2. Organisation Flashcards
What are cells?
The basic building blocks that make up all living organisms.
What is a tissue?
A group of similar cells that work together to carry out a particular function. Can include more than one type of cell.
List some examples of tissues in mammals.
- Muscular tissue: contracts to move whatever it’s attached to.
- Glandular tissue: makes and secretes chemicals like enzymes and hormones.
- Epithelial tissue: covers some parts of the body, eg. gut.
What is an organ?
A group of different tissues that work together to perform a certain function.
What tissues is the stomach made out of?
- Muscular tissue: moves the stomach wall to churn up the food.
- Glandular tissue: makes digestive juices to digest food.
- Epithelial tissue: covers the outside and inside of the stomach.
What is an organ system?
A group of organs working together to perform a particular function.
What organs is the digestive system made up of?
- Glands (eg. pancreas and salivary glands): which produce digestive juices.
- Stomach and small intestine: digest food.
- Liver: produces bile.
- Small intestine: absorbs soluble food molecules.
- Large intestine, absorbs water from undigested food, leaving faeces.
What are enzymes?
A protien which is a biological catalyst. Increases the speed of a reaction, without being changed or used up in the reaction.
Why are enzymes useful?
Reduces the need for high temperatures.
What is the substrate?
The substance that the enzyme acts upon.
How does an enzyme “recognise” its specific substrate?
A complementarily-shaped “active site” – a region on the enzyme which fits the substrate.
What two factors affect enzyme activity?
- Temperature
2. pH
How does changing the temperature affect the rate of enzyme activity?
Higher temperature increases the rate at first. But if it gets too hot some of the bonds holding the enzyme together will break, changing the shape of the enzymes active site, so the substrate won’t fit anymore. It is not ‘denatured’.
What is the optimum temperature for enzymes?
45°C.
How does pH affect enzyme activity?
If it’s too high or too low it interferes with the bonds holding the enzymes together changing the shape of the active site and denatures the enzyme.
What is the optimum pH for an enzyme?
Often pH 7. But pepsin works best at pH 2 to be well suited for the acidic conditions of the stomach.
Describe how you would investigate the effect of pH on enzyme activity.
- Put a drop of iodine solution into every well of a spotting tile.
- 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 gauze over the bunsen burner. Heat the water until it’s 35°C (use a thermometer). The temp should be kept constant.
- Use a syringe to add 1cm³ of amylase solution and 1cm³ of buffer solution with a pH of 5 to a boiling tube. Using test tube holders, put the tube into the beaker of water and wait for five minutes.
- Next use different syringes to add 5cm³ of starch solution to the boiling tube.
- Immediately mix the contents and start a stop clock.
- Use continuous sampling to record how long it takes for the amylase to break down all the starch. 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 remains browny-orange, starch is no longer present.
- Repeat the experiment with buffer solutions of different pH values to see how pH affects the time taken for the starch to be broken down.
- Control any variables each time to keep it a fair test.
How do you calculate rate of reaction?
1000/time or change/time.
Where is amylase made in the body?
- Salivary glands.
- The pancreas.
- The small intestine.
What does amylase break down and what is produced?
Starch to maltose and other sugars.
What does carbohydrase break down and what is produced?
Carbohydrates to simple sugars.
Where is protease made in the body?
- The stomach (called pepsin there).
- The pancreas.
- The small intestine.
What does protease break down and what is produced?
Protiens to amino acids.
Where is lipase made in the body?
- The pancreas.
2. The small intestine.
What does lipase break down and what is produced?
Lipids to fatty acids and glycerol.
What is the use of the products of digestion?
To make new carbohydrates, proteins and lipids. Some of the glucose that is made can be used in respiration.
Where is bile produced and stored?
Bile is produced in the liver and stored in the gall bladder before it’s released into the small intestine.
How does bile help the action of lipase?
- Provides alkaline conditions by neutralising acid from the stomach.
- Emulsifies fat to form small droplets with a larger surface area making digestion faster.
What is the function of the mouth in digestion?
To mechanically break up food into smaller pieces to increase surface area.
What are two functions of saliva in digestion?
- To moisten food to allow easier swallowing.
2. To start chemical digestion by containing salivary amylase.
What is the function of stomach acid?
To kill potentially pathogenic microorganisms in food.
What is the function of the small intestine?
To absorb carbohydrates, lipids, amino acids, vitamins and mineral ions from digested food.
Give an adaptation of a) the small intestine and b) cells lining the small intestine to aid absorption of digested molecules.
a) Small intestine has structures called villi which increase surface area.
b) Epithelial cells lining the villi have microvilli on their surface which further increase surface area.
What is the function of the large intestine?
To absorb water from digested food.
What is the function of the liver in digestion?
To produce bile, an emulsifying and neutralising substance.
What is the function of the gall bladder?
To store bile until it can be released into the small intestine.
What is the function of the rectum?
To store undigested material before excretion.
Describe how you would prepare a food sample for a food test.
- Get a piece of food and break it up using pestle and mortar.
- Transfer 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 the solid bits of food.
What would you use to test for sugars?
Benedict’s solution.
How would you use benedict’s solution to test for sugars?
- Prepare a food sample and transfer 5cm³ to a test tube.
- Prepare a water bath so that it’s set to 75°C.
- Add some benedict’s solution to the test tube (about 10 drops) using a pipette.
- Place the test tube in the water bath using a test tube holder and leave it in there for 5 minutes. Making sure the test tube is pointing away from you.
- If the food sample contains reducing sugar, the solution in the test tube will change from the blue colour to green, yellow or brick-red depending on how much sugar is in the food.
What would you use to test for starch?
Iodine solution.
How would you use iodine solution to test for starch?
- Make a food sample and transfer 5cm³ of your smaple to the test tube.
- Then add a few drops of iodine solution and gently shake the test 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 would you use to test for proteins?
Biuret solution.
How would you use biuret solution to test for proteins?
- Prepare food sample 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 purple. If no protein is present, the solution will stay blue.
What would you use to test for lipids?
Sudan III stain solution.
How would you use sudan III stain solution to test for lipids?
- Prepare a sample of the food you’re testing (no need to filter). Transfer about 5cm³ to 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 stains lipids. If the sample contains lipids, the mixture will seperate out into two layers. The top layer will be bright red. If no lipid is present, no seperate red layer will form.
Where are the lungs located?
The thorax.
Name the structure which carries air from the nose/mouth.
Trachea.
Name the two structures which branch off from the trachea.
Bronchi (singular: bronchus).
Name the structure which branch off from the bronchi.
Bronchiole(s).
What are the small gas exchange structures in the lungs called?
Alveoli (singular: alveolus).
Explain how gas exchange works.
- Blood passing next to the alveoli has just returned to the lungs from the rest of the body, so it contains lots of carbon dioxide and very little oxygen.
- Oxygen diffuses out of the alveolus (high concentration) into the blood (low concentration). Carbon dioxide diffuses out of the blood (high concentration) into the alveolus (low concentration) to be breathed out.
- When the blood reaches body cells oxygen is released from the red blood cells and diffuses into the body cells. At the same time, carbon dioxide diffuses out of the body cells into the blood where it is then carried back to the lungs.
How do you calculate breathing rate?
Breaths per minute = number of breaths/number of minutes.
What is the circulatory system made up of?
Heart, blood vessles and blood.
