Topic 2: Organisation Flashcards
What is a cell?
Basic building blocks of all living organisms
What is a tissue?
A group of similar cells working together to carry out a particular function
What is an organ?
A group of different tissues working together to carry out a particular function
What is an organ system?
A group of organs working together to carry out a particular function
What do enzymes act as?
Biological catalysts
What is a catalyst?
A substance which increases the speed of a reaction, without being changed or used up in the reaction
Explain how the ‘lock and key’ theory works? [3]
- Each enzyme has an active site with a shape that fits a substrate
- Enzymes are specific - one type of enzyme will only fit one type of substrate
- When the substrate binds to the active site, it breaks up to form the products
Was does the ‘induced fit’ model of enzyme action state?
That the active site changes shape a little to secure the substrate
Explain why temperature increases enzyme activity up to a certain point?
The enzymes and substrates move around faster meaning there are more collisions per second
Why is the name for the temperature when enzyme activity is at its highest?
Optimum temperature
What happens to the rate of enzyme activity after the optimum temperature? [3]
- The rate decreases
- This is because the enzymes denature
- The shape of the active site is changed so the substrate can no longer fit
What happens if the pH is too high or low for enzyme activity? [2]
- The enzyme denatures
- The shape of the active site is changed so the substrate can no longer fit
What is the equation for the rate of a reaction?
Rate = 1000/time
Why do starch, proteins and fats have to be broken down by digestive enzymes?
The molecules are too big to pass through the walls of the digestive system
Starch
i) Broken down by?
ii) Into what?
i) Amylase
ii) Maltose
Proteins
i) Broken down by?
ii) Into what?
i) Protease
ii) Amino acids
Lipids
i) Broken down by?
ii) Into what?
i) Lipase
ii) Glycerol and fatty acids
Where is amylase made?
- Salivary glands
- Pancreas
- Small intestine
Where is protease made?
- Stomach
- Pancreas
- Small intestine
Where is lipase made?
- Pancreas
- Small intestine
What is protease called in the stomach?
Pepsin
Where is bile produced?
Liver
Where is bile stored?
Gall bladder
Where is bile released?
Small intestine
Write and check
How does bile aid digestion? [4]
- Bile is alkaline, so it neutralises stomach acid and makes conditions in the small intestine alkaline
- The enzymes of the small intestine work best in these alkaline conditions
- Bile also breaks down fats into tiny droplets
- This gives a bigger surface area of fat for the enzyme lipase to work on, making digestion faster
What is the test for sugars?
Benedict’s
What colour change will occur if sugar is present?
Blue —> green, yellow, red
(depends how much sugar present)
What is the test for starch?
Iodine
What colour change will occur if starch is present?
Orange —> blue-black
What is the test for proteins?
Biuret
What colour change will occur if protein is present?
Blue —> purple
What is the test for lipids?
Ethanol
What colour change will occur if lipids are present?
Colourless —> cloudy white
Write and check
Describe the pathway of air when you breath in? [5]
- Air passes through our mouth or nose
- Then down our trachea
- It then divided between our two bronchi
- It then divided further into branch-like structures known as bronchioles
- It finally reaches small sacks known as alveloi, which carry out gas exchange
Describe the gas exchanges than occur across the alveoli [2]
- Oxygen diffuses out of the alveolus (high conc) into the blood (low conc)
- Carbon dioxide difusses out of the blood (high conc) into the alveolus (low conc)
Explain how oxygen diffuses into cells
When blood reaches body cells oxygen is released from red blood cells (high conc) and diffuses into the body cells (low conc)
Explain how carbon dioxide diffuses out of cells
Carbon dioxide diffuses out of body cells (high conc) into the blood (low conc)
How do you calculate breathing rate?
No. of breaths/no. of minutes
Write and check
Describe the pathway of deoxygenated blood through the heart [4]
- Blood flows into the vena cava
- Then into the right atrium
- The right atrium contracts pushing the blood into the right ventricle
- The ventricle contracts, forcing the blood out of the heart and to the lungs via the pulmonary artery
Describe the pathway of oxygenated blood through the heart [4]
- Blood flows into the pulmonary vein
- Then into the left atrium
- The left atrium contracts pushing the blood into the left ventricle
- The ventricle contracts, forcing the blood out of the heart and to the rest of the body via the aorta
Which side of the heart pumps deoxygenated blood to the lungs?
Right
Which side of the heart pumps oxygenated blood to the rest of the body?
Left
What is the function of the coronary arteries?
They supply oxygenated blood to the heart itself
What is the natural resting heart rate controlled by?
A group of cells in the right atrium
How do the cells in the right atrium act as a pacemaker?
