bio paper1

• What is the function of the nucleus?

  Contains DNA to control the cell
• What is the function of the cell membrane?

  Controls entry and exit of substances
• What is the function of the cell wall?

  Provides structure and support
• What is the function of mitochondria?

  Carry out respiration to release energy
• What is the function of ribosomes?


  Protein synthesis
• What is the function of chloroplasts?

  Carry out photosynthesis
• What is the function of a vacuole?

  Contains cell sap
• Define a prokaryote


  A cell that does not have a nucleus
• Define a eukaryote


  A cell that has DNA in a nucleus
• Name two cell structures that are in a eukaryote but not in a prokaryote

  Nucleus, mitochondria, chloroplasts
• What is a plasmid?


  A small loop of DNA in bacteria
• What is a plant cell wall made from?

  Cellulose
• How is DNA stored in a bacterial cell?

  As a single, free-floating loop; also on plasmids
• What is differentiation?


  The process by which cells become specialised
• What is the equation for magnification?


  Magnification = Image Size ÷ Actual Size
• A photograph of a cell is 15mm long. It has a magnification of 1100x. What is the actual size?

  0.0136mm, or 13.6µm
• A cell is 12µm wide. It is magnified by 450 times. How big is the image?

  5400µm, or 5.4mm
• If the image of a virus is 1.2mm, and its actual size is 0.2µm, how much has it been magnified by?

  6000 times
• Convert 38500µm into mm


  38.5mm
• How many µm are in 1mm?

  1000
• Write 17400m in standard form

  1.74 x 10^4 m
• Write 0.0034 in standard form

  3.4 x 10^-3
• How is a sperm cell adapted for its function?

  It has a tail to swim to the egg
• How is a nerve cell adapted for its function?

  It has a long axon to conduct impulses over long distances
• How is a muscle cell adapted for its function?

  It can contract to cause movement
• How is a root hair cell adapted for its function?

  It has a large surface area to increase osmosis of water
• How is a xylem cell adapted for its function?

  It has hollow ends to transport water
• How is a phloem cell adapted for its function?

  It has sieve tubes to transport sugars
• What is a stem cell?

  An undifferentiated cell that can differentiate to become any type of specialised cell
• Where are stem cells most commonly found in animals?


  In embryos and in bone marrow
• What is meristem tissue?


  Plant tissue containing stem cells
• When are plant cells able to differentiate?

  Throughout the whole life of the plant
• When do most animal cells differentiate?

  At an early stage of development (as an embryo)
• What is the "resolution" of a microscope?


  Resolution is the smallest distance between two separate points
• Why are electron microscopes better than light microscopes?

  They have a higher resolution and higher magnification
• Give an example of an organelle you could see with an electron microscope, but not with a light microscope?

  Ribosomes
• What shape is DNA?

  Double helix
• What molecule is DNA stored as?

  Chromosomes
• How are chromosomes usually found in body cells?

  In pairs
• What is a gene?


  A small section of DNA that codes for a specific protein