1. Maintaining A Balence Flashcards Preview

HSC Biology > 1. Maintaining A Balence > Flashcards

Flashcards in 1. Maintaining A Balence Deck (117):
1

Describe the role of enzymes in metabolism

Enzymes are necessary for all metabolic reactions. They increase the speed of a reaction by lowering the 'activation energy', thus requiring less energy for the reaction to occur.

2

Identify why enzymes have specifity on substrates

The shape of the active site is specific to a certain substrate, referred to as 'molecular recognition'.

3

Describe how enzymes are formed.

Enzymes are a type of protein. They are formed by a long polypeptide chain (anime acids in a specific sequence, bound by peptide bonds) which forms a 3D object

4

Describe the two different types of metabolic reactions involving enzymes

1. Catabolic pathway: breaking down of complex molecule into simpler molecules
2. Anabolic pathway: building up of simple molecules into complex molecules

5

Identify and describe the two different models which show specificity on substances

Lock and key model: the active site is exactly the same shape as the substrate
Induced fit model: active site is slightly different shape to substrate, so changes its shape

6

Define: co-factors

Small, inorganic molecules that help enzymes to act (not necessary)

7

Define: co-enzymes

organic molecules that usually bind to the active site (necessary)

8

Describe what amylase 1 catalyses and where in the body

Amylase 1 catalyses the conversion of starch to maltose in the mouth (pH 7)

9

Describe what protease catalyses and where in the body

Protease catalyses the conversion of proteins into peptides in the stomach (pH 1-2)

10

Describe what lipase catalyses and where in the body

Lipases catalyses the conversion of lipids into fatty acids and glycerol in the pancreas and small intestine

11

Describe what amylase 2 catalyses and where in the body

Amylase 2 catalyses the conversion of starch into disaccharides and trisaccharides in the pancreas

12

What affects the acidity of a substance?

The presence of hydrogen ions

13

Why can organisms only tolerate a narrow range of hydrogen ions concentrations?

pH denatures outside of optimal level

14

Explain why cells contribute most of their energy to maintaining _____?

Cells contribute most of their energy to maintain constant internal conditions.
This is because metabolic reactions can only occur waiting a narrow range of conditions. Outside of these conditions, the optimal efficiency of enzymes is decreased, either due to the slowing down or denaturing of enzymes.

15

Define: homeostasis

The maintenance of a relatively stable internal environment

16

Describe homeostasis and outline how it works

Homeostasis is a dynamic state as it attempts to maintain a stable internal environment despite a constantly changing external environment. It achieves this by activating internal control mechanisms to responded to internal changes as a result of external influences.

17

Identify the two major stages of homeostasis

1. Detaching changes from the stable state
2. Counteracting changes from the stable state

18

Identify the three functional components of a homeostatic control mechanism

1. A receptor: detects changes
2. A control centre: process information received (ie. hypothalamic in brain)
3. An effector: has an effect on stimulus

19

Outline the 7 steps involved in a homeostatic response

1. Stimulus in environment
2. Receptors detect stimuli
3. Sensory nerves conduct impulses to Connecter nerves
4. Connector nerves transmit impulses the brain
5. Hypothalamus coordinates a response
6. Motor neurones transmit impulse to effector cells
7. Effectors counteract stimulus

20

Outline the role of the nervous system in detecting and responding to environmental changes (homeostasis)

The role of the nervous system is to carry impulses throughout the body. Different cells in homeostasis transmit information throughout the body, which is facilitated by the nervous system.

21

Explain why life can only exist in a narrow range of conditions.

Life can only exist in a narrow range as enzymes (metabolic catalysts) are temperature sensitive. They thus denature when outside the optimal temperature range.
When temperatures are too low, the phospholipid layer can free and when temperatures are too high, the DNA double helix splits.

22

Describe how aquatic and terrestrial ectotherms respond to temperature change to assist in temperature regulation.

