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AQA AS Biology Unit 1: Biology and Disease
Most of the facts that you need to know to get through AQA AS Biology: Unit 1 (Biology and Disease) is in this deck.
137
Biology
12th Grade
02/16/2014

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Term
After a period of training, the heart rate is often decreased when at rest although the cardiac output is unchanged. Suggest an explanation for this.
Definition
Training builds up the heart muscle, so stroke volume is increased
Term
Complete the equation: Cardiac output =
Definition
heart rate x stroke volume
Term
Complete the equation: Pulmonary ventilation=
Definition
Tidal volume x breathing rate
Term
Describe in stages how Vibrio Cholerae causes dehydration and diarrhea after chloride ion channels in the epithelial cells are opened.
Definition
• Chloride ions diffuse into the lumen

• Water potential in epithelial cells increases

• Water moves by osmosis from the epithelial cells to the lumen, causing watery diarrhoea

• Ions diffuse from surrounding tissues into epithelial cells

• Water moves by osmosis from surrounding tissues into epithelial cells, causing dehydration.
Term
Describe the method of cell fractionation.
Definition
Cell membrane is destroyed; contents emptied into a test tube; a centrifuge separates organelles based on size and density
Term
Describe the seven main steps of carbohydrate digestion.
Definition
1. Food is broken down by chewing

2. Salivary amylase is mixed with food

3. Amylase hydrolyses starch to maltose - mineral salts in saliva maintain neutral pH

4. Food moves down oesophagus by peristalsis to stomach - acid denatures amylase

5. Food moves to small intestine and is mixed with pancreatic juice - hydrolysing remaining starch

6. Alkaline salts produced by intestinal wall and pancreas maintain neutral pH

7. Food pushes along small intestine - epithelial wall produces maltase, sucrase and lactase.
Term
Describe the structure of the Vibrio Cholerae bacterium.
Definition
Comma-shaped; has a single polar flagellum; some forms have a protective capsule
Term
Give four limitations of the SEM (scanning electron microscope).
Definition
Living specimens cannot be observed in a vacuum.

A complex staining process is required.

The sample may be contaminated by artefacts.

It has a lower resolving power than the TEM.
Term
Give four limitations of the TEM (transmission electron microscope).
Definition
Living specimens cannot be observed in a vacuum.

A complex staining process is required.

The specimen must be extremely thin.

The sample may be contaminated by artefacts.
Term
Give four risk factors, other than smoking, which are associated with emphysema.
Definition
Air pollution, chemicals, poisonous gases, asthma
Term
Give four steps to show what happens when we exhale.
Definition
1. Diaphragm muscles relax and diaphragm pulls back up

2. External intercostal muscles relax and ribs move back down due to gravity

3. Volume inside thorax decreases, so pressure increases

4. Air moves down a concentration gradient out of the lungs until equilibrium.
Term
Give four steps to show what happens when we inhale.
Definition
1. Diaphragm muscles contract and diaphragm flattens

