Science term 1 revision

• Response to stimuli: endocrine system ,nervous system -central nervous system , peripheral nervous system.
• stimulus -> receptor -> co-ordination centre -> effector -> response
• co-ordination centre: receives and processes electrical impulses from receptors.
• central nervous system - brain
• Effectors: bring about responses to the stimulus.
• Response : a muscular contraction or release of hormones.
• Reflexes: fast, automatic protective biological control systems that link a stimulus to a response.
• The Neural pathway that reflex actions follow is called the reflex arc. e.g. sneezing / focusing your eyes.
• The nucleus is an organelle
• cytoplasm and cell walls are NOT organelles.
• formula for microscopes: i= a x m. Or, image size= actual size x magnification.
• Factors that affect enzyme activity: pH, temperature, concentration of substrate
• Bile: neutralises acids / breaks down lipids.
• Dilute = more water
• Concentrated = more sugar
• Antigens are proteins. They are found on pathogens.
• Vaccine: a dead / inactive pathogen that is injected into the body.
• Risk factors of heart disease: smoking, alcohol, lack of exercise, high fat diet.
• Coronary heart disease can be treated by stents or stains.
• Antibiotics are for bacterial diseases or infections. They kill bacteria but not viruses
• Painkillers treat symptoms of diseases. They cannot kill pathogens.
• Antibiotic resistance occurs when an antibiotic can no longer kill a bacteria pathogen.
• V.C.A.R.P = Variation, Change, Advantage, Reproduce, Pass
• Variation : a mutation has caused a variation in the resistance to antibiotics.
• Change: the change in environment was the introduction of antibiotics.
• Advantage: resistance to antibiotics.
• Reproduce: resistant bacteria is able to reproduce.
• Pass: they can pass on gene for resistance to the antibiotics.
• Bohr first said that electrons orbit on energy levels.
• Chadwick discovered neutrons.
• Heart rate is controlled by a group of cells called pacemakers.
• Oxygen is a substance transported by blood.
• Cardiac muscle tissue is the main type of tissue in the heart wall.
• 3 stages of the cell cycle: interphase, mitosis, cytokenesis.
• Oxygen binds to Haemoglobin.
• Haemophilia: lack of / no platelets.
• HDL : high density lipids
• LDL: low density lipids
• Cardiovascular diseases: diseases that affect the circulatory system.
• translocation: transport of food and dissolved sugars.