Biology paper 1 - cell biology

• what is a eukaryotic cell


  plant, animal. fungi and protist cells
• what is a prokaryiotic cell


  bacteria cells
• characteristics of eukaryotic cells


  -larger and more complex. contain nucleus were genetic material is stored

  - has a mitochondria and chloroplasts
• characteristics of prokaryotic cells

  -No nucleus, mitochondria, or chloroplasts

  -has flagella, plasmids and a single DNA loop stored in its plasmids
• Observing bacteria in a simple light microscope requires a culture of bacteria and specific stains. Bacteria are seen like tiny coloured dots at the highest magnification of the microscope. Plant cells can be easily observed in the same microscope by only removing a piece of epidermis from a leaf.

  Explain

  why it is easier to prepare samples and view plant cells than bacterial cells using light microscopes(5 marks)

  Plants are formed by eukaryotic cells which are more complex and larger than prokaryotic cells, so plants are easily observed under light microscopy. (1) also ,Bacteria are prokaryotic cells, which are smaller and less complex than eukaryotic cells, (1)therefore, In plants, it is simpler to collect a sample because plants are multicellular organisms formed by thousands or millions of cells. (1)
• Sub-cellular structures in animal cells

  -Cell membrane

  -Cytoplasm

  -Nucleus

  -Mitochondria

  -Ribosomes
• sub cellular structures in plant cells

  -permenent vacuole

  -cell wall

  -chloroplasts
• cell differentiation in animal cells

  - differencate early in developmemt

  - new tissues rarely created
• cell differentiation in plants


  - retain the ability to diffrenceate throughout their lives

  - new tissues always created
• whats a root hair cell

  specialised plant cells that allow the plant to absorb more water and take in more minerals.

  - the have no chloroplasts but they do have long projections
• what a xylem


  they are specialised to send water up a plant and into the leaves

  - they are considered 'dead cells'

  - they have open ended cells that allow water to move up

  - they also have a substance within its cell walls called lignin to strengthen them
• what is a phloem


  its specialised to carry food products to where the plants need it

  - they have small holes to allow plants to move food to where they need it to be

  - in a heathy plant, the phloem is alive
• what are the two most important vareibles in magnification

  - magnification

  - resolution (the ability to distinguish between two objects close together)
• do body cells have more chromesones than sex cells?

  yes they do
• what are genes?


  Genes are sections of DNA that control a single genetic trait.
• what is the cell cycle


  series of events that cells go through as they grow and divide
• whats the order of the cell cy

  - initial growth stage

  - mitosis

  - cell division
• what structures are produced in the growth stage of a cell?


  - sub cellular structures

  - extra chromosomes

  -mitochondria

  - ribosomes
• what is mitosis


  a type of cell divison that creates identical daughter cells