Nature and Variety of Organisms

• Movement: move position as part of a cell
• Respiration: chemical reaction to provide energy for function
• Sensitivity: The ability to detect a change and respond to environment
• Control: homeostasis which is the control of the internal conditions
• Growth: produce new cells
• Reproduction: make new generation of cells
• Excretion: removal of metabolic waste
• Nutrition: taking in raw materials for survival
• The Eukaryotic organisms:

  1. Animals
  2. Plants
  3. Fungi
  4. Protoctists
• Prokaryotic organisms: Bacteria
• Multicellular organisms: animals, plants, some fungi
• Single-celled organisms: bacteria, some fungi, protoctists
• Plants have cell walls that contain cellulose. They store carbohydrates as starch or sucrose
• Animals store carbohydrates as glycogen. They have nervous co-ordination and can move from one place to another
• Eukaryotic organisms have nuclei whereas prokaryotic do not
• Bacterial cell:

  A) Cell wall

  B) cell membrane

  C) Cytoplasm

  D) Flagella

  E) ribosome

  F) plasmid

  G) circular chromosome of DNA

  
• Bacteria key points:

  • they have no nucleus
  • some do photosynthesis
  • Smaller than eukaryotic cells
  • Feed off other organisms dead or alive
• Example of bacteria

  • Lactobacillus used in production of yoghurt, it is a rod shaped bacterium
  • Pneumococcus causes pneumonia, it is a spherical bacterium
• Fungi Cell Organelles:

  There is also a food storage granule and vacuole

  A) Cytoplasm

  B) Ribosome

  C) Mitochondria

  D) Nucleus

  E) Cell wall

  F) Cell membrane

  
• Fungi cells key points:

  • No photosynthesis as they have no chloroplasts
  • Multicellular fungi bodies usually organised in mycelium made from thread-like structures called hyphae
  • Hyphae contains lots of nuclei, single-celled fungi have one nucleus
  • Cell wall is made of chitin
  • Carbohydrates are stored as glycogen
  • Some fungi carry out saprotrophic nutrition
• Examples of yeast:

  • multicellular - mucor that causes mould
  • single-cellular - yeast that is used in fermentation
• Saprotrophic nutrition: feeding by extracellular secretion of digestive enzymes onto food material in order to absorb the organic products. Bacteria and fungi do this
• Protoctist cells key points:

  • They can be similar to animal or plant cells
  • They are microscopic cells
• Examples of Protoctist cells:

  • Chlorella which is a plant-like cell as it has chloroplasts
  • Amoeba which is an animal-like cell and lives in pond water
  • Plasmodium which is a pathogen that causes malaria
• Examples of plants:

  • flowering plants - maize
  • herbaceous plants - peas, beans
• Pathogen - organism that causes disease. Fungi, protoctists, bacteria and viruses can be these
• Viruses Key Points:

  • Not living organism
  • Smallest as they are particle not cell
  • They are parasitic so can only reproduce inside living cells
  • They infect all types of organism
  • Variety of shape and size
• Virus Cell Diagram:

  A) Protein coat

  B) DNA or RNA

  
• Examples of Viruses:

  • Tobacco Mosaic Virus - discolours tobacco leaves by preventing formation of chloroplasts
  • Influenza - causes flu
  • HIV - causes AIDS
• DNA and RNA are nucleic acids