Extract from text: "ABSCISSION (Leaf fall) - Light levels fall  fall in conc. of auxin  Plant produces ethane  initiate gene switching, producing new enzymes  digest and weaken the cell walls in the outer layer of the abscission zone (separation layer) - Vascular bundles sealed off; fatty material deposited in the cells under the separation layer (forming the protective layer)  prevents entry of pathogens + waterproof - Cells in the separation layer retain water and swell  puts pressure on the weakened outer layer - Further abiotic factors (e.g. winds) blow the leaves off"

Extract from notes: "SEED GERMINATION - Seed absorbs water  embryo activated + produces gibberellins  stimulate production of enzymes (that break down food stores within the seed)  embryo uses food stores to produce ATP for building materials  grows and break through the seed coat - Evidence suggests gibberellins switch on genes  code for amylases and proteases (enzymes required for germination) - Evidence suggests that ABA acts as an antagonist to gibberellins  the relative levels of both hormones determine when a seed will germinate"

Investigating the rate of oxygen production in pondweed method, equipment, etc.

A simple poster of the carbon cycle (covers the OCR Biology A syllabus)

A synthetic routes post that covers all functional groups from A2 OCR Chemistry A.

A synthetic routes poster that covers all AS functional groups from the OCR A specification.

Extract from notes: "- Medulla oblongata is responsible for controlling heart rate; two centres within it that are linked to the SAN by motor neurones One centre increases heart rate: sends impulses through sympathetic nervous system  transmitted by the accelerator nerve One centre decreases heart rate: sends impulses through parasympathetic nervous system  transmitted by the vagus nerve Which centre is stimulated depends of info received by receptors in the blood vessels - BARORECEPTORS (pressure receptors) – detect changes in blood pressure; present in the aorta, vena cava and carotid arteries E.g. blood pressure low  heart rate needs to increase to prevent fainting - CHEMORECEPTORS (chemical receptor) – detect changes in the levels of CO2; located in the aorta, carotid artery and the medulla "

Extract from notes: "Sympathetic nervous system sends out impulses to glands + smooth muscles  tells adrenal medulla to release ADRENALINE and NORADRENALINE into bloodstream  cause changes in the body (e.g. increased heart rate) Hypothalamus stimulated the pituitary gland to secrete adrenocorticotropic hormone (ACTH)  travels in blood stream to adrenal cortex  activates may hormones (prepare body for threats)"

Extract from notes: "TYPE 1 DIABETES – inability to produce insulin - Unable to produce insulin - Beta cells in the islets of Langerhans do not produce insulin - Can’t be cured/prevented - Autoimmune disease: body’s own immune system attacks the beta cells - Begins in childhood TYPE 2 DIABETES – insulin resistance - Person’s beta cells do not produce enough insulin OR - Person’s body cells do not respond properly to insulin (the glycoprotein insulin receptors on their C.S.M don’t work properly)  body cells lose their responsiveness to insulin  do not take up enough glucose, leaving it in the bloodstream - Due to excess body weight, physical inactivity, habitual eating of refined carbohydrates - Begins 50+ years"

Extract from notes: "Normal blood conc. = 90 mg cm-3 INCREASING BLOOD GLUCOSE CONC. - DIET: eating carbohydrate-rich foods (pasta and rice)  they are broken down in the digestive system, releasing glucose  absorbed into the bloodstream  conc. rises - GLYCOGENOLYSIS: glycogen stored in liver + muscle cells broken down into glucose  released into bloodstream - GLUCONEOGENESIS: production of glucose from non – carbohydrate sources; (Liver can make glucose from glycerol and amino acids)  released into the bloodstream DECREASING BLOOD GLUCOSE CONC. - RESPIRATION: glucose in the blood used by cells to release energy; higher the level of physical activity  higher the demand for glucose (for muscles to contract)  greater decreases of blood glucose conc. - GLYCOGENESIS: production of glycogen; excess glucose is converted into glycogen  stored in the liver"

Extract from notes: "ROLE AS AN EXOCRINE GLAND - Mostly made of exocrine glandular tissue – produce digestive enzymes and pancreatic juice (an alkaline fluid)  both are secreted into ducts  leads to the PANCREATIC DUCT  released into the duodenum Digestive enzymes the pancreas produces: - Amylases: break down starch into simple sugars (e.g. Pancreatic amylase) - Proteases: break down proteins into amino acids (e.g. Trypsin) - Lipases: break down lipids into fatty acids and glycerol (e.g. Pancreatic lipase)"

Extract from notes: "Adrenal Cortex – outer region of the glands; Produces hormones vital for life; controlled by hormones from the pituitary gland - Types of hormones produced by the adrenal cortex: - Glucocorticoids: Cortisol – regulate metabolism of carbohydrate and proteins in the liver, blood pressure and cardiovascular function in response to stress; Glucocorticoid – regulate immune response; suppress inflammatory reactions - Mineralocorticoids: Aldosterone (maintains water balance between salt and water concentrations in the blood) - Androgens: Small amounts of male and female sex hormones; important in women after menopause"

Extract from notes: "FUNCTION OF THE NEPHRON ULTRAFILTRATION – process by which blood plasma is filtered through the walls of the Bowman’s capsule under pressure; occurs in the glomerulus and the cells lining the Bowman’s capsule - Urea, along with salt, water and glucose, etc., is extracted from the blood in the kidney - Glomerulus is supplied w/ blood by a wide AFFERENT arteriole (from the renal artery) - Blood leaves through the narrower EFFERENT arteriole; large pressure in the capillaries  forces blood out of the glomerulus capillary walls  fluid passes through the basement membrane (network of collagen fibres & proteins; the second filter) - Plasma contents can pass through the basement membrane, but erythrocytes and large plasma proteins are RETAINED in the capillary"