency Diseases

By |2025-02-12T09:16:24+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Iodised salt can prevent iodine deficiency Iodised salt can prevent iodine deficiency ZIMSEC O Level Combined Science Notes: Deficiency Diseases

  • A person might suffer from a deficiency disease if their diet lacks certain essential minerals and vitamins
  • Two essential minerals and vitamins are:
  • Iodine and
  • Vitamins

Iodine Goitre is a [...]
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The reduction process

By |2025-02-12T09:43:27+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes:  The reduction process

  • Reduction is the opposite of oxidation
  • Reduction is the removal of oxygen from a substance/compound
  • It can also be the addition of oxygen

The reduction of copper. Image credit chemistrydemos.co.uk The reduction of copper.

  • reducing agent removes oxygen or adds hydrogen
  • Metals cannot be […]
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Experiment: Purification of copper using electrolysis

By |2025-02-12T09:29:04+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Refining copper using electrolysis Refining copper using electrolysis ZIMSEC O Level Combined Science Notes: Experiment: Purification of copper using electrolysis

Aim: To investigate the process of refining copper using electrolysis

Materials: two strips of copper, sandpaper, copper sulphate solution, 12 volt dc supply/battery, beaker, ammeter/bulb

Method

  1. Clean two strips of copper using sandpaper
  2. Place them in […]
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