2. External intercostal muscles contract, pulling ribcage up and out

3. Volume inside chest cavity (thorax) increases, so pressure decreases

4. Air moves down a pressure gradient into the lungs
Term
Give as many risk factors as possible associated with coronary heart disease.
Definition
Diet - excess of saturated fats, cholesterol, salt; smoking; high blood pressure; high blood cholesterol level; obesity; lack of physical activity; alcohol
Term
Give three biological functions of lipids.
Definition
Any three of:
-energy storage
-cell membranes
-capturing light energy
-hormones and vitamins
-thermal insulation
-electrical insulation around nerves
-repels water from surfaces of skin, fur and feathers.
Term
Give three ways in which exercise can reduce the risk of CHD.
Definition
Prevents obesity; lowers blood pressure; increases fitness, building up heart muscles
Term
Give two advantages of oxygenated and deoxygenated blood being completely separate.
Definition
1. Blood reaching body tissue is maximally oxygenated
2. Blood at the gas exchange surface is maximally deoxygenated, maintaining a concentration gradient for gas exchange
Term
Give two reasons why it is difficult to eradicate TB by vaccination.
Definition
Antigenic variability; many vaccinated people destroy the bacterium before memory cells are produced.
Term
How are phagocytes attracted to a site of infection?
Definition
Pathogens release chemoattractants
Term
How do oral rehydration solutions work?
Definition
They contain water, glucose and ions; glucose and ions are absorbed by diffusion from the intestine to the epithelial cells, creating a water potential gradient by which water can be absorbed by osmosis
Term
How does emphysema reduce the efficiency of gas exchange?
Definition
Destroys alveolar walls
Term
How does fibrosis result in scar tissue?
Definition
Macrophages may accumulate in connective tissue between alveoli - eventually forming hard lumps
Term
How does inflammation occur?
Definition
Damaged cells release histamine - causes an increase in blood flow of the capillaries - platelets cause swelling and redness
Term
How does the immune system detect invading pathogens?
Definition
Invaded cell or phagocyte presents antigens of pathogens; these are recognized by the T-helper cells which receptor proteins complementary to the antigen
Term
In cell fractionation what are the three key conditions of the solution containing the sample and why?
Definition
Cold to reduce enzyme activity which could break down the organelles; isotonic to prevent organelles from bursting by osmosis; and buffered to maintain a constant pH, to prevent enzymes from denaturing.
Term
In practice, the theoretical resolving power of an electron microscope cannot always be achieved. Why not?
Definition
Due to human errors in the preparation of the sample
Term
In the cardiac cycle, what is the diastole?
Definition
The period during which the atria and ventricles are relaxed
Term
In what two ways can pathogens cause disease?
Definition
Damaging the host; producing toxins
Term
Name and describe a test for lipids and give the positive result.
Definition
Emulsion test; add sample to ethanol and shake; remove top layer and add remaining solution to water; positive result is a cloudy-white emulsion
Term
Name and describe a test for non-reducing sugars and give the positive result.
Definition
Negative result for Benedict's test; add hydrochloric acid and sodium hydrogencarbonate; repeat Benedict's test; positive result is a brick-red solution
Term
Name and describe a test for peptide bonds and give the positive result.
Definition
Biuret test; add equal volumes of sodium hydroxide and copper sulfate to the solution; positive result is a mauve-purple solution
Term
Name and describe a test for reducing sugars and give the positive result.
Definition
Benedict's test; heat sample with Benedict's reagent; positive result is a brick red solution.
Term
Name four natural defences of the body to pathogens.
Definition
Mucus layer; enzymes that break down pathogens; stomach acid; white blood cells
Term
Name four ways pathogens can enter the host body.
Definition
Cuts, bites; sexual transmission; gas exchange system; digestive system
Term
Name the two types of proteins used in facilitated diffusion.
Definition
Channel proteins and carrier proteins
Term
Name three things that happen during an asthma attack.
Definition
Muscle around bronchi contracts;
Mast cells release histamine, causing inflammation of the airways;
Extra mucus is produced.
Term
Name two types of phagocytes.
Definition
Macrophages and neutrophils
Term
Name two ways in which bacteria can resist phagocytosis.
Definition
producing chemicals which prevent WBCs from being attracted to the site
waxy cell wall makes digestion harder
Term
Simple diffusion across the plasma membrane is dependent on what two main properties?
Definition
Size and lipid solubility
Term
Suggest a reason why males are more likely to get CHD than females (other factors controlled).
Definition
Oestrogen can protect against CHD
Term
Suggest three ways in which drinking water can become contaminated by Vibrio Cholerae.
Definition
· Drinking water is not properly purified
· Untreated sewage leaks into water systems

