C7: systems Flashcards

Question

exam q: suggest lifestyle changes for patient with gall bladder removed.

Answer 1

gallbladder removed= no bile= no emulsification= can't breakdown fat= reduce fat in food/ take supplement

Answer 2

Palisade cells, stomata, xylem, phloem

Answer 3

- circulatory system - heart, vein, arteries, capillaries

Answer 4

- e.g. worms - do not have pipeway - humans (closed system): specialised cells e.g. heart pushes fluid into pipes to destination - worms: no specialised cells (cuz they're small) heart circulate fluid - blood just moves through the system

Answer 5

Pumps blood through blood vessels

Answer 6

veins- carries blood towards the heart (low pressure) arteries- thicker, more carries blood away from the heart capillaries- link arteries and veins and allow gas exchange, thin size (around a cell thickness) to get diffusion occuring

Answer 7

- plasma: liquid part of blood (includes minerals and dissolved liquids). The main role of plasma is to take nutrients, hormones, and proteins to the parts of the body that need it. - white blood cells: fight disease - red blood cells: carry oxygen and carbon dioxide - platelets: assist in blood clotting

Answer 8

Vein: low pressure Arteries: high pressure The blood pressure drops after the blood passes through the capillaries, reducing the resistance to allow blood flow at a lower pressure, veins have a lower blood pressure. Hence, arterial blood pressure is higher than venous blood pressure.

Answer 9

Vein: thin Artery: thick and muscular Since the blood pumped from the heart into the arteries flows at higher pressure than the blood in veins, hence arteries need to have thicker walls or else the high blood pressure might cause them to burst.

Answer 10

Between ribs

Answer 11

- Veins contain valves to ensure that the blood flows in only one direction, toward the heart. - Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction. - Sometimes muscle contractions may cause blood to be pushed back to body

Answer 12

4. Left atrium Left ventricle Right atrium Right ventricle

Answer 13

- The left side (arterial system) pumps blood to the body tissues and the right side (venous system) pumps blood to the lungs. - Deoxygenated blood travels to the right side of the heart via the vena cava. - The heart pumps the deoxygenated blood to the lungs where it releases carbon dioxide and receives oxygen. - The oxygenated blood travels via the pulmonary vein back to the heart from where it is pumped to all parts of the body. -

Answer 14

Veins: relies on muscle contractions to move the blood out Arteries: moves blood under high pressure from the heart

Answer 15

Left: pumps blood around the body so that nutrients can be distributed and wastes picked up Right: pumps blood to the lungs so it can pick up oxygen so it can pick up O2 and get rid of Co2.

Answer 16

= lungs Vein: carries oxygenated blood away from lungs Artery: carries deoxygenated blood to lungs

Answer 17

Inferior vena cava

Answer 18

Superior vena cava

Answer 19

- deoxygenated blood is pumped into the right atrium of the heart via the superior vena cava - it then enters the right ventricle - deoxygenated blood is then pumped to the lungs via the pulmonary artery to get oxygen - oxygenated blood is then pumped back into the left atrium of the heart via the pulmonary veine - it then enters the left ventricle - heart pumps out oxygenated blood through the aorta and then arteries to different parts of the body - they branch into arterioles upon reaching destination and then into smaller capillaries, where the speed of flow slows down

Answer 20

- They have specialised exchange surfaces (e.g. intestines, kidneys, lungs) - Due to their high complication, simple diffusion is too far away from the surface

Answer 21

They can get substances into the internal environment from external in an efficient manner.

Answer 22

Internal: exchange of gases with the internal environment in tissues External: exchange of gases with the external environment, occurring in the alveoli

Answer 23

- The pulmonary artery carries deoxygenated blood into the lungs from the heart, where it branches and eventually becomes the capillary network composed of pulmonary capillaries. - These pulmonary capillaries create the respiratory membrane with the alveoli. - As the blood is pumped through this capillary network, gas exchange occurs. - Although a small amount of oxygen is able to dissolve directly into plasma from the alveoli, most of the oxygen is picked up by red blood cells and binds to a protein called hemoglobin. - Oxygenated hemoglobin is red, causing the overall appearance of bright red oxygenated blood, which returns to the heart through the pulmonary veins. - Carbon dioxide is released in the opposite direction of oxygen, from the blood to the alveoli.

Answer 24

- Internal respiration is gas exchange that occurs at the level of body tissues - occurs as simple diffusion due to a partial pressure gradient like external respiration.

Answer 25

Holes (pores) on insects that allows diffusion

Answer 26

Inhaled: 0.04% Co2, 20% o2 Exhaled: 4% Co2, 16% o2

Answer 27

Inspiration and expiration.

Answer 28

Diffusion across semi-permeable membrane in the lungs.

Answer 29

The warmer it is, the easier it is to cross SPM.

Answer 30

Relating to the kidneys

Answer 31

- Aorta passes deoxygenated blood through the renal artery into the kidneys to be osmoregulated - Water exits kidneys - Osmoregulated blood exits the kidneys via the renal vein into the inferior vena cava

Answer 32

Some come directly from the heart and some already went to other body parts

Answer 33

- Birds convert urine to uric acid instead, excretted as a white paste through the cloaca - A cloaca is used to eliminate urine, feces, and reproductive fluids in birds, reptiles, amphibians, and a few branches of the mammal family tree.

