Science

• Things that make something alive

  • Diffusion
  • MRS C GREN
• Diffusion


  The net movement of particles from an area of high concentration to an area of low concentration (down the concentration gradient)
• Characteristics of living things

  • Movement
  • Reproduction
  • Sensitivity
  • Control (internal environment)
  • Growth
  • Respiration
  • Excretion
  • Nutrition
• Active transport


  Substance move against the concentration gradient from an area of low concentration to an area of high concentration
• Microscope


  • Eyepiece - the closest lens to the eye, magnifies the image of the large object
  • Objective - the lens nearest to the object, magnifies the image of the object
• Parts of an animal cell

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Mitochondria
  • Ribosome
• Parts of a plant cell

  • Nucleus
  • Cell membrane
  • Cell wall
  • Chloroplast
  • Vacuole
  • Mitochondria
  • Ribosome
• Cell membrane


  Controls what comes in and out of the cell
• Cytoplasm


  Where chemical reactions take place
• Nucleus


  Holds the DNA
• Mitochondria


  Where energy is released from food
• Ribosome


  Where protein synthesis occurs
• Cell wall


  Provides strength and support to the cell
• Chloroplast


  Where photosynthesis occurs
• As sugar concentration increases up to -0.5 mol/dm3


  The percentage gain in mass decreases
• As sugar concentration increases above -0.5 mol/dm3


  The percentage loss of mass increases
• Inputs and outputs of the regulatory system

  • Input - Oxygen, water, sugar, lipid, amino acids
  • Output - CO2, water, Urea, Heat, Salts
• Organs for excretion


  • Kidney - removes urea, water & ions from blood
  • Skin - removes water & salt by sweating
  • Lung - removes CO2 & water from blood
• Urea


  A protein-containing nitrogen waste product that is less toxic and easier to transport than ammonia
• Homeostasis


  Maintaining a constant internal environment
• Mechanisms for thermoregulation


  • Vasodilation - when body temp rises
  • Vasoconstriction - when body temp falls
• Negative feedback


  A corrective mechanism that detects a change and brings the system back to the normal level
• Communication systems


  • Nervous system (fast response)
  • Endocrine system (slower response)
• When cold


  Skin heat loss decreases, hair erector muscles contract, sweat glands are less active, blood vessels near skin constrict
• When hot


  Skin heat loss increases, hair erector muscles relax, sweat glands are more active, blood vessels near skin dilate
• Reflex arc


  The pathway taken by information in a reflex, which is processed in the spinal cord without going up to the brain
• Parts of the reflex arc

  • Receptor
  • Sensory neurone
  • Relay neurone
  • Motor neurone
  • Effector
• Lens


  Refracts light to focus it on the retina
• Focusing on near objects

  Ciliary muscle contracts, suspensory ligament slackens, lens becomes fatter, light is refracted more
• Focusing on far away objects

  Ciliary muscle relaxes, suspensory ligament stretches, lens becomes thinner, light is refracted less
• Biotic factors


  Any living factor that affects another organism
• Abiotic factors


  Non-living parts of the environment
• Ecosystem


  A biological community of interacting organisms and their physical environment
• Habitat


  The area or environment where an organism naturally lives
• Population


  All the members of the same species in a habitat at one time
• Community


  All the different species that coexist in a habitat at one time
• Niche


  The role of a species within an ecosystem
• Abiotic factors


  • Temperature
  • Light intensity
  • CO2 concentration
  • Wind intensity/direction
  • Moisture level
  • Mineral content of soil
• Trophic levels


  The different levels of a food chain
• Apex predators


  The organisms at the very top of the food chain