INHERITANCE

Genetics

Genetics is the study of Heredity. Heredity deals with the transmissions of characteristics from one generation to another.

Variations

Observable differences within a species are called variations. There arte two types of variations.

(a) Continuous variations. Observable differences within a species with intermediate forms are called continuous variations. E.g. height of students in a class, intelligence of students, Skin color. This is due to the result of two factors.

  1. The genes that are inherited by an individual.
  2. The effect of environment on the individual organisms.

The environmental factors are

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CELL

All living things are made up of cells. They are the basic structural and functional units of life. Robert Hooke discovered the cell in 1665. The average size of a cell varies between 10 micrometers (µm) to 150 micrometers (µm).

  • The simplest living organisms are made up of one cell only. These organisms are described as UNICELLULAR organisms.  E.g. Bacteria
  • Most other living organisms have many cells and are described as MULTICELLULAR organisms. E.g. Birds

A cell is a very small piece of transparent jelly-like substance, surrounded by a thin covering. The jelly is called the cytoplasm.  The covering is called the cell membrane. Most of the cells also have dark area inside the cell called a nucleus

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MESENTERY A new organ in Human

New organ discovered inside human body by scientists

mesentery-0

A new organ called mesentery has been discovered inside the human body.

It was previously thought to be just a few fragmented structures in the digestive system. The scientists have realized it is in fact one, continuous organ. Now we have 79 organs in our body.

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HUMAN DIGESTIVE SYSTEM

The digestive system also known as the alimentary canal or gut is a long tube running from the mouth to the anus, with associated organs together with a number of associated glands that help in digestion. The human digestive system is well adapted for digestion and absorption.

Digestion is the process by which insoluble, in diffusible form of food is converted into soluble,diffusible form form so that the food can be absorbed into the blood

There are five processes in digestion

  1. Ingestion
  2. Digestion
    • Mechanical digestion
    • Chemical digestion
  3. Absorption
  4. Assimilation
  5. Egestion
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DIFFUSION, OSMOSIS,AND ACTIVE TRANSPORT

DIFFUSION
Diffusion is the movement of molecules from a region of high concentration to a region of low concentration down a concentration gradient until evenly distributed.Concentration gradient: the difference in concentration between two regions.
Why does diffusion occur?
1. There is a great deal of empty space between molecules of all substances. (The spaces are more in gases, less in liquids, and least in solids).
2. As all the molecules are always in a constant random motion they collide all the time.

What are the factors affecting rate of diffusion?
1. Thickness of membrane: the thinner the cell membrane, the faster the diffusion.

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