Igcse Bio Notes

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IGCSE Biology Notes

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Unit 1 : Characteristics of living things

Biology is the study of living organisms. For something to be alive it needs to perform all seven functions of living things.MRS GREN Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition. 1. Movement Most organisms are able to move their whole body even plants can shift their stem towards the sunlight and their roots move towards healthy soil. 2. Respiration IT is the breakdown of food inside a living organism IT IS VITAL for survival. 2 types Aerobic Respiration which involves O2 & glucose breaking down to form CO2 water & ENERGY. Anaerobic Respiration which is the incomplete breakdown of food. Happens when there is not enough oxygen. Equation, Glucose & O2 (not enough) to form CO2 Lactic Acid or Alcohol (depending on the organism) & a little ENERGY. 3. Sensitivity It is the ability to detect and respond to a stimulus. 4. Growth It is the permanent increase in size and quantity of cells using materials absorbed from the environment. 5. Reproduction It is forming new individuals of the same species either sexual (2 parents) or asexual (1 parent) \ 6. Excretion It is removal of harmful products of metabolism. Egestion is the removal of undigested products which haven’t entered the cell. 7. Nutrition It is the intake of food material from the environment. Autotrophic nutrition: Organisms that make their own food such as plants. Heterotrophic nutrition: Organisms that need readymade food including herbivores, carnivores & omnivores.

Unit 2 : Classification
Classification is sorting organisms into smaller groups based on their similarities which then allows us to make comparison between them. Organisms are split into the following:

• • • • • • •

Kingdom Phylum Class Order Families Genus Species

Many Organisms

Few features in common

Individual Organism

Many features in common

A specie is a group of organisms that share the many...
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