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Flashcards by jess.rach5, updated more than 1 year ago
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Created by jess.rach5
over 9 years ago
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| Question | Answer |
| HOW ARE PHOSPHOLIPIDS ARRANGED IN A MEMBRANE? | IN A BILAYER HYDROPHOBIC FATTY ACID TAILS ON INSIDE HYDROPHILIC AND POLAR PHOSPHATE HEAD ON INSIDE |
| HOW IS THE GOLGI BODY INVOLVED IN SECRETION OF PROTEINS? | IT MODIFIES THEM AND PACKAGES THEM INTO VESICLES. IT THEN TRANSPORTS IT TO THE CELL SURFACE |
| WHY DO AREAS OF THE HEART DIE DURING A MYOCARDIAL INFARCTION? | THERE IS REDUCED BLOOD FLOW TO THE CORONARY ARERIES NOT ENOUGH OXYGEN IS SUPPLIED RESPIRATION STOPS SO CELLS DIE |
| WHY IS PRESSURE IN THE VENTRICLE RELATED TO THE THICKNESS OF THE VENTRICLE WALL | THICKNESS INCREASES AS VENTRICLES CONTRACT CONTRACTION CAUSES THE PRESSURE INCREASE |
| HOW IS PRESSURE IN THE VENTRICLE RELATED TO BLOOD FLOW IN THE AORTA? | PRESSURE IN VENTRICLE INCREASES, HIGHER THAN AORTA VALVES OPEN AND SO BLOOD MOVES IN |
| Describe how bacteria are destroyed by phagocytes. | 1. (Phagocyte engulfs) to form vacuole / vesicle / phagosome; 2. Lysosome empties contents into vacuole / vesicle / phagosome; 3. (Releasing) enzymes that digest / hydrolyse bacteria; |
| Explain how fibrosis caused by tuberculosis could have produced the changes in FEV. | (Fibrosis causes / due to), 1. Development of scar tissue / scarring / connective tissue; 2. Loss of elasticity / elastic tissue / elastin in lungs; 3. Restricts inhalation; 4. Breathe out less / reduced FEV due to reduced lung elasticity / scar tissue does not recoil / is not elastic / lung tissue does not recoil; |
| People given whole-cell vaccines were more likely to develop harmful side effects than the people given the vaccines containing parts of the bacterial cells | (Whole-cell vaccine), 1. Heat(ing) supposed to kill bacteria; 2. Some might be alive / active/ viable; 3. (If so) bacteria could reproduce; 4. Bacterium makes or contains toxin; 5. Toxin might not be affected / all destroyed by heat; 6. Bacteria or toxins attacking / killing person’s cells; |
| ) People given whole-cell vaccines produced a greater range of antibodies against the bacterium than the people given the vaccines containing parts of the bacterial cells | 1. (Contains) many different / greater range of antigens; 2. Each antigen causes its own immune response / production of / has a specific (type of) antibody; |
| Infection by the cholera bacterium can cause acute diarrhoea. Explain how. | 1. Toxin (produced by bacterium) causes (chloride) ions to move into (lumen of) intestine; 2. Water potential (of intestine contents) falls / water moves by osmosis into intestine/out of cells; |
| In areas where there are repeated outbreaks of cholera, most people who become infected by cholera bacteria do not become ill. Suggest and explain one reason why. | 1. Have produced memory cells; 2. After previous infection/vaccination; OR 3. Different forms of cholera; 4. Some don't produce much/any toxins; OR 5. Few bacteria ingested; 6. Not enough toxin to produce symptoms; OR 7. Some people naturally resistant to bacterium; 8. Because of structure of cell membranes / amount of secretions eg bile/pancreatic juices; |
| Describe how you would test a sample of food for the presence of starch. | 1. Add iodine/potassium iodide solution to the food sample; 2. Blue/black/purple indicates starch is present; |
| Microfold cells take up the antigens and transport them to cells of the immune system. Antigens are not able to pass through the cell-surface membranes of other epithelial cells. Suggest two reasons why. | 1. Not lipid soluble; 2. Too large (to diffuse through the membrane); 3. Antigens do not have the complementary shape/cannot bind to receptor/channel/carrier proteins (in membranes of other epithelial cells); |
| Scientists believe that it may be possible to develop vaccines that make use of microfold cells. Explain how this sort of vaccine would lead to a person developing immunity to a pathogen. | 1. (Vaccine contains) antigen/attenuated/dead pathogen; 2. Microfold cells take up/bind and present/transport antigen (to immune system/lymphocytes/Tcells); 3. T-cells activate B-cells; 4. B-cells divide/form clone/undergo mitosis; 5. B-cells produce antibodies; 6. Memory cells produced; 7. More antibodies/antibodies produced faster in secondary response/on reinfection; |
| Describe how a heartbeat is initiated and coordinated. | 1. SAN sends wave of electrical activity / impulses (across atria) causing atrial contraction; 2. Non-conducting tissue prevents immediate contraction of ventricles/prevents impulses reaching the ventricles; 3. AVN delays (impulse) whilst blood leaves atria/ventricles fill; 4. (AVN) sends wave of electrical activity / impulses down Bundle of His; 5. Causing ventricles to contract from base up; |
| Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta. | 1. Atrium has higher pressure than ventricle (due to filling/contraction); 2. Atrioventricular valve opens; 3. Ventricle has higher pressure than atrium (due to filling/contraction); 4. Atrioventricular valve closes; 5. Ventricle has higher pressure than aorta; 6. Semilunar valve opens; 7. Higher pressure in aorta than ventricle (as heart relaxes); 8. Semilunar valve closes; 9. (Muscle/atrial/ventricular) contraction causes increase in pressure; |
| Describe how the gut wall is adapted to push food down the oesophagus | Muscle (in walls); Circular and longitudinal; Contraction of circular (muscle pushes food down oesophagus); |
| Describe how gut wall is adapted to neutralise the stomach acid in the duodenum | Glandular cells/glands; Secrete alkali (mucus); |
