February 2025

Contraception: Abstinence

By |2025-02-12T09:46:09+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Couple holding hands. Image credit neguswhoread.com Couple holding hands. Image credit neguswhoread.com ZIMSEC O Level Combined Science Notes:Contraception: Abstinence

  • It involves total avoidance of sexual intercourse

Adavantages

  • Many couples agree to wait until marriage
  • There is no risk of contracting  Sexually Transmitted Infections
  • It is 100% effective
  • It is supported by most religious […]
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Digestive systems of cows and rabbits

By |2025-02-12T09:17:31+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Cows. Image credit creativeblogs.net Cows. Image credit creativeblogs.net ZIMSEC O Level Combined Science Notes: Digestive systems of cows and rabbits

  • Cows and rabbits are examples of herbivores.
  • They feed on plants e.g. grass and leaves.
  • Pant structures contain a large amount of cellulose which cannot be digested easily.
  • Cellulose is a fibrous carbohydrate.
  • Much […]
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Examining the structure of stems and roots

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

Tree roots. Image credit lawnsite.com Tree roots. Image credit lawnsite.com ZIMSEC O Level Combined Science Notes: Examining the structure of stems and roots

Aim: To examine the structure of roots and stems under a microscope/bio-viewer.

Materials: Bio-set and bio-viewers, microscopes, prepared slides of root and stem sections.

Method Structure of roots. [...] </p> </body></html>

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Reproduction in plants: Flowers and Pollination

By |2025-02-12T09:24:25+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The basic structure of a flower The basic structure of a flower: showing the reproductive organs ZIMSEC O Level Combined Science Notes: Reproduction in plants: Flowers and Pollination

  • Most plants have female and male sex cells which join at fertilization to produce seeds
  • This is known as sexual reproduction
  • Flowers are the reproductive organs […]
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Experiment: Comparing the water holding capacity of the soil

By |2025-02-12T09:42:30+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Testing the water holding capacity of soil Testing the water holding capacity of soil ZIMSEC O Level Combined Science Notes: Comparing the water holding capacity of the soil

Materials: Measuring cylinders, funnels, cotton wool, water, dry soil samples, stop watch/clock

Method

  1. Set up your apparatus as shown in the diagram
  2. Add known volume of water
  3. Measure […]
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Strength to Mass ratio

By |2025-02-12T09:13:19+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

The cross section of beams The cross section of beams ZIMSEC O Level Combined Science Notes: Strength to Mass ratio

  • Engineers do away with materials that are under little stress so as to be able to build efficient structures in terms of weight and cost
  • The material that lies close to the neutral […]
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The reaction of metals with dilute acids

By |2025-02-12T09:38:29+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment: The reaction of metals with dilute acids

  • Metals also react with dilute acids such as
  • Dilute hydrochloric acid
  • Hydrogen gas is released as a by product of the reaction
  • Metals such as calcium, magnesium and zinc that react with water react even more vigorously with dilute acids
  • Metals that react with […]
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Extraction of copper from sulphides

By |2025-02-12T09:26:36+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes:Extraction of copper from sulphides

  • Copper is extracted from various types of ore including sulphide ores
  • For example copper ores found on the Great Dyke near Mhangura is of the sulphide type
  • Once the sulphide ore is extracted from the earth
  • It is crushed to form a very fine powder which is then further […]
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