Key info

• Relfex arc: stimulus - receptor - sensory neurone - relay neurone - CNS - motor neurone - effector - response
• Cerebral cortex is responsible for things like consciousness, intelligence, memory and language
• Medulla controls unconscious activities
• The cerebellum is responsible for muscle co-ordination
• In bright light, the circular muscles in the iris contract and the radial muscles relax to make the pupil smaller
• In dim light, the radial muscles contract and the circular muscles relax which makes the pupil wider
• To look at near objects, the ciliary muscles contract which slackens the suspensory ligaments so the lens becomes fat and more light is refracted
• To focus on far away objects, the ciliary muscles relax which tightens the suspensory ligaments making the lens thinner and less light is refracted
• long sightedness is called hyperopia
• you can fix long sightedness with a convex lens
• short sightedness is called myopia
• you can fix short sightenedness with a concave lens
• thyroxine controls the rate of metabolism, heart rate and temperature
• glucagon is added if blood glucose level is too low
• insulin is added of the blood glucose level is too high
• oestrogen causes the lining of the uterus to grow
• oestrogen stimulates the release of LH and inhibits the release of FSH
• progesterone is produced the in ovaries
• progesterone maintains the lining of the uterus during the second half of the menstrual cycle
• progesterone inhibits the release of LH and FSH
• FSH is produced in the pituitary gland
• FSH causes an egg to mature in one of the ovaries- in a follicle
• FSH stimulates the ovaries to produce oestrogen
• LH is produced by the pituitary gland
• LH stimulates the release of an egg at day 14- ovulation
• The thyroid gland is in the neck
• giberellin stimulates plant stems to grow
• ethane stimulates ripening of fruit
• mutations change the sequence of DNA bases in a gene
• sexual reproduction produces genetically different cells via meiosis
• asexual reproduction produces genetically identical cells via mitosis
• meiosis produces four gametes and has 2 divisions
• Genetic engineering: useful gene isolated and inserted into the cells of the vector which is then introduced into the target organism.
• Speciation: populations of the same species become so different (due to isolation and natural selection) that they can no longer succesfully interbreed to profuce fertile offspring
• Kingdom - Phylum - Class - Order - Family - Genus - Species
• Light intensity is an abiotic factor
• New predators is a biotic factor