Biology

Characteristics of living organisms

All organism carry out the following;

  • they move
  • they respire
  • they responsed to their surronding ( sensitivity)
  • they grow and develop
  • they reproduce
  • they excrete waste
  • they require nutrition



 




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Variety of living organisms

Plants

They are multicellular organisms. Their cells contain chloroplast which  carry out photosynthesis and the cellulose walls store carbohydrates such as starch and sucrose. Examples include flowering plants such as maize

Animals

Are multicullar organisms Their cells do not contain chloroplast and have no cell wall. They usually have nervous cordination which allows them to move They often store carbohydrates as glycogen. Example include mammels ( such as humans) and insects (such as housefly and mosquito.

Protoctists

 Are microscopic single celled organisms which have a cell wall, cell membrane, cytoplasm and plasmid. They don't have a nucleus but contain a circular chromosone of DNA. Some bacteria carry out photosynthesis but most feed of other organisms dead or alive. Example include Lactobacillus which is used in the product of yoghurt and pneumococcus which acts a pathagon and causes pnemonia



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Variety of living organisms (continued)

Fungi

Can not carry out photsynthesis; their body is usually organised into mycelium made from thread like structures called hyphae which contain a nuclei. Some fungi are single celled whith walls made of of chitin; they feed by secreting digestive enzymes onto food and then absorb organic product this is known as saprotrophic nutrition. They store carbohydrates as glycogen. Examples include mucor which is a hyphai structure and yeast which is single celled.

Protoctists

Are microscopic single celled organisms like Amoeba which lives in pond water and has features like animal cells. While  Chlorella has chloroplasts and is more like plants.

Viruses

Are small particles and are smaller than bacteria; they are parisitic and can only reproduce inside living cells. They infect every type of organism. Have a wide variety of shapes and sizes, they have no cellular structure but have a protein coat and contain either DNA or RNA. 


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