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A Level Biology (SNAB) > Topic 1 > Flashcards

Topic 1 Flashcards

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1
Q

Why do only small animals have an open circulatory system?

A
  • Their surface area is small enough to rely on diffusion
  • Diffusion is only quick enough in small animals
    Because the rate of diffusion is inversely proportional to the distance travelled
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2
Q

What are the advantages of a double circulatory system?

A
  • Blood can pass slowly through the region where gas exchange occurs
  • This maximises the transfer of of O2 and CO2
  • But this causes a large pressure drop
  • Therefore blood is moved back to the heart
  • This allows the blood to be pumped around the body at high pressure
  • Allowing the organism to be very active
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3
Q

What are the disadvantages of a 3 chambered heart?

A
  • Oxygenated and deoxygenated blood are mixed
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4
Q

Why do animals have a heart and circulation?

A
  • Diffusion is too slow because of a small SA:V ratio
  • Which means materials can’t travel quick enough
  • So diffusion can’t support a high metabolic rate
  • Animals need to maintain a constant temperature (uses energy)
  • A heartbeat means blood can reach the capillaries quickly
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5
Q

What is the structure of the heart?

A

*SEE DIAGRAM
- Shown as if we were facing someone
- Left ventricle has thicker walls because a greater force is needed to push blood around the body
- Tricuspid valve has 3 flaps, preventing back flow into the right atrium
- Bicuspid valve has 2 flaps, preventing back flow into the left atrium
- Atria are smaller as they only have to collect blood
- The Vena Cava and Pulmonary Vein don’t have valves because the Vena Cava has low pressure and the right ventricle also has low pressure, as it has mostly emptied itself

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6
Q

What is intermolecular bonding in water?

A
  • There are strong covalent bonds between H and O
  • There are weak intermolecular bonds between each atom
    This creates a liquid that can be pumped around the body while carrying materials
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7
Q

What is adhesion?

A
  • The formation of hydrogen bonds between cellulose and water molecules
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8
Q

What is cohesion?

A

Where hydrogen bonds with water molecules

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9
Q

Why is water a good solvent?

A
  • Water is a good solvent of sonic, charged and polar chemicals
  • This is because of the attraction between particles in the chemicals and the polar water molecules (hydrophilic)
  • This allows for vital biochemical reactions to occur in the cytoplasm of cells
  • This allows substances to be transported around the body, as well as into it
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10
Q

Do non-polar substances dissolve?

A
  • No, as they are hydrophobic
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11
Q

What are the thermal properties of water?

A
  • Water has a high specific heat capacity
  • This is because it requires a large volume of energy to break the hydrogen bonds
  • This helps to avoid rapid changes in the internal temperature
  • This allows organisms to maintain a steady temperature
  • Water is at room temperature because the water molecule is polar
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12
Q

What is mass flow?

A
  • The process of materials being carried in a liquid in one direction to multiple exchange surfaces
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13
Q

What is the role of skeletal muscles in blood flow?

A
  • They push blood back up towards the heart
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14
Q

What are the steps of the skeletal muscles assistance in blood flow?

A
  1. Relax - The valves are closed
  2. Contract - The valves open and blood is rushed upwards
  3. Relax - The valves close as blood falls back
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15
Q

What is the structure and function of the arteries?

A
  • To carry blood away from the heart at high pressure
  • They have a tough outer layer to prevent bursting due to high pressure
  • They have a thick layer of muscle and elastic fibres to help pump blood through after each contraction of the heart
  • They have a narrow lumen to help maintain the high pressure, preventing back flow
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16
Q

What is the structure and function of the capillaries?

A
  • Supplies all cells with their requirements (O2) and removes their waste products (CO2)
  • They have a cell wall that is one cell thick - they don’t need a strong wall as most of the blood pressure has been lost
  • They have a narrow lumen - it is only just wide enough for a RBC to pass through
    The thin walls and narrow lumen bring blood into close contact with body tissues
  • This close contact means a small diffusion pathway and a large SA
  • The walls contain pores which allows WBC to enter/exit
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17
Q

What is the structure and function of veins?

A
  • They return blood to the heart at a low blood pressure
  • Their wall is thin and mainly fibrous tissue
  • They don’t require a strong wall as pressure has been lost
  • They have a wide lumen which means there is less resistance to the blood flow
  • They contain valves, which prevent back flow
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18
Q

What is the purpose of the cardiac cycle?

A
  • To flow blood from the vena cava and pulmonary veins to atria
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19
Q

What is the process of Atrial Systole?

A
  • The atria contracts and pumps into ventricles
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20
Q

What is the process of ventricular systole?

