February 2025

Population Dynamics

By |2025-02-12T08:59:06+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit idealscounseling.org

Image credit idealscounseling.orgZIMSEC O Level Combined Science Notes: Population Dynamics

  • Population-all the inhabitants of a particular place/area at one given time
  • The study of changes in population is known as demograph

Factors affecting population change

  • The birth rate-the number of live births per 1000 people per year.
  • Death/Mortality rate-is the number of […]
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Pesticide Warning Symbols

By |2025-02-12T09:09:54+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Image credit incomdirect.com Image credit incomdirect.com ZIMSEC O Level Combined Science Notes: Pesticide Warning Symbols

  • Pesticides are graded according to their toxicity i.e.
  • According to how harmful they are to humans.
  • Every pesticide must have a label that clearly shows its “danger” level show.
  • There are four common danger levels of chemicals.

Purple […]

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Science: Ecosystems

By |2025-02-12T09:38:28+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

An ecosystem diagram. Image credit ck12.org An ecosystem diagram. Image credit ck12.org ZIMSEC O Level Combined Science Notes: Ecosystems  

  • Is a self-contained system of interdependent organisms and their physical environment
  • An ecosystem can also be defined as a biological community of interacting organisms and their physical environment.
  • In an ecosystem a community of living […]
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Natural Ecosystems

By |2025-02-12T09:01:20+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Impala ecosystem Natural ecosystem. Image credit wordpress.com ZIMSEC O Level Combined Science Notes: Natural Ecosystems

  • In a natural ecosystem there is close interaction between the plants and animals
  • The green plants are the producers
  • The animals are the consumers
  • There are several levels of consumers
  • Primary consumers-these eat plants directly
  • They are also known as herbivores
  • Secondary […]
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Experiment: Testing the physical properties of metals and non-metals

By |2025-02-12T09:23:02+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Common non-metals. Image credit blogspot.com Common non-metals. Image credit blogspot.com ZIMSEC O Level Combined Science Notes: Experiment: Testing the physical properties of metals and non-metals

Aim:To examine the physical properties of metals and non-metals

Materials: aluminium foil, carbon rod taken from a torch cell, copper foil, gas jars of oxygen, hydrogen; sulpher, […]

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Introduction to acids

By |2025-02-12T08:59:45+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Introduction to acids

  • A lot of everyday materials are acidic
  • This means that they contain an acid
  • Examples of everyday materials that contain acids are:
  • Lemons and other citric fruits as well as materials that contain these for example Orange crush
  • Vinegar (contains ethanoic/acetic acid)
  • Battery acid (sulphuric acid)
  • Other acids include: […]
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Reversible reactions

By |2025-02-12T09:17:50+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Reversible reactions

  • In a reversible reaction there is a forward reaction
  • And a backward reaction
  • Both take place at the same time
  • As a result there is an equilibrium between the reagents and their products
  • That is at some point during the reaction process the amounts of both the reagents and their […]
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