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Section 1: The nature and variety of living organisms
a) Characteristics of living organisms

1.1 Understand that living organisms share the following characteristics:
Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition

b) Variety of living organisms
1.2 Describe the common features shared by organisms within the following main groups: plants, animals, fungi, bacteria, protoctists and viruses, and for each group describe examples and their features

Plants:
  • Multicellular
  • Cells contain chloroplasts to carry out photosynthesis
  • Have cellulose cell walls
  • Store carbohydrates as sucrose or starch
  • Examples: cereals (maize), herbaceous legumes (peas, beans)
Animals:
  • Multicellular
  • No chloroplasts
  • No cell walls
  • Most have nervous coordination
  • Able to move from place to place
  • Store carbohydrates as glycogen
  • Examples: mammals (humans), insects (mosquitoes)

Fungi:
  • Single celled or multicellular
  • Have a body called a mycelium - made up of thread-like structures called hyphae (which have many nuclei)
  • No photosynthesis
  • Cell walls made of chitin
  • Feed by saprotrophic nutrition - they secrete extracellular enzymes into the area around them to dissolve food materials. They then absorb the nutrients.
  • Can store carbohydrates as glycogen
  • Examples: mucor (has typical hyphal structure), yeast (single celled fungus)


Protoctists:
  • Microscopic single celled organisms
  • Some have chloroplasts and are similar to plant cells eg chlorella
  • Some are more like animal cells eg amoeba
  • Some are pathogens eg plasmodium, which causes malaria
Bacteria:
  • Microscopic single celled organisms
  • No nucleus
  • Circular chromosome of DNA and plasmids (extra bits of DNA)
  • Some can photosynthesise, bust most feed off living/dead organisms
  • Examples: lactobacillus bulgaricus (a rod shaped bacterium used to make yoghurt from milk), pneumococcus (a spherical bacterium that causes pneumonia)
Viruses:
  • Particles, not cells, smaller than bacteria
  • Can only reproduce inside living cells - they are parasitic
  • They can infect every type of living organism
  • Variety of shapes and sizes
  • No cellular structure - just a protein coat around genetic material (DNA or RNA)
  • Examples: influenza virus (a pathogen that causes the flu), tobacco mosaic virus (makes the leaves of the tobacco plant discoloured by stopping the production of chloroplasts)
Pathogens:
  • Organism that causes a disease
  • Can be fungi, bacteria, protoctists or viruses
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