A
  • The ventricles contract and pump blood to the arteries
  • The increased BP forces atrioventricular valves to shut and semi-lunar valves to open
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21
Q

What is the process of ventricular diastole?

A
  • Everything relaxes and the atria fills with blood
  • The increased BP in the atria opens the AV valves
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22
Q

Where does the left ventricle pump blood?

A
  • Thick muscle walls to pump blood around the body
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23
Q

Where does the right ventricle pump blood?

A
  • Thinner muscle walls to pump blood to the lungs
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24
Q

What is atherosclerosis?

A
  • When atheroma’s form inside the arterial walls, thus narrowing the artery
  • It increases the chances of blockages in arteries (thrombosis)
  • This can lead to a total blockage of coronary arteries = HA
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25
Q

What are causes of Atherosclorosis?

A
  • Damage to endothelium
    • Caused by HBP, toxins or oxidised LDL (REF to free radicals)
  • Inflammatory response
    • WBC leaves blood vessel to artery wall accumulating chemicals from the blood - especially Cholesterol
  • Calcium salts and fibrous tissue collects =ing a plaque
  • Loss of artery elasticity
  • Narrowing can lead to strain and +ve feedback
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26
Q

How does clotting occur at the atheroma?

A
  • Platelets change shape when they come into contact w/ damaged blood vessel
  • Stick to exposed collagen in artery wall
  • Form a temporary platelet plug =ing more platelets being activated
  • Blood contact w/ collagen =ing series of chemical changes
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27
Q

What is the process of atherosclerosis?

A
  1. Artery wall damaged so inflammatory response
  2. WBC enter wall bringing cholesterol which accumulates = Atheroma
  3. Calcium salts and fibrous tissue accumulate = Plaque
  4. Wall elasticity reduced and artery narrowed
  5. Raises BP = Atherosclerosis
  6. Platelets in contact w/ wall and become sticky
  7. Platelet plug forms =ing chemical changes
  8. Prothrombin → Thrombin → Fibrinogen → Fibrin
  9. Tangled mesh traps blood clots
  10. A blood clot forms which can lead to myocardial infarction
28
Q

What are macrophages?

A
  • Make proteins that act in 2 ways
  • ‘Punch’ holes in bacteria so that they die
  • Phagocytose them (eat them)
  • However it can’t deal w/ one particular microorganism as some will always survive
  • Also can’t remember past infections
29
Q

What is correlation?

A
  • When an increase/decrease can be linked to an increase/decrease in the other variable
30
Q

Does correlation = causation?

A

NO

31
Q

Why do people perceive risk wrong?

A
  • People guess the number of deaths per risk wrong mostly b/c:
  • Over/underestimate the danger
  • Forget about medical advancements
  • Over/underestimate the time it takes some illnesses to become fatal
32
Q

How do you design a good study?

A
  • Large sample size (to make it reliable)
  • Use of control variable (to compare against)
  • Clearly stated aim and hypothesis
  • A design appropriate to the question
  • Participants are representative (to make valid results)
  • Knowledgeable about what to look for during study and analysing results
  • Appropriate measurements are made (to be valid)
  • Methods used are repeatable (to be reliable)
  • Time scale is suitable
  • Other variables taken into account
  • Carried out by an unbiased company (to be reliable)
33
Q

What is a cohort study?

A
  • Follow a group of people over time to see who develops the disease
  • People’s exposure to risk factors are recorded and tested for correlation
34
Q

What is a case-control study?

A
  • A group of people w/ a disease compared w/ a control group
  • Information on risk factors is collected
35
Q

What are monosaccharides?

A
  • Have 2 or more hydroxyl groups
  • Either contain an aldehyde group (aldoses)
  • Or a ketone group (ketoses)
  • Formula = (CHշO)n
  • Ring formation
  • In aqueous solution aldehyde/ketone groups of a sugar molecule react w/ a hydroxyl group of the same molecule
  • Which closes the molecule into a ring
36
Q

What are Isomers?

A
  • Many monosaccharides differ only in their spatial arrangement
  • Small differences = minor changes in chemical properties
  • But recognised by enzymes and other proteins = important biological effects
37
Q

What are dissaccharides?

A
  • Carbon carrying aldehyde/ketone group can react w/ any hydroxyl group
  • Disaccharide (2 sugar units) = 2x monosaccharides (2x 1 sugar units)
  • Formed through a condensation reaction =ing water being released
  • Formula = Cx(HշO)n
38
Q

What are Oligosaccharides and Polysaccharides?

A
  • Short chains of molecules are called oligosaccharides
  • Long chains are called polysaccharides
  • Long and linear branched molecules can be made from repeating units
  • Oligosaccharides are non-digestible
  • Helps feed friendly bacteria so are referred to as prebiotics
  • Prebiotics in large intestine
39
Q

What are α and β links?