Ectotherms warm their body by absorbing heat.
Aquatic: no need as environment has little temperature variation.
Terrestrial: Netted Dragon lies in sun to absorb heat, lies flat to increase SA exposed to sun. Alpine Grasshopper colour changes from blue to black.

23

Describe how aquatic and terrestrial endotherms respond to temperature change to assist in temperature regulation.

Endotherms derive body heat from metabolism, thus requiring large amounts of energy.
Aquatic: Australian Fur Seal uses 'counter-current heat exchange' as heat is transferred from the arteries to the veins to maintain heat in the extremities.
Terrestrial: Red Kangaroo decreases physical activity (lowering metabolic rate), seeks shelter, has pale fur and thick to create insulation.

24

Identify some responses of plants to temperature change

Temperature controls germination, growing season, flowering and seed dispersal.
Plants will close stomates above 30 degrees Celsius (when closed, heat-shock portends are used as a protective coating for enzymes)
Native plants will respond by flowering or germinating after fire.
In cold temps, plants will becomes dormant.
Plant seeds germinate over a wide renege of temps, but are specific to each variety (enzyme specificity).

25

Describe the effect of substrate concentration on enzyme activity

The more concentrated the substrate, the faster the enzyme works, to a certain point. This is because there is a shorter distance for enzymes to move between substrates. However, it does not make a difference when the solution reaches saturation point as all the active sites are occupied so no further reactions can take place.

26

Describe the effect of pH on enzyme activity

pH is the measure of hydrogen ions. Living organisms can only tolerate a specific range of pH as outside the optimal range, the enzymes begin to denature by changing the shape of the active site.

27

Describe the effect of temperature on enzyme activity

to an extent, a reaction does increase with temperature as there is more kinetic energy for substrate molecules to collide with enzymes at an increased rate. However, bond a certain point, the rate decreases rapidly as the active site of the enzyme is altered.

28

Describe the role of the lymphatic drainage system

Maintains osmotic and fluid balance. Returns fluid from body's tissue back to the blood to drain interstitial fluid.

29

Identify the functions of the circulatory system (The Vampire Diaries is Best!)

Transport
Vasodilation/Vasoconstriction
Defence
Blood Clotting

30

Describe the composition of blood

55% Plasma (91% Water, 7% Protein, 2% Other solutes)
45: Formed Elements (99% Erythrocytes, 1% Leukocytes, 1% Platelets)

31

Identify the form, mode of transport and direction that carbon dioxide is carried

Form: Carbaminohaemoglobin, hydrogen carbonate ions, or as carbon dioxide
Mode: RBCs and plasma
From somatic cells to lungs

32

Identify the form, mode of transport and direction that oxygen is carried

Form: oxyhemoglobin
Mode: RBCs (haemoglobin)
From lungs to somatic cells

33

Identify the form, mode of transport and direction that water is carried

Form: water molecules
Mode: plasma
From digestive system and somatic cells to somatic cells

34

Identify the form, mode of transport and direction that salts is carried

Form: ion
Mode: plasma
From digestive system and somatic cells to somatic cells

35

Identify the form, mode of transport and direction that lipids is carried

Form: chylomicrons (triglycerides coated in protein)
Mode: lymph and plasma
From digestive system and somatic cells to somatic cells

36

Identify the form, mode of transport and direction that nitrogenous wastes is carried

Form: urea
Mode: plasma
From liver and somatic cells to kidneys

37

Identify the form, mode of transport and direction that products of digestion is carried

Form: seperate molecules
Mode: plasma
From digestive system and liver to somatic cells

38

Explain the adaptive advantage of haemoglobin

The adaptive advantage of haemoglobin gives mammals the ability to transport large quantities of oxygen to tissues. Haemoglobin molecules have four active sties, where oxygen binds to an iron ion, increasing the oxygen-carrying capacity of RBCs by 100x

39

Using chemical reactions, explain how oxygen is carried around the body as oxyhaemoglobin

