Organisation Flashcards
(196 cards)
1
Q
What is meant by a cell?
A
A basic building block of all living organisms.
2
Q
What is meant by a tissue?
A
A group of cells with a similar structure and function.
3
Q
What is meant by an organ?
A
A group of tissues performing specific functions.
4
Q
What is meant by an organ system?
A
A group of organs working together to perform specific functions within an organism’s body.
5
Q
What are the three main nutrients within food?
A
Carbohydrates (starch and sugars)
Protein
Lipids (fats and oils)
6
Q
Why do :
Carbohydrates (starch)
Protein
Lipids (fats and oils)
Have to be digested?
A
Because they are large molecules. Too large to be absorbed into the blood stream, so are digested so they can be absorbed by bloodstream.
7
Q
What occurs during digestion? Define digestion.
A
Process where large and complex molecules in food are broken down into smaller and simpler molecules so that nutrients from this can be absorbed into the bloodstream.
8
Q
Role of the mouth in the digestive system
A
-Where food is chewed.
- Saliva in the mouth contains enzymes (salivary amylase) which begin to digest the starch into smaller sugar molecules.
9
Q
Role of the oesophagus in the digestive system
A
Where food that is chewed by the mouth passes thru before reaching the stomach.
10
Q
What are the things the stomach does in digestion?
A
- The stomach begins the digestion of protein through the enzyme pepsin which it contains.
- Contains HCL which:
> Kills bacteria in food.
> Provides optimal acidic conditions/pH for enzyme activity to aid digestion. - Has stomach muscles - these contract to create a churning action which turn the food to a fluid to INCREASE SURFACE AREA FOR ENZYMES TO DIGEST.
11
Q
What two types of breakdown does digestion rely on?
A
Physical breakdown
Chemical breakdown
12
Q
Role of HCL in the stomach.
A
> Kills bacteria in food.
Provides optimal acidic conditions fo enzyme activity to aid digestion
13
Q
After food has been digested by the stomach, where does it go and what happens next?
A
Food Fluid after spending several hrs in the stomach passes into the small intestine.
Chemicals from pancreas and liver are released into the small intestine:
PANCREAS - releases pancreatic juice which contains enzymes which continue digestion of protein and carbs and BEGIN digestion of lipids.
LIVER and GALL BLADDER-
Gall bladder releases bile produced by the liver. The role of bile is to speed up the digestion of lipids by emulsifying them into small droplets = BIGGER SA for digestive enzymes to work on - and neutralise stomach (HCL) acid bc bile is alkaline.
Next, food fluid passes down the rest of small intestine and the WALLS release enzymes which continue the digestion of proteins and lipids
Now, small food molecules are absorbed into the bloodstream via diffusion or active transport.
14
Q
What organ does most digestion occur?
A
Small Intestine.
15
Q
Role of bile
A
LIVER and GALL BLADDER-
Gall bladder releases bile produced by the liver into small intestine through a tube. The role of bile is to speed up the digestion of lipids by emulsifying them into small droplets = BIGGER SA for digestive enzymes to work on - and neutralise stomach (HCL) acid bc bile is alkaline.
1 - To speed up the digestion of lipids bc it emulsifies fats (breaking big molecules into smaller droplets) - makes a larger SA for enzymes to work on.
2 - To neutralise stomach acidi food in small intestine bc bile is alkaline fo enzymes in SI to work effectively.
(remember to always mention both roles)
16
Q
True or false, bile is an enzyme?
A
False.
17
Q
What happens after the useful small molecules from food is absorbed by the bloodstream (from small intestine)?
A
Remainder of fluid food passes into large intestine which absorbs the excess water, producing faeces which is stored in the rectum until removed via egestion.
18
Q
What are the products of digestion used for by the body?
A
To produce new carbs, proteins and lipids in body, eg protein for enzymes.
Some glucose is used for respiration.
19
Q
digestive system labelled
A
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.niddk.nih.gov%2Fnews%2Fmedia-library%2F18162&psig=AOvVaw2aGXGP34vJP0GZNCG6-1V5&ust=1712216336336000&source=images&cd=vfe&opi=89978449&ved=0CBIQjRxqFwoTCLj9yIXFpYUDFQAAAAAdAAAAABAE
20
Q
What is meant by an enzyme?
A
A biological catalyst that speeds up chemical reactions in living organisms without being consumed or permanently altered in the process.
Enzymes a proteins, protein is a polymer made up of small molecules called?
Amino acids.
21
Q
What type of molecule is an enzyme?
A
A large protein molecule.
22
Q
What is meant by the active site of an enzyme.
A
The active site is where the substrate attaches to.
23
Q
What is meant by a substrate?
A
The molecule the enzyme is breaking down.
24
Q
Summarise the lock and key theory.
A
- Enzymes have a specific active site which is complementary to their substrate so they can bind to the substrate to form an enzyme-substrate complex, and break substrate molecule in to smaller ones to be absorbed by bloodstream.
25
True or false enzymes are specific.
True, their **active site** is specific to their substrate
26
What is protease and explain its role.
Protease is the enzyme that breaks down proteins.