Organisms e.g. shellfish feed on untreated sewage
Term
Suggest three ways in which high blood pressure increases the risk of heart disease.
Definition
Greater chance of an aneurysm; heart must work harder so is more prone to failure; artery walls may thicken, restricting blood flow
Term
The nucleus has an inner and outer membrane. What is this double membrane called?
Definition
Nuclear envelope
Term
What are atheroma?
Definition
Fatty deposits in the coronary arteries
Term
What are endotoxins?
Definition
Toxins which are only released when the cell dies and the cell wall disintegrates.
Term
What are exotoxins?
Definition
Toxins which are released from a bacterium as it grows.
Term
What are interferons?
Definition
Proteins produced by virus-infected cells which trigger the production of an inhibitor of the virus' mRNA, preventing it from replicating
Term
What are lipoproteins?
Definition
Complex associations of lipids, proteins and cholesterol
Term
What are the three stages of the cardiac cycle?
Definition
Atrial systole, ventricular systole, diastole
Term
What are the two pathogens that cause TB?
Definition
Mycobacterium tuberculosis and Mycobacterium bovis
Term
What can cause a polypeptide to coil and form an alpha helix?
Definition
Hydrogen bonds between N-H and C=O groups.
Term
What causes a blood clot to form at the site of a plaque?
Definition
Endothelium breaks down, blood platelets stick to the damaged site and a blood clot forms
Term
What causes atheroma to arise in the coronary arteries?
Definition
Damage to endothelium attracts white blood cells which absorb cholesterol-containing LDLs.
Term
What collective name is given to diseases such as emphysema? Name another example of this type of disease.
Definition
Chronic Obstructive Pulmonary Diseases (COPDs); chronic bronchitis
Term
What distinguishes a phospholipid from a triglyceride?
Definition
A phosphate-containing compound in the place of a fatty acid.
Term
What distinguishes high-density lipoproteins from low-density lipoproteins?
Definition
HDLs have a higher proportion of protein
Term
What does Vibrio Cholerae do upon infection?
Definition
Surviving bacteria which reach the intestines produce a toxic protein which binds to chloride ion channels of epithelial cells, causing them to open
Term
What force causes organelles to separate in ultracentrifugation?
Definition
Centrifugal force
Term
What four properties of exchange surfaces make them easily colonised by pathogens?
Definition
Thin; moist and sticky; good blood supply; large surface area
Term
What four roles do activated T-cells have?
Definition
Stimulating phagocytosis

Stimulating division of B cells by mitosis

Killing infected cells, either by producing perforin or by specializing to cytotoxic T-cells

