biology cells and control triple paper 1

• what does mitosis produce?

  two genetically identical daughter cells
• if a cell has two copies of each chromosome it is known as...

  diploid
• the cell cycle makes...

  new cells for growth and repair
• the stage of the cell cycle when the cell divides is called...

  mitosis
• multicellular organisms use mitosis to:

  • grow or replace damaged cells
• what are the 6 stages of the cell cycle?

  interphase, prophase, metaphase, anaphase, telophase and cytokinesis
• the rate at which cells divide by mitosis is controlled by...


  genes in the organism's DNA
• if there is a change in one of the genes that controls cell division...

  • the cell may divide uncontrollably, leading to a mass of abnormal cells called a tumour
  • if it invades and destroys surrounding tissue it becomes cancer
• cells spend most of their time in interphase
• what happens in interphase?

  • cell growth
  • organelle replication
  • DNA duplication forms X shaped chromosomes
• what happens in prophase?

  • membrane around nucleus starts to break down
  • spindle fibres appear
  • Chromosomes Condense
• what happens in metaphase?

  chromosomes line up on spindle fibres across middle of cell
• what happens in anaphase?

  chromosomes separated and chromatids moved to the poles of cell
• what happens in telophase?

  • membranes form around each set of chromosomes
  • these become nuclei of two new cells
• what happens in cytokinesis?

  • before the end of telophase
  • cell membrane and cytoplasm divide
• stem cells are:

  unspecialised cells
• differentiation is:


  the process of becoming specialised
• adult stem cells can produce...

  only certain types of specialised cells
• embryonic stem cells can produce...

  any other type of cell
• some issues with embryonic stem cells are that:

  • they could be rejected
• some issues with embryonic stem cells are that:

  • they can be rejected by the body
  • they can develop into cancer
  • can be seen as unethical as they can develop into babies
• adult stem cells are used to...

  replace damaged cells
• the central nervous system is made of:

  the brain & the spinal cord
• the brain is made up of

  billions of interconnected neurones
• the spinal cord is

  • a long column of neurones from the base of the brain down the spine
  • at several places down the cord, neurones branch off to connect with other parts of the body
• what is a neuron?

  • a specialised cell in the nervous system
  • transmits information through electrical and chemical signals
• what is the function of the cerebrum?

  controls memory, intelligence and language
• what is the function of the cerebellum?

  muscle coordination and balance.
• what is the function of the medulla oblongata?

  controls unconscious activities ie breathing and heart rate
• how are CT scans used to study the brain?

  they use x rays to produce images of the brain
• how are PET scans used to study the brain?

  patient ingests radioactive glucose

  active parts of the brain take in more glucose

  radiation coming from the brain can be detected
• damage to the spinal cord:

  reduces flow of information between brain and parts of the body
• why can problems in the CNS be difficult to treat?

  • neurones don't readily repair themselves
  • its not easy to access certain areas e.g. tumours in parts of the brain
  • treatment can cause permanent injury e.g. surgery on spinal cord
• the nervous system is made of the:

  • central nervous system
  • and the peripheral nervous system
• sensory recepetors =


  groups of cells that can detect changes in your environment (a stimulus)
• stimulus is detected by receptors then information converted to nervous (electrical) impulses sensory neurones carry this information to the CNS
• the CNS coordinates/responds to stimuli by sending impulses via motor neurones to an effector which responds accordingly
• effectors can be:

  muscles which contract

  glands which secrete hormones
• stimulus ->receptor ->sensory neurone ->CNS ->motor neurone ->effector ->response
• the connection between 2 neurones is a synapse

  across synapses chemical neurotransmitters diffuse nerve signals

  neurotransmitters then set off new electrical signal in next neurone