Proteins are made up of long chains amino acids. When digested, proteins are converted by protease back to individual amino acids. When amino acids are absorbed by body cells, they are joined together in a different order to make human proteins.
27
Where is protease found?
Stomach
Small intestine
Pancreatic fluid in pancreas.
28
What is starch?
A type of carbohydrate consisting of a chain of glucose molecules
29
What type of enzymes are carbohydrates broken down by.
Carbohydrases.
* Eg - amylase is a type of carbohydrase that breaks down starch to glucose, a type of sugar.
30
What enzyme breaks down starch?
Amylase.
31
Where amylase found?
Pancreatic fluid
Saliva
small intestine
32
Amylase breaks down starch to produce?
Simple sugars such as glucose
33
Carbohydrase breaks down carbohydrate to produce?
Glucose and simple sugars
34
Protease breaks down proteins to produce?
Amino acids.
35
A lipid molecule consists of how many molecules of glycerol and fatty acid?
1 lipid molecule =
1 molecules of glycerol and 3 molecules of fatty acids.
36
What enzyme breaks down lipid molecules?
Lipase.
37
Lipase breaks down lipid molecules to produce?
Glycerol and fatty acids.
38
Where is lipase found?
Pancreas
Small intestine
39
What also, as well as lipase aids the digestion lipids?
Bile.
- emulsifies lipid molecules, making them into smaller droplets to increase SA for lipase action.
- Is alkaline - neutralises stomach acid = optimum alkaline conditions for lipase
^^ Increasing the rate of lipid digestion by lipase.
40
Describe the affect of temperature on an enzyme using stages 1 2 and 3 (look at diagram).
Stage 1,
As temp increases so does enzyme activity
Bc there is more energy supplied meaning enzyme and substrate are moving faster.
This means there are more collisions per seconds between enzyme and active site
Stage 2, at the peak is the optimum temperature. This because enzymes are working at the fastest rate possible. This is because there is a max, frequency of collisions between substrate and active site.
Stage 3, When temperature is raised past optimal level, enzyme activity rapidly decreases to zero (enzymes stop working). This is because they begin to vibrate and shape of active site changes - so substrate can no longer fit in. Enzyme has denatured.
41
What is the optimum temperature in humans?
37 deg celcius
42
Describe the effect of altering pH of an enzyme.
- Every enzyme has an optimum pH, if pH is increased (more alkaline) or decreased (more acidic) the enzyme activity will fall as the active site changes shape/denatures.
43
An enzyme's optimum pH is acidic, what enzyme could this be?
protease enzyme
carbohydrase enzyme
44
An enzymes optimum pH is alkaline, what enzyme could this be?
Lipase
45
An enzymes optimum pH is slightly alkaline and slightly neutral, what enzyme could this be?
Amylase.
46
Describe how to prepare food sample when conducting chemical tests for nutrients.
- Take food sample and add distilled water.
- Grind the mixture w a mortar and pestle to make a paste.
- Transfer paste into a beaker and add more distilled water.
- Stir so chemicals in food dissolve into the water.
- Filter the solution to remove suspended food particles and for a clearer colour change to be seen.
47
Test for carbohydrates:
Starch = Iodine test
Reducing sugars = Benedict's
48
Test for protein:
Biuret's reagent (Copper II sulfate and sodium hydroxide).
49
Test for lipids:
Ethanol emulsion test.
50
Sources of error when conducting chemical tests for nutrients.
Colour change may be subtle and difficult to judge if the concentration of the test molecule is low (we can get many ppl to check).
51
Safety precautions when conducting chemical tests for nutrients.
- Tie hair back and when using open flame eg Bunsen burner when performing Biuret's test and water bath when performing Benedict's test .
- Handle Biuret's reagent w care as it contains copper II sulphate which is poisonous and sodium hydroxide which is corrosive. WEAR GLOVES, and wash immediately if it comes in contact w skin.
- Keep ethanol solution away from flames bc its highly flammable.
52
Describe test for starch
What test?
What do we do?
Positive colour change - from __ to __
IODINE TEST:
Add prepared food sample (2cm^3) into a test tube
Add a FEW drops of iodine solution into test tube using a pipette and mix.
If starch is present, the iodine solution will turn from brown to blue-black.
(note any colour change in a table of results)
53
Describe test for reducing sugars
Add prepared food sample (2cm^3) into a test tube.
Add an equal volume of Benedict's reagent (10 drops) using a pipette to the test tube containing the food sample solution.
Heat the test tube in a water bath at around 75°C for a few minutes.
If reducing sugars are present, the solution will change from blue to:
brick-red,
orange,
yellow
or green,
Indicating the presence of reducing sugars depending on the concentration ^^ respectively, most conc = brick-red.
note any colour change in a table of results.
54
Describe test for protein
Add a 2 cm^3 of Biuret's reagent to food sample (2cm^3) in a test tube, using a pipette.
Shake solution carefully to mix and wait for a few minutes.
If protein is present, the solution turns from blue to purple.
55
Describe the test for lipids
Add a few drops of cm^3 of ethanol and distilled water using a pipette to food sample (2cm^3) in appropriate apparatus.
