This page contains the AQA AS Biology B7 Mass Transport Questions and kerboodle answers for revision and understanding.This page also contains the link to the notes and video for the revision of this topic.
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C7.1Haemoglobin AQA AS Biology B7 Mass Transport Kerboodle Answers: Page No. 162
1. 2 pairs or polypeptides (α and β) link to form a spherical molecule. Each polypeptide has a haem group that contains a ferrous (Fe2+) ion. 2 Different base sequences in DNA -different amino add sequences -different tertiary I quaternary structure and shape -different affinities for oxygen. 3 If all oxygen molecules were released, there would be none in reserve to supply tissues when they were more active. 4 Carbon monoxide will gradually occupy all the sites on haemoglobin instead of oxygen. No oxygen will be carried to tissues such as the brain. These will cease to respire and to function, making the person lose consciousness.7.2 Transport of oxygen by haemoglobin AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 166
1 a 5.5 kPa. b 90%. c 72% (97%-25%) 2 a The curve is shifted to the right b Haemoglobin has become less saturated 3 Exercising muscles release heat shifting the curve to the right and causing the haemoglobin to release more oxygen to fuel the muscular activity. 4 At this partia l pressure of oxygen, lugworm haemoglobin is 90% saturated, more than enough to supply sufficient oxygen to the tissues of a relatively inactive organism. Human haemoglobin, by contrast, is only 10% saturated -insufficient to supply enough oxygen to keep tissues alive. 5 Respiration produces carbon dioxide. This builds up in the burrow when the ride is out. ff lugworm haemoglobin exhibited the Bohr effect, it would not be able to absorb oxygen when it was present in only very low concentrations in the burrow. 6 The higher part of the beach is uncovered by the tide for a much longer period of rime than the lower part. During this longer period all the oxygen in the burrow would be used up and the lugworm might die before the next tide brings in a new supply of oxygen.7.3 Circulatory system of a mammal AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 169
1 a Pulmonary artery b Aorta c Renal vein d Pulmonary vein; e Aorta 2 Low surface area to volume ratio; a high metabolic rate. 3 It increases blood pressure and therefore the rate of blood flow 10 the 1issues.7.4 The structure of the heart AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 171
1 Coronary artery 2 a Deoxygenated. b Deoxygenated. c Oxygenated 3 Pulmonary vein left atrium left ventricle aorta vena cava right atrium right ventricle pulmonary artery 4 The mixing of oxygenated and deoxygenated blood would result in only partially oxygenated blood reaching the tissues and lungs. This would mean the supply of oxygen to the tissues would be inadequate and there would be a reduced diffusion gradient in the lungs, limiting the rate of oxygen uptake.7.5 The cardiac cycle AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 176
1 Left ventricle 2 a True b True c False d False 3 a Muscular wall of atrium b Diastole c Semi-lunar valve 4 Training builds up the muscles or the heart and so the stroke volume increases I more blood is pumped at each beat. This means that, if the cardiac output is the same, the heart rate I number of beats per minute decreases. 5 One complete cycle takes 0.8s. Therefore the number of cycles in a minute = 60 ~ 0.8 = 75. As there is l beat per cycle then there are 75 beats in a minute. 6 52/0.065 = 80 beats min-17.6 Blood vessels and their functions AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 182
1 a Elastic tissue allows recoil and hence maintains blood pressure I smooth blood flow I constant blood flow b Muscle can contract. constricting the lumen of the anerioles and therefore controlling the flow of blood into capillaries; c Valves prevent flow of blood back LO the tissues and so keep it moving towards the heart I keep blood at low pressure flowing in one direction d The wall is very thin, making the diffusion pathway short and exchange of material rapid. 2 a C. b B. c E. d D. e A 3 Hydrostatic pressure (due to pumping of the heart) 4 Via the capillaries and via the lymphatic system7.7 Transport of water in the xylem AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 185