| Describe how the gut is adapted to absorb the products of digestion in the iluem. | Villi/microvilli; (Many) capillaries/lacteals; Single cell layer; Channel/carrier proteins; Mitochondria; Enzymes in membrane; Muscles (in villi); |
| Describe how solubility in lipid affects the rate of diffusion through a membrane. Explain your answer. | As lipid solubility increases the rate increases; (Membrane consists of (double layer) of lipid/phospholipids; |
| Describe how molecular size affects the rate of diffusion. Suggest an explanation for your answer | Small molecules diffuse faster; Higher kinetic energy / easier to pass through pores / between phospholipid molecules; |
| Name two factors which affect the rate of facilitated diffusion of a substance through a membrane | Concentration/diffusion gradient; Number of carriers/channel/proteins; Temperature; |
| Describe how you would use a biochemical test to show that a solution contained a non-reducing sugar, such as sucrose. | Test for reducing sugar / Benedictís test is negative; Boil/heat with acid and neutralise / use NaOH / use alkali; OR Use enzyme hydrolysis; |
| Order in which pellets were produced by ultracentrifugation 1 2 3 Chloroplasts 4 5 | 1 Cell walls 2 Nuclei 4 Mitochondria 5 Ribosomes; |
| Suggest why the rate of oxygen uptake was measured when the mammals were at rest. | Allows comparison (between different animals); (Rate of) respiration varies if animal is not at rest / animal moving; |
| Explain the role of phospholipids in the structure and functioning of cell membranes. | 1 Bipolar / hydrophobic and hydrophilic; 2 Forms bilayer; 3 Hydrophobic tail repelled by water / hydrophilic head attracted by water; 4 Allows movement of lipid soluble / non-polar molecules / water / gases / e.g. O2 and CO2 OR Prevents movement of water soluble/ polar molecules; 5 Allows membranes to fuse with other membranes / able to form vesicles / exocytosis and endocytosis; 6 Unsaturated fatty acids increase fluidity / flexibility / permeability; 7 Allows compartmentalisation / allows cells to maintain different concentrations of molecules on either side of the membrane; |
| Describe the processes involved in the digestion of triglycerides and the absorption of the products of this digestion in the small intestine. | 1 Bile emulsifies triglycerides / large droplets to smaller droplets; 2 Smaller droplets provide large surface area / faster digestion; 3 Lipase breaks down triglycerides; 4 Into fatty acids and glycerol / monoglycerides; 5 By hydrolysis; 6 Diffusion (facilitated diffusion and active transport neutral); 7 Recombination (in epithelial cells); 9 (Move into) lymph vessels; 10 Fatty acids / glycerol move into blood (capillaries); |
| Describe how a sample consisting only of chloroplasts could be obtained from homogenised plant tissue. | use of differential centrifugation; first/low-spin pellet discarded / spin at low speed to remove cell wall material/cell debris; supernatant re-spun at higher speed / until pellet with chloroplasts is found; method of identifying chloroplasts e.g. microscopy; |
| What's the function of the fatty acid tail in the phospholipid membrane? | Form impermeable barrier to water-soluble substances / selectively permeable / allows non-polar molecules to pass through; allows cell to maintain different concentrations either side; makes membranes self-sealing/able to fuse with other membranes/able to form vesicles / gives flexibility/fluidity; |
| Explain how the cells of the cortex and the epidermis support the stem. | cortex (cells) take up water by osmosis (from vascular tissue); become turgid; cells expand and press against each other/epidermis; idea of epidermis restricting/preventing expansion of stem section; physical/mechanical support of stem in terms of vertical support/prevent bending; |
| Explain how the structures of the stomach wall and the ileum wall are related to the functions of these organs. | stomach 1. extra muscle layers; churning action; 4. mucus to protect stomach wall/ acid/HCl to kill bacteria or optimal pH/ pepsinogen or pepsin for (protein) digestion; 8. villi; 9. microvilli on epithelial cells; 10. larger surface area for absorption; 11. single layer of cells / capillary/blood vessels close to surface; 12. short diffusion pathway; 13. (extensive) capillary network / large number of blood vessels 14. maintain diffusion gradient; 15. feature of transmembrane/carrier/transport/intrinsic protein / many mitochondria; 16. active uptake/facilitated diffusion; 18. carry away lipids/fats or equivalent; 20. secrete alkaline fluid which neutralises acid (suitable environment for intestinal enzyme 21. correct named enzyme + location e.g. maltase in membrane of epithelial cells; |
| Bile is made in the liver. Explain one function of bile. | emulsifies fats; increases surface area for lipase / faster rate of digestion by lipase; OR bile (is alkaline) neutralises acidic material / chyme from the stomach; provides optimum pH for (digestive) enzymes; |
| Explain how three features of a plasma membrane adapt it for its functions. | 1. phospholipid bilayer (as a barrier); 2. forms a barrier to water soluble / charged substances / allows non-polar substances to pass OR maintains a different environment on each side; 3. bilayer is fluid; 4. can bend to take up different shapes for phagocytosis / form vesicles; 5. channel proteins (through the bilayer)/intrinsic protein; 6. let water soluble/charged substances through / facilitated diffusion; 7. carrier proteins (through the bilayer); 8. allow facilitated diffusion / active transport; 9 surface proteins / extrinsic proteins, glycoproteins / glycolipids; 10 cell recognition / act as antigens / receptors; 11 cholesterol; 12 regulates fluidity / increases stability; |
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