Answer 34

1. RBC, WBC, platelets -> none excreted 2. H2O-> some excess excreted 3. Glucose-> none excreted 4. Na+, Cl- -> some excess excreted 5. O2, Co2-> not excreted through kidney pathway 6. Blood proteins-> none excreted 7. Urea-> all excreted

Answer 35

1. Produce bile 2. Breakdown RBC, hormones, drugs, cholesterole 3. Deaminate excess protein to urea 4. Store glycogen (convert from glucose) 5. Make blood proteins

Answer 36

- The respiratory centre in hindbrain receives nervous impulses from higher centres in forebrain - Hindbrain receptor centre has receptors that are sensitive to e.g. Co2, when there is excess Co2, signal will be sent to muscles to exhale - Nerves connect respiratory centre in hindbrain to intercostal muscles, as well as phrenic nerve to diaphragm - Phrenic nerve sends signals that cause the diaphragm to contract (become thicker and flatter), giving the lungs room to expand and take in air (inhalation

Answer 37

- pattern of growth of tracheoles can be modified according to needs of the tissues - if a body segment is deprived of oxygen by cutting its main trachea, the tracheoles of neighbouring segments respond by growing towards the deprived segment

Answer 38

Air enters the insect's body through the spiracle and enters the trachea. From the trachea the air moves to the small tracheoles. The tracheoles end within the body cells. Gases move by diffusion within the tracheal system

Answer 39

Unconscious actions

Answer 40

- nerve signals notify it to contract - contracts and becomes flatter - makes space in cavity (not lungs)

Answer 41

Efferent nerves pass from the respiratory centre in hindbrain to muscles responsible for inspiration (intercostal muscles and diaphragm)

Answer 42

Signal to the respiratory centre the degree of expansion of the lungs. When the lung volume increases, it results in an inhibition of further inspiratory activity

Answer 43

- Rhythmic discharge of impulses from the respiratory centre initiates inspiration - range of expansion of the pharynx limits its extent

Answer 44

Nerve centers in the thoracic and abdominal g

Answer 45

- The respiratory centre is influenced by impulses from various receptors which can alter the normal pattern of breathing. - e.g. stimulation of receptors sensitive to an increased level of Co2 in the blood will raise the ventilation rate - e.g. irritation of nose and throat will initiate sneezing and coughing - e.g. breathing is temporailu inhibited during swallowing reflex - Also under influence of higher centres in the brain, allowing voluntary changes in breathing

Answer 46

The protective fluid-filled sac around the heart

Answer 47

The walls of the left ventricle are thicker and more muscular than those of the right ventricle. The difference affects shape of the ventricular cavities, so right ventricle is twisted over the right.

Answer 48

Provides air to the alveoli for this gas exchange process.

Answer 49

At the respiratory membrane, where the alveoli and capillary walls meet, gases move across the membranes, with oxygen entering the bloodstream and Co2 exiting. - blood is oxygenated and Co2 removed from body in this process

Answer 50

The exchange surface has a large surface area, provided by a large number of alveoli, the surface is only one cell thick, and it is supplied with blood by a very dense capillary network.

Answer 51

- Located at the very end of the bronchioles, air is passed through the bronchiole to the alveoli - Capillaries wrap around the alveoli to conduct gas exchange via diffusion

Answer 52

- Air containing a higher concentration of O2 is drawn into the alveoli - In the alveoli, oxygen diffuses through the semi-permeable membrane(1 cell layer of alveoli and 1 cell layer of capillary) into the bloodstream, driven by the concentration gradient (O2 moves from area of higher conc in alveoli to an area of lower conc in blood) - Co2 is released from the blood to the alveoli - the original blood (from pulmonary artery from right side of heart from body tissues via veins) is then transformed into oxygen rich blood - O2 rich blood then transported to body parts via pulmonary capillary, to pulmonary vein, to left side of heart, then to body tissues via arteries

Answer 53

Alveoli: - 1 cell thick (thin) - round structure increases SA making it more efficient - moist for gases to dissolve - warm Capillary: - 1 cell thick (thin)

Answer 54

- External: Exchange of gases with external environment that occurs at the alveoli of the lungs - Internal: exchange of gases with the internal environment that occurs in the tissues

Answer 55

- small amount is able to dissolve directly into plasma from the alveoli - most picked up by RBC and binds to a protein called hemoglobin

Answer 56

- concentration gradient occurs as there is a higher conc of o2 in bloodstream than in tissue cells - causing co2 to diffuse out of the cell and o2 to diffuse into the cell

Answer 57

1.5% transported directly in the bloodstream, 98.5% bound to hemoglibin and is carried to the tissues.

Answer 58

The properties of water (denser and more viscous than air, and the oxygen in it is less concentrated and diffuses more slowly) compared to simply air means that fishes require a special type of respiratory organ and ventilation mechanism.

Answer 59

- Water drawn into the pharynx either through its mouth or thru its spiracle. - Water flow into where gills are located and diffusion of oxygen occur (from higher concentration water to lower concentration capillaries in gills) - Gills are built as strands to have a large SA:V area to maximize diffusion - branchial valve in each gill ensure direction of water movement - afferent branchial artery located close to gill arch brings deoxygenated blood to the lamellae (thin, sheet-like structure in the gills where oxygen diffuse through to enter the blood - efferent branchial arteries carry blood away from the lamellae to the dorsal aorta

Answer 60

Best for blood and water to flow in opposite directions- counterflow system.

Answer 61

- Insects - Spiracles on either side of the thorax and abdomen open into a system of tracheal tubes. - The spiracles are guarded by valves or hairs to prevent excessive evaporation through them - kept permanently open by chitin - Spiracles and trachea permit the passage of air to a further system of tubes, the tracheoles. - that is extremely numerous and extend deep into all of the tissues, especially muscles

Answer 62

answers in photos

Answer 63

The removal from the body of the toxic waste products of metabolism The term is specifically taken to mean nitrogenous waste such as urea and ammonia - Other materials like Co2 and bile pigments are also waste products of metabolism

Answer 64

The process by which the osmotic pressure of the blood and tissue fluids is kept constant. - also with respect to concentration of the various solutes normally present in the body fluids (glucose, salts and the like)

Answer 65

In the kidneys

Answer 66

It produces a liquid called urine,

Answer 67

To purify the blood which flows through it, extracting and eliminating harmful substances and ensuring that it has the correct composition.

Answer 68

Filtration, reabsorption. The fluid components of the blood are filtered from the glomerulus into the capsular space. As the result fluid flows along the tubules, useful substances are reabsorbed bac into the bloodstream while unwanted substances flow on to the ureter as urine.

Answer 69

Glucose: 100% reabsorbed in the proximal tubule Chloride ions: reabsorbed in the distal tubule Urea: typically little absorbed Water: reabsorbed

Answer 70

Active transport. Diffusion alone cannot account for the transfer of these materials as it occurs against a concentration gradient.

