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What is Biology?

Biology is the branch of science that deals with the study of living things. In Greek, Bios means life while Logos means knowledge.

Branches of biology

There are two main branches:

  1. Botany: Study of plants
  2. Zoology: Study of animals

The others include:

  1. Ecology: Study of living things in their surroundings.
  2. Genetics: The study of inheritance and variation.
  3. Entomology: Study of insects
  4. Parasitology: Study of parasites
  5. Taxonomy: Study of classification of organisms
  6. Microbiology: Study of microscopic organisms
  7. Anatomy: Study of structure of cells
  8. Cytology: Study of cells
  9. Biochemistry: Study of chemical changes inside living organisms

Name at least six other smaller branches of biology  (6 marks).

Importance of Biology

  1. Solving environmental problems e.g.  Food shortage, poor health services, pollution, misuse of environmental resources etc.
  2. Choice of careers e.g. Medicine, Agriculture, public health, Veterinary, Animal husbandry, Horticulture, Dentistry etc.
  3. Acquiring scientific skills e.g. observing, identifying, recording, classification, measuring, analyzing, evaluating etc.
  4. International co-operation e.g.  Development of HIV\AIDS vaccine, fight against severe Acute respiratory Syndrome (SARS), fight to save ozone layer from depletion, management of resources through international depletion.


  • Help on study of other subjects
  • Learn what living things are made up of and their bodies work
  • Acquire knowledge about plant and animal diseases and their treatment.
  • Know the effects of our bodies on drug and substance abuse and can kill.
  • Learn about HIV\AIDS diseases and other viral diseases e.g. its treatment—balanced diets, proper hygiene, spreading, sexual behavior, cultural practices etc.

List five professional occupations that require the study of biology. (5 marks)

Characteristics of living things;

  1. Nutrition: Process by which living things acquire and utilize nutrients: plants photosynthesize; animals feed on already manufactured foods.
  2. Respiration: energy-producing process occurring in all the cells of living things.
  3. Gaseous Exchange: where living things take in air (oxygen) and give out air(carbon iv oxide) across respiratory surfaces.
  4. Excretion: Process by which waste or harmful materials resulting from chemical reactions within cells of living things are eliminated. Excess of such materials poison living things.
  5. Growth and Development: Growth –is the irreversible increase in size and Mass.—Essential for body function.  Development –Irreversible change in complexity of the structure of living things.
  6. Reproduction: Process by which living things give rise to new individuals of the same kind.
  7. Irritability: Is the ability of living things to perceive changes in their surroundings and respond to them appropriately. E.g. reaction to changes in temperature, humidity, light, pressure and to the presence of certain chemicals.
  8. Movement: Change in position by either a part or the whole living thing. Locomotion – Progressive change in position by the whole living thing. In animals, movement include; swimming, walking, running, flying. In plants, closing of leaves, folding of leaves, closing of flowers, growing of shoots towards light etc.


  1. List four uses of energy obtained from the process of respiration. (4 marks).
  2. List six characteristics of living things (6 marks).

Collection of specimens

Apparatus used

  1. Sweep net: for catching flying insects.
  2. Fish net: For trapping small fish and other small water animals.
  3. Pooter:For sucking small animals from rock surfaces and tree barks.
  4. Bait trap: For attracting and trapping small animals e.g. rats.
  5. Pit fall trap: For catching crawling animals.
  6. Pair of forceps: picking up small crawling animals e.g. stinging insects.
  7. Specimen bottles:  keeping collected specimen. Larger specimens require large bottles.
  8. The magnifying lens: Instrument used to enlarge objects. Lenses are found in microscope and the hand lens (magnifier). Its frame is marked e.g. x8 or x10—indicating how much larger will be the image compared to object.

Precautions during Collection and Observation of specimens

  • Collect only the number of specimen you need.
  • Do not harm the specimens during the capture or collection exercise.
  • Handle dangerous or injurious specimens with care e.g. stinging plants or insects i.e. use forceps or hand gloves.
  • The teacher will immobilize highly mobile animals. (diethyl ether, formalin, chloroform)
  • Do not destroy the natural habitat of the specimens.

Practical activity 2

Practical activity 3

Comparison between plants and animals

Green in colour( have chlorophyll)Lack chlorophyll thus feed on readymade food.
Their cells have cellulose cell walls.Cells lack cellulose cell walls.
Respond slowly to changes in the environment.3. Respond quickly.
Lack specialized excretory organs.4. Have complex excretory organs.
Do not move about.5. Move about in search of food and water.
Growth occurs in shoot and root tips.(apical growth)6.Growth occurs in all body parts9intercalary growth).
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