Unit 3 part 2 Flashcards
Fish - Explain two ways in which the structure of fish gills is
- Many lamellae / filaments so large surface area;
- Thin (surface) so short diffusion pathway;
Absorption - how is the golgi apparatus involved in the absorption of lipids.(3)
- Modifies / processes triglycerides;
- Combines triglycerides with proteins;
- Packaged for release / exocytosis OR Forms vesicles;
Absorption – Explain how monosaccharides and amino acids are absorbed into the blood (5)
- Some by facilitated diffusion (when higher concentration in lumen)
- Sodium ions actively transported from ileum cell to blood;
- Maintains / forms diffusion / concentration gradient for sodium to enter cells from gut (and with it, glucose);
- sodium ions enter cell by facilitated diffusion and bring with it a molecule of glucose by co-transport;
- Facilitated diffusion of glucose into blood/capillary;
Haemoglobin - Binding of one molecule of oxygen to haemoglobin makes it easier for a second oxygen molecule to bind. Explain why. (2)
- Binding of first oxygen changes tertiary / quaternary (structure) of haemoglobin; Ignore ref. to ‘positive cooperativity’ unqualified Ignore ref. to named bonds Accept conformational shift caused
- Creates / leads to / uncovers second / another binding site
OR
Uncovers another iron / Fe / haem group to bind to;
Explain how changes in the shape of haemoglobin result in the S-shaped (sigmoid) oxyhaemoglobin dissociation curve (2)
- First oxygen binds (to Hb) causing change in shape;
- (Shape change of Hb) allows more O2 to bind (easily) / greater saturation with O2 OR Cooperative binding;
Haemoglobin - Haemoglobin is a protein with a quaternary structure. Explain the meaning of quaternary structure (1).
(Molecule contains) more than one polypeptide (chain)
Haemoglobin - Describe the advantage of the Bohr effect during intense exercise. (2)
- Increases dissociation of oxygen; Accept unloading/ release/reduced affinity for dissociation
- For aerobic respiration at the tissues/muscles/cells
OR
Anaerobic respiration delayed at the tissues/muscles/cells
OR
Less lactate at the tissues/muscles/cells;
Haemoglobin - Describe and explain the effect of increasing carbon dioxide concentration on the dissociation of oxyhaemoglobin. (2)
- Increases/more oxygen dissociation/unloading OR Deceases haemoglobin’s affinity for O2; Accept more readily Accept releases more O2
- (By) decreasing (blood) pH/increasing acidity;
Haemoglobin – Animals living at high altitudes shift to left (3)
- high altitudes have a low partial pressure of O2;
- high saturation/affinity of Hb with O2 (at low partial pressure O2);
- sufficient/enough O2 supplied to respiring cells / tissues;
Haemoglobin – why small animals have curved to the right (2)
- Mouse haemoglobin/Hb has a lower affinity for oxygen
OR
For the same pO2 the mouse haemoglobin/Hb is less saturated
OR
At oxygen concentrations found in tissue mouse haemoglobin/Hb is less saturated; For ‘Hb is less saturated’ accept ‘less oxygen will be bound to Hb’.
- More oxygen can be dissociated/released/unloaded (for metabolic reactions/respiration); Accept ‘oxygen dissociated/released/unloaded more readily/easily/quickly’
Haemoglobin – why curve to the right for more active animals (2)
- Curve to the right so lower affinity / % saturation (of haemoglobin);
- Haemoglobin unloads / dissociates more readily;
- More oxygen to cells / tissues / muscles;
- For greater / more / faster respiration;
Heart & circulation – dissection - three control measures the student must use to reduce the risks associated with carrying and using a scalpel.
- Carry with blade protected / in tray
- Cut away from body;
- Cut onto hard surface;
- Use sharp blade;
- Dispose of used scalpel (blade) as instructed;
Heart & circulation – dissection. Control measures when packing away (2)
- Carry/wash sharp instruments by holding handle OR Carry/wash sharp instruments by pointing away (from body)/down; Accept for ‘instruments’, a suitable named example, eg. scalpel
- Disinfect instruments/surfaces; Accept for ‘instruments’, a suitable named example, eg. scalpel Accept for ‘disinfect’, sanitise OR use antiseptic
- Disinfect hands OR Wash hands with soap (and water); Accept for ‘disinfect’, sanitise OR use antiseptic
- Put organ/gloves/paper towels in a (separate) bag/bin/tray to dispose;
Heart & circulation - Give the pathway a red blood cell takes when travelling in the human circulatory system from a kidney to the lungs. (3)
- Renal vein;
- Vena cava to right atrium;
- Right ventricle to pulmonary artery;
Heart & circulation - Name the blood vessels that carry blood to the heart muscle. (1)
Coronary arteries;
Heart & circulation - Calculate Cardiac Output (1)
Cardiac Output = Stroke Volume x Heart Rate
Heart & circulation – what causes the semi-lunar valve to close (1)
Because pressure in aorta higher than in ventricle;
Heart & circulation – explain how the atrioventricular valve is closed (2)
- ventricle contracts and volume decreases
- pressure (ventricle) increases so higher than pressure of left atrium;
Heart & circulation - Explain how an arteriole can reduce the blood flow into capillaries. (2)
- Muscle contracts;
- Constricts/narrows arteriole/lumen;
Heart & circulation - Artery – Structure and Function (5)
- Elastic tissue to allow stretching/recoil/ smooths out flow of blood/maintains pressure;
- (Elastic tissue) stretches when ventricles contract OR Recoils when ventricle relaxes;
- Muscle for contraction/vasoconstriction;
- Thick wall withstands pressure OR stop bursting;
- Smooth endothelium reduces friction;
Heart & circulation - Explain four ways in which the structure of the aorta is related to its function.