1 Water leaves from the air spaces in a plant by a process called transpiration a. This takes place mainly through pores called stomatab in the epidermis of the leaf. Water evaporates into the air spaces from mesophyll cells. As a result these cells have a lower I reduced I more negativec water potential and so draw water by osmosis d from neighbouring cells. In this waY, a water potential gradient is set up that draws water from the xylem. Water is pulled up the xylem because water molecules stick together — a phenomenon called cohesion e. During the night the diameter of a tree trunk increasesf.7.8 Transport of organic substances in the phloem AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 190
Transport of sucrose in plants occurs in the tissue called phloem a, from places where it is produced, known as sourcesb, to places where it is used up or stored, called sinks c. One theory of how it is translocated is called the mass flow d theory. Initially the sucrose is transferred into sieve tubee elements by the process of co-transport f. The sucrose is produced by photosynthesizing/chloroplast containingg cells that therefore have alower/more negative h water potential due to this sucrose. Water therefore moves into them from the nearby xylem i tissue that has a higher/less negativej water potential. The opposite occurs in those cells (sinks) using up sucrose, and water therefore leaves them by the process of osmosisk.7.9 Investigating transport in plants AQA AS Biology B7 Mass Transport Kerboodle Answers : Page No. 192
1 a There would be a large swelling above the ring in summer but little, if any, swelling in winter. b ln summer the rate of photosynthesis, and therefore produaion of sugars, is greater due to higher temperature!>, longer daylight and higher light intensity. The translocation of these sugars leads to their accumulation, and therefore a swelling, above the ring. Ln winter lower temperatures, shorter daylight and lower light intensity mean the rate of photosynthesis is less and any swelling is therefore smaller. ln deciduous plants, the lack or leaves means there is no photosynthesis and therefore no swelling at all. 2. H the squirrel strips away the phloem around the whole circumference of the branch it may not have sul’ficient sugar for i1s respirarion to release enough energy for survival as none can reach it from other parts of the plant. 3 If the branch has sufficient leaves to supply its own sugar needs from photosynthesis, rather than depending on supplies from elsewhere, it might survive for a while a t least. 4 It is unlikely that squirrels would strip bark from around the whole circumference of a large tree trunk. Any intact phloem could still supply sufficient sugars to its roots to allow it to survive. 5 a It takes time for the sucrose from the leaves to be transported across the mesophyll of the leaf by diffusion and then to be actively transported into the phloem. b The sucrose in 1he phloem is diluted with the water that enters it from the xylem. A little sucrose may be converted to glucose and used up by the leaves during respiration but this alone would not be sufficient to explain the reduction in concentration in the phloem. Banner 2Practice questions: Chapter 7: Page No. 194-195
1 (a) High(er) affinity for oxygen / absorbs/loads more oxygen. At lower partial pressure (of oxygen) / lower pO2. (b) 1. (Hydrostatic) pressure lower in capillary/blood / higher in tissues/tissue fluid.- Water (returns).
- By osmosis.
- Water potential lower/more negative in blood/capillary / higher/less negative water potential in tissues / via water potential gradient.
- Due to protein (in blood).
- (Returns) via lymph (system/vessels).
- So contractions are stronger / harder;
- (Arteriole) narrows/constricts/reduces size of lumen/vessel / vasoconstriction.
- Less/no water removed (into capillary).
- By osmosis (into capillary).
- Transpiration highest around midday.
- Middle of day warmer / lighter.
- (Increased) tension / water potential gradient.
- Cohesion (between water molecules);
- (Aorta wall) stretches.
- Because ventricle/heart contracts / systole / pressure increases.
- (Aorta wall) recoils.
- Because ventricle relaxes / heart relaxes /diastole / pressure falls.
- Maintain smooth flow / pressure.
- High blood / hydrostatic pressure / pressure filtration.
- Forces water / fluid out.
- Large proteins remain in capillary.
- Low water potential in capillary / blood.
- Due to (plasma) proteins.
- Water enters capillary / blood.
- (By) osmosis.
- Correct reference to lymph.
- Casparian strip blocks apoplast pathway / only allows symplast pathway.
- Active transport by endodermis.
- (Of) ions/salts into xylem.
- Lower water potential in xylem / water enters xylem by osmosis /down a water potential gradient.
- Evaporation / transpiration (from leaves).
- (Creates) cohesion / tension / H-bonding between water molecules / negative pressure.
- Adhesion / water molecules bind to xylem.
- (Creates continuous) water column.