Biology Flashcards
What are the 4 types of pathogen?
- Bacteria
- Viruses
- Fungi
- Protozoa
Where is glycogen mostly stored?
- The liver
- The muscles
What is pepsin and where is it found?
Protease in the stomach.
What enzyme is used to break down starch?
Amylase
Where is amylase produced?
1) Salivary glands
2) Pancreas
3) Small intestine
What is starch broken down into by amylase?
Sugars, such as maltose.
Where is protease produced?
1) Stomach
2) Pancreas
3) Small intestine
Where is lipase produced?
1) Pancreas
2) Small intestine
What is a blood clot?
A mesh of protein fibres (fibrin fibres) that plugs a damaged area and stops bleeding.
What are the risks of excessive blood clotting?
1) Stroke
2) Deep vein thrombosis (DVT)
What drugs can be taken to reduce the risk of excessive blood clotting?
- Warfarin
- Heparin
- Aspirin
What is the name for a condition where the blood does not clot easily?
Haemophilia
What causes haemophilia?
The body can’t produce a certain clotting factor.
What does adrenaline do?
It increases the heart rate, so that muscles get sufficient oxygen supplied to them.
What is a pacemaker and how does it work?
- A group of cells that tells the heart how fast to beat.
* Cells produce a small electrical current that spreads to surrounding cells, causing them to contract.
What are the two pacemaker groups in the heart?
1) SAN - Sino-atrial node
2) AVN - Atrio-ventricular node
What does the sino-atrial node (SAN) do?
Stimulates the atria to contract.
What does the atrio-ventricular node (AVN) do?
Stimulates the ventricles to contract.
Describe in detail how the heart’s pacemakers work.
1) The sino-atrial node (SAN) produces an electric current that spreads to the atria.
2) This current stimulates the atrio-ventricular node (AVN) to produce a current that causes the ventricles to contract.
3) This means that the atria always contract before the ventricles.
What do ECGs record?
The electrical activity of the heart.
What can ECGs be used to show?
- Heart attacks
- Irregular heartbeats
- General health of the heart
Describe the shape of a normal ECG heartbeat.
- Flat
- Small curved bump upwards (atria contraction)
- Flat
- Small, sharp downwards peak followed by a large, sharp upwards peak, then tiny sharp downwards peak (ventricle contraction)
- Flat
- Small curves bump again upwards (ventricle relaxation)
- Flat
(See diagram)
Practice drawing out the shape of a normal ECG.
See diagram.
Describe the ECG for ventricular fibrillation.
Small, sharp squiggly fluctuations (as ventricles contract erratically).
What is ventricular fibrillation?
When the heart quivers instead of pumping, due to disorganised electrical activity.
Describe the shape of the ECG for a heart attack.
- Flat
- Small upwards bump
- Flat
- Small, sharp downwards peak followed by a large, sharp upwards peak -> On the way down this is bulging outwards rather than a sharp downwards line
- Flat
What is an echocardiogram?
An ultrasound scan of the heart.
What can an echocardiogram be used to show?
- An enlarged heart
- Decreased pumping ability
- Valve function (tears, infection and scarring)
What could an enlarged heart indicate?
Heart failure
What could decreased pumping ability of the heart indicate?
Cardiomyopathy
What is a neurone?
A nerve cell.
What are the parts of a neurone?
- Long axon
- Fatty sheath around axon
- Dendrites
- Cell body
What is an axon?
- Long section of cytoplasm in a neurone
* TRANSMITS the impulse (to next dendrite)
Why does the axon usually have a fatty sheath around it?
- Allows the signal to be transmitted quickly
* Acts as an insulator, shielding the neurone from neighbouring cells
What is a dendrite?
- Branched ending of a neurone
* PICKS UP impulses from other cells (their axons)
What are the three types of neurone?
1) Sensory
2) Relay
3) Motor
Describe the structure and function of a sensory neurone.
- One long dendrite carries nerve impulse from receptor cells to cell body
- One short axon carries the signal to the axon terminal, which takes it to the CNS
(See diagram pg 41)
Describe the structure and function of a relay neurone.
- Many short dendrites carry nerve impulses from the sensory neurones to the cell body
- Many short axons carry nerve impulses from the cell body to motor neurones
(See diagram pg 41)
Describe the structure and function of a motor neurone.
- Many short dendrites carry nerve impulses from the CNS to the cell body
- One long axon carries nerve impulses from the cell body to effector cells.
(See diagram pg 41)
What is the difference between axons and dendrites?
- Dendrites - Carry signal to cell body
* Axons - Carry signal away from cell body
How many axons and dendrites does a sensory neurone have?
- Axons - One short one
* Dendrites - One long one
How many axons and dendrites does a relay neurone have?
- Axons - Many short ones
* Dendrites - Many short ones
How many axons and dendrites does a motor neurone have?
