organisation key recall Flashcards
What are cells?
The simple building blocks of life
What is a tissue?
Lots of similar cells working together to perform a particular function
What is an organ?
Lots of similar tissues working together to perform a particular function
What is an organ system?
Group of different organs working together to perform a particular function.
What tissues are found in the stomach?
The stomach is an organ, as it has epithelial tissue, glandular tissue (which produces acid/enzymes) and muscular tissues.
Which organs can be found in the digestive system?
Examples include: the stomach, small intestine, large intestine, liver and pancreas.
What is the function of the mouth?
The mouth contains teeth, which chews the food to break it into smaller pieces (mechanical digestion). The smaller pieces can be swallowed more easily and increase the surface area of the food, so that enzymes can digest foods faster.
The food is mixed with saliva, which makes it easier to swallow. Saliva also contains the enzyme amylase, which breaks down carbohydrate molecules into simple sugars. Saliva is produced by the salivary glands.
What is the pH of the stomach?
pH 2
What is the name of the acid in the stomach and what is its function?
Hydrochloric acid. The acid destroys pathogens in food.
What is the function of the stomach?
To mix food with digestive juices (such as the stomach acid). Protein digestion begins in the stomach.
What is the function of liver?
Produces bile
What is the function of bile?
Emulsifies fats – breaks large fat droplets into smaller ones, this increases surface area, so enzymes (lipases) can break down fats faster
Bile is alkaline, so neutralises stomach acid that makes its way to the small intestine – optimum pH for enzymes .
What is the function of the gall bladder?
To store bile before it is released into the small intestine.
What is the function of the pancreas?
To produce the digestive enzymes and to control blood glucose levels.
What is the function of small intestine?
It is where most of the chemical digestion (i.e. digestion using enzymes) takes place and where digested nutrients are absorbed into the blood.
What is the function of the large intestine?
The large intestine absorbs the water from our food. Anything that remains is indigestible and is excreted as faeces.
What is the function of the gut bacteria and where is it mainly located?
Gut bacteria help to digest food and help us to form some types of vitamins from our food. The gut bacteria are mainly located in the large intestine.
What are enzymes?
Enzymes are protein molecules that act as biological catalysts, and speed up reactions.
What is the lock and key method?
Describe the function of the following enzymes:
a) Carbohydrase
b) Amylase
c) Lipase
d) Protease
Different enzymes have different shaped active sites (like a lock). A specific substrate fits into the active site (like a key) to form an enzyme-substrate complex. Each substrate can only fit with its specific enzyme and each enzyme has only one job.
a) Breaks down carbohydrates into simple sugars (Carbohydrates -simple sugars)
b) Breaks down starch into glucose (Starch - glucose)
c) Breaks down lipids into 3 fatty acids and 1 glycerol molecule (Lipids - fatty acids + glycerol)
d) Breaks down proteins into amino acids
(Proteins - amino acids)
Describe enzyme activity at:
Very low temperature
Very high temperature
Include a sketched and annotated graph with your answer.
PICTURE HERE
At low temperature, the particles have very little kinetic energy, so there are fewer collisions therefore fewer enzyme-substrate complexes are made and the reaction is slower.
At high temperature, the particles have more energy and so move faster. There are more successful collisions. But if the temperature continues to increase the enzyme denatures permanently: the active site changes shape and so the substrate cannot fit into active site anymore and the reaction stops.
Sketch and annotate a graph to show what happens to the rate of enzyme action at different pH’s.
PICTURE HERE
The optimum pH for the graph shown is pH 8. On either side of this number the rate of enzyme activity is not optimal, because the pH changes the active site and therefore the substrate does not fit as easily. At pH values further away from the optimum, the enzyme becomes denatured: the active site changes shape and the substrate no longer fits into the active site. The reaction stops.
Describe the food tests for:
Proteins Sugars (glucose) Starch Lipids/fats test 1 Lipids/fats test 2
In all cases, the food should be ground into smaller pieces using a pestle and mortar.
Use Biuret reagent – colour change from blue to lilac
Use Benedict’s reagent and incubate at 80°C in a water bath – colour change from blue to brick-red
Use iodine – colour change from orange to blue-black
Use Sudan III – the mixture will separate into 2 layers, with the top layer being red
Use the emu.sion test using ethanol and water – the mixture will go cloudy as fats/lipids cannot dissolve in water.
Describe an experiment to investigate the optimum temperature of amylase. State how you would change this experiment to test for the optimum pH.
- Set a water bath at 20°C
- Incubate 1 ml of amylase and 1 ml of starch, in separate test tubes, in the water bath for 5 minutes to ensure both solutions get up to temperature.
- Add a drop of iodine to each well of a spotting tile. The iodine will be orange.
- After 5 minutes, mix the amylase and starch together, start a timer and add a drop from the mixture into the first well of the spotting tile (time 0). -The iodine should turn blue-black as the enzyme has not had time to break the starch down.
- Use a dropping pipette and add a drop from the amylase/starch mixture to a new well containing iodine every 30 seconds.
- When the iodine stays orange (i.e., stops changing colour), the amylase has digested all of the starch.
- Repeat this experiment twice more for this temperature and then repeat again using different temperatures, such as 30°C, 40°C and 50°C.
- The optimum temperature will be where the amylase has taken the shortest time to completely digest the starch – so where the fewest wells have been used.
Variables: Control = same concentration of starch, same concentration of amylase, same volume of starch, same volume of amylase. Independent = temperature Dependent = time for iodine to stop changing colour.
To change this experiment to test for the optimum pH, you would incubate the starch and the enzyme in solutions of different pHs, but keep the temperature the same.
Describe the pathway air takes to the lungs when it is inhaled through the nose.
Nose - nasal cavity - trachea - bronchi - alveoli
Note: bronchus = single bronchi; alveolus = single alveoli
