B2 Flashcards
What are cells?
Basic building blocks of all living organisms
What is a tissue?
- Group of similar cells that work together to carry out a particular function
- Can include more than one type of cell
What is an organ?
A group of different tissues that work together to perform a certain function
What are organs organised into?
Organ systems, which work together to form organisms
State an example of an organ system which several organs work together to digest and absorb food
The digestive system
What is metabolism?
All the chemical reactions that go on inside an organism’s body.
With all the reactions in the body, what happens?
- These reactions build up molecules, and break them down
- They are controlled by enzymes
What is glycogen broken down for?
- To meet short-term demands for energy
How does temperature affect enzyme reaction?
- The rate of an enzyme-catalysed reaction increases as the temperature increases.
- However, at high temperatures the rate decreases again because the enzyme becomes denatured and can no longer function.
What happens to an enzyme when the temperature increases?
- As the temperature increases so does the rate of enzyme activity.
- An optimum activity is reached at the enzyme’s optimum temperature.
- A continued increase in temperature results in a sharp decrease in activity as the enzyme’s active site changes shape. It is now denatured.
How does the change in PH affect enzyme reaction?
- Changes in pH can alter the shape of an enzyme’s active site.
- Each enzyme work bests at a specific pH value.
(In the graph above, as the pH increases so does the rate of enzyme activity. An optimum activity is reached at the enzyme’s optimum pH, pH 8 in this example. A continued increase in pH results in a sharp decrease in activity as the enzyme’s active site changes shape. It is now denatured.)
What does the optimum pH depend on?
- Depends on where it normally works.
- E.g enzymes in the small intestine have an optimum pH of about 7.5, but stomach enzymes have an optimum pH of about 2.
When do enzymes work well? (Substrate)
- Enzymes will work best if there is plenty of substrate.
- However, the rate of enzyme activity does not increase forever.
- As a point will be reached when the enzymes become saturated and no more substrates can fit at any one time even though there is plenty of substrate available.
What does substrate concentration do to enzymes?
- As the substrate concentration increases so does the rate of enzyme activity.
- An optimum rate is reached at the enzyme’s optimum substrate concentration.
- A continued increase in substrate concentration results in the same activity as there are not enough enzyme molecules available to break down the excess substrate molecules.
State the equation to find rate of reaction in enzymes
Rate of reaction = amount of substrate used or amount of product formed / time taken
Why do enzymes catalyse specific reactions in living organisms?
Due to the shape of their active site
Explain the ‘lock and key theory’ for enzymes
- Enzymes are specific to one type of substrate as they have an active site that has a complementary shape to one substrate type only.
- Once the substrate has fitted perfectly into the active site it forms an enzyme-substrate complex
(See page 25 for this)
What does the amylase enzyme help break down?
Starch into sugars
What does the protease enzyme help break down?
Proteins into animo acids
What does the lipase enzyme help break down?
Lipids into glycerol and fatty acids
Where is amylase made in?
Salivary glands, pancreas and small intestine
Where is protease made in?
Stomach, pancreas and small intestine
Where is lipase made in?
Pancreas and small intestine
Where does amylase work in?
Mouth and small intestine
Where does protease work in?
Stomach and small intestine
Where does lipase work in?
Small intestine
What do digestive enzymes convert food into?
Small soluble molecules that can be absorbed into the bloodstream
What are the products of digestion used for?
Building new carbohydrates, lipids and proteins. Some glucose is used in respiration
What is bile and what does it do?
Bile is made in the liver and stored in the gall bladder.
- It is alkaline to neutralise hydrochloric acid from the stomach.
- It also emulsifies fat to form small droplets which increases the surface area.
- The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.
Practical 3
AAAA
Practical 4
AAA
What is the structure of the heart?
- Heart has 4 chambers (Right and left ventricle, right and left atrium),
- Muscular pump that circulates blood around the body.
- Right side of the heart only pumps de-oxygenated blood towards the lungs so that it can pick up oxygen.
What is the function of the heart?
- Muscle at the centre of your circulation system. - Pumps blood around your body as your heart beats.
- This blood sends oxygen and nutrients to all parts of your body, and carries away unwanted carbon dioxide and waste products
What is the structure of the lungs?
- There are two lungs and a bronchus leads into each one.
