Biology Notes

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1.1 Understand that living organisms share the following characteristics: they require nutrition they respire they excrete their waste they respond to their surroundings they move they control their internal conditions they reproduce they grow and develop.

Characteristics of living organisms include;

M ovement

R espiration

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. This is called homeostasis. Finally, all living organisms can diet

Variety of Living Organisms

Living organisms are classified into 5 groups, each of which has certain characteristics you need to learn


1. Multicellular organisms

2. Cells contain chloroplasts and are able to carry out photosynthesis

3. Cells have cellulose cell walls

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).


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).


1. They are saprophytic and feed by excreting digestive enzymes onto food and absorbing 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).


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 (a rod-shaped bacterium used in the production of yoghurt from milk) and Pneumococcus (a spherical bacterium that causes Pneumonia)


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 protoctists are multicellular (e.g. seaweeds, yes they're NOT plants!)


1. Much smaller than bacteria. They are not made from cells

2. Totally parasitic and reproduce inside host cells

3. They infect every type of living cell

4. They have the structure below (learn it, it comes up!)


The Envelope is used to gain entry into host 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).

Pathogens are microorganisms that cause disease.

Humans need to eat a balanced diet. This…


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