DON'T FILTER WHEN PREPARING - bc lipid molecules can stick to filter paper.
Pour mixture into test tube with equal volume of distilled water.
If lipids are present, a white emulsion is formed on the surface of the mixture.
- ethanol is highly flammable, ensure no naked flames are present.
56
Positive result for starch
Brown to Blue black.
57
Positive test for reducing sugars
Blue to any colour of rainbow depending on conc: brick red, orange, yellow, or green.
In an exam say brick-red when necessary.
58
Positive test for protein
Blue to purple.
59
Postive test for lipids (ethanol emulsion test)
White emulsion is formed on surface of mixture.
60
Positive test for lipids (Sudan III Test)
2 layers formed -
top layer = bright red
bottom layer = colour of original mixture
61
Describe test for lipids (sudan III)
Using a pipette 3 drops of Sudan III stain solution to prepared food sample (5cm^3) in a test tube.
DON'T FILTER WHEN PREPARING - bc lipid molecules can stick to filter paper.
Gently shake the tube in order to mix the mixture,
Sudan III stain solution stains lipids. If lipids is present in sample, mixture will form 2 layers; the top layer will be bright red (if no lipids present, mixture doesn't form two layers).
62
True or False, Benedict's test works for non-reducing sugars eg sucrose?
FALSE. no colour change will occur if we try.
63
Why don't we filter when preparing our food sample to check for presence of lipids?
bc lipid molecules can stick to filter paper which will affect results.
64
Structure of proteins, starch and sugars
Draw
65
Describe how to investigate the effect of pH on the rate of reaction of the enzyme amylase.
- Place one drop of iodine solution using a pipette, into each well of a spotting tile.
- Take 3 test tubes, and in the 1st there's 2cm^3 starch solution, in the 2nd there's 2cm^3 of amylase solution and in the 3rd there's 2cm^3 of pH 5 buffer solution (SAB).
- Place all three test tubes in a water bath at 30 deg Celsius and leave them to heat for 10 mins to allow solutions reach 30 deg.
- Combine 3 solutions into a new test tube and mix with a stirring rod.
- Immediately return the test tube containing the mixture into water bath and start a stop watch for 30 secs.
- After 30 secs, use stirring rod to transfer 1 drop of solution into each well in spotting tile containing iodine solution.
- Iodine should turn blue-black if starch is present.
- Take a sample every 30 seconds and continue until iodine remains brown/orange.
- When iodine remains brown, it means starch is no longer present in solution (reaction has completed)
- Record the time that the reaction completed within in a table.
- Repeat this experiment for different pH buffers (6, 7 and 8).
- Plot a graph for rate of enzyme reaction against pH
- Calculate rate of reaction: rate = change/time
66
What does amylase break down starch to?
Maltose.
67
What is buffer solution used for?
A buffer solution is used to maintain a stable pH level in a solution, resisting changes in pH when small amounts of acid or base are added.
- we can use them to alter pH.
68
What issues are there when investigating the effect of pH on the rate of reaction of the enzyme amylase.
- INTERVALS BETWEEN TESTING MAY BE TOO LONG TO ACCURATELY FIND THE TIEM TAKEN FOR STARCH TO BE COMPLETELY BROKEN DOWN: We take sample every 30 seconds meaning we only have an approximate time which reaction finished - instead we should take sample every 10 seconds to be more specific.
- When we look for the time iodine doesn't become blue-black from brown, it isn't always obvious as colour change is gradual, one well may have blue mixed w v little brown - so ask many ppl to check to see when reaction has finished.
69
Safety precautions when investigating the effect of pH on the rate of reaction of the enzyme amylase.
- Be careful when using Bunsen burner; tie hair back and use goggles.
-
70
Order of digestive system.
Mouth
Osophagus
Stomach
Small intestine (liver and pancreas come in)
Large intestine
Rectume
71
Adaptations of the small intestine for absorption of products of digestion.
1) Very Long. This provides a large SA for products of digestion to be absorbed (faster diffusion/AT).
2) Interior of small intestine is covered in villi. This increases SA for products of digestion to be absorbed by bloodstream.
3) Villi is covered in microvilli on their surface. This further increases SA for absorption.
4) Villi have a good blood supply. Blood rapidly absorbs products of digestion - this maintains a steep conc gradient increasing rate of absorption.
5) Villi have a thin membrane; short diffusion path for absorption.
If products aren't absorbed by diffusion they are absorbed by AS.
72
True or false, fish have a single circulatory system?
TRUE:
Heart - Gills - Organs.
blood passes through the heart once during one complete circuit through the body.
73
What is the issue with a single circulatory system?
Blood loses pressure so blood travels slowly, so a great deal of oxygen cannot be delivered to organs in a specific time - less O2 for respiration - more anaerobic respiration.
74
Do humans have a double circulatory system?
YES.
blood passes through the heart twice during one **complete circuit through the body**
75
Why do humans have a double circulatory system?
