B1 Cells

• axon is a long extension from the cell body that transmits electrical impulses to other cells
• Name the animal organelles and their functions


  Nucleus- contains the cells dna, control cell function

  Cytoplasm- where the chemical reactions take place

  Mitochondria- where cell respiration takes place, which releases energy.

  Ribosomes- site of protein synthesis

  Cell membrane- controls what goes in and out of the cell, partially permeable
• Name the plant specific organelles their functions


  Cell wall- provides support and structure for the cell, made of cellulose

  Vacuole- contains the cell sap

  Chloroplasts- where photosynthesis takes place, contains chlorophyll that absorbs light
• Describe the features of plant stem cells

  • can differentiate throughout their life
  • found at the meristems- areas of the plant that are continuously growing (tips of roots and shoots)
• Describe the features of adult stem cells

  • can’t differentiate into every type of cell
  • can only differentiate into different types of blood cells: platelets , WBCs , RBCs
  • found in bone marrow
  • can divide by mitosis
• How are root hair cells specialised for its function ?

  Specialised for absorbing water & minerals

  • has lots of mitochondria to provide energy needed for active transport
  • thin walls for a short diffusion pathway
  • long hairs that provide a large SA for absorption
• How are muscle cells specialised for its function? 


  Muscle cells are specialised for contraction

  • lots of mitochondria for energy needed for contraction
  • long so they have space to contract
• How are nerve cells specialised for its function 


  Nerve cells are specialised for rapid signalling. It’s function is to carry electrical signals from one part of the body to another

  • long to cover more distance
  • have branched connections at their ends to connect to other nerve cells and form a network
  • covered with a fatty sheath- insulates the nerve cell and speeds up the nerve impulse
• How is a sperm cell specialised for its function

  Sperm cells are specialised for reproduction. its function it’s to get the male dna to the female dna.

  • haploid cell- carries half of the genetic material
  • stream lined head and tail for swimming
  • lots of mitochondria to provide energy
  • enzymes in its head to digest through the egg cell membrane
• What does cell differentiation mean?

  the process by which a cell changes to become specialised for its job
• What are the optimum conditions for bacteria reproduction?

  • warm
  • moist
  • plenty of nutrients
• How do you calculate the no. of bacteria in a population?

  1. make sure the units are the same
  2. total time/mean division time
  3. 2 to the power of divisions to get the no. of cells
• Describe the process of binary fission

  1. cell grows
  2. genetic material is replicated (nucleoid, plasmids)
  3. 2 circulate strands of dna move to opposite sides of the cell
  4. plasmids either side are random + don’t always split equally
  5. a new cell wall form down the centre of the cell
  6. the two halves pull apart, forming two daughter cells
  7. simple process + doesn’t take long
• what does a bacterial cell need to do before division?

  • grow
  • replicate genetic material
• what is binary fission?

  • the process by which prokaryotic organisms, like bacteria, divide & reproduce
  • type of reproduction and cell division
  • asexual reproduction
• Describe the general features of specialised exchange surfaces

  • large SA:V ratio so more particles can pass through at once
  • very thin membranes for a short diffusion distance
  • good blood supply to maintain a good concentration gradient as blood is constantly replaced
  • diffusion gradient that particles can diffuse down
  • permeable surfaces that substances are able to pass through
• Name 2 molecules that can’t pass through a partially permeable membrane

  • starch
  • proteins
• What molecules can pass through a partially permeable membrane?

  • water
  • glucose
  • amino acids
• Why can small organisms like uni cellular bacteria rely on diffusion across their surface to exchange everything they need?


  they have a high sa:v ratio
• Describe a way to treat a patients faulty cells

  1. extract embryonic stem cells from early embryos
  2. grow them in laboratory
  3. stimulate them to differentiate into whichever type of specialised cell we want
  4. Give the patient new, properly functioning cells to replace their faulty cells
• What are the drawbacks of using embryonic stem cells?

  Requires embryonic stem cells

  • which are in limited supply
  • ethical issues surrounding this

  Rejection

  • the body/immune system tries to destroy them because it identifies them as foreign
  • this risk can be reduced by giving the patient immunosuppressants (doesn’t always work, side effects)
• How can stem cells be used in medicine 


  used to treat conditions be by replacing the faulty cells (damaged or don’t work properly) with properly working cells

  Diabetes

  • damage to pancreas cells that normally produce insulin

  Paralysis

  • sometimes caused by damage nerve cells

  Sickle cell anaemia

  • caused by misshapen blood cells
• What is the formula for total magnification?

  total mag= eyepiece mag x objective lens mag
• What happens at each stage of the cell cycle?

  Interphase: Growth and DNA replication, ribosomes/mitochondria increase in num. Mitosis: Division of the nucleus- one ‘arm’ of each chromosome is pulled to opposite poles of the cell Cytokinesis: Cytoplasm and membrane divide to form 2 identical daughter cells.
• Name the organelles in a bacterial cell and their functions

  cell wall

  cell membrane

  cytoplasm

  • circular strand of dna- contains genes needed to survive and reproduce
  • plasmids- carries extra genes
  • flagella- propels the bacteria
• What is the difference between an object and an image

  object- real object or sample you’re looking at

  image- the image that we see when we look down the microscope
• What is magnification


  how many times larger the image is than the object
• What is resolution? 


  the shortest distance between two points that can still be distinguished as two separate entities (how detailed the image is?)
• Compare the use of light microscopes and electron microscopes

  • L- easy to use
  • E- hard to use
  • L- relatively cheap
  • E- very expensive
  • L-rely on light
  • E- uses electrons instead of light
  • L- max resolution is 0.2ųm
  • E- max resolution is 0.1nm
  • L- individual cells
  • E- sub-cellular structures + 3D images
• Name 2 key features of stem cells

  • able to differentiate into specialised cells
  • can divide by mitosis to form new cells
• • Cell walls provide structural support to plant cells and prevent them from bursting due to osmosis.
• • Chloroplasts contain chlorophyll, which allows plants to convert sunlight into food during photosynthesis.