A
  • The hydroxyl group can rapidly change
  • α hydroxyl group is below
  • β hydroxyl group is above
  • As soon as one sugar is linked to another the forms are frozen
  • (1-4) glycosidic link 1 = carbon no. of first mono, 4 = carbon no. of second
40
Q

What is starch?

A
  • α glucose arranged in a helix
  • Energy stored in plant cells
  • Insoluble
  • Doesn’t draw water into cells
  • Doesn’t easily diffuse into cells
  • Compact
  • Easily transported when hydrolysed into α-
    glucose
41
Q

What is glycogen?

A
  • Energy stored in animal cells
  • Similar storage advantages to starch
  • Shorter chains = more highly branched
  • Even more readily hydrolysed
42
Q

What are lipids?

A
  • Insoluble in water
  • 3 fatty acids and a glycerol
  • Triglyceride = 3 fatty acids and a glycerol
    (lipid)
43
Q

What is the condensation reaction?

A
  • Produces a fat and HշO
  • 1st a monoglyceride is formed
  • 2nd a diglyceride is formed
  • 3rd a triglyceride is formed
  • Unsaturated fats are found mainly in plants
  • Ester bonds are formed b/w glycerol and
    fatty acids
44
Q

The Energy Balance

A
  • Mass of calories needed each day depends on:
    - Volume of energy body uses at rest
    (basal metabolic rate)
    - Energy used as a result of eating (specific
    dynamic action)
  • The volume of physical activity carried out
  • Energy requirement < energy intake = weight
    gain
  • Energy requirement > energy intake = weight
    loss
  • Energy intake = total energy output (heat +
    work + energy storage)
  • RDA = recommended daily intake
  • DRV = dietary reference values
  • L/HRNI = lower/ higher reference nutrient
    intake
45
Q

What is Cholesterol?

A
  • C27H46O
  • w/o cholesterol body couldn’t function
  • Help form/repair cell membranes and some
    hormones
  • Links fatty acids together to stabilise and
    strengthen cell membranes
  • Carried by proteins (when together called
    lipoproteins)
46
Q

What are the sources of cholesterol?

A
  • Liver (80%)
  • Food (20%)
47
Q

What are things that affect cholesterol levels?

A
  • Genetics
  • Physical activity
  • Stress
  • Diet/ habits (eg. smoking
48
Q

What are HDL’s?

A
  • Is good cholesterol
  • Unsaturated
  • Less likely excess will be deposited on artery
    walls
  • Higher % protein than LDL (more dense)
  • Transport cholesterol to liver for elimination
  • So ↓blood cholesterol and helps to remove
    fatty plaques of atherosclerosis
49
Q

What are LDL’s?

A
  • Carry cholesterol away from the liver
  • Excess can be deposited on artery wall
  • So known as bad cholesterol
  • Triglyceride + cholesterol + protein = LDL
  • Bind w/ receptor sites on cells
  • Excess overloads membrane receptors =
    ↑blood cholesterol
  • Saturated fats ↓activity of LDL receptors
    so LDL not removed from the blood (+ve
    feedback)
50
Q

Fats in the diet

A
  • Saturated = raise blood cholesterol (no double bonds)
  • Mono-unsaturated = can ↓cholesterol and improve balance b/w HDL and LDL
  • Polyunsaturated = ↑activity of LDL receptor site to actively remove them from blood
51
Q

Free Radicals

A

= Any atom/molecule w/ an ‘unpaired’ electron (not a cell)
- Unpaired electron is restored to a pair by pulling a hydrogen atom from another
- Causes damage to DNA, proteins, lipids, cell membranes and mitochondria
- Produced w/n
- Mitochondria in respiration reactions
- Reactions inv. Hydrogen peroxide can = hydroxyl radicals
- The breakdown of toxic chemicals and their products
- WBC and them destroying bacteria and virus infected cells
*. Causes CHD
- LDL’s undergo oxidation b/c of free radicals - released from endothelial cells
- Attracts macrophages and initiates atherosclerosis plaque formation
- Larger no.s of free radicals mean more LDL’s are oxidised

52
Q

Antioxidants

A
  • Helps reduce levels of free radicals
  • Sources inc. tea, red wine, fruit, veg, legumes
  • They neutralise free radicals
53
Q

Vitamin C

A
  • An antioxidant
  • Oxidised LDL is more readily taken up by the WBC involved in atherosclerosis
54
Q

