Topic one: cell biology

• Name the main organelles of a plant cell

  • Nucleus
  • cytoplasm
  • cell membrane
  • mitochondria
  • ribosomes
  • cell wall
  • Permanent vacuole
  • chloroplasts
• name the main organelles of a animal cell

  • Nucleus
  • cytoplasm
  • cell membrane
  • mitochrondria
  • ribosomes
• What is the function of the nucleus 


  Contains genetic material that controls the activities of the cell
• What is the function of cytoplasm

  A gel like substance where most chemical reactions happen
• What is the function of the cell membrane

  Holds the cell together and controls what goes in and out
• What is the function of mitochondria

  Where most of reactions for aerobic respiration take place. Respiration transfers energy that the cells need to work.
• What is the function of ribosomes

  Where proteins are made in the cell
• What is the function of the cell wall

  provides structure to cell
• What is function of chloroplasts

  Where photosynthesis occurs, they contain a green substance called chlorophyll which absorbs light for photosynthesis
• What is a eukaryotic cell

  Contains a nucleus eg. Plant and animal cells
• What is a prokaryotic cell


  Doesnt contain a nucleu eg. Bacterial cells
• Describe the difference in how the genetic material is found within eukaryotic and prokaryotic cells 


  Eukaryotic- DNA is in a nucleus

  prokaryotic-DNA is a single molecule found free in the cytoplasm
• What is the function of a plasmid


  Replicate and move between cells so that genetic information can be shared
• What is cell differentiation

  The process by which a cell changes to become specialised for its job
• Describe the differences between magnification and resolution in light and electron microscopes

  a electron microscope has a much higher magnification and resolving power than a light microscope
• What is a stem cell 


  Unspecialised cells that can differentiate to form many types of cells
• name some conditions that may be helped with the treatment of stem cells 


  insulin producing cells- diabetes

  nerve cells-people Paralysed by spinal injuries

  embryonic stem cells- to replace faulty cells in sick people
• What are some ethical or religious objections of using stem cells

  They believe that life begins at conception which means the embryo is still alive
• What are potential risks of using stem cells


  Stem cells grown in labs could become contaminated with a virus which is passed on the the patient
• What is the definition of diffusion 


  The spreading out of particles from an area of higher concentration to lower concentration
• What factors affect diffusion

  1. Concentration gradient
  2. temperature
• Why do single felled organisms have a large surface area to volume ratio

  To allow sufficient transport of molecules in and out the cell
• how is the small intestine adapted for exchanging materials

  • The inside has millions of tiny projections called villi
  • they increase the surface area so that digested food is absorbed quicker into the blood
  • single layer of surface cells
• How are the lungs adapted for gas exchange

  They have millions of tiny air sacks calles aleveoli where gas exchange takes place

  aleveoli have: -large surface area

  - moist lining for absorbing gases

  - thin walls

  - good blood supply
• how are fishes gills adapted for gas exchange

  -thin plates called gill filaments which give big surface area for gas exchange

  -gill filaments have tiny structures called lamellae which increase surface area

  -lamellae have lots of blood capillaries to speed up diffusion
• How are plants leaves and roots adapted for gas exchange 


  -flattened shape of leaf increases area of exchange surface

  • spongy mesophyll cells are covered with thin layer of water, gasses dissolve in this as they move in and out the cell
• What factors increase the effectiveness of an exchange surface

  A large surface area
• What is osmosis 


  The movement of water molecules across a partially permiable membrane from a region of higher water concentration to a region of lower water concentration
• What is active transport

  The net movement of particles from an area of low concentration to an area of high concentration using energy
• Describe the features and functions of a root hair cell


  Hairs- for a large surface area for absorbing water and mineral ions from soil
• Describe the use of active transport in animals 


  -allows sugars eg. Glucose to be transported into bloodstream from the lumen of the small intestine
• Explain the difference between diffusion osmosis and active transport 


  -diffusion and osmosis don’t require energy active transport does

  -diffusion and osmosis move down the concentration gradient where as active transport moves against the concentration gradient

  -osmosis is water particles active transport mineral ions
• What is the relative size of a bacteria cell

  0.5-5 micrometer
• How are sperm cells specialised for function

  -the acrosome in the head contains enzymes so it can penetrate the egg

  -tail enables the sperm to swim

  -middle peice has mitochondria to release energy needed to swim and reach egg
• How are nerve cells specialised for function

  -nerve cell is extended so nerves can run to and from different parts of the body to the central nervous system

  -cells has extensions and branches so it can communicate with other nerve cells mucles and glands

  -cell is covered with fatty sheath Which insulates cell and speeds up nerve inpulses
• How are muscle cells specialised

  -contain filaments of protein that slide over each other to cause contraction

  -contain mitochondria for energy for muscle contraction
• How is a root hair cell specialised 


  -large surface area to provide contact with soil
• How are xylem cells specialised

  -no top and bottom walls between vessels so constant column of water runs through cells

  -walls are thick and woody for structure
• How are phloem cells specialised

  -companion cells provide energy
• Why is cell division important in multicellular organisms

  For growth and development