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Edexcel IGCSE Revision notes

Written by Tim Filtness

Biology IGCSE Revision Workbook
Trippple Award Specification (4BIO) Examination in 2011

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IGCSE Revision Notes
Trippple Award Specification Key words are underlined in red. Practical work is printed in italics.

Edexcel IGCSE Revision notes

Written by Tim Filtness

Section 1: The nature andvariety of living organisms
Characteristics of living organisms include;

M ovement R espitation S ensitivity G rowth R eproduction E xcretion N utrition
In addition, all living organisms contain nucleic acids (DNA) and have the ability to control their internal conditions. Finally, all living organisms can die. Living organisms are classified into 5 groups, each of which has certaincharacteristics you need to learn

Plants: Plants
1. Multicellular organisms 2. Cells contain chloroplasts and are able to carry photosynthesis 3. Cells have cellulose cell walls out

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Edexcel IGCSE Revision notes

Written by Tim Filtness

4. They store carbohydrates as starch or sucrose. Examples include flowering plants, such as a cereal (e.g. maize) and a herbaceous legume (e.g. peas or beans).Animals: Animals
1. Multicellular organisms 2. Cells do not contain chloroplasts and are not able to carry out photosynthesis 3. Cells have no cell walls 4. They have a nervous system 5. They often store carbohydrate as glycogen Examples include mammals (e.g. humans) and insects (e.g. housefly).

Fungi: Fungi
1. They are saprophytic and feed by excreting digestive enzymes onto food andabsorbing the digested products 2. Cells do not contain chloroplasts and are not able to carry out photosynthesis 3. Cells are joined together to form threads, called hyphae. Hyphae contain many nuclei, because they are made from many cells. 4. Cell walls are made from chitin (a protein) 5. They store carbohydrates as glycogen. Examples include Mucor and Yeast (which is single celled).

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Written by Tim Filtness

Bacteria: Bacteria
1. Made from single cells 2. Cells do not contain a nucleus, but have a small piece of circular DNA instead (a bacterial chromosome). 3. Some bacteria can carry out rudimentary photosynthesis, but most are saprophytes 4. They have the structure below (learn it, it comes up!)

Examples include Lactobacillius bulgaricus (arod-shaped bacterium used in the production of yoghurt from milk) and Pneumococcus (a spherical bacterium that causes Pneumonia)

Protoctisis: Protoctisis
Basically, everything that doesn’t fit into the other kingdoms! Most are single celled organisms which can either; 1. Have animal-like characteristics (e.g. Amoeba) 2. Have plant-like characteristics (e.g. Chlorella) However, some protoctisisare multicellular (e.g. seaweeds, yes they’re NOT plants!)

Viruses: Viruses
1. 2. 3. 4. Much smaller than bacteria. They are not made from cells Totally parasitic and reproduce inside host cells. They infect every type of living cell They have the structure below (learn it, it comes up!)
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Edexcel IGCSE Revision notes

Written by Tim Filtness

The Envelope is used to gain entry intohost cells. The Capsid is a protein coat and is used to protect the genetic information and give the virus structure The DNA or RNA (a different type of nucleic acid) contain the code for building new viruses. Examples include the Tobacco Mosaic Virus and the Influenza virus (which causes ‘flu).

Section 2: Structures and Functions in Functions Living Organisms
a) Levels of organizationOrganisms are made from organizations of smaller structures. You need to know the following hierarchy of structures. Organelles – intracellular structures that carry out specific functions within a cell Cells – the basic structural and functional unit from which all biological organisms are made

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Edexcel IGCSE Revision notes

Written by Tim Filtness

Tissues – a group of specialized cells,...