Paper 2

• What is the function of the nervous system

  It enables humans to react to their surroundings and to coordinate their behaviour-this includes both voluntary and involuntary actions
• What is the structure of the nervous systems

  It is made up of the central nervous system (CNS) and a network of nerves. The CNS comprises the brain and spinal cord
• What are the 5 parts of a reaction for the nervous system

  Stimulus, Receptor, Coordinator, Effectors, Response
• What is the stimulus in a nervous system response

  It is a change in the environment which is detected by the receptors
• What does the receptors do in the nervous system response

  Information from receptors passes along cells (neurones) to the CNS as electrical impulses
• What does the coordinator do in the nervous system response

  The CNS coordinates the body’s response to the stimulus
• What does the effector do in the nervous system response

  They bring about a response, such as glands secreting hormones or muscles contracting
• What does the response do in the nervous system response

  The body responds to the stimulus
• What are factors affecting reaction time

  Tiredness, Distractions, Caffeine, Alcohol
• What is homeostasis 


  It is the regulation of internal conditions (of a cell or whole organism) in response to internal or external changes, to maintain optimum conditions for functioning
• What is maintained for optimum function

  Blood glucose concentration

  Body temperature

  Water levels
• What 2 responses are involved of homeostasis

  Nervous response and chemical response
• What are all the control systems involved in homeostasis

  -Receptor cells, which detect stimuli

  -Coordination centres(like the brain, spinal cord and pancreas)which receive and process information from the receptors

  -Effectors(muscles or glands), which produce responses to restore optimum conditions
• What is a reflex arc 


  They are reflex actions of the nervous system that are automatic and rapid-they do not involve the conscious part of the brain
• Why are reflex actions importation

  they are important for survival because they prevent damage to the body
• What are neurones 


  They carry electrical impulses around the body - relay neurones connect sensory neurones to motor neurones
• What are synapses 


  they are gaps between neurones, which allow electrical impulses in the nervous system to cross between neurones
• What is variation

  The differences in the characteristics of individuals in a population
• What can be the difference for variation

  The genes they have inherited e.g. eye colour

  The environment they grew up in e.g. language

  A combination of gene and environment
• What is a mutation

  It is a change in a DNA sequence
• What is selective breeding

  It is the process by which humans breed plants and animals for particular genetic characteristics
• What are the processes of selective breeding

  1.Choose parents with the desired characteristics from a mixed population

  2.Breed them together

  3.Choose offspring with the desired characteristics and breed them together

  4.Continue over many generations until all offspring show the desired characteristics
• What are the benefits of selective breeding

  Disease resistant in food crops

  animals produce more milk or meat

  domestic dogs with gentle nature

  larger or unusually flowers
• Disadvantages of selective breeding

  Can lead to inbreeding, where some breeds are particularly prone to inherited defects or disease

  Reduces variation, meaning all members of a species could be susceptible to certain diseases
• What is Genetic engineering

  It is a process that involves changing the genome of an organism by introducing a gene from another organism to produce a desired characteristic
• What are the benefits of Genetic engineering

  -Potential to overcome some inherited human disease

  -can lead to higher value of crops as GM crops have a bigger yields than normal

  -crops can be engineered to be resistant to herbicides
• What are the risks of Genetic engineering

  -Genes from GM plants and animals may spread to other wildlife, which could have devastating effects on an ecosystem

  -Potential negative impacts on population of wild flowers and insects

  -Ethical concerns, like people could manipulate the genes of get used for certain characteristics

  -Health concerns as eating crops that are GM have not been fully explored