February 2025

The structure of the leaf and photosynthesis

By |2025-02-12T08:56:55+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The external structure of the leaf. Image credit passmyexams.co.uk The external structure of the leaf. Image credit passmyexams.co.uk ZIMSEC O Level Combined Science Notes: The structure of the leaf and photosynthesis

  • The leaves are the main organs of photosynthesis.
  • Their structure is adopted for the process of photosynthesis.
  • Veins-vein networks support the physical structure […]
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Respiration

By |2025-02-12T09:36:04+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Respiration

  • During the gaseous exchange process oxygen is taken into the body and carbon dioxide is expended.
  • Oxygen is needed to burn fuels to release energy.
  • Food is a fuel and oxygen is used by th cells to “burn” the fuel.
  • The burning process is very slow and there are not flames involved.

    • […]

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Asexual reproduction

By |2025-02-12T09:34:33+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

A bud on a sugarcane cutting. Image credit 10degreesabove.com A bud on a sugarcane cutting. Image credit 10degreesabove.com ZIMSEC O Level Combined Science Notes: Reproduction in plants: Asexual reproduction/ Vegetative reproduction  

  • Is also known as asexual reproduction
  • This takes place when plants reproduce without producing seeds
  • Such plants have modified stems, roots or […]
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Selection

By |2025-02-12T08:59:43+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Selection

  • Each time male and female individuals reproduce they create an offspring that is different from themselves
  • This changes accrue over time to bring about much change in the descendants as there is inter-breeding between many individuals in each generation
  • This changes might result in the offspring having certain advantageous characteristics that are […]
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Experiment: to show changes in shape and volume of iodine crystals when they are heated

By |2025-02-12T09:11:39+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

sublimation_of_iodine-min

ZIMSEC O Level Combined Science Notes: An  experiment To show changes in shape and volume of iodine crystals when they are heated

Materials: evaporation dish/tin lid, glass filter funnel, burner, burner stand, one iodine crystal

Method

  1. Place the iodine crystal into an evaporation dish
  2. Put the filter funnel upside down over the crystal
  3. Warm the crystals […]
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Properties of Nonmetals vs metals

By |2025-02-12T09:21:43+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Common metal objects. Image credit blogspot.com Common metal objects. Image credit blogspot.com ZIMSEC O Level Combined Science Notes: Experiment: Properties of Metals and Non-Metals

  • Elements can be divided into two groups:
  • Metals and Non-metals
  • Examples of metals are: copper, zinc, iron, gold, silver, chrome, lead and tin
  • Almost all metals have certain properties that makes them […]
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Experiment: Reducing Iron oxide using aluminium

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

ZIMSEC O Level Combined Science Notes: Experiment: Reducing Iron oxide using aluminium

Aim: To remove oxygen from iron oxide using aluminum

Materials: sand, tin can, safety screen, magnesium ribbon and magnesium powder, wooden splint, aluminum powder, dry iron oxide, barium preoxide

Reducing iron oxide using aluminum oxide Reducing iron oxide using aluminum oxide

Method

  1. Fill the tin […]
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Experiment: The rate of reactions and temperature

By |2025-02-12T09:16:26+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Relationship between temperature and rate of reaction. Image credit bu.edu Relationship between temperature and rate of reaction. Image credit bu.edu ZIMSEC O Level Combined Science Notes:Experiment: The rate of reactions and temperature

Aim:  To find the effect of temperature on the rate of reaction: using hydrochloric acid and sodium thiosulphate

Materials: flask, […]

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Coating metals/Protecting metals from corrosion

By |2025-02-12T09:31:18+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Investigating the rusting or iron Investigating the rusting or iron ZIMSEC O Level Combined Science Notes: Coating metals/Protecting metals from corrosion

  • Steel has many uses for example construction and to make utensiles
  • This is because it is cheap and strong
  • It is however susceptible to rusting
  • This is because it combines […]
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