Answer 71

Conserve water.

Answer 72

Extra long. Produces particularly concentrated urine.

Answer 73

Secretion and regulation. - lowers the urea content of the blood, clearing the body of toxic nitrogenous waste.

Answer 74

- completely reabsorbed, none being present in urine normally - if the amount of glucose in blood exceeds a certain threshold value, it begins to appear in the urine.

Answer 75

Freshwater: a fish is hypertonic to its environment, therefore water continually flows into the fish via osmosis. Saltwater: a fish is hypotonic to its environment, therefore fish continually flows out of the fish via osmosis.

Answer 76

- water enters the fish due to osmosis - drinks very little water, virtually all water taken in travels across gills for gas exchange - produces dilute urine to maintain cell salts balance - because fish still loses salts via skin and urine, it has specialised cells in the gills to gain salts - fish produce ammonia (turning unto urea/uric acid takes lots of energy) because of the continual diluting of body fluids and expulsion of large amounts of dilute urine

Answer 77

- Water leaves the fish due to osmosis - Ocean fish drink water thru the mouth to compensate for water loss, they excrete excess salts through cells in their gills - produce concentrated urine in small amounts to maintain cell salts balance - produces nitrogenous wastes in the form of mainly urea that is less toxic than ammonia, requiring less dilution by water

Answer 78

Mammals: urea Freshwater fish: ammonia Saltwater fish: urea Birds, reptile, insect: uric acid

Answer 79

- Lungs - Trachea-> bronchi (bronchioles also)-> alveoli

Answer 80

- moist (to allow diffusion) - very thin (diffusion) - high blood flow (maintains a steep conc. gradient between o2 and co2 in alveoli and blood for faster diffusion) - large SA:V ratio (efficient diffusion)

Answer 81

- pushed right up against walls of capillaries - wall cells extremely thin - allowing diffusion to occur

Answer 82

From where cellular respiration has been conducted around the body.

Answer 83

Used by fish to maximize diffusion by pumping blood in the opposite direction to the flow of water. - maximum diffusion is 50% ratio if co-current diffusion is used - counter-current flow is far more efficient and allows the fish to get a much higher percentage of O2 out of water - important bc there is less o2 in water than there is in air, therefore needs to be more efficient

Answer 84

1. Insects - use tiny pipes along their abdomen which have little openings called spiracles - little pipes are like mini trachea that goes down to the cellular level 2. Amphibians - live in water therefore some o2 can diffuse across the skin - still have simple lungs, but can get around 20% of o2 through lungs - moist membrane-> able to diffuse

Answer 85

Created from breakdown of protein (protein molecule contains nitrogen)

Answer 86

It's toxic because it joins with hydrogen to form ammonia

Answer 87

- humans convert this to urea, which requires energy, but uses less water to excrete it (than the amount of water freshwater fish uses for ammonia) - freshwater fish pees a lot of urine with little ammonia and many water (don't want to waste energy converting it to urea)

Answer 88

Remove urea from the blood while retaining everything else that is needed by the body.

Answer 89

Nephron. It filters the blood, removes the urea, and keeps all the good stuff (RBC, WBC, glucose, salts, water). Rest is flushed out through the bladder in urine.

Answer 90

Small stuff like vitamins, salt, H2O comes out

Answer 91

- active transport gets water out before urea gets to the collecting duct capillaries wrap around tube, water diffuse back in through osmosis

Answer 92

maintaining right levels of water and dissolved substances in body.

Answer 93

- They sit in an egg for at least 6 weeks and may get intoxicated if toxic wastes like urea and ammonia are excreted

Answer 94

Longer. To maximize water reabsorption.

Answer 95

Maintaining the right amount of water and other substances within the body

Answer 96

Adrenal glands. Aldosterone controls the reabsorption of ions (Na+, K+, Cl-) in the tubule.

Answer 97

Excess H2O: receptors in hypothalamus senses change in blood osmolarity. - hypothalamus signals the pituitary gland to release less ADH - as less ADH is released, the permeability of the collecting duct cells decreases, thus more water is released through the tube instead of being reabsorbed

Answer 98

A negative feedback loop is a normal biological response in which the effects of a reaction slow or stop that reaction.

Answer 99

- Receptors in hypothalamus senses lack of H20 - transmission occurs from hypothalamus to the pituitary gland, signaling the adrenal glands to release more ADH - More ADH increases permeability of the collecting duct. thus more H20 is reabsorbed into the bloodstream

Answer 100

Anti-diuretic hormone

Answer 101

Mucks up with release of ADH-> less reabsorption

Answer 102

Proximal tubule= glucose diffuses back into the bloodstream through protein channels Henle's loop= permanent active transport occurs, making the surroundings of the Henle's loop extremely concentrated, creating a concentration gradient for water to diffuse out and reabsorb Distal convoluted tubule: active transport

Answer 103

In thru trachea, bronchi, bronchioles, then alveoli, then diffused into bloodstream

Answer 104

Part before distal convoluted tubule: trying to retain as much water as possible Part after dct: homeostatic control

Answer 105

k: regulate water and mineral salts concentration s: regulated body temp l&p: blood glucose

Answer 106

sweat-> concentrated blood-> concentrated urine produced (to reabsorb more water) drink-> diluted blood-> dilute urine produced (less water reabsorbed)

Answer 107

Cold-blooded animals, thermoconformers. Body temperatures vary with temperature

Answer 108

Reptiles, fish, amphibians

Answer 109

Warm-blooded animals, thermoregulators. Keep temp constant by increasing metabolic rate

Answer 110

protect the body (epidermis) - to provide mechanical protection - to prevent bacterial entry - to reduce water loss temperature regulation (hair) excretion of sweat (sweat gland) store fats (subcutaneous fat) sensation (numerous receptors ) production of vitamin D under ultra-violet light (inner epidermis)

Answer 111

1. More sweat is produced by sweat glands – evaporation of sweat takes away heat which produces a cooling effect 2. Vasodilation of skin arterioles – arterioles near the surface of the skin dilates – to let more blood flows near the skin surface – to have more heat lost by conduction & radiation 3. Erector muscles relax – hairs lie flat on the skin – reduce thickness of air trapped among the hairs (not effective in human because human hairs are short) 4. Develop thinner subcutaneous fat & shed fur – as long term responses – increase heat loss 5. Decrease metabolic rate & muscle contraction – gain less heat