- Each Bronchus splits into hundreds of smaller tubes, called bronchioles.
- Each bronchiole leads into tiny air sacs called an alveoli (singular, alveolus).
- Each alveoli is surrounded by at least 1 capillary.
What is one of the functions of the lungs? (Begins with v)
Ventilation:
- Air needs to be moved in and out of the lungs. - Oxygenated is moved in, and then gas exchange happens, and then the now deoxygenated air is moved out.
What is one of the functions of the lungs? (Begins with g)
Gas Exchange:
- There is gas exchange between the oxygenated air in the alveoli, and the blood in the pulmonary capillaries.
What is the aorta?
- Largest artery in the body
- Carries oxygenated blood away from the left ventricle to the body.
What is the vena cava?
- Largest vein in the body
- Carries deoxygenated blood from the body back to the heart
What is the pulmonary artery?
- Pulmonary artery carries deoxygenated blood away from the right ventricle to the lungs
What is the pulmonary vein?
- Pulmonary vein returns oxygenated blood from the lungs to the heart
What is the coronary arteries?
- Coronary arteries supply the heart.
- The heart, like all other muscles in the body, needs oxygen to drive aerobic respiration.
- Coronary arteries are found on the surface of the heart, and they supply it with oxygen.
- In CHD, fatty deposits narrow the coronary arteries.
What is the trachea?
- Brings air into the lungs.
- Supported by rings of cartilage that prevent it collapsing.
What is the bronchi?
- Branches off the trachea to bring air into the lungs.
- Also supported by rings of cartilage.
What is the alveoli?
Small air sacs that are the site of gas exchange.
What is the capillary network surrounding the alveoli?
- The alveoli are surrounded by tiny blood vessels, called capillaries.
- The alveoli and capillaries both have very thin walls, which allow the oxygen to pass from the alveoli to the blood.
- The capillaries then connect to larger blood vessels, called veins, which bring the oxygenated blood from the lungs to the heart.
What is the natural resting heart rate controlled by?
A group of cells located in the right atrium that acts as pacemaker.
What are artificial pacemakers used for?
Electrical devices used to correct irregularities in the heart rate
The body contains three different types of blood vessel what are they?
- Arteries
- Veins
- Capillaries
How does the structure of arteries relate to their functions?
- Has a arrow lumen and thick muscular walls to maintain the high pressure so that blood can be pushed far distances around the body.
- The artery is made up of a thick layer of smooth muscle which allows it to exert a high pressure during contraction.
How does the structure of veins relate to their functions?
- Veins provide the tubing to take blood back to the heart.
- Veins have a thinner wall because they do not have to deal with constant changes in blood pressure with heart contractions, and the blood moves more slowly through them
How does the structure of capillaries relate to their functions?
- Capillaries have very thin walls that are only 1 cell thick.
- These walls are also very permeable (leaky!!).
- This allows the carbon dioxide, oxygen and nutrients to diffuse between cells and vessels.
- They carry blood at a very low pressure so don’t need any muscular walls.
State the equation to calculate blood flow?
Cardiac output(cm^3) per minute = heart rate in beats per minute x stroke volume(cm^3) per beat
Note:
AQA says that students should be able to use simple compound measure such as rate and carry out rate calculation for blood flow
What is blood?
A tissue consisting of plasma, in which the red blood cells,white blood cells and platelets are suspended
What is the function of red blood cells?
- Red blood cells transport the oxygen required for aerobic respiration in body cells.
- They must be able to absorb oxygen in the lungs, pass through narrow blood capillaries , and release this oxygen to respiring cells.
What is the function of white blood cells?
- WBCs are the protective armies of the body, helping to protect against infection and foreign pathogens.
- Some WBCs (phagocytes) engulf and eat pathogens in a process called phagocytosis.
- Other WBCs (lymphocytes) produce antibodies or antitoxins to fight against pathogens
What is the function of platelets?
- Platelets are fragments of cells that are used to clot the blood.
- Without platelets, there would be excessive bleeding every time you cut yourself and had a wound.
- By clotting, platelets reduce blood flow around the wound.
- Clotting also prevents pathogens from entering your wound.
What is the function of plasma?
- Plasma is a watery fluid in which holds all the components of blood flow.
- Plasma carries platelets, red and white blood cells, carbon dioxide, digested food including glucose, amino acids and soluble nutrients.