- Axons - One long one
* Dendrites - Many short ones
How does ecstasy work?
- It blocks sites in the brain’s synapses where where the transmitter chemical serotonin is removed
- Since serotonin can’t be removed, its concentration increases
- So the mood of the person is enhanced
What are hormones?
Chemical messengers which travel in the blood to activate target cells.
Compare nerves and hormones.
NERVES: • Fast action • Act for a short time • Act on a precise area HORMONES: • Slow action • Act for prolonged time • Act in general way
Remember to revise negative feedback.
Pg 45
What is the processing centre for body temperature?
The thermoregulatory centre (hypothalamus).
What part of the brain is responsible for body temperature control?
Hypothalamus
Remember to revise temperature control.
Pg 46
What are the 3 roles of the kidneys?
1) Removal of urea
2) Adjustment of ions
3) Adjustment of water content
What things can affect the production of ADH?
1) Alcohol
2) Ecstasy
How does alcohol affect the amount of urine produced?
Alcohol supresses ADH production, which means less water is reabsorbed by the kidneys. This leads to a larger volume of more dilute urine.
How does ecstasy affect urine and how?
- It stimulates the production of ADH
- So more water is reabsorbed by the kidneys
- And so there is less urine and it is more concentrated
How does alcohol affect urine and how?
- It suppresses the production of ADH
- So less water is reabsorbed by the kidneys
- And so there is more urine and it is more dilute
How does ecstasy affect urine and how?
- It stimulates the production of ADH
- So more water is reabsorbed by the kidneys
- And so there is less urine and it is more concentrated
What are some concerns surrounding gene therapy?
- Could cause unexpected changes, which would be inherited by future generations
- Could lead to the creation of ‘designer babies’
What are the two methods of gene therapy?
1) Changing the genes in the body cells
2) Changing the genes in the gametes
Why can’t nitrogen from the atmosphere be used by plants and animals directly?
It is very reactive.
What is nitrogen needed for by plants and animals?
Making proteins for growth.
Why can’t nitrogen from the atmosphere be used by plants and bacteria directly?
It is very reactive.
What are the 4 stages of the nitrogen cycle?
1) Nitrogen fixation
2) Decomposition
3) Nitrification
4) Denitrification
How does nitrogen from the atmosphere get taken up by plants and animals?
- It must be in the form of nitrogen compounds (e.g. nitrates).
- Plants absorb nitrates from the soil.
- Animals can only take in nitrogen by consuming other organisms.
What are the 4 stages of the nitrogen cycle?
1) Nitrogen fixation
2) Decomposition
3) Nitrification
4) Denitrification
What is the nitrogen fixation stage of the nitrogen cycle?
The process by which nitrogen in the soil is converted to nitrogen compounds in the soil.
What are the two types of nitrogen fixation?
1) Lightning -> Energy in a lightning bolt is sufficient to make nitrogen react with oxygen in the air
2) Nitrogen-fixing bacteria -> Convert nitrogen into nitrogen-containing compounds
Where are nitrogen-fixing bacteria found?
- Soil
* Nodules on roots of legumes
What are the two parts of the nitrification stage of the nitrogen cycle?
1) Ammonium compounds -> Nitrites
2) Nitrites -> Nitrates
What is the nitrification stage of the nitrogen cycle?
The process by which nitrifying bacteria in the soil turn ammonium compounds into compounds that can be absorbed by plants.
What are the two parts of the nitrification stage of the nitrogen cycle?
1) Ammonium compounds -> Nitrites
2) Nitrites -> Nitrates
What type of bacteria are involved in the denitrification stage of the nitrogen cycle and how does this work?
- Denitrifying bacteria
- These use nitrates in the soil in respiration (which produces nitrogen gas).
- This can only happen in anaerobic conditions.
When can denitrification happen?
In anaerobic conditions, e.g. waterlogged soil.
What type of bacteria are involved in the denitrification stage of the nitrogen cycle and how does this work?
- Denitrifying bacteria
- These use nitrates in the soil in respiration (which produces nitrogen gas).
- This can only happen in anaerobic conditions.
Remember to revise the nitrogen cycle.
Pg 77 and 78.
What are the 4 types of bacteria involved in the nitrogen cycle?
1) Nitrifying bacteria
2) Denitrifying bacteria
3) Decomposer bacteria
4) Nitrogen-fixing bacteria
Remember to revise the nitrogen cycle.
Pg 77.
What are the 4 types of bacteria involved in the nitrogen cycle?
1) Nitrifying bacteria
2) Denitrifying bacteria
3) Decomposer bacteria
4) Nitrogen-fixing bacteria
Give an example of mutualistic bacteria in the nitrogen cycle.
Nitrogen-fixing bacteria provide the plant with nitrogen compounds and in return get carbohydrates.