1.2-1.4: The variety of living organisms

5 kingdoms of living things

- animals
- plants
- fungi
- protoctists
- prokaryotes

eukaryotes

multicellular or unicellular organisms made up of cells that contain a nucleus with a distinct membrane

eukaryotic organisms

animals, plants, fungi and protoctists

prokaryotes

unicellular organisms that do not contain a nucleus, smaller than eukaryotes

features of animal cells

- multicellular
- membrane-bound organelles
- heterotrophic
- store carbohydrates as glycogen

examples of animals

- mammals
- insects

features of plant cells

- multicellular
- membrane-bound organelles
- cell walls made out of cellulose
- cells contain chloroplasts
- feed by photosynthesis
- store carbohydrates as starch or sucrose

examples of plants

- flowering plants
- maize
- herbaceous legume

nucleus

contains genetic material and control centre of the cell

cytoplasm

A jellylike fluid inside the cell, site of chemical reactions, support for organelles

cell membrane

controls which substances can enter or leave the cell

ribosomes

site of protein synthesis

mitochondria

powerhouse of the cell, organelle that is the site of (energy) production

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

chloroplasts

contain chlorophyll for photosynthesis

vacuole

A sac inside a cell that acts as a storage area and contains cell sap

features of fungal cells

- usually multicellular but some are unicellular
- made up of thread-like structures known as hyphae that contain many nuclei
- membrane-bound organelles
- cell walls made of chitin
- saprotrophic nutrition
- some are parasitic
- some store carbohydrates as glycogen

Examples of fungi

- moulds
- mushrooms
- yeasts
- mucor

features of protoctist cells

- microscopic
- uni-cellular
- membrane-bound organelles
- some have cells walls and chloroplasts
- some protoctists photosynthesise and some feed on organic - substances made by other living things

Examples of protoctists

amoeba, paramecium, plasmodium, chlorella

features of bacterial cells

- microscopic
- uni-cellular
- have a cell wall (not made of cellulose), cell membrane, cytoplasm and plasmids
- lack a nucleus but contain a circular chromosome of DNA
- some can carry out photosynthesis but most feed off other organisms

examples of bacteria

- Lactobacillus
- Pneumococcus

lactobacillus bulgaricus - structure

rod-shaped bacterium usedd in the production of yoghurt from milk

pneumococcus - structure

spherical bacterium acting as a pathogen causing pneumonia

pathogen

an organism that causes disease

examples of micro-organisms that are pathogens

- Bacteria
- Fungi
- Protoctists
- Viruses

viruses

non-living particles

How do viruses reproduce?

they take over a host cell

features of viruses

- small particles
- parasitic and can only reproduce inside living cells
- infect every type of living organism
- no cellular structure
- have a protein coat and contain one type of nucleic acid, either DNA or RNA

examples of viruses

tobacco mosaic virus (TMV)
HIV
influenza

Tobacco Mosaic Virus (TMV)

a widespread plant pathogen that causes discolouring on leaves by preventing chloroplast formation

human immuno-deficiency virus (HIV)

a virus that can lead to AIDS

influenza

infects humans to cause the flu