They produce small electrical impulses which spread to the surrounding muscle cells, causing then to contract
How does an artificial pacemaker work? [2]
- The little device is implanted under the skin and has a wire going to the heart
- It produces an electrical current to keep the heart beating regularly
What is the function of arteries?
To carry blood away from the heart
What is the function of veins?
To carry blood to the heart
What is the function of capillaries?
To exchange materials at tissues
How are arteries adapted to perform their function? [3]
- Walls are thick compared to the size of the lumen
- Walls contain thick layers of muscle - strong
- Walls contain elastic fibres - allow them to stretch and spring back
What is blood pressure like in arteries?
High
How are veins adapted to perform their function? [3]
- Thin walls
- Large lumen
- Valves
What is blood pressure like in veins?
Low
Why does the heart need valves?
To stop blood flowing in the wrong direction
What do capillaries branch off?
Arteries
How are capillaries adapted to perform their function? [2]
- Permeable walls - allows substances to diffuse in and out
- One cells thick walls - decreases the distance of diffusion, increasing rate
How would you calculate the rate of blood flow?
Volume of blood/no. of minutes
What is the job of red blood cells?
To carry oxygen from the lungs to the body cells
How are red blood cells adapted to perform their function? [2]
- Biconcave shape - large SA for absorbing oxygen
- No nucleus - allows more rrom to carry oxygen
What is the red pigment in blood called?
Haemoglobin
What happens to haemoglobin in the lungs?
It binds to oxygen to become oxyhaemoglobin
What happens to oxyhaemoglobin in body tissues?
It splits into oxygen and haemoglobin to release oxygen into the cells
What are 3 things a white blood cell can do?
- Engulf unwelcome microorganisms
- Produce antibodies to fight microorganisms
- Produce antitoxins to neutralise toxins produced by microorganisms
What is the name of the process by which white blood cells engulf unwelcome microorganisms?
Phagocytosis
Do white blood cells have a nucleus?
Yes
What are platelets?
Small fragments of cells
Do platelets have a nucleus?
No
What is the function of platelets? [2]
- To help blood clot at a wound
- Stop blood pouring out and stop microorganisms getting in
What can a lack of platelets cause? [2]
- Excessive bleeding
- Bruising
What is the function of plasma?
To carry everything in blood
What happens in coronary heart disease? [4]
- Layers of fatty material build-up inside the coronary arteries
- This causes the arteries to become narrow
- Reduces the flow of blood through the arteries
- Results in a lack of oxygen to the heart muscle
What can coronary heart disease result in?
A heart attack
How can stents be used to treat coronary heart disease? [4]
- Stents are tubes inserted inside arteries
- They push the artery wall out, squashing fatty deposit
- This keeps the artery open
- Ensures the supply of oxygenated blood to the heart is not interrupted
Advantages of stents [3]
- Lowers the risk of a heart attack
- Effective for a long time
- Quick surgery and recovery time
Disadvantages of stents [3]
- Risk of complications during operation (e.g. heart attack)
- Risk of infection from surgery
- Risk of blood clots developing
What do statins do? [2]
- Reduces the amount of bad cholesterol in the blood
- Slows down the rate of fatty deposits forming
Advantages of statins [3]
- Lowers the risk of coronary heart disease and heart attacks
- Can increase the amount of good cholesterol
- May prevent some other diseases
Disadvantages of statins [3]
- Long-term drug, must be taken regularly - risk of someone forgetting to take them
- Side effects e.g. headaches, kidney failure
- Effect isn’t instant
What does good cholesterol do in the blood?
Removes bad cholesterol
In what 2 circumstances is an artifical heart usually used?
- Keep a person alive waiting for a donor heart
- To help a person recover by allowing the heart to rest and heal
What is the main advantage of an artificial heart?
Less likely to be rejected than a donor heart
Disadvantages of an artificial heart [3]
- Surgery can lead to bleeding and infection
- Don’t work as well as natural hearts - mechanics can fail
- Patients have to take blood thinners - can cause problems with bleeding if hurt
What 3 things can cause faulty valves?
- Heart attacks
- Infection
- Old age
What are the 2 types of replacement valves?
- Taken from human or other mammals
- Man-made
What is the main advantage of replacing a valve?
Less drastic procedure than a whole heart transplant
What is the main disadvantage of replacing a valve?
Still a major surgery which can lead to blood clots
How can a faulty heart valve lead to poor blood circulation? [2]
- Valves may not be able to open properly, meaning less blood can flow through them
- They can become leaky, meaning blood is able to flow in both directions
Define ‘health’
State of mental and physical well-being
What is a communicable disease?