- It also carries urea, hormones, antibodies, antitoxins, proteins and heat energy
Note:
AQA says that students should be able to recognise different types of blood cells in a photograph or diageam, and explain how they are adapted to their functions
What are the advantages of treating conory heart diseases with drugs(statins)?
- Reduce the risk of heart attack.
- Studies have shown a decrease in ‘bad cholesterol’ and an increase in ‘good cholesterol’.
- Used to reduce high cholesterol levels that have genetic causes.
- May have beneficial effects on other conditions.
- Cheap to administer.
What are the disadvantages of treating conory heart diseases with drugs(statins)?
- Not suitable for people with liver disease.
- Some side effects.
- Must be taken for life.
- Should not be taken if pregnant or breastfeeding.
What are the advantages of treating cardiovascular diseases with mechanical devices? (Stents)
- Restore blood flow through the heart.
- Less risk of complications in surgery than heart transplant.
What are the disadvantages of treating cardiovascular diseases with mechanical devices? (Stents)
- Biological valves may wear out.
- Blood clots may stick to mechanical valves
- Anti-blood clotting drugs need to be taken which increase risk of further illness.
What are the advantages of treating cardiovascular diseases with a heart transplant?
Improves quality of life and can be lifesaving.
What are the disadvantages of treating cardiovascular diseases with a heart transplant?
- Few donor hearts are available.
- Recovery time is long.
- There is a risk of rejection by the body’s immune system.
- Expensive operation and aftercare.
What happens in conory heart disease?
- There is a fatty material build up inside coronary arteries narrowing down.
- This reduces the flow of blood through the coronary arteries,resulting in a lack of oxygen to the heart muscle.
What are stents used for
Stents are used to keep the coronary arteries open.
What are statins used for?
Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit
What are the consequences of faulty valves?
- Open as wide as it should, restricting blood flow through the heart - this means less blood reaches the body, pressure builds up and the lungs can swell with fluid
- Close properly and allow blood to leak back through into the atrium
A patient will not always have symptoms. A scan of the heart can diagnose the problem.
What are the symptoms of faulty valves?
- When symptoms are present, these are shortness of breath, dizziness, rapid heart rate and chest pain.
- The problem can lead to heart failure.
How do you solve faulty heart valves?
Using biological or mechanical valves
What is used in case of heart failure?
- A donor heart, heart and lungs can be transplanted.
- Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery
What is the relationship between health and disease?
- In the past health has been thought of as just the absence of disease, however today it is thought of more as the state of physical and mental wellbeing.
- Factors can work together to affect physical and mental health.
What is a disease?
A disease is a disorder that affects health by affecting an organism’s body, organs, tissues or cells.
What are two types of diseases are there?
Communicable diseases and non-communicable diseases, which are major causes for ill health
What is a communicable disease?
- Diseases that can spread from person to person or between animals and people.
- They can be caused by things like bacteria, viruses, parasites and fungi.
- They’re sometimes described as contagious or infectious diseases.
- Measles and malaria are examples of communicable diseases.
What is a non-communicable disease?
- Non-communicable diseases are those that cannot spread between people or between animals and people.
- They generally last for a long time and get worse slowly.
Give examples of communicable diseases
- Measles
- Malaria
Give examples of non-communicable diseases
- Asthma
- Cancer
- Coronary heart disease
State different types of diseases that may interact
• Defects in the immune system mean that an individual is more likely to suffer from infectious diseases.
• Viruses living in cells can be the trigger for cancers.
• Immune reactions initially caused by a pathogen can trigger allergies such as skin rashes and asthma.
• Severe physical ill health can lead to depression and other mental illness.
Note:
AQA says that students should be able to translate disease incidence information between graphical and numerical forms, construct and interpret frequency tables and diagrams, bar charts and histograms, and use a scatter diagram to identify a correlation between two variables.
Note:
AQA says that students should understand the principles of sampling as applied to scientific data, including epidemiological data.
What is the human and financial cost of non-communicable diseases to an individual?
Human - Reduces quality of life and mental health
Financial - Reduces the ability ro work and earn money
What is the human and financial cost of non-communicable diseases to a local community?
Human - Affects people around the individual who take care for them
Financial - Increased cost of healthcare to treat the individual
What is the human and financial cost of non-communicable diseases to a nation?