Answer 112

1. Vasoconstriction of skin arterioles – arterioles near the surface of the skin constrict – to let less blood flows near the skin surface – to have less heat lost by conduction & radiation 2. Erector muscles contract – pull hairs erect for trapping more air – thicker layer of air acts as a good insulator of heat 3. Less sweat is produced by sweat glands – reduce heat loss by evaporation 4. Develop thicker subcutaneous fat & thicker fur – as long term responses – reduce heat loss 5. Increase metabolic rate & muscle contraction – gain more heat

Answer 113

No more energy to power muscles= will lost heat rapidly in the cold

Answer 114

insulin secreted from the islets of Langerhans in pancreas

Answer 115

malfunction of pancreas (does not secrete enough insulin)

Answer 116

- auto-immune disease - Body kills cells (islets of langerhans) that produce insulin - can't regulate blood glucose levels - born with it

Answer 117

High blood sugar

Answer 118

Gestational diabetes, caused by parasite within eating up all the sugars, causing difficulty of body to use insulin effectively

Answer 119

- blood sugar spikes after meal and becomes too high - pancreas stimulated by brain to secretes more insulin - liver converts glucose to glycogen - cells take in more sugar from blood - blood glucose declines to a set point - stimulus for releasing more insulin disappears

Answer 120

- blood sugar too low - pancreas secretes less insulin - liver produces glucagon that breaks down glycogen into glucose - blood glucose level rises to set point - stimulus for releasing more glucagon disappears

Answer 121

- lifestyle - excessive periods of time with v. high blood sugars (high sugar/ fat diet) - causes resistance of cells to insulin - resulting as them stop responding to insulin (won't absorb more/less sugar on demand)

Answer 122

Skin, hypothalamus, ->sweating, hairs stand up, shivering, vasodilation/ vasoconstriction.

Answer 123

- Nervious system signals dermal blood vessels to dilate and sweat glands to secrete - body heat is lost to its surroundings - drops towards normal

Answer 124

- Nervious system signals dermal blood vessels to constrict and sweat glands to remain inactive - body heat is conserved - drops towards normal - if body temp continues to drop, nervous system signals muscles to contract involuntarily - muscle activity generates body heat - return to normal

Answer 125

1. Nervous system: - thermoreceptors detect changes - communicating to hypothalamus to react - faster with shorter lasting impact 2. Endocrine system: - hormonal system - slower, longer lasting impact, more generalised

Answer 126

- teeth - length of digestive tract

Answer 127

PCT: passive LOH: both (thin top half passive, thick bottom active transport) DCT: active inwards to bring in urea and toxins Collecting duct: passive flow out everything else

Answer 128

HCL: stomach Amylase: salivary glands, small intestine, pancreas Lipase: pancreas Protease: stomach and pancreas

Answer 129

Section of Digestive System Mechanical Digestion Chemical Digestion Mouth * needed to include something mechanical for ½ mark * just ‘mechanical’ not awarded mark * could use any of the following: chewing/teeth & tongue/increases SA:V * needed to mention something chemical OR which substance was being chemically digested here for ½ mark * just ‘chemical’ not awarded mark * ½ mark awarded for any of the following: amylase/bread/carbohydrates/enzyme * lipase also awarded ½ mark as many students mentioned lingual lipase (outside course but correct) Stomach * needed to include something mechanical for ½ mark * just ‘mechanical’ not awarded mark * the term peristalsis was not awarded mark * could use any of the following: churning/muscle contractions * needed to mention something chemical OR which substance was being chemically digested here for ½ mark * just ‘chemical’ not awarded mark * ½ mark awarded for any of the following: pepsin/protease/ham/protein * lipase also awarded ½ mark as many students mentioned gastric lipase (outside course but correct) Small Intestine * needed to include something mechanical for ½ mark * just ‘mechanical’ not awarded mark * peristalsis gained ½ mark * bile emulsifying lipids/fats gained ½ mark * needed to mention something chemical OR which substance was being chemically digested here for ½ mark * just ‘chemical’ not awarded mark * ½ mark awarded for any of the following: trypsin/protease/ham/protein * ½ mark awarded for any of the following: amylase/bread/carbohydrates * ½ mark awarded for any of the following: lipase/butter/lipids Students needed to mention absorption in the small intestine for ½ mark Large Intestine Students needed to mention absorption of water in large intestine for ½ mark. Accessory Organs * Students could include bile emulsifying lipids/fats for ½ mark here OR in small intestine (did not gain marks both times if repeated) * needed to mention liver ½ mark * needed to mention pancreas ½ mark * Students could include the different enzymes acting in the small intestine here with the pancreas (did not gain marks both times if repeated)

Answer 130

. Diffusion works along a concentration gradient, in this case oxygen moves from a high concentration to a region of lower concentration until an equilibrium is reached (1). If the oxygen is being diffused to a changing concentration gradient, opposite to the concentration of oxygen in the blood, then more can be diffused (1). Could also include: moist membrane, blood supply, thin membrane, large surface area at least two wellexplained points for full marks

Answer 131

If the gills become thicker and join there will be less SA for the diffusion of oxygen which would decrease the rate of diffusion (1). Increases diffusion distance for gases so do not move unto blood as efficiently (1).

Answer 132

The following conclusions were awarded ½ mark each; Mice treated with amylase inhibitor had lower BG than those without Mice treated with amylase inhibitor had decreasing BG levels over duration Mice without amylase inhibitor had consistent BG levels Amylase inhibitor can help with diabetes/to lower BG Amylase breaks down larger carbohydrates to assist digestion/absorption Any explicit reference to data in the graph

Answer 133

BG high (½), pancreas detects (½), pancreas secretes insulin (½), insulin travels to liver (and other tissue cells) (½), liver converts glucose to glycogen (tissues increase uptake) (½), facilitates cellular glucose uptake (½), BG decreases (½). BG low (½), pancreas detects (½), pancreas secretes glucagon (½), glucagon travels to liver (½), liver converts glycogen to glucose (½), BG increases (½).

