1(b) Variety of living organisms

1.2 describe the common features shown by eukaryotic organisms: plants, animals, fungi, and protoctists. 1.3 describe the common features shown by prokaryotic organisms such as bacteria. 1.4 understand the term 'pathogen' and know that pathogens may include fungi, protoctists, bacteria and viruses

Eukaryotic organisms

Organisms that have a nucleus.

→ Animals, Plants, Fungi, Protoctists

Prokaryotic organisms

Organisms that do NOT have a nucleus.

→ Bacteria

Taxonomy

The study of classification of living organisms.

Characteristics of Animals

1. multicellular

2. do not have a cell wall

3. store carbohydrates as glycogen (=many glucose molecules→polysaccharide)

4. cells do not contain chloroplasts, not able to carry out photosynthesis

5. usually have nervous coordination and are able to move from one place to another

Example of Animals

• Mammals, e.g. humans

• Insects, e.g. houseflies and mosquitos

Characteristics of Plants

1. multicellular

2. have a cell wall made of cellulose

3. store carbohydrates as starch or sucrose

4. cells contain chlorophyll and are able to carry out photosythesis

Example of Plants

• flowering plants such as a cereal

• herbaceous legume such as beans, peas

Characteristics of Fungi

1. not able to carry out photosythesis

2. body usually organised into a mycelium (network of fibres) made of hyphae (thread-like structure) which contain many nuclei.

3. some are unicellular, some are multicellular

4. have a cell wall made of chitin

5. feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products(=saprotrophic nutrition)

6. may store carbohydrates as glycogen

Examples of Fungi

• single-celled: yeast

• typical fungal-hyphal structure: Mucor (makes bread rise)

Characteristics of 1.Protoctists

1. microscopic, unicellular

2. some, like Amoeba, that lives in pond water, have features like an animal cell

3. others, like chlorella, have chloroplasts and are more like plants

4. pathogenic example: Plasmodium(causes malaria)

Characteristics of Bacteria

1. microscopic unicellular organisms

2. have a cell membrane, cell wall made of peptidoglycan, cytoplasm, plasmids(small loops of DNA)

3. lack a nucleus but contain a circular chromosome of DNA

4. some can photosythesise but most feed off other living or dead organisms

5. some have flagella for movement

6. some have a slime layer or capsule

Examples of Bacteria

• Pneumococcus, a spherical-shaped bacteria that causes Pneumonia

• Lactobacillus bulgaricus (latin scientific name, needs to be underlined in the exam!!!!), a rod-shaped bacteria used in the production of yoghurt from milk

Characteristics of Virus

1. not living organism

2. small particles, smaller than bacteria

3. contain one type of nucleic acid, either RNA or DNA

4. have a protein coat

5. lack a cellular structure

6. wide variety of shapes and sizes

7. infect all types of living organisms

8. are parasitic- can only reproduce inside living cells

Examples of Virus

• Tobacco mosaic virus - causes discolouring of the leaves by preventing the formation of chloroplasts

• HIV causes AIDS

• Influenza causes flu

Pathogen

Organism or virus that cause disease. May include fungi, protoctist, bacteria, virus.

A pathogenic example of a protoctist

Plasmodium, which causes malaria.

A pathogenic example of a bacterium

Pneumococcus, spherical-shaped bacterium that causes Pneumonia.

A pathogenic example of a fungus

Athlete’s foot