Science Test 2 Revision

• Living


  Something that exhibits all seven processes of living things
• Non-living


  Something that has never been alive
• Dead


  Something that used to exhibit all the processes of living things
• MRS GREN


  • Acronym for the seven processes performed by all living things
• Processes performed by living things


  1. Movement

  2. Respiration

  3. Sensitivity

  4. Growth

  5. Reproduction

  6. Excretion

  7. Nutrition
• For something to be living, it must show all the seven processes of living things
• Movement from one location to another is easy to see, but sometimes movement can be difficult to observe
• If an organism can move, respirate, sense, grow, reproduce, excrete (get rid of waste), needs nutrition it is living
• A non-living object is one that has never been alive
• Something that is dead used to exhibit all the processes of living things
• Sometimes it is not so easy to decide if something is living or non-living
• Prokaryotes


  • Unicellular
  • Consisting of one cell
• Prokaryote


  A unicellular organism that lacks a nucleus
• Eukaryote


  An organism that contains a nucleus
• Extremophile


  An organism that thrives in conditions of extreme temperature, pH or chemical concentration
• Most living organisms on Earth are unicellular, meaning they exist as single cells
• Unicellular organisms are microscopic, meaning they are too small to see without a microscope
• Types of unicellular organisms


  • Prokaryotes
  • Eukaryotes
• Prokaryotes


  • Unicellular and very simple
  • Have no nucleus
  • Protected by a cell wall
• Due to the work of Carl Woese, prokaryotes are divided into two distinct groups: the bacteria and the archaea
• The bacteria and archaea groups are ancient and have a lot in common, but they are genetically quite different
• There are currently 35 recognised phyla (plural of phylum) in the animal kingdom
• Animals can be classified based on whether or not they have a backbone
• Vertebrate


  An animal with an internal backbone or endoskeleton
• Invertebrate


  An animal with no internal backbone, may have a hard outer casing called an exoskeleton
• Vertebrate and invertebrate are not used as an official level in the classification system
• Sessile


  Fixed in one place and not able to move
• Poriferans (Sponges)


  • Simple animals with no organs
  • Sessile
  • Feed by filter-feeding
• Platyhelminthes (Flatworms)


  • Soft, unsegmented bodies
  • Flattened shapes to allow them to easily obtain oxygen and nutrients
  • Most species can be cut in half and then regrow new bodies
  • Many are parasites
• Annelids (Ringed worms)


  • Soft, segmented bodies
  • Need a moist environment, can survive on land
• Cnidarians (Stinging aquatic invertebrates)


  • Soft, hollow body
  • Have stinging cells that are used for feeding and defence
  • Can replace lost or damaged parts by regeneration
• Nematodes (Roundworms)


  • Soft, unsegmented bodies
  • Many species are parasitic
• Molluscs (Soft-bodied invertebrates)


  • Have a muscular foot or tentacles
  • Have a mantle (a cover or outer layer), and for some it forms a shell
• Arthropods (Invertebrates with an exoskeleton, segmented bodies and paired jointed limbs)


  • Make up 80% of all animal species
  • Have complex sensory organs such as compound eyes and antennae for hunting and detecting threats
• Echinoderms (Marine invertebrates)


  • Have a hard, spiny or bumpy covering
  • Have specialised organs, but no brain and no blood
  • Most have radial symmetry
• Chordates


  Animals that at some point in their life possess a notochord, gills on the neck, a nerve running up the back and a tail
• Humans are chordates, although they only have these features before birth
• Humans have a long nerve running up their back called the spinal cord, which connects the brain to the rest of the body and is protected by bones called vertebrae
• Animals with vertebrae are called vertebrates
• Humans, all other mammals, fish, reptiles, amphibians and birds all belong to the chordate phylum but are further grouped into classes based on their similar characteristics