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32 Cards in this Set
- Front
- Back
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What is a risk factor? |
Something which increases the chance of a disease
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In which chamber of the heart is the highest pressure reached? |
The left ventricle |
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How does the structure of the left ventricle cause high pressure? |
It has the thickest walls, so contractions are stronger |
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Why does an antibody only detect one antigen? |
The antibody's variable region has a specific amino acid sequence which codes for the shape of the binding site. This binding site is only complementary to a certain antigen, allowing it to form an antigen-antibody complex. |
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Explain how vaccines protect people against disease (5 marks) |
1)Vaccines contain antigens 2)Antigens are on dead pathogens 3)Memory cells are made 4)Second exposure- memory cells recognise pathogen 5)Produce more antibodies, quicker 6)Antibodies destroy pathogens 7)Herd immunity-fewer people to pass on disease |
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What is the function of a chloroplast? |
It uses light for photosynthesis to produce carbohydrates |
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How does courtship increase the probability of successful mating? |
It attracts the same species It attracts a mate It indicates fertility May stimulate the release of gametes |
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How can substitution in DNA effect an enzyme? |
It alters the base sequence, coding for a different amino acid. This changes the primary structure, and consequently, the active site shape. This means the substrate is no longer complementary and can't bind. |
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How do proteins provide evolutionary information? |
The amino acid sequences which create the proteins can be analysed. The more similar they are, the more closely related the species are. |
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Why does comparing the base sequence of genes provide us with more information than comparing proteins? |
It looks at introns and exons. It's also more useful because each amino acid is coded for by more than one triplet-degenerate |
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Why is it important to take a large number of samples when looking at biodiversity? |
Produces a more reliable mean/average Reduces effect of extreme values Allows anomalies to be identified Represetative |
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What causes root pressure? |
Ions and salts being actively transported into the xylem, which reduces water potential. This means water moves in by osmosis |
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Explain how oxygen is loaded, unloaded and transported in the blood (6 marks) |
1)Haemoglobin has a high affinity for oxygen and forms oxyhaemoglobin. 2)Found in red blood cells (erythrocytes) 3)Loading takes place in lungs 4)At high partial pressure of oxygen 5)Unloads to respiring tissue 6)At low partial pressures of oxygen 7)Unloading linked to higher CO2 concentration |
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Why is diarrhoea a symptom for people who can't produce the lactase enzyme (lactose intolerant)? |
The lactose reduces water potential i the gut, so water moves in via osmosis. |
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Explain why emphysema reduces the efficiency of gas exchange in the lungs (4 marks) |
1)Alveoli break down 2)Smaller surface area 3)Less diffusion 4)Less elastin-reduced recoil 5)Not as much air removed 6)Reduced diffusion gradient |
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How are epithelial cells lining the small intestine adapted for the absorption of glucose? |
1)Microvili 2)Increases surface area 3)Many mitochondria 4)Produce ATP for active transport 5)Carrier proteins for active transport 6)Chanell/carrier proteins for facilitated diffusion 7)Membrane bound enzymes 8)Sodium+glucose co-transporter |
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How many milliseconds are in a second? |
1,000 |
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How many grams are in a milligram? |
1,000 |
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Why you would measure a drug used in units of time and mass of patients? |
Allows comparisons between different lengths of treatments and different masses of volunteers |
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How do pathogens cause disease? |
They kill cells and secrete toxins |
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Why is the lactase enzyme usually put in beads when milk is passed through? |
So the enzyme can be reused So the enzyme doesn't have to be removed It allows a continuous process |
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Why do the airways become narrower during an asthma attack? |
Muscle contracts and the lining is inflamed |
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Explain the principles of a TEM |
Electrons pass through the specimen. Denser parts absorb more electrons. So, denser parts appear darker Electrons have a short wavelength, so they give a high resolution |
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Explain the limitations of a TEM |
Can only be done in a vacuum, so no living specimens Specimens must be thin Artefacts can be present Only produces 3D images Complex staining process |
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Similarities between starch and cellulose |
Both are polysaccharides Both contain glucose Both have 1,4 glycosidic bonds Both have hydrogen bonds |
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How does starch differ from cellulose? |
Starch has alpha glucose Starch has a helical structure Starch also has 1,6 glycosidic bonds Doesn't have fibres Monomers are the same way up No hydrogen bonds between molecules |
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How are sieve cells adapted for mass transport? |
Few organelles and little cytoplasm means the tubes are hollow so flow is easier |
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How is virus DNA different to eukaryotic? |
The percentage of C to G and A to T are different. This means there are no base pairings Therefore it's single stranded |
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What are 5 ways in which courtship behaviour increases the probability of successful mating? |
It allows them to recognise the same species It stimulates gamete production Allows them to attract the opposite sex It indicates sexual maturity It can form a pair bond |
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Why is it important that the specimen viewed with a light microscope is thin? |
So light is allowed through and a few layers of cells can be seen |
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What does the golgi apparatus do? |
It modifies proteins, packages them into vesicles and then transports them to the cell's surface. |
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What is the function of the centromere? |
It holds 2 sister chromatids together It attaches the chromatids to the spindle fibre It allows the chromatids to separate |