Answer 134

. The hole in the septum means that oxygenated and deoxygenated blood will mix (1). Therefore, blood going to the body will not be fully oxygenated (½), decreasing/lowering the rate of aerobic respiration causing tiredness (½). The heart will try and pump blood faster to get more oxygen to the body (½), making the ventricles work more and thus making them thicker (½).

Answer 135

The stoma must be open for photosynthesis to allow CO₂ into the leaf and release excess oxygen produced into the atmosphere (1). When the stomata are open for gas exchange, water can be evaporated out (½) assisting in the directional flow of water from roots to leaves (½). When the stomata are closed transpiration rate slows (1).

Answer 136

Any 2 of the following: large proteins, enzymes, fatty acids & glycerol, platelets, red blood cells, white blood cells (½ for each).

Answer 137

Any 2 of the following: urea, amino acids, glucose, ions, salts, water, minerals (½ for each)

Answer 138

Increased production of ADH (½) acts to make collecting duct more permeable to water (½) through increased opening of aquaporin transport proteins (½). This means that more water in reabsorbed back into the body (1) creating urine which is more concentrated (1). ½ mark for mentioning darker colour or increased smell of urine produced.

Answer 139

W the liver (1/2 mark for identifying the liver and 1 1/2 for describing function related to digestion). Processes all food that is absorbed into the bloodstream from the digestive system. OR Production of bile to emulsify fats in the duodenum ½ mark given for answers relating to glucose or glycogen storage or toxin removal as these are not strictly digestive system roles.

Answer 140

Coarse vegetation: 1 mark for appropriate feature and 1 mark for explanation. Correct answers include but are not limited to: * More and larger grinding teeth. * Enlarged parts of the gut that allow for extra time for enzymes to breakdown material (e.g. the foregut of cattle) or provide fermentation chambers for bacteria to breakdown the cellulose material further (e.g. the caecum). Additional stomachs. * large stomach to store bulky food

Answer 141

C) Lower negative pressure in legs allows some blood flow back to the heart (1) due to the valves being squeezed 0.5. Valves prevent backflow of blood (1). The movement of skeletal muscle encourages blood to flow back to the heart (1) as this forces the smooth muscle in the veins to contract (0.5).

Answer 142

The person is losing protein through the kidneys (½). Protein molecules are generally too large to be forced out of the blood during ultrafiltration (½) but in this case, they are. The proteins are then lost from the body in the urine. The body has no mechanism for reabsorbing protein because this is not normally required (½). as can be seen in the table Person B has 16 units in its urine whereas Person A does not. (½). Just talking about protein being high in person B and not changing between glomerular filtrate and urine only received 1 mark.

Answer 143

Process using 14C = translocation (photosynthesis accepted) (½) Process using eosin dye = transpiration (½)

Answer 144

Yes. The dye and water travels through xylem tissue from roots to leaves (½). High heat from the steam jacket does not affect xylem cells (½) because they are lignified, dead cells (½).

Answer 145

Shading of the whole plant above the steam jacket (although it was acceptable to not shade the left leaf) (2). 14CO2 is used by the plant in photosynthesis (½) to make glucose that contains 14C (½). Translocation of glucose (½) occurs through the plant via phloem tissue (½). No 14C glucose is found below the steam jacket (½) because the high heat kills the living phloem cells (½).

Answer 146

. Insulin helps maintain homeostasis of blood glucose levels (½). Insulin control of blood glucose is part of a negative feedback control system (½). Blood glucose levels increase following a meal (this is the stimulus) (½). This increase is detected by the (islets of Langerhans) the pancreas (this is the receptor) (½). The pancreas (beta cells) secretes the hormone insulin (this is the messenger) into the blood stream (½). Insulin travels to the liver (this is the effector organ) (½). The liver is activated to absorb blood glucose and synthesise glycogen for storage (½). Body cells/skeletal muscle cells are activated to absorb glucose from the blood (½). This brings blood glucose levels back down (this is the response) (½). Consequences of low insulin production (Type 1 diabetes)/resistance to insulin (Type 2) will be the inability to bring blood glucose levels back down (½). So, diabetics are likely to require insulin injections/suffer from (anything sensible such as) kidney disease, glucose in their urine, high blood pressure, cardiovascular problems, circulatory issues, tissue necrosis, gangrene, ill health, eye problems, premature death (½). For full marks, descriptions of the roles of the pancreas and the liver, insulin action and consequences (plural) for diabetics needed to be addressed. Correct application of the elements of the negative feedback control model, enriched quality of answers given, but were not necessary for full marks.

Answer 147

The question only asks for a statement of features of alveoli which would help insulin to pass into the blood efficiently and therefore, listing of features without explanation attracted full marks. Features listed included: * Alveoli have thin walls * Alveoli have a moist internal surface * The combined surface area of all alveoli is very large * Alveoli have a good blood supply 1 mark for each of the above points correctly stated.

Answer 148

Co2: liver +, small intestine +, active muscle + Glucose: liver -, small intestine +, active muscle - Urea: liver +, small intestine O, active muscle O

Answer 149

Blood carbon dioxide levels increased at Y because the liver cells are respiring (using oxygen) and producing CO2 (1). Blood glucose levels decreased at Y because the excess glucose (from the digestion of food) is EITHER taken out of the blood and stored as glycogen (1) OR it is used in cellular respiration (1). Blood urea levels increased at Y because excess amino acids (from the digestion of food) are broken down/deaminated and converted to urea by the liver (1).

Answer 150

Aquatic: I and IV (½). Higher concentration of ammonia (animal 1 -68% and animal IV 73.3% of nitrogen excreted) (½). Ammonia is toxic and requires a lot of water to remove it / soluble in water and diffuses away (1). Needs to be constantly/rapidly removed due to toxicity / in the most energy efficient form, as the animal makes use of the watery environment so it doesn't have to expend energy on converting ammonia to less toxic waste (1).