Human - Increased social issues such as obesity, and reduced morale
Financial - Increased cost of research into proventing non-communicable disease
What is the human and financial cost of non-communicable diseases to a globally?
Human - Increased deaths
Financially - Reduced supply of labour, and hence efficiency of economies
What is the effect of lifestyle factors of diet,alcohol and smoking on the incidence of non-communicable diseases at a local level?
If you decide to increase your alcohol intake, smoking or worsen your diet, you would increase your risk of non-communicable diseases on a local level
What is the effect of lifestyle factors of diet,alcohol and smoking on the incidence of non-communicable diseases at a national level?
- If an area is more impoverished, there may be an increase in alcohol intake and smoking.
- This would lead to a greater incidence of non-communicable diseases on a national level
What is the effect of lifestyle factors of diet,alcohol and smoking on the incidence of non-communicable diseases at a global level?
- If a country is less economically developed, it may have a worse diet, higher rate of smoking and greater alcohol intake on the whole, thus leading to higher rate of non-communicable disease in that nation.
- This shows the effect of lifestyle factors on a global level.
What are risk factors linked to?
An increased rate of a disease
What can risk factors be linked to?
Aspects of a persons lifestyle and substances in a persons body or environment
What has a casual mechanism been proven for?
Some risk factors, but not in others
State risk factors for diseases
• The effects of diet, smoking and exercise on cardiovascular disease.
• Obesity as a risk factor for Type 2 diabetes.
• The effect of alcohol on the liver and brain function.
• The effect of smoking on lung disease and lung cancer.
• The effects of smoking and alcohol on unborn babies.
• Carcinogens, including ionising radiation, as risk factors in cancer.
What is the principles of sampling as applied to scientific data in terms of risk factors?
- Epidemiology is the study of the distribution and patterns of health and disease, in and across populations.
- Scientists study the incidence of disease, using medical records, and use medical research to investigate causes of disease.
- When investigating health and disease, and risk factors are involved, scientists can’t study every person on the planet. Scientists must study samples.
What must samples be?
They must be representative - reflect the population under study
What must samples not be?
- Focus on certain groups and ignore others
- Be affected by bias
How do you obtain a representative sample?
- The study must be wide, and cover all groups in the population being studied
- The study must be random within these groups
When working with samples of human populations, studies must take account of possible variations owing to differences. State what they are
- Between the sexes
- Resulting from people of different ages taking part
- In people’s lifestyles, which could affect the study
What is the problem with sampling and what do scientists do to remove it?
- In scientific studies, it may be difficult to control lifestyle factors that have the potential to affect the study, particularly if the study is long-term.
- People involved in a long-term study of the effects of alcohol intake, for instance, will have different lifestyle factors, for instance diet and exercise, that could potentially affect the results of the study.
How do scientists remove the problems when sampling patients?
- Where possible, scientists adjust data mathematically so that factors can be removed that might distort a comparison between groups.
- Data must be adjusted, for instance, to make allowances for the effects of age on rates of disease.
What is cancer?
- Cancer is caused as a result of changes in the DNA of cells that lead to uncontrolled growth and division - this can result in the formation of a tumour (a mass of cells)
- Usually tumours form as a result of loss of control of the cell cycle.
What are different types of tumours you can get?
- Benign tumours
- Malignant tumours
What are benign tumours?
- Growths of abnormal cells which are contained in one area, usually within a membrane.
- They do not invade other parts of the body
What are malignant tumours?
- Malignant tumour cells are cancers.
- They invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours
What have scientists been able to identify with cancers?
- There are lifestyle risk factors for various types of cancer.
- There are also genetic risk factors for some cancers
State examples of plant tissues
- Epidermal tissues
- Palisade mesophyll
- Spongy mesophyll
- Xylem and phloem
- Meristem tissue found at the growing tips of shoots and roots
What is the function of epidermal tissues in a plant?
- Epidermal tissue has a waxy cuticle.
- This covers the plant to decrease water loss by evaporation.
- Moreover, it is transparent so all light can make its way through.
What is the function of palisade mesophyll in a plant?
- Light absorption happens in the palisade mesophyll tissue of the leaf.
- Palisade cells are column-shaped and packed with many chloroplasts .
- They are arranged closely together so that a lot of light energy can be absorbed.
