Biology Paper 2

• Homeostasis

  the conditions inside your body need to be kept steady even when the external environment changes

  this is important because your cells need the right conditions to be able to function properly
• Homeostasis

  homeostasis is all about the regulation of the conditions inside the body to maintain a stable environment
• Negative Feedback Counteracts Change

  1. receptor
  2. coordination centre
  3. effector
• receptor

  detects a stimulus- level is too high
• coordination centre

  receives and processes information then organises a response
• effector

  produces a response which counteracts the change and restores the optimum level
• Pituitary Gland

  produces many hormone

  sometimes called 'the master gland'

  these hormones act on other glands directing them to release hormones to bring about change
• Ovaries 


  produces oestrogen which is involved in the menstrual cycle
• Testes 


  produces testosterone which controls puberty and sperm production
• thyroid

  produces thyroxine which is involved regulating things like:

  rate of metabolism

  heart rate

  temperature
• Adrenal Gland

  produces adrenaline which is used to prepare the body for a 'flight or fight' response
• pancreas

  produces insulin which is used to regulate the blood glucose level
• nerves

  very fast action

  act for a very short time

  act on a very precise area
• hormones

  slower action

  act for a long time

  act in a more general way
• FSH

  produced in the pituitary gland

  causes an egg to mature

  stimulates the ovaries to produce oestrogen
• LH

  produced by the pituitary gland

  stimulates the release of an egg at day 14 (ovulation)
• oestrogen

  produced in ovaries

  causes the lining of uterus to grow

  stimulates the release of Lh and inhibits release of FSH
• progesterone

  produced in the ovaries by the remains of the follicle after ovulation

  maintains the lining of the uterus during the second half of the cycle

  inhibits the release of LH and FSH
• what does the pill contain?

  oestrogen and progesterone
• habitat

  the place where an organism lives
• population

  all the organisms of one species living in a habitat
• community

  population of different species living in a habitat
• abiotic factors

  non-living factors
• biotic

  living factors
• ecosystem

  interaction of a community of living organisms with the non living parts of their environment
• Plants need light and space as well as water and minerals to grow.

  animals need space, food,water and mates
• central nervous system

  in vertebrates this consist of the brain and spinal cord only

  in mammals the CNS is connected to the body by sensory and motor neurones
• sensory neurone

  neurones that carry information as electrical impulses from the receptors to the CNS
• Motor Neurone

  the neurones that carry electrical impulses from the CNS to effectors
• effectors

  all your muscles and glands which respond to nervous impulses
• synapse

  the connection between two neurones is called a synapse

  the nerve signal is transferred by chemicals which diffuse across the gap
• reflexes

  rapid automatic response to a certain stimuli that don't involve the conscience part of the brain
• reflex arc

  go through the spinal cord or unconscious part of the brain
• Order through central nervous system

  impulse

  sensory neurone

  synapse

  relay neurone

  motor neurone

  effector
• where is the adrenal gland?

  just above the kidneys
• where is the thyroid gland?

  the neck
• Gene

  small section of DNA

  each gene codes for a particular sequence of amino acids
• what is a genome?

  fancy term for the entire set of genetic materials
• Sexual Reproduction

  genetic information from two organisms is combined to produce an offspring which is genetically different to either parent

  the mother and father produce gametes by meiosis
• Asexual Reproduction

  only one parent so the offspring are genetically identical

  
  

  happens by mitosis

  
  

  clones