Answer 151

Terrestrial: 11 and 111 (½). 111: highest concentration of uric acid in animal III-80.8% of nitrogen excreted (½). Uric acid is solid, insoluble and nontoxic (½). Uric acid can be stored as insufficient water (water in a desert environment needs to be conserved) to flush waste away (1). I I: highest concentration of urea in animal II-85% of nitrogen excreted (½). Urea is soluble and is flushed through kidneys/stored for short periods of time (½). So long as there is some water available in the terrestrial environment, urea is primarily excreted as it saves energy in comparison to uric acid production (1).

Answer 152

The table shows an inverse relationship between humidity and transpiration rate as increasing humidity results in a decrease in transpiration (1). Transpiration is the movement of water through a plant (½) as the concentration gradient becomes less steep with increasing humidity (½), a slower rate of diffusion of water vapor occurs (harder for water to evaporate) (½) this results in a decrease in the transpiration rate (½).

Answer 153

Feature 1: Thick waxy cuticle surrounds the leaf (½). Explanation: The waxy cuticle reduces the amount of evaporation from leaf cells (½). By having a waterproof waxy layer/barrier all around the leaf (½), not just on top which conserves moisture (½). As a result, less water is drawn into the leaves (½) therefore reducing the rate of transpiration (½). Feature 2: Sunken Stomata (½). Explanation: This gives the plant a more humid microclimate at the leaf surface / site of water loss in pits (½) which decreases the concentration gradient from the leaf (½), ensuring less water evaporates from the leaf (½) therefore reducing the rate of transpiration (½). Other acceptable: Feature: Shape of leaf / fairly round cross-section / thicker mesophyll layer*/position of vascular bundle (½). Explanation: Reduces SA:Vol ratio of the leaf which reduces water loss for the leaf (½) because there is less exposed surface to lose water compared the volume of the leaf (½). The thicker cross-section of leaf also creates a greater distance between the xylem and the stomata (½) which increases the time taken for water movement, thereby slowing the rate of transpiration (½). * Storage of moisture and heat reducing capacity was also considered. * Increase in diffusion distance. Feature: Stomatas close during the day. Not a structure, however some marks were awarded for explanation of preventing water loss and slowing transpiration.

Answer 154

False (½) Ecto means outside(1/2), therefore ectotherms rely on heat from outside i.e. external sources (½) to provide energy (1/2). Examples of ectotherms include 'cold-blooded' animals such as lizards or snakes which rely on behavioural responses to change body temperature (½)

Answer 155

True (½) Larger bodies generally have a lower SA:Vol ratio (1) which means that the rate of heat loss is slower compared with smaller-bodied animals (½).

Answer 156

Stimulus: (½ mark given if student identified the word stimulus with the actual stimulus) - Increasing temperature (½). Receptor: (½) - hypothalamus in the brain/thermoreceptors in skin or muscles (½). Transmission of message: (½ ditto) - nerve signal sent from thermoreceptors to hypothalamus, secretion of thyroid releasing hormone (TRH) to pituitary gland, thyroid stimulating hormone (TSH) from pituitary to thyroid, secretion of T3 & T4 hormones from thyroid, nerve signal sent to skin (any for ½). Effector: (½) - blood vessels dilate to radiate heat / sweat glands open to allow evaporative cooling, behaviour response to move into cooler area, reduction of basal metabolic rate to reduce heat production (any two for ½ mark each). Response: (½) - The skin / body is cooled (½). Body temperature reduces / restores homeostasis via a negative feedback loop (½) e.g. the response acts in the opposite direction to the stimulus and hence maintains a steady state for the organism (½). Students do not need to include the five main headings to gain full marks as students may give a full description without them.

Answer 157

- reabsorption of water and mineral ions. (1/2) Storage and formation of undigested waste ready for elimination (1/2)

Answer 158

- the left ventricle has a much thicker muscular wall than the right ventricle(1/2 - the left side is responsible for pumping oxygenated blood to tissues trhoughout the body/ high pressure needed (1) - right ventricle only pumps deoxygenated blood to the lungs/ less pressure (1/2)

Answer 159

Unicellular organisms - large SA:Vol ratio - Entire cell is in contact with environment/ allows exchange of materials as molecules can be exchanged rapidly without a transport system. Multicellular organism - Low SA:Vol ratio - Transport system delivers and removes molecules (e.g. nutrients, gases and wastes) rapidly to and from all cells - So relying on exchange by diffusion would be inefficient as most cells are at a distance from the environment.

Answer 160

Bright light initiates an increase in photosynthesis (1), so that the radioactive carbon can be captured quickly and tracked to see the effects of ring barking. Photosynthesis produces glucose which captures the C-14 in its product, glucose.(1) This is then moved by translocation ot other parts of the plant where it may be needed. (1)

Answer 161

- Plant A (1)- The C-14 is tracked above the leaf to just below position X(0.34) and below the leaf to the root (0.44). It does not appear above position X (0.00). This indicates that the ring barking must have caused a disruption to translocation process as the phloem vessels at position X have been damaged/ cut off (11/2 marks) - Plant B- position Y- no C-14 would have occurred in the root but would have occurred to the stem apex (1/2 mark) - Plant C- ringed at position X and position Y- no C-14 would have been tracked above or below X and Y (1/2 amrk) - Plant D- no ringing- C-14 would have been found in all parts of the plant. Ringbarking stops the flow of sugar (C-14) via translocation (1/2 mark)

Answer 162

As the level of ADH increases (7-22 units), the rate of urine production decreases (2.1- 1.3 ml/min) As the ADH level decreases (22-7 units), the rate of urine production increases (1.3-2.1 ml/min) When the rate of urine production remains constant (2/1 ml/min), the level of ADH also remain constant (7 units)

Answer 163

Stimulus- decrease in water content (osmotic concentration) of blood (1). Amount of water (1/2) Receptor- osmoreceptors in the hypothalamus detect the low water content of the blood(1) Transmission- hypothalamus signals the pitutiary gland (1/2) to release more ADH into the blood stream (1/2) Effector- kidney collecting tubules (1/2( in nphron become more permeable to water (1/2) Response- more water is reabsorbed by kidney tubules and less urine is produced/ the urine is more concentrated (1/2) The process of decreasing the stimulus to maintain homeostasis is an example of negative feedback (1/2)

