TOPIC 2 - ORGANISATION Flashcards
What is muscular tissue?
It contracts to move what it is attached to.
What is glandular tissue?
It makes and secretes chemicals like enzymes and hormones.
What is epithelial tissue?
Covers some parts of the body eg inside of the gut.
What is tissue?
A group of similar cells that work together to carry out a particular function. It can include more than one type of cell.
What is an organ?
A group of different tissues that work together to form a certain function.
What is an organ system?
An organ system is a group of organs working together to perform a particular function.
For example, the digestive system breaks down and absorbs food. It is made up of these organs:
Glands - produce digestive juices
Stomach and small intestine which digest food
The liver which produces bile
The small intestine which absorbs soluble food molecules.
The large intestine which absorbs water from indigested food leaving faeces.
Explain the digestive system as an organ system.
The digestive system breaks down and absorbs food. It is made up of these organs:
Glands - produce digestive juices
Stomach and small intestine which digest food
The liver which produces bile
The small intestine which absorbs soluble food molecules.
The large intestine which absorbs water from indigested food leaving faeces.
What are enzymes?
A catalyst is a substance which increases the speed of a reaction, without being changed or used up in a reaction.
They act as biological catalysts.
They are large proteins made up of chains of amino acids. These chains fold into unique shapes, which enzymes need to do their jobs.
How do enzymes work?
Usually involves things being split apart or joined together.
Every enzyme has an active site with a unique shape that fits onto the substance involves in a reaction.
Catalysts usually only catalyse one specific reaction.
This is because for the enzyme work, the substrate has to fit in the active site. If the substrate doesn’t match the active site, then the reaction won’t be catalysed.
This is known as the LOCK AND KEY
How do temperature and pH effect enzymes?
A higher temperature will increase the reaction rate at first. However, if it gets too hot, the enzyme becomes denatured. This means the active site changes shape, so the substrate won’t fit anymore.
All enzymes have an optimum temperature they work best at.
Enzymes can also become denatured if the pH is too high or too low. All enzymes have an optimum pH that they work best at, this if often 7. However, pepsin is an enzyme in the stomach used to break down proteins. It works best at pH 2, which means it is well suited to the acidic conditions there.
What is the practical to investigate the effect of pH on enzyme activity?
The enzyme amylase catalysts the breakdown of starch to maltose. It is easy to detect starch using iodine solution - if starch is present, the iodine solution will change from browny-orange to blue-black. This is how you investigate how pH affects Amylase activity:
-put a drop of iodine solution into every well of the spotting tiles
- place a Bunsen burner on a heat-proof mat, and a tripod and gauze over the Bunsen burner. Put a beaker of water on top of the tripod and heat the water until it is at 35 degrees Celsius. Try to keep the temperature constant throughout the experiment.
Use a syringe to add 1ml of amylase solution and 1ml of a buffer solution with a pH of 5 to a boiling tube. Using a test tube holder, put the tube into the beaker of water and wait for 5 minutes.
Next, use a different syringe to add 5ml of a starch solution to the boiling tube. Immediately mix the contents of the boiling tube and start a stop clock.
-use continuous sampling to record how long it takes for the amylase to break down all of the starch. To do this, use a dropping pipette to take a fresh sample from the boiling tube every 30 seconds and put a drop into a well. When the iodine solution remain browny-orange, starch is no longer present.
Repeat the whole experiment with buffer solution of different pH values to see how pH affects the time taken for the starch to be broken down.
Remember to control any variables each time (eg concentration and volume of amylase solution) to make it a fair test.
What is the formula to calculate the rate of a reaction?
Rate = 1000/time.
What does the enzyme carbohydrase do?
Carbohydrases convert carbohydrates into simple sugars.
Eg amylase is an example of carbohydrase. It breaks down starch.
Amylase is made in the salivary glands, pancreas, and the small-intestine
What does the enzyme protease do?
Proteases convert proteins into amino acids.