In lungs, oxygen diffuses out of the alveoli and into the bloodstream where it binds to haemoglobin:
Hb + 4 Oxygen -> Hb(oxygen)4

40

Using chemical reactions, explain how oxygen is released in the body

Oxygenated blood is transported to somatic cells where it is released:
Hb(oxygen)4 --> Hb + 4 Oxygen

41

Identify and describe the three types tissue that make blood vessels

1. Connective tissue: outmost layer with thick muscles to allow the vessel to retract and stretch
2. Middle tissue: smooth muscle and elastic fibres
3. Endothelium: innermost layer of flattened cells to provide a smooth layer with resistance to blood flow

42

Describe the artery in regards to structure and function

Structure: thick connective tissue and middle layer of muscle to pump blood under high pressure and control blood flow and an endothelium
Function: distributing oxygenated blood from the heart to somatic cells

43

Describe the capillary in regards to structure and function

Structure: only a thin, porous endothelium to enable exchange of materials. RBCs move in single-file.
Function: exchange vessels

44

Describe the vein in regards to structure and function

Structure: thinner walls than arteries and relies on skeletal muscles to move blood through. Flaps of tissue as valves to ensure that blood moves in one direction
Function: collecting vessels to return blood back to the heart.

45

Describe the changes in the chemical composition of blood as it interacts with four different organs

Lungs: blood enters low in carbon dioxide and high in oxygen, due to gaseous exchange leaves high in oxygen and low in carbon dioxide
Wall of small intestine: blood enters low in nutrients and absorbs nutrients for digested food in the villi
Liver: blood enters high in toxins in the hepatic portal vein, leave low in toxins
Kidneys: blood enters high in urea, salts and water, composition of blood leaving is dependant on the needs of the body

46

Describe the need for oxygen in living cells

Oxygen is required to undergo cellular respiration, which converts chemical energy (glucose) to usable energy (ATP -> ADP).

47

Describe the process of respiration

Occurs in the mitochondria and process 38 ATP per glucose. When energy is needed a phosphate group is removed from ATP. Aerobic occurs in two steps:
1. Glycolysis: glucose splits into 2 pyruvic acids (2 ATP) in the cytoplasm
2. Krebs Cycle: in mitochondria, combustion of pyruvic acid to form carbon dioxide, water and 36 ATP
In anaerobic respiration, pyruvic acid is converted to alcohol and lactic acid for short periods of high energy

48

Explain how the removal of carbon dioxide is essential

Carbon dioxide is an unwanted by-product of cellular respiration. It must be removed from the body as it readily reacts with water in the blood to form carbonic acid (lowers pH). Carbon dioxide is excreted in the lungs through gaseous exchange and travels there are carbonic acid, carbaminohaemoglobin or a carbon dioxide in the plasma.
Respiratory surfaces have low carbon dioxide concentration to they readily diffuse.

49

Identify and describe the four different structure which form the xylem

1. Vessel Members: stacked on top of each other and end walls are broken (pitted walls)
2. Trachieds: long cells with tapering cells, strongly lignified
3. Fibres: long strands of lignin to give structure support
4. Parenchyma: structural support and site of food storage

50

Identify and describe the three forces in which water moves in the xylem

1. Transpirational pull: negative pressure created are water evaporates, drawing more water into the stomata
2. Capillarity: relies on cohesive and adhesive forces
3. Root pressure: water moves into the root (root hairs), forcing water into the aerial parts of the plant

51

Does mineral ions move by passive or active transport?