Answer 164

1. Thin cell walls/ one cell thick- allow exchange of substances (gases/ nutrients/ wastes) to easily and quickly diffuse/ pass through them to the cells OR very selectively pemeable enabling substances to diffuse quickly 2. Moist surfaces- ions already dissolved allows for diffusion across the membrane 3. Large network of capillaries- (large SA:V ratio)- allows maximum exchange as capillaries near all cells due to huge SA. Or able to build networks to increase delivery and remove water by increasing SA around tissue/ increasing exchange rates. 4. Ability to become leaky- for effective fighting invades/ rapid rate of diffusion to affected areas. 5. Thin bore- only allowing one red blood cell through at any time which increases diffusion of gases from blood to tissue (short distance of diffusion) 6. Vasodilation/ constriction- increase/decrease permeability

Answer 165

Oxygen percentages drop by over 4% as this is being used in the body for aerobic respiration (1), this is equivalent to the increase in CO2 which is the waste product of the same process and is to be expected (1). Nitrogen is almost unchanged, which is to be expected as it is neither absorbed nor excreted by the body (1). Water vapour will normally be saturated by the time the air is breathed out as the exchange surfaces in the lungs have to be moist for gas exchange to take place (1).

Answer 166

The amount of gas exchange depends on the rate of diffusion and the surface area that it is exchanged over (1). 375 million alveoli (with high SA: V ratio) means a very large surface area for gas exchange to occur across (1). Having less than 1mm thickness between the blood in the capillaries and air in the alveoli means a small diffusion distance, creating a rapid rate of diffusion (1).

Answer 167

) ADH is important in regulating blood concentration. If blood concentration is too high (not enough water), then more ADH is released from the pituitary gland (1). This increases the permeability of the collecting tubules so more water is absorbed into the blood, which brings the blood concentration back to normal (1). This is a negative feedback mechanism for osmoregulation (1).

Answer 168

c) The loop of Henle reabsorbs water and salt, by maintaining a salt gradient.

Answer 169

Pathway element Corresponding Letter Negative feedback response E/F Stimulus A/F Effector D Receptor B Control Centre B Message C

Answer 170

If the changes happen rapidly it is more difficult for the system to adjust. (1) Takes time for the system to respond and adjust, levels may have varied again by the time response is enacted. (1) Response continues until levels too low which acts as another stimulus to trigger another response, continues to vary within a range around the norm. (1) System requires a variation in levels to begin the adjustment process, system cannot predict changes. (1) The environment (stimulus) is not stable, therefore there will always be change to counteract by the body. (1) Varying levels of cellular respiration (aerobic or anaerobic) produces varying levels of CO2 in the body. (1) Varying levels of breathing and taking in various gases causes differing levels in body. (1) Body undertaking different levels of activity will have different levels of CO2 due to different levels of pulmonary / cellular respiration. (1) Body requires some CO2 for concentration gradient/ maintaining blood pH levels. (1) Body can cope with some small variation, without needing to respond. (1) Levels of CO2 vary in the body (½). System efficiency can be affected by disease. (½) Too many signals can lead to one being missed (½) System can over compensate / overshoot in response to stimulus. (½) It is a short term response (½) System can only do so much, levels could get too high to counteract (½)

Answer 171

- February (summer): there is more available light so stomata are open at 5am for photosynthesis until 10am and again from 4pm to 6pm (½). When stomata are open, a transpiration stream occurs leading to a water loss of 4 units (1). Thus in the hottest part of the day (from 10am to 4pm) stomata close to preserve water (½). June (winter): there is less available sunlight, so to maximise photosynthesis, stomata are open from 10am-4pm in the hottest part of the day (1). This is when up to 6 units of water are lost through transpiration (more than summer) (½), however as there is usually a high rainfall in winter, high rates of water loss can be maintained (½)

Answer 172

(ii)By removing phloem, the glucose made from photosynthesis in the leaves (½) cannot be transported below this point to the roots (½) to be used in cellular respiration (½) for active transport, growth and repair in roots/all cells  death.

Answer 173

(c) – The production of ammonia uses less energy than the production of uric acid – Conservation of water is not important for turtles living in aquatic environments and can therefore dilute ammonia quickly to non-toxic levels – Turtles living in a desert environment produce non-toxic uric acid which is insoluble and can be excreted as a paste. – Uric acid can accumulate in the body without causing problems (any 3 of the above points for 3 marks)

Answer 174

villi/microvilli provide a large SA: Vol for the absorption of digested foods; * lining only one cell thick to minimise distance products of digestion have to travel to get to the blood stream. * good blood supply ensuring that absorbed components are removed from villi quickly, thereby maintaining concentration gradient and so increasing rate of absorption. * cells contain mitochondria for the active uptake of some digested materials * folded intestinal lining slowed down passage of food and increased time available for absorption. Any 2 of the above, well explained, gained 2 marks each.

Answer 175

(b) Possible effects: dehydration due to less absorption of water; diarrhoea; less microbial fermentation of food; reduced vitamin production by bacteria; reduced absorption of some ions; inability to store faeces. (maximum 2 marks) Possible compensations: increased intake of water, relevant vitamins, minerals in diet; greater reabsorption of water and ions from filtrate in kidney; adjustment to the amount of fibre in diet; if only a small amount removed the remaining intestine may be able to compensate; if large amount removed a colostomy bag may be needed. (1 mark)

Answer 176

e) pumps blood to heart and lung. This allows the uptake of O2 and removal of CO2

Answer 177

Small intestine

Answer 178

(b) Lungs: * Large surface area of alveolus. (½). Exchange of gases occurs across surfaces, so the larger the surface area, the more rapidly exchange will occur. (½). * Rich blood supply in capillaries (½). The large number of capillaries maintains blood flow close to alveoli thus maintaining a high concentration gradient. This results in high levels of exchange of molecules into and out of the blood. (½) Also large surface area between capillaries and walls of alveoli (½). * Thin membranes (½). This reduces the distance molecules must diffuse to reach or leave the blood, maintaining a high concentration gradient and so increasing efficiency of exchange. (½). * Moist surfaces. (½). Transport of molecules is facilitated when they are in solution. (½). PLUS Leaves: * Leaves contain stomata on their surface, (½) that open to allow exchange of gases, in particular CO2 in & O2 out. (½) * Large surface area (½) of cavity inside leaf to maximize gaseous exchange. (½) OR Many long thin leaves with numerous stomata to increase surface area for exchange (1). * Cavity inside leaf in close proximity to the cells/air spaces between the spongy mesophyll cells (½) maintains a high concentration gradient and ensuring efficient internal gaseous exchange. (½) * The internal surface of the leaf cavity is coated in a layer of moisture (½) this allows for the dissolving of the gases. (½).

