biology paper 2

• receptor-cells that detect stimuli (change in the enviroment)
• coordination centre-processes information received from the receptors
• effectors- they bring responses to, to bring the body back to an optimum level (glands or muscles)
• receptor cells convert a stimulus into an electrical impulse
• the electrical impulses travel along along cells called the sensory neurone to the CNS
• synapses are gaps between two neurones
• chemicals diffuse across the sensory neurone
• pituitary gland- ghe master gland which secrets hormones into the blood
• pancreas- secrets insulin and controls blood glucose levels
• thyroid gland - secrets thyroxine controlling metabolism , heart rate and temperature
• adrenal gland- secrets adrenaline , the bodys response to dangerous situations
• ovary- secrets oestrogen
• testes-secrets testosterone
• FSH- causes the egg too mature
• oestrogen- causes the lining of the uterus to grow
• progesterone-maintains the lining of the uterus and supports pregnancy
• too keep your internal environment stable your body uses a mechanism called negative feedback
• the CNS is connected to the body by sensory neurones and motor neurones
• sensory neurones carry electrical impulses from the receptors to the CNS
• motor neurones carry electrical impulses from the CNS to the effectors
• a gene is a small section of DNA found on a chromosone
• each gene codes for a specific sequence of amino acids what make a protien
• genome is the entire set of genetic material in an organism
• sexual reproduction is where the genetic material from two parents produce offspring which are genetically different
• in sexual reproduction the mother and father produce gametes by meiosis
• a gamete only contains half the number of chromosomes compared to a human cell
• sexual reproduction involves the fusion of the male and female gametes
• in asexual reproduction theres only one parent so the offspring are genetically identical
• a sexual reproduction happens by mitosis and has exactly the same genetic material as the parent cell , this is called a clone
• a mutation is a random change in an organisms DNA
• Carl Linnaeus classified the living organisms into groups
• the classification -kingdom-phylum-class-order-family-genus-species
• the three domain system was created by Carl woese
• archea- primitave bacteria
• bacteria- true bacteria however different to archea as they have different biochemicals
• eukaryota- plants, animals, fungi and protists
• if the two alleles are the same then its homozygous
• if the two alleles are different its hetrozygous
• your genotype is the combination of alleles
• your phenotypes are physical characteristics