B1

• What is a eukaryotic cell?

  Cells that: 1) always have a nucleus 2) have a cell membrane and cytoplasm 3) make up plants and animals
• What are eukaryotic organisms?

  Organisms which contain eukaryotic cells, like plants and animals
• What is a prokaryotic cell?

  Cells that: 1) do not have a nucleus (DNA is stored in the cytoplasm) 2) are smaller than eukaryotic cells
• What type of cell is a bacterial cell: prokayrotic or eukaryotic?

  prokaryotic
• What are prokaryotes?

  Usually single-celled organisms- no nuclei or organelles.
• What is smaller: an plant cell or a bacterial cell?

  Bacterial cell.
• What are the two forms of DNA found in bacterial cells?

  1) Circular strand of DNA which floats freely in the cytoplasm 2) Plasmids - small rings of DNA.
• How can you identify a prokaryotic cell?

  It doesn't have a nucleus
• How can you identify a eukaryotic cell?

  It has a nucleus
• What is the role of the nucleus in a cell?

  Contains DNA
• What is the role of the ribosomes in a cell?

  Make proteins
• What is the role of the cytoplasm in a cell?

  Where chemical reactions happen
• What is the role of the mitochondria in a cell?

  Where aerobic respiration occurs
• What is the role of the vacuole in a cell?

  Stores sap
• What is the role of the chloroplasts in a cell?

  Where photosynthesis happens
• What is the role of the cell membrane?


  Controls what enters and exits the cell
• What is the role of the cell wall?


  Strengthens the cell
• What is the function of sperm cells?

  Reproduction
• What is the function of muscle cells?

  Movement
• What is the function of nerve cells?

  Carrying messages quickly
• What is the function of root hair cells?

  Absorption of water and mineral ions
• What is the function of phloem cells?

  Transporting cell sap / food (translocation)
• What is the function of xylem cells?

  Transporting water (transpiration) and dissolved minerals
• How are sperm cells specialised for reproduction?


  1) Long tail + streamlined head to swim to egg 2) Contain lots of mitochondria for respiration to generate energy for movement 3) Acrosome (layer round head) contains digestive enzymes to break down egg's membrane
• How are muscle cells specialised for contraction?

  Contain lots of mitochondria for respiration to generate energy for contraction
• How are nerve cells specialised for rapid signalling?

  1) Long axon to carry information over long distances 2) branches so that it can communicate with many other cells 3) covered with a fatty sheath which increases the speed that the message moves at
• How are root hair cells specialised for absorption?

  Large surface area for absorption
• How are xylem cells specialised for the transportation of water?

  Dead cells form long, hollow tubes up which water can travel with little resistance
• How are phloem cells adapted for the transportation of food substances

  Living cells with few organelles form long tubes up which cell sap / food can travel with little resistance
• What is cell differentiation?

  when a cell becomes specialised (which means when it acquires different structures to enable it to carry out a certain function)
• When do animal cells usually differentiate?

  at an early stage
• When do plant cells usually differentiate?

  anytime throughout their life
• How do electron microscopes compare to light microscopes?

  Electron microscopes: higher magnification, higher resolving power, more expensive
• What equation links size of image, size of object, and magnification?

  magnification = size of image ÷ size of real object
• How did electron microscopes affect biologists?

  they allowed biologists to see and understand many more sub-cellular structures
• What are chromosomes?


  Coiled up lengths of DNA molecules.
• How many chromosomes are in a human body cell?

  23 pairs (46 in total)
• Why do body cells normally have two copies of each chromosome?

  One from the mother, one from the father.
• What do genes control?

  The development of different characteristics.
• What is the cell cycle?

  The process in which a cell grows, then divides to form two genetically identical cells