January 2023

Causes of infertility

By |2022-09-15T12:37:49+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Sterility can cause strain in a relationship. Image credit colossiansfamilynetwork.org Sterility can cause strain in a relationship. Image credit colossiansfamilynetwork.org ZIMSEC O Level Combined Science Notes: Causes of infertility

  • Sterility is the inability to reproduce
  • There are a number of causes for sterility
  • Low sperm count (makes it […]
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Products of digestion and the Absorption and Assimilation processes

By |2022-09-15T12:41:45+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Human nails, one of the products of assimilation. Image credit arithmaroo.com Human nails, one of the products of assimilation. Image credit arithmaroo.com ZIMSEC O Level Combined Science Notes:Products of digestion and the Absorption and Assimilation processes

  • After food has been digested in can now be used.
  • The end products ( which would […]
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Nutrition

By |2022-09-15T12:40:40+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

A balanced diet. Image credit healthandstylish.com A balanced diet. Image credit healthandstylish.com ZIMSEC O Level Combined Science Notes: Nutrition

  • Nutrition is that branch of science that deals with nutrients and nutrition especially in humans
  • It is concerned with  ensuring that humans are eating foods that provide necessary nutrients for health and growth
  • Nutrients […]
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Advantages and disadvantages of vegetative production

By |2022-09-15T12:40:31+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Sugarcane field. Image credit gov.ph Sugarcane field. Image credit gov.ph ZIMSEC O Level Combined Science Notes: Reproduction in plants: Advantages and disadvantages of vegetative (asexual) production  

  • A lot of plants which grow using the vegetative method of reproduction are able to produce seeds
  • They use vegetative reproduction because it has certain advantages

Advantages

  • New […]
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Selection

By |2022-09-15T12:40:23+02:00January 24th, 2023|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 |2022-09-15T12:40:13+02:00January 24th, 2023|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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Experiment:Making magnesium oxide compound

By |2022-09-15T12:39:45+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment:Making magnesium oxide compound

Aim: To make a compound of magnesium and oxygen (magnesium oxide)

Materials: magnesium ribbon, sandpaper, tongs, burner

Burning metals in air, Magnesium oxide. Burning metals in air, Magnesium oxide.

Method

  1. Clean a piece of magnesium ribbon with sandpaper
  2. Examine the magnesium and note its physical properties
  3. Hold the […]
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Experiment: Investigating the rusting of iron

By |2022-09-15T12:39:33+02:00January 24th, 2023|Notes, O Level Science Notes, Ordinary Level Notes|

Investigating the rusting or iron Investigating the rusting of iron ZIMSEC O Level Combined Science Notes: Experiment: Investigating the rusting of iron

Aim: Investigating the rusting (oxidation) of iron

Materials: 4 iron nails, 1 steel nail, a piece of copper/brass, 5 test tubes, cotton wool, solid calcium chloride, magnesium ribbon

Method

  1. Half fill two test tubes with […]
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Experiment: The rate of reactions and temperature

By |2022-09-15T12:39:24+02:00January 24th, 2023|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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