What is the function of spongy mesophyll in a plant?
- Spongy mesophyll cells are covered by a thin layer of water.
- Gases dissolve in this water as they move into and out of the cells.
- When the plant is photosynthesising during the day, these features allow carbon dioxide to diffuse into the spongy mesophyll cells, and oxygen to diffuse out of them.
What is the function of xylem and phloem in a plant?
Xylem transports water and mineral salts from the roots up to other parts of the plant
What is the function of a phloem in a plant?
Phloem transports sucrose and amino acids from the leaves and other parts of the plant
What is the function of meristem tissues in a plant?
- Plant meristems divide to produce cells that increase the height of plants, the length of roots and the girth of the stem.
- They also produce cells that develop into leaves and flowers.
- This is so they can differentiate into specialised cell types depending on where they are in the plant.
What is the leaf?
- The leaf consist of a broad, flat part called the lamina, which is joined to the rest of the plant by a leaf stalk or petiole.
- This is running through the petiole are vascular bundles, which then form the veins in the leaf.
- Although a leaf looks thin, its is made up of several layers of cells.
What is the epidermis in a plant?
- Plants are covered by epidermal tissue.
- Epidermal tissue has a waxy cuticle.
- This covers the plant to decrease water loss by evaporation.
- Moreover, it is transparent so all light can make its way through.
What is a guard cell surrounding the stomata and what is its function?
- Guard cells are adapted to their function by allowing gas exchange and controlling water loss within the leaf.
- The size of the stomatal opening is used by the plant to control the rate of transpiration and therefore limit the levels of water loss from the leaf.
- This helps to stop the plant from wilting.
How is the structure of root hair cells adapted for its function?
- Root hair cells are adapted for taking up water and mineral ions by having a large surface area to increase the rate of absorption.
- They also contain lots of mitochondria , which release energy from glucose during respiration in order to provide the energy needed for active transport.
How is the structure of xylem cells adapted for its function?
- They lose their end walls so the xylem forms a continuous, hollow tube.
- They become strengthened by a substance called lignin .
- Lignin gives strength and support to the plant.
How is the structure of phloem cells adapted for its function?
- Contain sieve tubes which are specialised for transport and have no nuclei .
- Each sieve tube has a perforated end so its cytoplasm connects one cell to the next.
- Sucrose and amino acids are translocated within the living cytoplasm of the sieve tubes.
What is transpiration?
When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf
What is the effect of changing temperature on the rate of transpiration?
As temperature increases, so does the rate of transpiration as the water particles gain more energy to diffuse into the plant evaporate out of the stomata.
What is the effect of changing humidity on the rate of transpiration?
- When the air is more humid, the concentration gradient is reduced.
- This means that the rate of diffusion is lowered and so the transpiration rate is reduced.
- Transpiration is affected by air movement. As the movement of air increases, the concentration gradient is increased, so the rate of transpiration increases.
What is the effect of changing air movement on the rate of transpiration?
This increases the rate of transpiration as it removes water vapour from leaf surfaces; more water diffuses from the leaf
What is the effect of changing light intensity on the rate of transpiration?
- A greater light intensity increases the rate of transpiration.
- This is because a greater light intensity increases the rate of photosynthesis, which requires more carbon dioxide in leaves.
Note:
AQA says that students should be able to understand and use simple compound measures such as the rate of transpiration
Note:
AQA says that students should be able to:
- Translate information between graphical and numerical form
- Plot and draw appropriate graphs, selecting appropriate scales for axes
- Extract and interpret information from graphs, charts and tables
What is the process of transpiration?
When the plant opens its stomata to let in carbon dioxide, water on the surface of the cells of the spongy mesophyll and palisade mesophyll evaporates and diffuses out of the leaf
What is the process of translocation?
- Translocation is the movement of sugar produced in photosynthesis to all other parts of the plant for respiration and the other processes described above.
- This occurs in phloem cells.
What is the structure of the stomata?
- The stomata consist of minute pores called stoma surrounded by a pair of guard cells.
- Stomata, open and close according to the turgidity of guard cells. - The cell wall surrounding the pore is tough and flexible.
What is the function of stomata?
- They control water loss and gas exchange by opening and closing.
- They allow water vapour and oxygen out of the leaf and carbon dioxide into the leaf.
