Organisation - biology Flashcards
Cells
Basing building blocks that make up all living organisms
Differentiation
The process by which cells become specialised for a job. Occurs during the development of multicellular organisms
What do specialised cells form
Tissues which form organs which form organ systems
Tissue
A group of similar cells that work together to carry out a particular function
Tissues in mammals
-Muscle tissue which contracts to move whatever it’s attached to
- Glandular tissue which makes and secretes enzymes and hormones
- Epithelial tissue, which covers some parts of the body
Organ
A group of different tissues that work together to perform a certain function
What tissue is the stomach made up of and what do the tissues do
-Muscular tissue moves the stomach wall to churn the food
- Glandular tissue makes digestive juices to digest food
- Epithelial tissue covers the outside and inside of the stomach
Organ system
Group of organs working together to perform a particular function
How are organs used in the digestive system to break down and absorb food
- Glands produce digestive juices
- The stomach and small intestine digests food
- The liver produced bile
- The small intestine absorbs soluble food molecules
- The large intestine absorbs water from undirected food, leaving faeces
What do enzymes reduce the need for
Reduce the need for high temperature
Catalyst
Substance that increases the speed of a reaction without being changed or used up in the reaction
What are enzymes made up of
They are all large proteins and all proteins are made up of chains of amino acids
How do enzymes catalyse a reaction through the lock and key model
Every enzyme has an active side with a unique shape that fits onto the substance involved in the reaction. This is because for the enzyme to work the substance has to fit into its active site.
Problem with lock and key model
It is simpler than how enzymes actually work. In reality the active site changes shape a little as the substrate binds to it to get a tighter fit.
How does temperature affect enzymes
A higher temperature increases the rate at first but if it gets too hot some of the bonds holding the enzymes together break. This changes the shape of the active sight of the enzyme so the substrate won’t fit anymore. The enzyme is said to be denatured
How does pH affect enzymes
If it’s too high or too low throw pH interferes with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme.
What it’s the optimum pH of an enzyme
Often neutral pH 7 but not always
Why has the stomach got a pH of 2
Pepsin, an enzyme used to break down proteins in the stomach , works best at pH 2 which means it is well suited to the acidic conditions their
Practical to investigate the effect of pH on enzyme activity
Set up a Bunsen burner, heatproof mat, tripod and gauze.
Place a beaker of water on the gauze and adjust the flame to keep the water at about 35°C.
Now put a drop of iodine solution into each spot of a spotting tile.
Add 2 cm3 of amylase enzyme solution to a test tube.
Place 2 cm3 of starch solution into the same tube.
Finally add 1 cm3 of pH solution to the tube. This will keep the pH constant.
Mix the solution in the test tube and place it into the beaker of water on the Bunsen burner.
Use a pipette to remove a few drops of solution every 20 seconds from the test tube and put them into a different well of the spotting tile.
Repeat until the iodine solution stops turning black.
Record the time this takes.
Repeat with different pH solutions.
How to calculate the rate of reaction
100 divided by time (units are in s to the power of minus one)
What do digestive enzymes do
Break down big molecules - starch, proteins and fats
Why are digestive enzymes used to break down starch, fats and proteins
They’re too big to pass through walls of the digestive system so they have to be broken down into smaller molecules. These smaller soluble molecules can pass easily through the walls of the digestive system allowing them to be absorbed into the bloodstream
What enzyme breaks down starch and what is it broken into
Amylase converts starch into simple sugars
Where is amylase made
Made in salivary glands the pancreas and the small intestine
What enzyme breaks down proteins and what is it broken down into
Protease converts proteins into amino acids
Where is protease made
The stomach
The pancreas
The small intestine
What enzyme breaks down lipids and into what
Lipase converts lipids into fatty acids and glycerol
What are products of digestion used for
To make new carbohydrates, proteins and lipids.
Some of the glucose that’s made is used in respiration
What does bile do
Neutralises stomach acid and emulsifies fats
Where is bile produced, stored and released
In the liver but stored in the gall bladder before it’s released into the small intestines
How does bile neutralise the stomach
The hydrochloride acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. Bile is an alkaline so neutralises the acid and makes conditions alkaline. The enzymes in the small intestine work best in these alkaline conditions.
How does bile emulsify fats
Breaks the fat into tiny droplets which gives a much bigger surface area of fat for the enzyme lipase to work on which makes digestion faster.
Where are enzymes used in the digestive system produced
Glands and the gut lining
Journey of digestive system
Food enters the body in the mouth. Mechanical digestion occurs by the teeth which breaks it into small pieces. Amylase in the saliva is secreted into the mouth by the salivary glands to start breaking down starch from the food into maltose. It then is sent down the oesophagus to the stomach.The stomach churns and pummels the food and digests proteins with the pepsin. The hydrochloric acid in the stomach kills most of the bacteria in the food.
The food is then sent to the small intestine where bile and enzymes are released.Lots of digestive enzymes made in the pancreas are released into the small intestine. Food molecules are now much smaller so can be absorbed through specialised intestinal walls and into the bloodstream. Food passes through the large intestine where excess water is absorbed from the food. It is finally stored in the rectum as faeces and excreted from the body through the anus.
Test for sugars
- Prepare a food sample and transfer 5cm cubed to a test tube
- Prepare a water bath so that it’s set to 75 degrees
- Add some Benedict’s solution to the test tube using a pipette
- Place the test tube in the water bath and leave for 5 mins
Colour change for Benedict’s solution if sugar is present
Blue to green, yellow or brick red depending on how much sugar is in the food
Test for starch
Make a food sample and transfer 5cm cubed into a test tube
- Add a few drops of iodine solution and gently shake the tube
Colour change for iodine solution if starch is present
Browny orange to blue-black
Test for proteins
Makes a food sample and transfer 5cm cubed to a test tube
Add 2cm cubed of biuret solution to sample and mix
Colour change for biuret solution if iodine is present
Blue to purple
Test for lipids
Prepare sample of food but don’t filter
Transfer 5cm cubed into test tube
Use a pipette to add 3 drops of Sudan III stain solution
Colour change for Sudan III solution
The top layer will be bright red
What are lungs protected by
The ribcage and surrounded y pleural membrane
Journey of the air you breathe in
Goes through the trachea, splits into two tubes called bronchi, one going into 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
What blood passes next to the alveoli
Has just returned from the rest of the body so it contains lots of co2 and very little oxygen.
How does deoxygenated blood gain oxygen
Oxygen diffuses out of the alveolus into the blood. Carbon dioxide diffuses out of the blood into the alveolus to be breathed out
What happens 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. It’s then carried back to the lungs.
What does the double circulatory system do
The right ventricle pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart.
The left ventricle pumps oxygenated blood around all the other organs of the body. The blood gives up its oxygen at the body cells and the deoxygenated blood returns to the heart to be pimped out to the lungs again.
What are the walls of the heart made up of
Mostly muscle tissue