B2 Flashcards
What is bile?
- It is made in the liver.
- Excess bile is stored in the gall bladder.
- It helps speed up the digestion of lipids.
What does bile do?
- Converts large lipid droplets into smaller droplets, emulsifying the lipid. This increases the surface area, which increases the rate at which the lipid is broken down by the lipase.
- Bile is alkaline, so it neutralises the stomach acid, creating alkaline conditions in the small intestine. This increases the rate of lipid digestion by lipase.
Explain why a person with a leaky heart valve has difficulty exercising.
- Back-flow of blood can occur.
- Less blood is pumped around the body.
- Less oxygen is supplied to cells.
- So less aerobic respiration happens.
- So less energy is released.
- So there is less efficient muscle contraction.
- Anaerobic respiration takes place.
- Lactic acid builds up.
- This causes muscle fatigue.
- Less removal of carbon dioxide from the blood.
Evaluate the uses of mechanical and biological heart valve replacements.
Mechanical Valves:
+ Longer lasting.
+ Survival rate at five years is higher.
+ Lower percentage of deaths due to heart-related problems.
- Blood clots on the brain are more likely after surgery.
- Anti-clotting medication must be taken for the rest of their life.
- Medication can lead to excessive bleeding after injury.
- Some patients say they can hear the valves opening and closing.
Biological Valves:
+ No additional medication is required.
- Ethical issues surrounding the use of animal tissue.
- Valve may harden.
- More likely to need another new valve.
- More likely to be rejected.
- More likely to need immuno-suppressant medication.
Both Valves:
+ Both are readily available.
+ Little wait time.
How are alveoli developed for gas exchange?
- Large surface area to increase the rate of diffusion.
- Thin walls for a short diffusion pathway.
- Good blood supply to maintain a high concentration gradient.
- Well ventilated to maintain a high concentration gradient.
How many types of tumours are there?
Two:
1) Benign.
2) Malignant.
Describe the two types of tumours.
Benign - Found in one area and does not spread to other parts of the body.
Malignant (Cancer) - Cells break off and invade other tissues, then travel through the bloodstream to form secondary tumours.
What are the risk factors for cancer?
Genetics:
- Breast, prostrate and large intestine cancer.
Lifestyle:
- Smoking: Lung Cancer.
- Ultraviolet Light: Skin Cancer.
- Alcohol: Mouth and throat cancer.
Substances in the Environment (Radon):
- Radon is a radioactive gas which increases the risk of developing lung cancer.
- Radon releases ionising radiation which damages DNA causing uncontrollable cell division.
What is the leaf?
An organ.
How many parts of the leaf and there and what are they?
1) Waxy cuticle layer.
2) Epidermis (upper and lower).
3) Palisade mesophyll.
4) Spongy mesophyll.
5) Pores called stomata.
6) Xylem tissue.
7) Phloem tissue.
What are the functions and adaptions of each part of the leaf?
1) Waxy cuticle layer:
- Thin layer of oily material.
- Reduces the evaporation of water or stops the leaf from drying out.
2) Epidermis:
- Protects the surface of the leaf.
- Transparent so it lets light pass through to the photosynthetic cells below.
3) Palisade mesophyll:
- Consists of palisade cells.
- Lost chloroplasts that contain chlorophyll for photosynthesis.
4) Spongy mesophyll:
- Full of air spaces to allow CO2 to diffuse to the palisade cells.
- Lots of chloroplasts that contain chlorophyll for photosynthesis.
5) Stomata:
- For gas exchange and control water vapour (water loss).
- Allow CO2 to come in and O2 to go out.
6) Xylem tissue:
- Transports dissolved mineral ions.
- Magnesium is used to make chloroplasts.
- Transports water from the roots to the stems and leaves.
- Some water is used in photosynthesis.
7) Phloem tissue:
- Transports dissolved sugars produced by photosynthesis from the leaves to the rest of the plant.
- This movement is called translocation.
What is digestion?
The process of nutrients being absorbed from food into the body.
What is an enzyme?
- A large protein molecule.
- A biological catalyst that doesn’t get used up.
Describe the ‘lock and key’ theory.
- Enzymes are specific.
- The substrate has to have a complimentary shape to the active site on the enzyme.
Name the 3 types of enzymes.
- Amylase.
- Protease.
- Lipase.
Where is protease made and what does it break down?
- Small intestine, pancreas and stomach.
- Breaks down protein into amino acids.
Where is amylase made and what does it break down?
- Small intestine, pancreas and salivary glands.
- Breaks down starch into simple sugars such as glucose.
