February 2025

Machines

By |2025-02-12T09:35:16+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Gears in a machine. Image credit wall.alphacoders.com Gears in a machine. Image credit wall.alphacoders.com ZIMSEC O Level Combined Science Notes: Machines

  • A machine is a device that makes work easier either by:
  • Reducing the effort (force) required to lift the load or
  • By changing the direction in which the effort is […]
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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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Geographical organisation structure

By |2025-02-12T09:07:17+02:00February 12th, 2025|Notes, O Level Business Studies Notes, Ordinary Level Notes|

ZIMSEC O Level Business Studies Notes: Geographical based organisational structure

  • This is when an organisations divisions, operations, duties and positions are based geographical area, country, regions, provinces, towns or districts
  • Usually there is a Head Quarters to which all the subdivisions and their related personnel report to
  • The head quarters administers […]
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Communication in business: Face to face

By |2025-02-12T09:37:55+02:00February 12th, 2025|Notes, O Level Business Studies Notes, Ordinary Level Notes|

Interpersonal communication. Image credit darryllshaw.co.uk

ZIMSEC O Level Business Studies Notes: Leadership:One to one (interpersonal communication)

  • It is the exchange of information and ideas between two people
  • It involves face to face communication, verbal/spoken communication and non-verbal communication in form of gestures
  • It is the most frequently used form of communication when […]
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Population growth

By |2025-02-12T09:04:16+02:00February 12th, 2025|Notes, O Level Geography, Ordinary Level Notes|

ZIMSEC O Level Geography Notes: Population: Population growth

  • is an increase in the number of people that reside in a country, state, county, or city
  • There are several factors which affect the growth of a population
  • A country’s population grows as a result of natural births taking place within the community/country/region
  • Births increase the population
  • It can also grow […]
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Sobhuza versus Zwide

By |2025-02-12T09:17:26+02:00February 12th, 2025|Notes, O Level History Notes, Ordinary Level Notes|

Nguni apparel. Image credit BBC

ZIMSEC O Level History Notes: Crisis in Nguniland: Sobhuza versus Zwide

  • Zwide Kalanga (1758-1825) was the king of the Ndwandwe/Nxumalo nation circa 1805 to circa 1820
  • Around the time Zwide was king the Ndwandwe were a growing military power
  • Zidwe was an ambitious leader keen on expanding […]
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