Those that can spread from a person to person or between animals and people
What is a non-communicable disease?
Those that cannot spread between people or between people and animals
What is the main cause of ill health?
Diseases
What other factors affect health? [3]
- Diet
- Stress
- Life situation
What knock-on effect can defects in the immune system cause?
An individual is more likely to suffer from infectious diseases
What knock-on effect can ill physical health cause?
Poor mental health
What knock-on effect can viruses living in cells cause?
Cancer
What knock-on effect can an immune response to a pathogen cause?
Trigger allergies (e.g. skin rash or asthma)
What is a risk factor?
Things that are linked to an increase in the likelihood that a person will develop a certain disease
What can smoking cause? [3]
- Cardiovascular disease
- Lung disease
- Lung cancer
What are the 2 categories for risk factor?
- Aspects of a peron’s lifestyle
- Substances in the person’s body or environment
How does smoking cause cardiovascular disease?
It damages the walls of the arteries
How does smoking cause lung cancer/disease?
Damages the cells in the lining of the lungs
What can obesity cause?
Type 2 diabetes
What can drinking too much alcohol cause? [2]
- Liver disease
- Brain damage
What will the affect of smoking/drinking while pregnant have?
Cause health problems for the baby
What can cause cancer?
Exposure to radiation
What is the human cost of non-communicable diseases? [2]
- People with disease may have a lower quality of life
- Can cause stress to loved ones
What is the financial cost of non-communicable diseases? [2]
- Cost to the NHS treating diseases
- More time off work leading to Government having to give financial support
What is cancer?
Uncontrolled cell growth and division
Characteristics of benign tumours [3]
- Tumour stays in one place - doesn’t invade other tissues
- Isn’t normally dangerous
- Tumour isn’t cancerous
Characteristics of malignant tumours [3]
- Tumour grows and spreads to neighbouring healthy tissues - forming secondary tumours
- Dangerous
- Tumour is cancerous
What are 3 lifestyle risk factors of cancer?
- Smoking
- Obesity
- UV exposure
What is an example of genetics increasing the likelihood of cancer?
Mutations in the BRCA genes have been linked to an increased likelihood of developing breast and ovarian cancer
Why is the epidermal tissue covered with a waxy cuticle?
Reduces water loss by evaporation
Why is the upper epidermis transparent?
Allows light to pass through to the palisade layer
Why is the palisade layer near the top of the leaf?
So they can receive the most light to carry out photosynthesis
Why are there air spaces in the spongy mesophyll?
Increase the rate of diffusion of gases
Why does the lower epidermis have little holes called stomata?
To let CO₂ diffuse directly into the leaf
What does the phloem transport?
Food
What does the xylem transport?
Water and mineral ions
What is translocation?
The process by which the phloem transports food substances made in the leaves to the rest of the leaf for immediate use or storage
What is transpiration?
The movement of water from the roots, through the xylem and out of the leaves
What is the xylem strengthened with?
Lignin
How does light intensity affect transpiration rate?
The brighter the light, the greater the transpiration rate
Why does the rate of transpiration decrease in the dark? [3]
- Stomata close as it gets dark
- Photosynthesis can’t happen in the dark so they don’t need to open to let in CO₂
- When the stomata are closed, very little water can escape
How does temperature affect transpiration rate?
The warmer it is, the faster the transpiration rate
Why does transpiration happen faster in warmer temperatures? [2]
- The water particles have more energy
- So they evaporate and diffuse out of the stomata more quickly
How does air flow affect transpiration rate?
The better the air flow, the greater the transpiration rate
Why does transpiration happen faster in good air flow? [3]
- Water vapour is swept away quickly
- This maintains a low concentration of water in the air outside the leaf
- Diffusion then happens quickly, from an area of high conc. to an area of low conc.
How does humidity affect transpiration rate?
The drier the air, the faster the transpiration rate
Why does transpiration happen faster in dry conditions? [2]
- There is minimal water in the air
- So diffusion happens quickly, from an area of high conc. to an area of low conc.
What opens and closes the stomata?
Guard cells
Guard cells
What happens when a plant has lots of water? [3]
- Guard cells fill with water and go plump and turgid
- Opens the stomata
- Gases can be exchanged for photosynthesis
Guard cells
What happens when a plant is short of water? [3]
- Guard cells lose water and become flaccid
- Closes the stomata
- Helps stop too much water vapour escaping
How are guard cells adapted to open and close? [2]
- Thin outer walls
- Thickened inner walls
Why are more stomata found on the lower side of a leaf?
Less water is lost through the stomata because it is shaded and cooler