We are relatively larger organisms, smaller SA:VOL so humans have a double circulatory system to efficiently separate oxygenated and deoxygenated blood, ensuring optimal oxygen delivery to ALL body tissues and effective removal of carbon dioxide rapidly, in a given time.
draw timeline diagram.
76
What is meant by the heart?
The heart is an organ consisting of mainly muscle tissue that pumps blood around the body in a double circulatory system.
77
How many chambers does the heart have?
4 chambers.
Right and Left atrium.
Right and Left ventricle.
78
What are atria separate from ventricles by?
Valves.
79
4 main blood vessels.
Vena cava.
Pulmonary artery.
Pulmonary vein.
Aorta.
80
Describe the pattern of blood flow in the heart.
- Deoxygenated blood from body enters the right atrium via the vena cava and oxygenated blood from lungs enters the left atrium via pulmonary vein, this occurs simultaneously.
- Muscles in atria contract and blood is forces into the right and left ventricles at the same time.
- Muscles in ventricles contract and force blood out of the heart (R - lungs and L - whole body).
- The valves prevent blood from flowing backwards into the atria when ventricles contract.
81
Purpose of valves:
- The valves prevent blood from flowing backwards into the atria when ventricles contract.
82
How is the left ventricle of the heart adapted for to pump blood around the body? (4 marks)
The left ventricle of the heart has a thicker and more muscular wall than the right. (1)
Bc the left ventricle pumps oxygenated blood from the lungs to the WHOLE body. (1)
While the right ventricle only pumps oxygenated blood to the lungs. (1)
So muscular wall provides a GREATER FORCE for oxygenated blood to be pumped at a GREATER PRESSURE from left ventricle to the whole body., (1)
83
Explain the purpose of coronary arteries (3 marks).
- What, where, why + link.
They're arteries that branch out of the aorta and spread out into the heart muscle. (1)
This allows them to provide oxygen to the muscle cells of the heart (1)
The oxygen is used in RESPIRATION to provide energy for contraction (1)
84
What group of cells control the natural resting heart rate?
Pacemaker cells.
85
Where is the pace maker found?
In the right atrium.
86
What can doctors do when the pacemaker stops working correctly?
They can implant an artificial pacemaker - a small electrical device that correct irregularities in the heart rate - when an individual has an irregular heart beat.
87
What is the role of arteries?
To carry high pressure blood from the heart to organs in the body.
Aorta - O blood Away
Pulmonary artery - DO blood Away.
(veins carry blood to the heart, typically deox. apart from PV which carry oxygen-rich blood).
88
ADAPTATION OF ARTERIES x 2
- V thick muscular walls - to withstand high pressure from blood flow.
- Smaller lumen
- Elastic fibres - to withstand high pressure from blood flow, blood travels in high pressure surges - allows to stretch and recoil.
(DONUT)
89
Purpose of capillaries:
To facilitate the exchange of nutrients eg glucose, gases eg O2 and CO2, and waste products between the bloodstream and cells + tissues.t
O2 and GLUCOSE TO cells from blood.
CO2 from cells blood
90
Adaptations of capillaries x2
- Thin wall (one cell thick) - Shorter distance for diffusion increases rate of diffusion of substances between cells and blood.
- Permeable walls - Substances can easily diffuse in and out of cells to and from the bloodstream.
91
Purpose of veins
To carry low pressure deoxygenated blood back to the heart from organs.
92
Adaptations of veins
- Thin wall - bc blood pressure is low so wall doesn't need to be thick.
- Valves - To prevent back flow of blood (when blood flows backward, valves shut + in correct direction, they open).
- Wide lumen (tube) allows more low pressure blood to flow thru.
93
Where are arteries, capillaries and veins found
Arteries - Heart (blood to body)
Capillaries - Organs (blood to cells)
Veins - Deoxygenated blood back to the heart.
94
State the 4 parts of the blood.
- Plasma (liquid)
In the plasma we find.
- Red Blood Cells
- White Blood Cells
- Platelets.
95
What is the plasma and its job?
- The Liquid part of the blood, and its job is to transport DISSOLVED SUBSTANCES around the body.
It also carries the other parts of blood.
96
What dissolved substances does the plasma transport around the body?
- CO2 produced by aerobic respiration in cells from organs to lungs
- Urea from liver to kidney for excretion.
- Soluble digestion products eg glucose from small intestine to organs
- Hormones
- Proteins
- Antibodies and Antitoxins produces by RBC.
97
What is the role of RBC
To transport oxygen from lungs to body cells in haemoglobin.
98
Adaptations of RBC
- Contain haemoglobin - this binds to oxygen in lungs to form oxyhemoglobin. When RBC travel to organs, oxyhemoglobin releases the oxygen.
- No nucleus - which allows for more hemoglobin meaning more oxygen can be carried by it to body cells/organs.
- Biconcave disc - provides greater SA for oxygen to diffuse in and out of RBC rapidly.
99
Role of white blood cells.
They form part of the immune system to defend against infection by making antibodies.
100
Adaptations of white blood cells:
- Can change shape - this allows them to engulf unwanted harmful microorganisms in the body during phagocytosis.
- Contain a nucleus - The nucleus contains DNA which encodes for the instructions that the WBC need to do their job.
