biology paper 1

• what are eukaryotic cells?


  Cells with a nucleus and membrane-bound organelles

  animal and plant cells
• what are prokaryotic cells?

  bacterial cells

  cytoplasm and cell membrane surrounded by a cell wall

  dna loop

  plasmids
• what are eukaryotic cells measured in?

  micrometers
• what are prokaryotic cells measured in?

  nanometres
• what do animal cells have in them?

  nucleus

  mitochondria

  ribosomes

  cytoplasm

  cell membrane
• what do plant cells have in them

  same sub-cellular structures as animal cells but have:

  chloroplasts

  permanent vacuole filled with cell sap

  cell wall
• Plant cells


  Have the same sub-cellular structures as animal cells, but with the addition of chloroplasts, a permanent vacuole filled with cell sap, and a cell wall made out of cellulose
• Algae also have a cellulose cell wall
• Nucleus


  Contains the genetic material
• Mitochondria


  Provides energy by carrying out respiration
• Ribosomes


  Carries out protein synthesis
• Cytoplasm


  Where most of the chemical reactions happen
• Cell membrane


  Controls the movement of substances in and out of the cell
• Chloroplast


  Absorbs light for photosynthesis
• Permanent vacuole


  Filled with cell sap to help keep the cell turgid
• Cellulose cell wall


  Gives strength to the cell and supports the plant
• Plasmids


  Additional genetic material
• how to use a light microscope?

  1. place the specimen on stage
  2. switch on microscope
  3. x4 objective lens is clicked into place
  4. specimen into focus by using the coarse focus
  5. when in focus, move the objective lens to x10
  6. repeat with the different objective lens
• what do group of similar cells come together to create?

  tissue
• what does a group of tissue can come together as?

  organs
• what does organs come to be organised as?

  organ systems eg circulatory system
• how are nerve cells specialised? 


  long thin axon helps nerve impulses

  dendrites to past nerve impulses to nerve cells
• how is a muscle cell specalised?

  mitochondria for energy
• how are phloem cells specialised?

  small holes in end plates to allow sugar
• why does mitosis occur?

  1. growth of multicellular organisms
  2. repair of damaged tissues
  3. replacement of cells
  4. asexual reproduction
• what are stem cells?

  undifferentiated cells that can become any type of specialised cell
• what are the advantages and disadvantages for using stem cells as therapeutic cloning? 


  advantage:

  1. no rejection of cells/organs by patient
  2. no waiting time

  disadvantages:

  1. transfer of viral infection
  2. ethical/religious objections
• what is diffusion?


  net movement of particles from a low concentration to a high concentation
• what are the factors that increase the rate of diffusion?

  1. concentration gradient increases
  2. temperature increases
  3. surface area increases
• what is osmosis?


  a movement of water from a region of high water concentration to a region of low water concentration
• what is active transport?

  movement of particles against the concentration gradient
• what are the three main nutrients

  carbohydrates, and protien and lipids
• how are food molecules broken down

  enzymes
• how does the mouth break down food?

  enzymes in the saliva digest the starch into smaller sugar molecules
• what does the oesophagus do to break down food molecules?

  passes food down too the stomach and the stomach enzymes begin to break down proteins
• what does the stomach contain?

  hydrochloric acid
• what does the churning action of the stomach help?

  turns the food into a fluid which increases the surface area for enzymes to digest
• where does the fluid now

  go?

  small intestine
• where is chemicals released from?

  liver and the pancreas
• what does the pancreas release?


  enzymes which help continue the digestion of starch and protein. also help start the digestion of lipids