rachel

/Rachel Majaya

About Rachel Majaya

She holds a Bachelor of Science Honors in Applied Biology and Biochemistry from National University of Science and Technology, a Certificate in Good Clinical Practices from National Institute on Drug Abuse Clinical Trials Network, a Certificate in Leadership from Deloitte and Certificate in Chemistry Laboratory Experiments from Helsinki Metropolian University of Applied Sciences, Finland.

March 2017

Chemical building blocks of Life: Water

By |2018-03-03T10:59:46+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

Water is life

ZIMSEC O Level Biology Notes:Chemical building blocks of Life: Bio-molecules

Water

Structure of a water molecule

  • Water is essential for life.
  • Approximately 75% earth’s surface is water.
  • Life evolved in water.
  • An average adult body is 50 to 65 percent water
  • This rises to about 80% in a child
  • A water molecule is made up of 2 hydrogen atoms […]
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Biology Notes: Water and its properties: Transparency and high heat of evapouration

By |2018-03-03T12:06:15+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes: Properties and Biological significance of water

Property: High heat of vaporization

  • This is a measure of the heat energy required to vaporize a liquid to overcome the attractive forces between its molecules so that they can escape as a gas.
  • A relatively large amount of energy is needed to vaporize water.
  • This is due […]
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Biology Notes: Water and its properties: Transport medium and specific heat capacity

By |2018-03-03T10:44:39+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: Transport medium

  • Water is a neutral liquid medium because it has a pH of 7.

Biological role of this property

  • Water’s solvent properties also mean that it acts as a transport medium in the blood transporting cells, lymphatic and excretory system, the alimentary canal and in the xylem and phloem.

Property: High […]

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Biology Notes: Water and its properties: Polar solvent

By |2018-03-03T10:34:23+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: Polar solvent

  • Water is an excellent solvent for ions and polar molecules because the water molecules attract to them, collect and separate them.
  • This is what happens when a substance dissolves in water.
  • Once a chemical is in solution, it is free to move about and react with other chemicals.
  • […]

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Biology Notes: Water and its properties: Surface tension

By |2018-03-03T10:28:00+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: High surface tension and cohesion (adhesion and cohesion)

  • Cohesion is the force whereby individual molecules stick together.
  • Adhesion is the force whereby water molecules stick to other surfaces.

Biological role

  • Cohesion helps water to move as an unbroken column in the xylem tubes in plants.
  • Adhesion helps the water to stick […]
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Biology Notes: Water and its properties: Density and heat fusion

By |2018-03-03T10:22:45+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

ZIMSEC O Level Biology Notes:Properties and Biological significance of water

Property: High heat of fusion

  • This is a measure of the heat energy required to melt a solid (ice).
  • Liquid water must lose a large amount of heat energy to freeze.

Biological role

  • Contents of cells and their environment are therefore less likely to freeze.
  • This is an advantage for bodies of […]
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Biology Notes: Causes of accidents in the laboratory

By |2017-03-30T07:34:47+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

Nitric acid fumes. Image credit amazingrust.com

ZIMSEC O Level Biology Notes:Causes of accidents in the laboratory

  • Fire – There should never be open flames in the lab. Make it a working rule that water is the only nonflammable liquid you are likely to encounter.
  • Explosion – Never heat a closed system or […]
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Biology related careers

By |2017-03-30T07:26:00+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

There are many Biology Related Careers. Image credit corning.com

ZIMSEC O Level Biology Notes:Biology related careers

These fall into the biology of applied sciences such as Agriculture, Medical science, Breeding, Forestry and Horticulture, Fishery, Pest Control and Animal Husbandry. The list is not exhaustive.

  • Medical Doctor
  • Nurse
  • Dermatologist
  • Biological Technician
  • Medical and Health […]
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Principal Branches of Biology

By |2017-03-30T06:59:45+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

A fish pond teeming with biological specimen. Image credit bigrockponds.com

ZIMSEC O Level Biology Notes:Principal Branches of Biology

  • The division and different branches of science are constantly spreading with the increase of knowledge in science.
  • The two main branches of science are Physical science and Biological Science.
  • Physical Science is also called […]
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Biology Notes: Emergency Procedures in the Lab

By |2017-03-30T06:42:49+00:00March 30th, 2017|Notes, O Level Biology Notes, Ordinary Level Notes|

Use the available First Aid Kit whenever there is an injury. Image credit MediaWiki

ZIMSEC O Level Biology Notes:Emergency Procedures

  • Immediately alert your instructor in case of ANY accident or fire.

A: Fire

  • In the event that your hair or clothing catches fire — DO NOT RUN. This will fuel the fire. STOP […]
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