Active transport

52

Identify the three pathways for water to enter the xylem from root hairs

1. across cell walls and membranes
2. through cytoplasm and plasmodesmata (symplast)
3. through cell wall (apoplast)

53

Identify the three different types of structural support that lignin given to trachieds

1. Annular
2. Spiral
3. Pitted

54

Identify the pathway that sucrose travel to get to the transport vessel

Source cells --> Companion Cells --> Sieve Tube Elements

55

Describe the 2 ways in which sucrose travels to the phloem

Symplastic loading: travels through the cytoplasm via plasmodesmata to sieve tube elements
Apoplastic loading: move through cell walls to sieve tube elements, crossing cell membrane to phloem

56

Describe the pressure-flow model

As sucrose enters the phloem, the concentration and water decreases (high osmotic pressure), water thus moves from the xylem to the phloem, thinning the sucrose and depositing into sink cells by pressure gradient. As sucrose is deposited into sink cells conc of water increases and so moves back into the xylem to source cells.

57

Define: Translocation

transport of organic materials from source (supply) to sink (growth)

58

Describe the structure of phloem

Comprised of sieve tube elements, which are stacked with perforated sieve plates. Cytoplasm of sieve tube elements are interconnected through pores. During differentiation, cell nucleus breaks down and thus can not control itself. Companion cells lie next to the tube elements and have a nucleus to carry out metabolic functions and transport nutrients. Lateral sieve areas have plasmodesmata which connect companion cells and sieve elements together.

59

Identify and describe the three major properties of blood tested in Arterial Blood Gas Analysis (ABG)

1. Oxygen concentration: oxygen diffuses across a gas-permeable membrane causing an electrochemical reaction
2. Carbon dioxide concentration: sensors detect a pH change in a solution of bicarbonate as carbon dioxide moves through a gas-permeable membrane
3. pH measuring using a glass electrode of known pH

60

Describe how the components of a biosensor

1. Transducer - converts biochemical to electrical signals
2. Bioreceptor - reacts with substance tested

61

Outline the use of ABGs and the conditions under which they are used

Invasive - requires 40mL of blood drawn from patient. Measures oxygen and carbon dioxide directly from blood
Electrochemical - uses a sensor to convert chemical properties to electrical values
What it measures - oxygen concentration, carbon dioxide concentration, pH
Conditions - monitor oxygen, carbon dioxide and pH levels, effectiveness of breathing, lung transplant, acid-base levels
Research - ABGs that measure glucose, electrolyte and haemoglobin levels

62

Outline the use of Pulse Oximeters and the conditions under which they are used

Non-invasive - probe attached to finger or earlobe. Measures oxygen indirectly
Optical - sensor to translate physical property to electrical signal
What is measures - oxygen concentration (two light-emitting electrodes, red and infrared, are shone through extremity. Amount of light absorbed by receptor is reflective of the amount of oxygen in blood), pulse rate
Research - carbon dioxide sensors and digital signal processing, using mobile phones to collect data

63

Identify the two benefits of separating blood

1. donated blood is use more effectively, for more than one person
2. patient only receives blood needed (not unnecessary increase in blood volume

64

Identify the primary roles of RBCs, WBCs, Platelets and Plasma in donated blood

RBCs: transport oxygen
WBCs: fight infection
Platelets: blood clotting
Plasma: blood volume expander

65

Describe the use of whole blood

Replace large amounts of blood loss - requires cross-matching

66

Describe the use of packed RBCs

Treatment of anaemias (plasma would result in increased blood volume)

67

Describe the use of platelet concentrates

Stops bleeding; used as a preventative before surgery. Used in cancer patients to reduce bacterial contamination

68

Describe the use of Fresh Frozen Plasma

Management of disease where there is a breakdown of clotting mechanisms, blood volume expander

69

Describe Cryoprecipitate and its use

Plasma that is rapidly frozen and thawed. Helps control bleeding

70

Describe Stable Plasma Protein Solution and its use

Plasma fraction in which protein is quickly frozen and dried to a white powder. Used for emergency replacement of lost blood volume and particularly in remote areas

71

Define: Artificial Blood

fluid designed to carry and transport oxygen and carbon dioxide in the body (can't do other functions)

72

Identify why the research into artificial blood started and the need for it

Failed attempts to find artificial blood in WW I and II. Blood loss is an issue as oxygen can not be transported to cells, carbon dioxide can not be removed, short storage life, difficulty of transportation and cross-matching of blood

73

Identify why a resurgence into artificial blood occurred in the 1980s

An appearance of HIV in blood recipients due to the short window in which diseases can not be detected in blood.

