IGCSE>SECTION-1>1-CHARACTERISTICS OF LIVING ORGANISMS
Class presentation
CHARACTERISTICS OF LIVING ORGANISMS
THE DAWN OF LIFE
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1_ NUTRITION
Nutrition is the taking in of nutrients (food) which are organic molecules and mineral ions, providing raw materials or energy for growth, tissue repair and reproduction.
Nutrition in plants and animals:
Nutrition in plants and animals:
- Plants make their food using the process of photosynthesis, whilst animals obtain `food 'ready-made' by eating them.
2_ EXCRETION
Excretion as removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials, and substances in excess of requirements.
Excretion and egestion:
Excretion and egestion:
- Excretion is the removal of waste which are byproducts of chemical reactions takes place in cells.(Metabolic waste)
- Egestion can be defined as the discharge of undigested food particles or matter from the body of an animal.
3_ RESPIRATION
Respiration as the chemical reactions in cells that break down nutrient molecules and release energy for metabolism.The form of respiration that release the most energy uses oxygen.
Breathing and respiration:
Breathing and respiration:
Breathing
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Respiration
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4_ SENSITIVITY
- Sensitivity as the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses.
- These responses often involve movement (an action by an organism causing a change of position or place).
5_ REPRODUCTION
- Reproduction is the processes that make more of the same kind of organisms- new individuals.
- An organisms may split into two, or reproduction may be a more complex process.
6_ GROWTH
- Growth as a permanent increase in size and dry mass by an increase in cell number or cell size or both.
- Most living organisms start their lives as a single cell, too small to be seen with naked eye. This cell divides many times to produce an organism made up of thousands or million of cells. The new cells become specialized and form tissue and organ. so growth involves an in increase in size and mass
7_ MOVEMENT
- Movement as an action by an organism or part of an organism causing a change of position or place.
- Movement and locomotion:
- Locomotion refers to the movement of an organisms from place to place. Movement refers to a change in position of any part of an organism's body, but does not necessarily involve locomotion.