101
What is the role of platelets?
Tiny fragments of cells whose job is to help the blood to clot.
This stops micro-organisms from entering and from blood pouring out.
102
Describe the role of platelets in blood clotting. (4 marks)
- Platelets stick to the damaged blood vessel wall.
- They change shape and release chemical signals.
- This attracts more platelets to the site of injury.
- The platelets clump together to form a temporary plug.
- They also release substances that start the clotting process.
- This leads to the conversion of fibrinogen to fibrin.
- Fibrin reinforces the platelet plug, forming a stable blood clot.
103
What can lack of platelets lead to?
Excessive bleeding and bruising
104
Blood donations; what are the reasons for blood donations/transfusions?
- To replace blood lost in an injury.
- Some people are given platelets from blood to help in clotting.
- Proteins extracted from blood can be useful for antibodies.
105
Problems w blood transfusion
- Compatitbility - patients blood must be the same type as donor or body's immune system will reject the blood and patient could die.
- Infection - diseases can be transmitted thru blood
However in UK blood is screened.
106
Define blood.
Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended.
107
What is coronary heart disease and consequence?
In coronary heart disease layers of fatty material build up inside the coronary arteries, narrowing them.
This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle, so less respiration = less contraction = less blood flow around body (slower).
In extreme cases, this can result in a heart attack.
108
True or false, cardiovascular diseases are communicable?
False. Cardiovascular diseases are non-communicable diseases so cannot be passed from person to person.
They are not infectious.
109
2 ways to treat coronary heart disease:
Statins
Stents
110
What are statins?
What are their advantages and disadvantages?
Statins are drugs that reduce the level of cholesterol in the blood, which in turn slows down the rate at which fatty material builds up in the arteries.
Advantages
- Effective; have been proven to reduce the risk of coronary heart disease.
- Not an invasive process (no surgery)
- They increase levels of good cholesterol LDL
Disadvantages
- Can cause unwanted side effects eg liver problems
- Need to be taken continuously
111
What a stent?
A tube inserted into the coronary artery that keeps it open.
ADVANTAGES
- Blood can flow normally thru the artery.
- Effective for lowering risk of heart attack.
DISADVANTAGE
- Surgically invasive
- There is a chance blood clots can form near the stent
- Surgical risks eg heart attack during the procedure.
- Doesn't directly treat the underlying causes of the disease.
- Infection during surgery
112
Name 2 other heart issues aside from coronary heart disease.
- Faulty valves (leaky, don't fully open)
- Heart failure
113
Explain the issue with a faulty valve that does not fully open.
- Some valves are faulty and do not fully open when blood is flowing in the correct direction. (into atria when ventricles contract).
- This means the heart has to pump much harder to pump blood through the valves to around the body, and less blood is being pumped around the body.
- This causes the heart to enlarge.
- Also means less blood is being transferred around the body in a given time, (blood is been pumped around the body more slowly).
- Meaning less oxygen is being delivered to cells for aerobic respiration.
- Means cells have to respire anaerobically.
- This leads to a build up of lactic acid.
- So person feels more weak and tired.
114
Explain the problem with leaky heart valves.
- Back flow of blood.
- Means less blood is being transferred around the body in a given time, (blood is been pumped around the body more slowly).
- Meaning less oxygen is being delivered to cells for aerobic respiration.
- Means cells have to respire anaerobically.
- This leads to a build up of lactic acid.
- So person feels more weak and tired.
115
How can we medically solve the issue of faulty and leaky valves?
- Mechanical valves.
- Animal/Biological valves.
116
Evaluate the use of mechanical valves. (2 pos 2 neg and just).
5 marks.
ADVANTAGES
- Can last a life time
- Proven to successfully treat faulty valves - so its efficient.
- No rejection by immune system
DISADVANTAGES
- May lead to clotting of blood around it.
- Constant medication is needed to prevent clotting an which could pose as an inconvenience.
- Surgically invasive process
- Overall I feel they are useful bc they allow for patients to be treated and they are manmade so more ethical.
117
Evaluate the use of animal/biological valves (5 marks)
ADVANTAGES
- Works very well (efficiently) proven to be successful.
- No anti-clotting drugs needed.
DISADVANTAGES
- Only lasts 12-15 years.
- Potential transfer of infection
- Potential rejection by immune system
- Ethical objections
Overall I think animal valves are useful in medicine to treat faulty valves as they provide a way individuals can live normally without weakness and lethargy.
118
What is meant by heart failure?
Heart failure occurs when patients cannot pump enough blood around the body.
119
How can patients with heart failure be treated?
Donated heart, or Donated 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.
120
What are the issues with heart donations (or heart and lungs)
- Low supply of donors, there are not enough donated hearts (and lungs) to treat every patient.
- Possibility of rejection by immune system - so patient must take drugs to prevent this.
121
What is the purpose of an artificial heart?
they are used to keep patients alive whilst waiting for a heart transplant.
OR to allow the heart to rest as an aid to recovery after surgery.
122
Issues with artificial hearts.
- Not a long term solution to heart failure.