DCPIP Experiment

A
  • DCPIP is a redox dye (blue when oxidised)
  • When reduced it turns clear (OIL RIG)
  • Vitamin C is ascorbic acid, reduces DCPIP to colourless slightly pink solution

Method:
1. Have 5 test tubes of the same volume of DCPIP→for validity→glass
2. Then use a pipette to place 1 drop of a substance into a test tube→to see if it goes clear→long contact w/ DCPIP = irritation // eyes
3. Keep adding one drop of the substance, till you can’t see the DCPIP, keeping record of how many drops→to see how many drops are necessary→glass // DCPIP
4. Once the DCPIP has disappeared, compare it to a calibration curve of DCPIP volume against vitamin C content→to know vitamin C content
5. Then repeat experiment w/ different substances→to compare
6. Repeat whole experiment and create an average→for reliability
* If its a solid to be tested
- Take a small section and put into a test tube to a depth of ~2cm
- Add a similar volume of distilled water and stir w/ a glass rod
- Leave for a few minutes, and then carry out normal experiment

55
Q

Effect of Heart Rate in Daphnia

A
  • Daphnia:
  • Transparent so can easily see the heart beating
  • Counting number of beats may be difficult b/c its quick and their legs
  • Freezing them beforehand slows down heart rate
  • Or count the rate of leg beats, which is proportional to HR
  • Control Group: recording HR of Daphnia in culture solution
  • Distilled water may increase HR as less O2
  • Blind study may be better so counters don’t assume or bias results
  • Problems
  • Human error
  • difficult to count HR
  • making caffeine solutions
  • counting for different lengths of time
  • Stress on Daphnia may increase HR
  • Ethical problems
  • Daphnia are living creatures and don’t deserve to be put under stress
  • Microscope lights may be hot, so burn Daphnia
  • Many Daphnia’s may die as a result of the experiment
  • Control variables
  • Temperature of the solution
  • Size/ age/ gender of the daphnia
  • Time spent counting Daphnia
56
Q

Effect of Heart Rate in Daphnia - Method

A
  1. Place a few strands of cotton wool on a cavity slide→restrict flea movement→glass
  2. Using a pipette transfer the Daphnia, and add pond water to the slide→for normal breathing rate→glass // water
    • Use as much water as possible, to keep O2 levels high
  3. Use a stopwatch and count the no. of heart beats in 10 seconds→to record heart rate
  4. Repeat procedure using other Daphnia, and create an average→for validity
  5. Repeat previous steps using different caffeine solutions→for reliability
  6. Record results in a suitable format and present them in an appropriate graph→for validity and reliability
57
Q

What are the habits that can increase risk of CVD?

A
  • Smoking
  • Caffeine
  • Cholesterol levels (esp. LDL cholesterol)
58
Q

What can reduce risk of CVD?

A
  • Scientific Knowledge of:
  • Diet
  • Obesity indicators
  • BMI
  • Waist-to-hip ratio
  • Exercise
  • Smoking
59
Q

Diuretics

A
  • Increase urine volume
  • Rids body of excess fluids and salts
  • Blood volume falls
  • Lower stroke volume
  • BP drops
60
Q

Beta Blockers

A
  • Blocks the response the heart gives to hormones, eg. adrenaline
  • Contractions less strong = lowered HR and BP
61
Q

Diuretics and Beta Blockers - Side Effects

A
  • General: prolonged BP = dizziness = falls/ injuries
  • Which can be life threatening in elderly
  • Specific: dry cough, abnormal heart rhythms, fatigue, swelling of ankles, constipation, impotence
  • They can mask benefits and lead to patients dropping treatment
62
Q

Diuretics and Beta Blockers - Benefits

A
  • They lower BP
  • Means ↓ risk of CVD, which inc. life threatening conditions (eg. heart attack)
63
Q

Statins

A
  • What it does:
  • Inhibits cholesterol synthesis in the liver
  • Increases LDL uptake
  • Improves the balance of HDL:LDL
  • Improves the lining of the endothelium
64
Q

Statins - Side Effects

A
  • Muscle pain, constipation, nausea and changes in attitude
65
Q

Anticoagulant and Platelet inhibitory drugs

A
  • Prevents blood clotting easily
  • Prescribed after surgery from thrombosis
  • Anticoagulants, eg. Warfarin
  • Interfered w/ manufacture of prothrombin
  • Platelet inhibitors, eg. Aspirin
  • Make platelets less sticky
  • Reduces blood clotting
66
Q

Anticoagulant and Platelet inhibitory drugs - Risks

A
  • Aspirin = irritates stomach lining, can cause bleeding
  • Careful monitoring of any drug is needed to prevent internal bleeding, eg. in the brain

A Level Biology (SNAB) (4 decks)

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