Proteases are made in three places: the stomach (pepsin), the pancreas and the small intestine.
What do the enzyme lipase do?
Lipases convert lipids into glycerol and fatty acids.
Lipases are made in two places: the pancreas and the small intestine.
What does bile do?
Bile neutralises the stomach acid and emulsifies fats.
Bile is produced in the liver. It is stored in the gall bladder before it is released into the small intestine.
The hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. Bile is alkaline - it neutralises the acid and makes conditions alkaline. The enzymes in the small intestine work best in these alkaline conditions. It emulsifies fats. This means it breaks the fat into tiny droplets. This gives a much bigger surface area of fat for the enzyme lipase to work on - which makes digestion faster.
What enzymes are in the salivary glands?
The salivary glands produce amylase enzyme in the saliva.
What does the liver do?
The liver is where bile is produced. Bile neutralises acids and emulsifies fats.
What does the stomach do?
It pummels the food with its muscular walls.
It produces protease enzyme, pepsin.
It produces hydrochloric acid for two reasons:
- to kill bacteria
- to give the right pH for the protease enzyme to work (pH 2 — acidic).
What does the pancreas do?
The pancreas produces protease, amylase and lipase enzymes. It releases these into the small intestine.
What does the gall bladder do?
The gall bladder is where bile is stored, before it is released into the small intestine.
What does the small intestine do?
The small intestine produces protease, amylase and lipase enzymes to complete digestion.
This is also where the digested food is absorbed out of the digestive system into the blood.
What does the large intestine do?
The large intestine is where excess water is absorbed from the food.
What does the rectum do?
The rectum is where the faeces are stored before until they leave through the anus.
How can you prepare a food sample for food testing?
Get a piece of food and break it up using a pestle and mortar.
Transfer the ground up food to a beaker and add some distilled water.
Give the mixture a good stir with a glass rod to dissolve some of the food.
Filter the solution using a funnel lined with filter paper to get rid of solid bits of food.
What test do you do to test for sugars?
You use the Benedictus test for sugars.
(For reducing sugars)
Prepare a food sample and transfer 5cm*3 to a test tube.
Prepare a water bath so it is set for 75 degrees Celsius.
Add some Benedictus solution (about 10 drops) to the solution using a pipette.
Place the test tube in the water bath using a test tube holder and leave it in there for 5 mins. Make sure the tube is pointing away from you.
If the food sample contains a reducing sugar, the solution in the test tube will change from the normal blue colour to green, yellow or brick-red. The colour change spends on how much sugar is in the food.
What test do you do for starch?
Use iodine solution to test for starch.
Make a food sample and transfer 5cm*3 of your sample to a test tube.
Then add a few drops of iodine solution and gently shake the tube to mix the contents. If the sample contains starch, the colour of the solution will change from browny-orange to black or blue-black.
What test can you do to test for proteins?
Use the biuret test to test for proteins.
Prepare a sample of your food and transfer 2cm3 of your sample to a test tube.
Add 2cm3 of biuret solution to the sample and mix the contents of the tube by gently shaking it.
If the food sample contains protein, the solution will change from blue to pink or purple. If no protein is present, the solution will stay blue.
What food test do you do for lipids?
Use the Sudan III test for lipids.
Prepare a food sample (you don’t need to filter it). Transfer 5cm*3 into a test tube.
Use a pipette to add 3 drops of Sudan III stain solution to the test tube and gently shake the tube.
Sudan III stain solution stains lipids. If the sample contains lipids, the mixture will separate out into two layers. The top layer will be bright red. If no lipids are present, no separate red layer will form at the top of the liquid.
Explain the lungs and their role.
The lungs are protected by the rib cage and are surrounded by pleural membranes. The air enters the trachea. This splits into two tubes called bronchi (each one is a bronchus), one going to each lung. The bronchi split into progressively smaller tubes called bronchioles. The bronchioles finally end at small bags called alveoli where the gas exchange takes place.
