Extract: "Iodine/thiosulfate titrations can be used to determine the concentration of Cu2+ ions in a solution. The brass solution will be able made up into a solution, placed in the conical flask and dissolved in concentrated nitric acid and neutralised to form a Cu2+ (aq) ions. This is where the copper in brass is converted in a neutral solution containing Cu ions. The copper ions then react with Iodine ions (I-) to form a white precipitate of copper (I) iodide and a solution of iodine. The iodine produced in the mixture is then titrated with a standard solution of sodium thiosulfate (listed in the equipment.) You then carry out the relevant calculations to find out the percentage composition of Copper in the original brass alloy. To detect the end-point of the titration, you add small amounts of starch to form a deep blue-black colour that helps you identify a clear end-point colour. End point: all the iodine reacted & blue-black colour disappears. The chemistry on which this analysis of brass is based on redox titration; the relevant equations:"
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"
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"
This bundle includes the following topics:
- Hormonal Communication
- Structure & Function of the Pancreas
- Regulation of blood glucose conc.
- Diabetes and its control
- Coordinated responses
- Controlling Heart Rate
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 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: "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
- 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:
"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:
"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: "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: "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"