Developing into memory cells for future infection
Term
What four things must a microorganism do to be considered a pathogen?
Definition
gain entry to the host
colonise the tissue of the host
resist the defences of the host
cause damage to the host tissues
Term
What four types of bonds hold a protein's tertiary structure in place?
Definition
Disulfide bridges, hydrophobic interactions, van der Waals forces and ionic bonds.
Term
What happens after a T-helper cell binds to an antigen-presenting cell?
Definition
The T-helper cell is activated and divides rapidly by mitosis.
Term
What happens after the formation of a phagosome?
Definition
Phagosome fuses with a lysosome to form a phagolysosome which contains enzymes and toxic chemicals which digest the pathogen
Term
What happens during the diastole?
Definition
Blood enters the left atrium from the pulmonary vein and right atrium from the vena cava; pressure in atria increases; atrioventricular valve opens; blood flows from atria to ventricles
Term
What is a catabolic reaction?
Definition
A reaction which breaks larger molecules into smaller ones.
Term
What is a risk factor?
Definition
A measure of the probability that damage to health will occur as a result of the hazard
Term
What is an anabolic reaction?
Definition
A reaction which links smaller molecules into larger ones.
Term
What is an aneurysm?
Definition
When the artery is weakened by damage to the artery wall and swells up due to blood pressure
Term
What is an antigen?
Definition
A substance, usually a protein, that is recognized as foreign by the immune system and therefore stimulates an immune
Term
What is an infection?
Definition
When a pathogen gains entry into a host and colonises a tissue.
Term
What is atherosclerosis?
Definition
The narrowing of the arteries due to atheroma
Term
What is excretion?
Definition
Removing toxins from the body
Term
What is formed when the cell membrane of a phagocyte fuses around a bacterium?
Definition
Phagosome
Term
What is it called when the artery is weakened by damage to the artery wall and swells up due to blood pressure?
Definition
Aneurysm
Term
What is myocardial infarction?
Definition
The medical term for a heart attack
Term
What is perforin and how does it kill infected cells?
Definition
A protein released by T-cells which perforates the plasma membrane, causing it to become freely permeable to all substances, so that the cell dies.
Term
What is plaque in the arteries?
Definition
The rough surface of atheroma
Term
What is the endothelium of an artery?
Definition
The layer of cells lining the inside of the artery
Term
What is the first step in humoral immunity?
Definition
The surface antigens of the invading pathogen are taken up by B cells
Term
What is the function of glycoproteins?
Definition
They enable the cell to be recognised by other cells and proteins
Term
What is the function of the Golgi apparatus?
Definition
Processes and packages proteins
Term
What is the function of the rough endoplasmic reticulum (RER)?
Definition
Protein synthesis
Term
What is the main difference between bronchitis and emphysema?
Definition
Bronchitis affects the bronchi, emphysema affects the alveoli
Term
What is the medical term for the death of heart muscle tissue which results in a heart attack?
Definition
Myocardial infarction
Term
What is the name of fatty deposits in the arteries?
Definition
Atheroma
Term
What is the name of the blood vessels that supply the heart muscle with oxygenated blood?
Definition
Coronary artery
Term
What is the name of the condition where a blood clot forms in an artery?
Definition
Thrombosis
Term
What is the name of the covalent bonds in polysaccharides?
Definition
Glycosidic bonds
Term
What is the name of the covalent bonds in triglycerides?
Definition
Ester bonds
Term
Suggest two organelles you would expect to find in abundance in a cell that produces a lot of protein.
Definition
Ribosomes, rough endoplasmic reticulum
Term
What is the name of the fibres through which electrical impulses travel from the bundle of His to the heart muscles, causing the ventricular systole?
Definition
Purkinje fibres
Term
What is the name of the group of cells in the centre of the heart which receives electrical impulses from the SAN?
Definition
Atrioventricular node (AVN)
Term
What is the name of the group of cells which transmit electrical impulses that cause heart muscle to contract?
Definition
Sinoatrial node (SAN)
Term
What is the name of the instrument used to separate organelles in cell fractionation?
Definition
Ultracentrifuge
Term
What is the name of the layer of cells lining the inside of an artery?
Definition
Endothelium
Term
What is the name of the muscle fibre through which electrical impulses travel from the AVN to the bottom of the ventricles?
Definition
Bundle of His
Term
What is the name of the process by which cells are broken down in fractionation? What instrument is used to do it? What is the name of the resulting fluid?
Definition
Homogenation; homogeniser; homogenate
Term
What is the name of the process by which food moves down the oesophagus, and how does it work?
Definition
