(b) variety of living organisms

eukaryotic

contains a nucleus

prokaryotic

does not contain a nucleus

common features shown by plants

• eukaryotic

• multicellular

• carry out photosynthesis

• store carbohydrates as starch or sucrose

• e.g. cereal (maize) or herbaceous legume (peas or beans)

common features shown by animals

• eukaryotic

• multicellular

• usually have nervous coordination → are able to move from one place to another

• often store carbohydrates as glycogen

• e.g. mammals (humans) or insect (housefly or mosquito)

common features shown by fungi

• eukaryotic

• can be uni or multicellular

• usually organised into a mycelium made from thread-like structures called hyphae containing many nuclei

• saprotrophic nutrition

  • extracellular secretion of digestive enzymes onto food material and absorption of the organic products

• may store carbohydrates as glycogen

• e.g. mucor (has the hyphal structure) or yeast (unicellular)

common features shown by protoctists

• eukaryotic

• unicellular

• basically the group where the odd ones out go

• e.g. amoeba (lives in pond water, has animal cell-like features), chlorella (more like plants)

common features shown by bacteria

• prokaryotic

• unicellular

• have a plasmid instead of nucleus

• some carry out photosynthesis but most feed off other organisms

• e.g. lactobacillus bulgaricus (rod-shaped bacterium used in the production of yoghurt from milk) or pneumococcus (spherical bacterium that acts as a pathogen causing pneumonia)

common features shown by viruses

• not living organisms

• parasitic - can only reproduce inside living cells, not on their own

• infect every type of living organism

• wide variety of shapes and sizes

• no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA.

• e.g. tobacco mosaic virus (causes discolouring of the leaves of tobacco plants by preventing chloroplast formation) or influenza (causes the ‘flu’) or HIV (causes AIDS)

pathogens include:

• fungi

• bacteria

• protoctists

• viruses