B2 - Organisation Flashcards
(23 cards)
What does the digestive system do?
Breaks down food you eat into useful nutrients for your body to use
Describe the processes of the digestive system.
Teeth: Break down food mechanically - saliva contains amylase
Stomach: Contains HCL & enzymes that break down food chemically
Liver: Produces bile (stored in the gallbladder before going to small intestine). Bile emulsifies lipids to form droplets (increasing their surface area)
Pancreas: Secrets amylase which breaks down starch into glucose in the small intestine
Nutrients like glucose are absorbed into the bloodstream by the villi in the small intestine (starch is too large)
Water is absorbed into the bloodstream in the large intestine
What are enzymes?
Special proteins that act as biological catalysts - often breaking down molecules into shorter ones (polymers into monomers)
They are specific so only break down substrates that fit their active site (‘lock and key’ principle)
Name the enzymes and their functions.
1 - Proteases break down proteins into amino acids
2 - Lipases break down lipids into glycerol & fatty acids
3 - Carbohydrates break down carbohydrates into simple sugars
E.g Amylase breaks down starch into glucose
What is enzyme activity?
The rate of reaction
It increases with temperature until the enzyme dentures (active site changes shape)
- Same is true for too high or low pH
Need OPTIMUM condition for max rate/activity
Describe the enzyme practical.
1 - Mix Amylase with starch and start timer
2 - Remove a few drops from mixture every 10 seconds and add to iodine
3 - Record the time taken for no starch to be detected (will remain orange)
4 - Repeat at different temperatures or with different pH buffer solutions added
5 - Optimum pH/temp is between two lowest times
What are the 4 food tests?
1 - Starch: Iodine - orange to black
2 - Sugars: Benedict’s solution - blue to orange
3 - Protein: Biuret’s reagent - blue to purple
4 - Lipids: Cold ethanol - cloudy
How does air move through the body?
1 - Down the trachea
2 - Into the bronchi
3 - Then the bronchioles
4 - The ends up in the alveoli (air sacs) where it diffuses into the blood vessels around it
5 - The oxygen diffuses into the bloodstream and binds to the haemoglobin in red blood cells to be transported
Carbon dioxide and water will also diffuse out
How are the alveoli adapted for their role?
They have a large surface area to allow gas exchange to occur at a fast rate
Why is the heart a double circulatory system?
Blood enters the heart twice every time it is pumped round the body
- Deoxygenated blood enters from the right
Describe the process of the heart.
1 - Deoxygenated blood enters from the right side - vena cava (from body) - and enters into the right atrium
2 - The valve between the right atrium and right ventricle prevents backflow so deoxygenated blood doesn’t go back into the body
3 - The heart muscles contract so the blood goes through the pulmonary artery to the lungs to be oxygenated
4 - It then comes back into the heart from the lungs through the pulmonary vein into the left atrium
5 - Then it goes into the left ventricle and out to the body through the aorta
Why does the left side of the heart have thicker walls?
Due to the higher pressure needed to pump blood to the body
- The right ventricle only pumps blood to the lungs
How does the heart contract?
A group of cells near the right atrium create an electrical pulse that causes the heart to contract
(can use a pacemaker if not working)
What are arteries?
They carry blood away from the heart meaning they carry oxygenated blood (except for the pulmonary artery)
- They have thick walls & thin lumen to withstand high pressure
What are veins?
They carry blood to the heart meaning they carry deoxygenated blood (except for the pulmonary vein)
- Have thin walls & wide lumen
- Have valves to prevent backflow (can be replaced with artificial ones faulty)
What are capillaries?
Arteries split and become smaller and smaller until they become capillaries
- Once cell thick walls to allow fast diffusion between blood cells
What is Coronary heart disease (CHD) ?
The coronary artery delivers blood to the heart so it can keep pumping
- CHD is when that artery is blocked
It the coronary artery is blocked by the build up of fatty deposits a heart attack can occur - CVD (Cardio-vascular disease)
- STATINS are drugs that reduce these fatty deposits
- a STENT can be inserted to open up the vessel
What are communicable and non-communicable diseases?
Communicable - Caused by a pathogen
Non-communicabl - Cause comes from inside the body
Give examples of non-communicable diseases.
- Diabetes
- Heart disease/CVD/CHD
- Liver disease
- Lung disease
- Cancer
What is cancer and what are carcinogens?
Cancer is a result of damaged cells dividing uncontrollably, leading to tumours
- Benign cancers: don’t spread through the body - relatively easy to treat
- Malignant cancers: the cancerous cells spread through the body
A carcinogen is the name given to anything that increases the risk of cancer
Name the main parts of the plant and their roles.
Leaf: Where photosynthesis takes place, producing food for the plant - water evaporates out from there, allowing transpiration to take place
Xylem: Continuous tubes that carry water & dissolved mineral ions upwards - transpiration (undirectional) rate increased with increased air movement or temperature & decreased humidity
Phloem: Tubes of cells that carry sugars (e.g sucrose) and other nutrients to where needed
Translocation - Bidirectional
Roots: Water enters through osmosis, mineral ions enter by active transport
Meristem: Stem cell reproduction
Flower: Reproductive organs
How can the rate of transpiration be increased?
1 - Increasing the temperature
2 - Decreasing the humidity
3 - Increasing the air movement
Name each part of the leaf structure and their roles.
Waxy cuticle: Waterproof to stop water loss from top of leaf
Upper epidermis: Transparent to let light through
Palisade mesophyll: Most photosynthesis takes place here
Spongey mesophyll: Gaps to facilitate gas exchange (large surface area)
Vein/Vascular bundle: Xylem & phloem
Lower epidermis: Bottom of leaf
Stomata: Holes in lower epidermis to allow gases in/out, including water
Guard cells: change size to control rate of gases entering & exiting through stomata