Peristalsis - a series of muscular contractions push the food down the oesophagus
Term
What is the name of the property of the heart that allows it to beat independently of the nervous system?
Definition
Myogenic
Term
What is the name of the rough surface of atheroma?
Definition
Plaque
Term
What is the principal risk factor associated with emphysema?
Definition
Smoking (90% of cases)
Term
What is the purpose of connective tissue between the atria and ventricles?
Definition
Insulates the ventricles from the electrical signal from the SAN, preventing them from contracting from the top
Term
What is the purpose of inflammation?
Definition
Helps to prevent more pathogens from entering a wound and can destroy pathogens and reduce damage
Term
What is the purpose of the atrial systole?
Definition
To squeeze remaining blood from atria to ventricles once pressure equilibrium is reached
Term
What is the purpose of the atrioventricular valves?
Definition
Prevent backflow of blood from ventricles to atria
Term
What is the purpose of the semi-lunar valves?
Definition
Prevent backflow of blood from arteries to ventricles
Term
What is the purpose of the ventricular systole?
Definition
Pressure in ventricles increases; semi-lunar valves open and blood travels from right ventricle to pulmonary artery and from left ventricle to aorta
Term
What is the purpose of ventilation?
Definition
To maintain a concentration gradient of oxygen and carbon dioxide between the alveoli and capillaries.
Term
What is the region enclosed by the inner membrane of mitochondria called?
Definition
(Mitochondrial) matrix
Term
What is the role of antibodies in immunity?
Definition
They bind to the complementary antigens of invading pathogens and cause them to clump together so that they can be ingested by phagocytosis.
Term
What is the role of memory cells in immunity?
Definition
Storing the shape of the antigens of pathogens for future infection by the same pathogen
Term
What is the role of plasma cells in immunity?
Definition
Producing antibodies complementary to the antigens of invading pathogens
Term
What is the role of the smooth endoplasmic reticulum (SER)?
Definition
Chemical modification of molecules
Term
What is the study of the incidence of disease called?
Definition
Epidemiology
Term
What is the term for the narrowing of the arteries due to atheroma?
Definition
Atherosclerosis
Term
What is the typical resolution of a light microscope?
Definition
200nm
Term
What is the typical resolution of an electron microscope?
Definition
0.5nm
Term
What is thrombosis?
Definition
A condition where a blood clot forms in an artery
Term
What molecules react to form a triglyceride?
Definition
Three fatty acids and a glycerol.
Term
What substance acts as an inflammatory mediator?
Definition
Histamine
Term
What things can cause damage to the endothelium of coronary arteries?
Definition
Uneven blood flow, high blood pressure, viral infection or chemical pollutants in the blood
Term
What two types of cell do B cells differentiate into?
Definition
Plasma cells and memory cells
Term
What type of nerves cause heart rate to decrease?
Definition
Parasympathetic nerves
Term
What type of nerves cause heart rate to increase?
Definition
Sympathetic nerves
Term
When a person starts to breathe out, the percentage of oxygen in the air first exhaled is the same as the percentage of oxygen in the atmospheric air. Explain why.
Definition
This air is from the nose/trachea/bronchi; gas exchange occurs only in the alveoli.
Term
Where do B lymphocytes develop?
Definition
Bone marrow
Term
Where do T lymphocytes develop?
Definition
Thymus gland
Term
Which of the four chambers of the heart produces the greatest blood pressure?
Definition
Left ventricle
Term
Which side of the heart contains oxygenated blood?
Definition
Left
Term
Why can living specimens not be observed under an electron microscope?
Definition
The sample must be in a vacuum.
Term
Why do electron microscopes have a greater resolving power than light microscopes?
Definition
The beam of electrons has a smaller wavelength than light.
Term
Why do glandular cells in the salivary glands, for example, have a lot of endoplasmic reticulum?
Definition
They secrete digestive enzymes so carry out a lot of protein synthesis.
Term
Why do people suffering from TB cough up blood and mucus?
Definition
TB pathogen multiplies, creating cavities in the lung tissue - parts of lung collapse, allowing fluids to enter the lungs.
Term
Why do phospholipid bilayers form in water?
Definition
Phospholipids have a hydrophilic head and a hydrophobic tail.
Term
Why do unsaturated fats have a lower boiling point than saturated fats?
Definition
"Kinks" at sites of C=C double bonds prevent molecules from packing closely together.
Term
Why is the wall of the left ventricle thicker than the wall of the right ventricle?
Definition
The same volume of blood must be pumped over a much greater distance (the systemic circuit rather than the pulmonary circuit)
Term
Why must electron micrographs be produced in a vacuum?
Definition
Electrons can be absorbed by air and would not reach the sample
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