February 2025

The siphon

By |2025-02-12T09:08:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Siphons being used for irrigation. Image credit wonderopolis.org Siphons being used for irrigation. Image credit wonderopolis.org ZIMSEC O Level Combined Science Notes: The siphon

  • In a siphon pressure is greatest in the lower end of the pipe
  • The pressure will cause the liquid to flow out
  • This reduces the pressure […]
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Diseases: Cholera

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

People fetching contaminated water. Image credit mg.co.za People fetching contaminated water. Image credit mg.co.za ZIMSEC O Level Combined Science Notes: Diseases: Cholera

  • I usually spread by contaminated food and/or water
  • The cholera pathogen is a bacterium called Vibrio cholerae
  • It is an infectious disease
  • The pathogen lives and multiplies in the digestive […]
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Contraception: The use of spermicides

By |2025-02-12T09:43:53+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Couple having dinner. Image credit singleblackmale.org Couple having dinner. Image credit singleblackmale.org ZIMSEC O Level Combined Science Notes:Contraception:Ways to prevent pregnancy

  • Spermicides are sperm killing chemicals

How it works

  • Are usually in the form of jelly cream placed into the vagina before sexual intercourse
  • The chemical kills spermatozoa

Effectiveness

  • 60-95%

Advantages

  • Does not require […]
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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 […]
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Animal Parasites and diseases

By |2025-02-12T09:30:38+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Ticks on bull. Image credit morningagclips.com Ticks on bull. Image credit morningagclips.com ZIMSEC O Level Combined Science Notes: Animal Parasites and diseases

  • Farmers in Zimbabwe typically raise goats, cattle, chickens and sheep.
  • Disease spread much more quickly where large numbers of the same type of livestock are kept close together when compared […]
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Experiment: Finding soil organisms

By |2025-02-12T08:56:32+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Finding soil organisms. Finding soil organisms. ZIMSEC O Level Combined Science Notes: Experiment: Finding soil organisms

Materials: digging tools, pen and paper, tweezers, gauze, beaker, filter tunnel, light bulb, clamp stand, microscope/hand lens, containers

Method

  • Go out and look for soil organisms. Look for things such as holes in the soil
  • Take soil samples
  • Set up […]
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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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