- Increase the risk of blood-clotting.
- It is mechanical so parts could wear out and the motor could fail.
123
What is the role of the lungs
To supply oxygen to blood so it can be transported to cells for aerobic respiration, and to remove CO2 waste product.
124
Formula to calculate the rate of flow of blood.
Volume/time in minutes.
125
Where is the lungs found?
In the thorax.
126
What are lungs protected by?
The ribcage.
127
Explain the process of ventilation - INHALATION.
- External intercostal muscles contract
- So ribcage is pulled upwards and outwards
- Diaphragm contracts and flattens/
- So volume of lungs/thorax decreases.
- Pressure in lungs increases.
- Air is taken into the lungs
128
Summarise the process of gas exchange in the lungs.
Mout or nose
Trachea
Bronchi
Bronchioles
Alveoli in Lungs
Bloodstream
129
Alveoli adaptations:
- Each alveolus is v small - larger SA:Vol ratio for diffusion = faster rate of diffusion
- Alveoli are arranged in clusters - provides a greater SA = faster rate of diffusion
- Alveoli are surrounded by many capillaries meaning there's a good blood supply - a steep conc. gradient is maintained = faster rate of diffusion
- alveoli have thin walls - shorter distance for diffusion = faster rate of diffusion
- Moist walls - gases can dissolve onto moisture - greater rate of diffusion
*Diffusion =/ gas exchange of CO2 and O2
130
How are the lungs adapted for gas exchange?
Talk abt
- Alveoli + adaptations
- Capillaries
- How humans hv 2 instead of 1?
131
To calculate breathing rate:
number of breaths taken/time in mins
132
Adaptations of trachea.
Contain rings of cartilage which prevent it from collapsing when we inhale.
133
Explain the relationship between lungs and heart.
Heart pumps Deox blood to lungs and there it collects oxygen to become oxygenated.
Oxygenated blood returns back to heart and blood is pumped around the whole body to all the organs and body cells.
134
How many lungs do humans have?
2 (1 pair)
135
How many bronchi in each lung?
1 - each bronchi subdivides into tubes called bronchioles which have tiny air secs in their ends called alveoli.
136
Define ventilation:
Movement of air in and out of the lungs that enables large volumes of gas to be exchanged.
137
Explain the process of ventilation EXHALATION:
-Intercostal muscles relax.
- The ribcage is pulled downwards and inwards.
- Diaphragm relaxes and moves upwards.
- Volume of lungs decreases.
- Pressure in lungs increases.
- Air is expelled from lungs.
138
Where is carbon dioxide carried?
In blood plasma
139
How does breathing increase the rate of diffusion?
(3 marks)
- Takes fresh O2 into alveoli and removes CO2
- Maintains a steep conc gradient
- Increases rate of diffusion
140
True or false, cell division by mitosis is tightly controlled by genes?
True.
141
What leads to uncontrolled growth by mitosis?
Changes in genes/Mutations - so genes can't tell cells when to divide or not leading to the formation of a tumour
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Beningn tumours
- Non-cancerous growths of abnormal cells found within ONE area.
- Usually contained within a membrane.
- So they do not invade other parts of the body, instead, they stay in one place.
- However they can grow until there's no more room.
- This can cause pressure and damage to an organ/organs which is dangerous.
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Malignant tumours
- Cancerous growths of abnormal cells that invade other parts of the body.
- M cells move into bloodstream and travel to stay in other organs/parts of the body to form new tumours called secondary tumours.
- Both made up of many cells.
differences + sims
- M = cancerous B isn't
- M invades other tissues B doesnt
- B is contained within a membrane - - M isn't
- Both made from cells
- Both caused by abnormal cell division
- Both tumours
- Both cause damage to neighbouring cells if pressure is applied.
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Compare being and malignant tumours (6 marks)
Similarities
- Both caused by abnormal/uncontrolled cell division by mitosis.
- Both can cause damage to organs if tumour pressure is applied.
- Both made from cells
- Both tumours
differences
- M = cancerous B isn't
- M invades other tissues B doesnt
- B is contained within a membrane M isn't
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True or false malignant tumours are classed as cancerous?
True.
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Risk factors for cancer:
- Genetics - humans can inherit increased risk of getting cancer from parents
- Lifestyle - eg Smoking can cause sun cancer, exposure to UV light from sunbathing can cause skin cancer, Alcohol - mouth and throat cancer.
- Environment - some people work and live in areas that have radioactive gases EG radon. Radon is radioactive and releases ionising radiation which can lead to genetic mutations/DNA damage - leading to uncontrolled cell division - leading to cancerous tumours.
147
Define communicable disease.
Diseases that are spread from person to person eg Measles.
148
True or false, communicable diseases are spread by pathogens such as bacteria or viruses?
True.
149
Define non-communicable disease.
A disease that cannot be passed from person to person eg Coronary heart disease.
150
What causes ill-health?
Diseases
Stress
Poor Diet
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What is meant by health?
A state of physical and mental well-being.
152
True or false, different diseases can interact? Give an example.
True.
Eg Tuberculosis can usually be fought of by strong immune systems, but people with HIV have a defective immune system meaning that their risk of contracting TB is higher.