Answer 179

On a dull day the total area of open stomata would be similar but less water would be lost by evaporation Stomata may stay open to increase opportunity for CO2 uptake and max rate of photosynthesis in low light.

Answer 180

(b) The best answers included three major points. These were: * Deoxygenated blood flowing to the right ventricle did not all go to the lungs to be re-oxygenated. * The oxygenated blood and deoxygenated blood mixed so that the amount of oxygenated blood flowing in the blood vessels was reduced. * Haemoglobin has a bluish hue in the blood vessels compared with the bright red appearance of the oxyhaemoglobin.

Answer 181

Plants are autotrophs (1/2) synthesizing their own amino acids(1/2). They synthesis exactly what is required (1/2) therefore there are no excess amnio acids in plants.

Answer 182

Tadpoles produce ammonia which is very soluble (1/2) and very toxic (1/2). However, because they live in freshwater there is plenty of available water (1/2) to flush out this toxic waste product. On land there is less available water (1/2) and so adult frogs convert ammonia to urea which is less soluble and less toxic (1/2) therefore it can accumulate before being flushed out.

Answer 183

Uric acid is insoluble and non-toxic (1/2) so it can accumulate and be excreted as a paste, conserving water (1/2).

Answer 184

- The stimulus (1/2) was increase concentration of CO2 in the blood or a decrease in pH of the blood (1/2) or exercise (1/2). - This change is registered by receptors (1/2) in aorta or carotid arteries (1/2) - Communication or message or nervous impulse (1/2) between receptors and effector is by means of nerves. - The effector (1/2) is the pacemaker in the heart or the heart (1/2) - An increase in CO2 in blood as registered by the receptors results in more nervous impulses from the medulla causing the pacemaker of the heart to [increase the heart rate(1/2]. - The increase in the heart rate is the response (1/2) and when blood is pumped more quickly to the (lungs, CO2 will be expelled more quickly or CO2 will diffuse from the alveoli (1/2)). - Because the response removes the original stimulus the control centre decreases nervous stimulation (1/2) of the cardiac pacemaker, this is an example of homeostasis by negative feedbackk (1/2).

Answer 185

The hole in the septum means that oxygenated and deoxygenated blood will mix (1). Therefore, blood going to the body will not be fully oxygenated (½), decreasing/lowering the rate of aerobic respiration causing tiredness (½). The heart will try and pump blood faster to get more oxygen to the body (½), making the ventricles work more and thus making them thicker (½).

Answer 186

a) It has been reabsorbed back into the blood in the nephron. It might be sugars or nutrients which are small enough to go through the filter but needed by the body so reabsorbed

Answer 187

c) It would be a large molecule and could not go through the filtration. This would include things like haemoglobin.

Answer 188

d) To ensure food in broken down to small enough particulars to absorb into the blood. This way it is broken down before reaching place of absorption instead of trying to do it all at the one site which would be slower.

Answer 189

c) Large SA: V due to villi extending out into small intestine. Large blood supply right to the surface of small intestine to facilitate nutrients absorbing across.

Answer 190

B high urine conc. Means retention of water. Greatest activity time is at night when cooler. Short digestive track means it is carnivore as proteins are easily digested.

Answer 191

Adaptation ( ½ ) how it contributed to efficient gas exchange ( ½ ) in animals ( ½ ) and in plants ( ½ ) for each of three adaptations. Lungs (Max 3 marks) Leaf (Max 3 marks) Large SA :V Large surface area of alveolus. (½). Exchange of gases occurs across surfaces, so the larger the surface area, the more rapidly exchange will occur. (½). Large surface area (½) of cavity inside leaf to maximize gaseous exchange. (½) OR Many long thin leaves with numerous stomata to increase surface area for exchange (1). Moist Environment Gases dissolved in water (1/2) are more exchanged more readily into the cells (1/2). Animals do this by having their lungs inside their body (1/2) or by having a moist ling to the lungs (1/2) Similarly the inside of the leaf is kept moist (1/2) due to the transpiration of water vapour out of the stomata. Thin exchange membrane Thin membranes (½). This reduces the distance molecules must diffuse to reach or leave the blood, maintaining a high concentration gradient and so increasing efficiency of exchange. (½). Cavity inside leaf in close proximity to the cells/air spaces between the spongy mesophyll cells (½) maintains a high concentration gradient and ensuring efficient internal gaseous exchange. (1) Maintenance of a concentration gradient OR short distance for gases to diffuse Rich blood supply in capillaries (½). The large number of capillaries maintains blood flow close to alveoli thus maintaining a high concentration gradient. This results in high levels of exchange of molecules into and out of the blood. (½) The close proximity between air spaces and cells using the gases for photosynthesis along with the numerous stomata on their surface, (½) that open to allow exchange of gases, in particular CO2 in & O2 out. (½)

Answer 192

higher higher lower slightly higher/ same

Answer 193

Blood from other animals: 1 mark for appropriate feature and 1 mark for explanation. Correct answers include but are not limited to: * A very simple gut with only a small and short large intestine since blood is a very easy substance to digest. * The components of blood already contain products from digestion and other components would only need simple processing. No fibre or larger molecules requiring complex digestion. * Sharp mouthpiece for penetrating skin.

Answer 194

Z the large intestine, colon or small intestine (1 mark for 1 any), which is mostly responsible for the absorption of water in preparation for excretion of faeces in normal circumstance. In this case not enough water is being absorbed (1).