organisation and the digestive system (required practical) Flashcards
what are organ systems?
a group of organs working together to perform a function.
what is an organ?
a group of different tissues working together to perform a function.
what is a tissue?
a group of similar cells working together to perform a function. (can include more than one type of cell)
what are cells?
basic building blocks that make up all living organisms.
what are enzymes?
an enzyme is a catalyst that increases the speed of a reaction without being changed or used up in the reaction.
what are enzymes made of? (i don’t know if this is important)
large proteins made of chains of amino acids folded into unique shapes.
what is the active site of an enzyme?
the part of an enzyme where a substrate binds to and a chemical reaction takes place.
why is the lock and key model kinda wrong?
the active site changes shape a little bit to get a tighter fit on the substrate. (induced fit)
what is the optimum pH and temperature for an enzyme?
the temperature and pH that an enzyme works most efficiently at.
how do you investigate the effect of pH on enzymes? (practical)
the enzyme amylase catalyses starch to maltose, starch can be detected with iodine. (brown-orange → blue-black)
1. put a drop of iodine solution into every well of a spotting tile.
2. use a bunsen burner (on a heat proof mat) and a tripod and gauze to heat a beaker of water to 35°c. (use a thermometer)
3. use a syringe to add 1cm³ of amylase solution and 1cm³ of a pH 5 buffer solution (resists pH change) to a boiling tube.
4. put the boiling tube in the 35°c water for 5 minutes.
5. use a new syringe to add 5cm³ of starch solution to the boiling tube.
6. instantly mix the solution and start a timer.
7. every 30 seconds add a drop of this solution to a well on the spotting tile.
8. when the iodine solution remains brown-orange starch isn’t present.
9. repeat this test multiple times with different pH buffer solutions to see how pH affects the time for the starch to break down.
(to calculate the rate of reaction 1000 ÷ time)
what does amylase protease lipase and carbohydrase do?
amylase - starch → maltose - salivary gland, pancreas, small intestine.
protease - protein → amino acid - stomach (pepsin), pancreas, small intestine.
lipase - lipid → glycerol and fatty acids - pancreas, small intestine.
carbohydrase (inc amylase) - carbohydrates → simple sugars
what does bile do?
bile neutralises stomach acid so small intestine enzymes work better. (produced in liver, stored in gall bladder, released into small intestine)
emulsifies fat into droplets. (bigger surface area for enzymes)
what are the components of the digestive system and their purpose?
- salivary glands - amylase enzyme
- oesophagus
- stomach - crushes food with muscles - pepsin enzyme - hydrochloric acid
- liver - makes bile
- gall bladder - stores bile
- pancreas - releases protease amylase lipase to small intestine
- small intestine - absorbs digested food - protease amylase lipase enzyme
- large intestine - excess water is absorbed from food
- rectum - poo is stored
how do you test for sugars, starch, proteins, lipids? (practical)
prepare a food samples.
1. break up a piece of food with a pestle and mortar.
2. put the food in a beaker with distilled water.
3. stir and filter with a funnel and filter paper. (just liquid)
test for sugar with benedict solution.
1. put 5cm³ of a food sample in a test tube.
2. add 10 drops benedict solution.
3. put the test tube in a 75°c water bath for 5 minutes.
4. if sugar blue → green, yellow, red.
test for starch with iodine solution.
1. put 5cm³ of a food sample in a test tube.
2. add a few drops of iodine solution and shake the tube.
3. if starch orange → black, blue-black
test for protein with biuret.
1. put 2cm³ of a food sample in a test tube.
2. add 2cm³ biuret solution and shake the tube.
3. if protein blue → purple.
test for lipids with sudan III.
1. put 5cm³ of unfiltered food sample in a test tube.
2. add 3 drops sudan III and shake the tube.
3. if lipids (separate layers) top layer → bright red.
what is the thorax?
the top part of your body. (that is it)
what is the path of air to get to the alveoli?
oesophagus → trachea → bronchi → bronchioles → alveoli.
how does gas exchange work at the alveoli?
the lungs contain millions of alveoli air sacs, surrounded by blood capillaries.
1. blood passing next to the alveoli has just returned from the body and has a lot of carbon dioxide. (little oxygen)
2. oxygen diffuses out the alveoli to the blood and carbon dioxide does the opposite.