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Give an example of how disease can be triggered by the immune system:
ALLERGIES:
Immune system fights off pathogen, but person can be left w allergies eg dermatitis or asthma.
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Give an example of how 1 disease can lead to another.
HPV can lead to cervical cancer. (HPV infect cells of cervix).
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Give an example of how mental illnesses can be triggered by physical illnesses
Someone w arthritis - difficulty socialising - triggers depression.
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Summarise 4 ways diseases can interact:
Physical - Mental
Immune system - Allergies
Defective immune system - Higher risk of contracting a disease
HPV - cancer
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What is meant by epidemiology?
The study of the distribution and determinants of health-related conditions in populations.
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How can a correlating risk factor be deduced?
- SAMPLE - SCATTER GRAPH - CORRELATION
- Pick what you think is the risk factor for a disease eg smoking + lung cancer.
- Pick a sample and see how many people are associated w the risk factor and from those, how many people have the disease.
- Plot this on a scatter graph; risk factor on x and disease on y
- See the correlation; if positive, that risk factor is a correlating risk factor.
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Does correlation prove cause?
NO - It only suggests that they may be linked.
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After deducing a correlating risk factor, what do scientist do?
They look for a causal mechanism (scientific reason)
161
Define causal mechanism in biology:
The specific process or pathway that explains how a cause leads to a disease.
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What is meant by a carcinogen?
A substance that can cause cancer by damaging the genetic material (DNA) in cells, leading to uncontrolled growth and division of cells.
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Problems with sampling to get correlating risk factors
- Small sample = non-representative = biased.
So get a large sample.
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Risk factors for cardiovascular diseases:
- Poor diet - fatty diets = build up of bad cholesterol, salty diet = increase in blood pressure.
- Lack of excercise (build up of fat)
- Smoking
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How can the risk of developing cardiovascular diseases be reduced?
By exercising.
Healthy diet.
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Risk factor for lung cancer:
Smoking - cigarette smoke contains carcinogens (as a substance that can cause cancer by damaging the genetic material (DNA) in cells, leading to uncontrolled growth and division of cells).
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Smoking while pregnant can cause:
- Miscarriage
- Low mass birth
- Premature birth
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Drinking alcohol while pregnant can cause:
- Fetal alcohol syndrome (learning, mental or physical problems)
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Drinking alcohol effect on body:
- Memory loss
- Liver cirrhosis
- Liver cancer
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Type 2 diabetes:
People struggle to control blood glucose levels - can lead to blindness or amputation of limb.
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Factors that can cause type 2 diabetes
- Obesity
eg tm alcohol drinking - obestity - cancer (this shows how risk factors can interact).
172
True or false, the leaf is an organ?
True.
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Amylase is a polymer, it is made up of smaller molecules called?
Amino acids.
174
What is the role of the Epidermal tissue.
The epidermal tissue is a tissue that covers the whole plant (upper and lower epidermis - these are made up of epidermal cells.)
ADAPTATIONS AND ROLES
- Upper epidermal is transparent which allows light to pass through to photosynthetic cells bellow (palisade mesophyll cells) to carry out photosynthesis.
- The epidermal tissue protects the surface of the leaf.
- Covered in waxy cuticle; this helps to reduce water loss from plant by evaporation, as waxy cuticle prevents water from moving out of the plant.
(prevent water loss, allow light to pass thru)
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Palisade mesophyll tissue
Found underneath the upper epidermal tissue;
- Where photosynthesis occurs
- Has lots of chloroplasts; this allows for photosynthesis to occur rapidly.
- They are positioned at the top of the leaf under transparent upper epidermal tissue, so light can pass and can receive lots of light for photosynthesis to occur.
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Spongy mesophyll tissue
Has lots of air spaces, this allows gases to easily diffuse in and out of cells.
- Lots of air spaces increase SA so more gas can pass through quickly.
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Xylem
FOUND IN ROOTS STEMS AND LEAVES.
Made up of dead cells joined together creating a continuous tube;
this allows the movement of water and mineral ions from the roots through the stem to the leaves (always say through stem), where it evaporates and leaves the plant. This is called the transpiration stream.
Contains a chemical called lignin and holes called bordered pits;
Lignin makes leaves strong and waterproof, so water cannot leave except through bordered pits; this allows minerals to go to specific places in the plant.
-- Unidirectional movement of food substances.
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Phloem
Elongated cells with holes in their cells wall ends (the end walls are called sieve plates).
Many organelles from the cell are removed so cell sap can move through.
Food substances can be moved in both directions (bidirectional movement of food substances, dissolved), from the leaves where they are made for use, or from the storage parts (underground) to the parts of the plant that need it. This is called translocation.
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Meristematic tissue
Found in growing tips of roots and tips shoots of plants. (SAY TIPS)
Able to differentiate into different types of cells.
This helps the plant to grow.
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What is meant by translocation?
The movement of food substances made in leaves up or down the phloem for immediate use or storage.
- Phloem - bidirectionally.
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What is meant by transpiration?
The loss of water vapour from the leaves and stems of plants.