- Elastic tissue to allow stretching / recoil / smoothes out flow of blood / maintains pressure;
- (Elastic tissue) stretches when ventricles contract OR Recoils when ventricle relaxes;
- Muscle for contraction / vasoconstriction;
- Thick wall withstands pressure OR stop bursting;
- Smooth endothelium reduces friction;
- Aortic valve / semi-lunar valve prevents backflow.
Heart & circulation fish – describe type of circulation in fish (1)
- Single circulatory system
- chambers/1 ventricle1 atrium
- One vein carrying blood towards the heart/ One artery carrying blood away
Tissue fluid - Explain how water from tissue fluid is returned to the circulatory system.(4)
- (Plasma) proteins remain; Accept albumin/globulins/fibrinogen for (plasma) protein
- (Creates) water potential gradient
OR Reduces water potential (of blood);
- Water moves (to blood) by osmosis;
- Returns (to blood) by lymphatic system;
Tissue fluid - Explain the role of the heart in the formation of tissue fluid. (2)
- Contraction of ventricle(s) produces high blood / hydrostatic pressure;
- (This) forces water (and some dissolved substances) out (of blood capillaries);
Tissue fluid - High absorption of salt from the diet can result in a higher than normal concentration of salt in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid.
Explain how. (2)
- (Higher salt) results in lower water potential of tissue fluid;
- (So) less water returns to capillary by osmosis (at venule end); OR
- (Higher salt) results in higher blood pressure / volume;
- (So) more fluid pushed / forced out (at arteriole end) of capillary;
Tissue fluid - High blood pressure leads to an accumulation of tissue fluid. Explain how. (2)
- High blood pressure = high hydrostatic pressure;
- Increases outward pressure from (arterial) end of capillary / reduces inward pressure at (venule) end of capillary;
- (So) more tissue fluid formed / less tissue fluid is reabsorbed.
Tissue fluid - Formation and reabsorption (8)
- At arteriole end high hydrostatic pressure/blood pressure;
- Hydrostatic pressure higher than effect of osmosis;
- Small molecules/named example eg glucose; water
- Forces out;
- Proteins remain in blood/ not removed as they are too large to leave capillary;
- Increasing/giving higher concentration of blood proteins so proteins lower water potential of blood;
- Water/fluid moves back into blood;
- Water moves by osmosis
Water - Describe the cohesion-tension theory of water transport in the xylem. (5)
- Water lost from leaf because of transpiration / evaporation of water (molecules) / diffusion from mesophyll / leaf cells;
OR
Transpiration / evaporation / diffusion of water (molecules) through stomata / from leaves;
- Lowers water potential of mesophyll / leaf cells;
- Water pulled up xylem (creating tension);
- Water molecules cohere / ‘stick’ together by hydrogen bonds;
- (forming continuous) water column;
- Adhesion of water (molecules) to walls of xylem;
Water - T A potometer measures the rate of
water uptake rather than the rate of transpiration.
Give two reasons why the potometer does not truly measure the rate of transpiration.(2)
- Water used for support / turgidity; Accept: water used in (the cell’s) hydrolysis or condensation (reactions) for one mark. Allow a named example of these reactions
- Water used in photosynthesis;
- Water produced in respiration;
- Apparatus not sealed / ‘leaks’;
Water - Give two precautions the students should have taken when setting up the potometer to obtain reliable measurements of water uptake by the plant shoot. (2)
- Seal joints / ensure airtight / ensure watertight; Answer must refer to precautions when setting up the apparatus Ignore: references to keeping other factors constant
- Cut shoot under water;
- Cut shoot at a slant;
- Dry off leaves;
- Insert into apparatus under water;
- Ensure no air bubbles are present;
- Shut tap;
- Note where bubble is at start / move bubble to the start position;
Sucrose - Describe the transport of carbohydrate in plants. (5)
- (At source) sucrose is transported into the phloem/sieve element/tube;
- By active transport OR By co-transport with H+; Accept co-transport with hydrogen/H ions
- By companion/transfer cells;
- Lowers water potential in phloem and water enters by osmosis; Accept pressure gradient? For ‘phloem’ accept ‘sieve element/tube’.
- (Produces) high (hydrostatic) pressure;
- Mass flow;
- Transport from site of photosynthesis to respiring cells OR Transport from site of photosynthesis to storage organ OR Transport from storage organ to respiring cells;
Sucrose - Use your understanding of the mass flow hypothesis to explain how pressure is generated inside this
phloem tube.(3)
- Sucrose actively transported (into phloem);
- Lowering/reducing water potential OR More negative water potential;
- Water moves (into phloem) by osmosis (from xylem);
Sucrose - Phloem pressure is reduced during the hottest part of the day. Use your understanding of transpiration and mass flow to explain why.(3)
- High (rate of) transpiration/evaporation;
- Water lost through stomata OR (High) tension in xylem;
- (Causes) less water movement from xylem to phloem OR Insufficient water potential in phloem to draw water from xylem;
