Biology Paper 1

• What are light microscopes used for?

  Allow you to see the outlines of cells

  • cheaper to make
• What are electron microscopes used for?

  allow you to visualize finer details including sub-cellular structures

  • greater resolving power
  • higher resolution
• equation used to work out magnification

  Magnification = $\frac{image\ size}{object\ size\ }$
• What are Eukaryotic cells?

  Plant and animal cells that have a cell membrane, cytoplasm, and genetic information enclosed in a nucleus
• What are Prokaryotic cells?

  Bacterial cells, where the genetic material is not enclosed in a nucleus, instead there is a plasmid loop of DNA
• How to bacteria reproduce?

  Binary Fission
• What are stem cells?

  An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, from which other cells are able to differentiate
• What are examples of specialised cells in animals?

  • Sperm cells
  • Nerve cells
  • Muscle cells
• What are examples of specialised cells in plants?

  • root hair cells
  • xylem cells
  • phloem cells
• Where are stem cells made?

  Bone Marrow
• How many cells are made at the end of mitosis?

  2 daughter cells
• How many cells are made at the end of meiosis?

  4 daughter cells
• What is a diploid cell?

  cells with 23 PAIRS of chromosomes
• What is a haploid cell?

  only contains 1 set of chromosomes so 23 IN TOTAL
• What cells are made from Mitosis?

  Diploid cells used for growth and repair
• Describe the process of Mitosis.

  1. Chromosomes replicate, duplicating sub-cellular structures
  2. The nuclear membrane dissolves
  3. Two sets of chromosomes line up along the equator of the cell
  4. Both sets of chromosomes are pulled to the opposite poles of cell
  5. Nucleus divides
  6. Cytoplasm divides forming two cells
• What are some similarities between eukaryotic and prokaryotic cells?

  • both have cytoplasm
  • both have cell membranes
  • they both contain genetic material
  • they both contain ribosomes
• What are the differences between eukaryotic and prokaryotic cells?

  • prokaryotic are smaller
  • prokaryotic have no mitochondria
  • prokaryotic have no nucleus
  • prokaryotic have a single loops of DNA
  • prokaryotic has plasmids
• What are some examples of specialized cells in animals?

  • sperm cell
  • nerve cells
  • muscle cells
• What are some examples of specialized cells in plants?

  • root hair cells
  • xylem cells
  • phloem cells
• What happens to a cell when it differentiates?

  acquired different sub-cellular structures to enable it to carry out a certain function
• What type of cell differentiates at an early stage?

  Animal cells
• What type of cell retains its ability to differentiate throughout its life?

  Plant cells
• What is diffusion?

  The net movement of particles from an area of higher concentration to an area of lower concentration
• Factors which affect the rate of diffusion are:

  • concentration gradient
  • temperature
  • surface area of membrane
• How is oxygen diffused into a cell?


  Cells are surrounded by a high concentration of oxygen meaning they move down a concentration gradient, into the cell
• How is carbon dioxide moved out of a cell?

  Lower concentration in the outside of cells causes it to move down a concentration gradient
• How does urea diffuse out of a cell?

  Lower concentration outside of cells
• What is Osmosis?

  The diffusion of water molecules from a dilute solution to a concentrated solution through a partially permeable membrane
• Dilute solutions contain a...

  high concentration of water
• Concentrated solutions contain a ...

  low concentration of water
• What is active transport?

  The movement of substances from a dilute solution to a more concentrated solution (against a concentration gradient). This required energy from respiration
• What is an example of active transport in plants?

  mineral ions to be absorbed into the plant root hairs from very dilute solutions in the soil
• What is an example of active transport in animals?

  Sugar molecules from gut to blood