It is a consequence of gaseous exchange, as the stomata open this can occur.
- Xylem - unidirectionally.
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How does carbon dioxide diffuse into the leaves?
Information on stomata and guard cells.
From the air into the stomata (pores).
PROBLEM; water can be lost through this, so leaves keep stomata open for as short a time as possible to maximise CO2 absorption and minimise water loss.
So how do stomata open and close?
- Guard cells (guard cells open and close, which widens/reduces the size of stomata).
Each stoma is formed from the gap between two guard cells.
HOW DO GUARD CELLS OPEN AND CLOSE?
- When plant has lots of water (so doesn't need to worry about conserving it) guard cells will be turgid, this makes the gaps between them larger so more CO2 gas can diffuse thru for photosynthesis.
- When plant becomes short of water the guard cells lose water due to osmosis and become flaccid and this makes the gap between each guard cell, ie the stoma smaller. This way less H2O will be lost, and less CO2 will be taken into and used alongside H20 for photosynthesis.
- Guard cells are sensitive to light; close at night time when no light so photosynthesis isn't taking place so don't need CO2 = less water loss.
- Most stomata at bottom of the leaf bc more shaded so more colour = less evaporation of water.
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Suggest why most stomata are found at the bottom of the leaf.
Bottom of leaf is more shaded so more colour = less evaporation of water, so less water loss.
184
Water is taken in by the roots, transported up the plant and **lost from the leaves**, which scientific term describes this movement of water?
The transpiration stream.
NOT TRANSPIRATION = evaporation of water, transpiration stream is the actual movement of water before it is evaporated.
Remember, it says 'Lost from leaves' so must be transpiration NOT osmosis.
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Describe the process of the transpiration stream.
The question may say 'the process by which water is taken by the roots, transported up the plant and lost from the leaves', this means transpiration stream - DO NOT SAY TRANSPIRATION.
- transpiration - loss of water/ evaporation from leaves or stem.
- transpiration STREAM = MOVEMENT of water through xylem tissue and mesophyll cells.
- Transpiration stream starts with evaporation of water from the cells in the leaf.
- The water vapour diffuses through the air spaces in the spongy mesophyll and out of the leaves through the stomata into atmosphere.
- Water vapour diffuses from xylem into the leaf to replace water that has been lost.
- And water diffuses from soil into the root hair cells and up the xylem vessels into the leaf to also replace water that has been lost.
- This process is called the transpiration stream.
summary
(evaporation from leaf cells, v vapour diffuses thru air spaces in spongy mesophyll and out of stomata in leaves to surroundings/environment. Water is replaced how? water vapour from surroundings diffuses into xylem in leaf and water is diffuses from soil into root hair cells up xylem vessels to leaf = transpiration stream).
186
Compare the structure and function of xylem tissue and phloem tissue.
187
Why is transpiration important?
Explain 3 reasons
It brings water to the leaf and water molecules are required for photosynthesis.
It transports dissolved mineral ions such as magnesium ions which have important roles in plants such as making chlorophyll.
Transpiration (evaporation of water from leaf) is important because it cools the leaf down; this is important in warm temperatures - optimum plant temp for photosynthesis.
(think of the cognito water molecule chain thing).
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What are the factors that affect the rate of transpiration?
Temperature; the rate of transpiration increases as temperature increases because water molecules have more energy so more likely to evaporate, this keeps the concentration gradient steeper so rate of transpiration = faster (think of diffusion of water vapour)
Light intensity; this is because stomata, which are sensitive to light intensity open in brighter conditions for CO2 to enter for photosynthesis - at the same time more water vapour can leave so increased rate of transpiration.
Air flow; under windier conditions, more wind to take away water molecules - this maintains a steep concentration gradient so rate of transpiration = faster (link to diffusion).
Humidity; the drier/more humid the air is, the faster the rate of transpiration because water vapour in plant will diffuse from an area of higher conc in plant to lower conc in surroundings, so more evaporation.
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Increased humidity will increase or decrease the rate of transpiration?
Decrease.
190
Increased light intensity will increase or decrease the rate of transpiration?
Increase.
191
Increased temperature will increase or decrease the rate of transpiration?
Increase.
192
Increase wind will increase or decrease the rate of transpiration?
Increase.
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How do guard cells work?
- Open in light conditions
- Close when plant has enough water (swell/turgid)
- Open when plant needs more water (flaccid)
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How can transpiration be measured?
Using a potometer - this measures the rate of transpiration by placing a plant in a tube of water and measuring the distance travelled by a bubble (this bubble is water entering the plant/uptake - this indicates the rate of transpiration as water can only enter plant if water leavers via transpiration).
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What is meant by translocation?
Translocation is the movement of food substances up or down the phloem for immediate use or storage.
REMEMBER:
- glucose used to produce energy from respiration.
- OR can be stored as insoluble starch.
Glucose/sugars and water = cell sap, cell sap travels up through PORES of the phloem cells; the phloem cells are attached end-to-end to form a tube.
196
What do pacemaker cells do?
Send small electrical impulses into walls of heart causing them to contract.