74

Identify and describe the four types of blood substitutes

1. Perflurocarbons - carries oxygen in a dissolved from, and carries up to 50x more than plasma. Difficult to combine in bloodstream as it must be combined with lipids (emulsion)
2. Haemoglobin-based oxygen carriers (HBOCs) - extracts haemoglobin from outdated blood
3. Crystalloids - volume expander
4. Colloids - volume expander

75

Identify the three currently available blood substitutes with a gas transporting function

1. "Perfortan" - treats chock, blood loss, trauma and burns
2. "Oxygent" - assists oxygen delivery in patients at risk of acute tissue deficit. Does not bind chemically to oxygen. Used for stroke, sickle cell anaemia
3. "PHER-O2" - 1/900th size of RBCs to can transport oxygen to inaccessible parts of the body

76

Identify 3 reasons why research into artificial blood is needed

1. can be stored for long periods of time without refrigeration
2. cheap
3. no cross-matching
4. no risk of infection
5. allows people with religious conviction to gain treatment

77

Describe why the concentration of water is kept within a narrow range of conditions

Water is imperative to the functioning of life because it is a major competent of cells and is involved in most metabolic reactions

78

Identify the four major properties of water in the body

1. Solvent: was wate ris a polar molecule, it is able to dissolve other mineral ions and polar molecules. Metabolic reactions require dissolved solutes
2. Medium for metabolic reactions
3. High specific heat capacity
4. Lubricant: prevents friction between surfaces of skeleton, organ and muscle

79

Define: Hypertonic

When the concentration of solutes outside the cell is greater than inside the cell

80

Define: Isotonic

When the concentration of solutes outside the cell is equal to inside the cell

81

Define: Hypotonic

When the concentration of solutes outside the cell in lower than the inside of the cell

82

Explain why the removal of wastes is essential for metabolic activity

Major function of homeostasis is to stop by-products of metabolism from accumulating and poisoning body fluids. Build-up of wastes impact the functioning of enzymes, which catalyse metabolic reactions.

83

Identify and describe the two major body processes while produce large amounts of wastes

1. Respiration: produces carbon dioxide which is excreted in the process of gaseous exchange. It must be removed as it readily reacts with water to form carbonic acid, increasing the acidity of blood. This impacts metabolic reactions as the enzymes begin to denature outside of conditions
2. Deamination: breaking down of amino acids, producing ammonia which increases pH. Mammals convert to urea or uric acid.

84

Identify the function of urine production

Urine production aims to maintain homeostasis by regulating the volume and composition of blood

85

Identify the two major roles of the kidney

Excretion and osmoregulation

86

Identify and describe the three major functions of the kidney

1. Filtration: high blood pressure forces water, urea, salts and solutes from glomerulus into Bowman's Capsule. Non-selective to all small molecules
2. Reabsorption: allows for the recovery of important ions, nutrients and water from filtrate. Occurs in proximal and distal convoluted tables, LOH. Involves passive and active transport
3. Secretion: as filtration does not force all wastes out of the blood, secretion is necessary to remove large wastes from the bloodstream. Involves both passive and active transport

87

Describe the problems with diffusion as a transport mechanisms is moving nitrogenous wastes

1. Rate of movement is too slow: nitrogenous wastes must be moved quickly in order minimise damage, but rate of diffusion slows as equilibrium is approached.
2. Not all wastes are removed: as diffusion stops at equilibrium, no wastes can be removed beyond this point

88

Describe the problems with osmosis as a transport mechanisms in removing nitrogenous wastes

1. Too much water lost as urine: water will move into urine by osmosis, resulting in large water loss from the body
2. movement of water may make wastes too dilute for excretion be diffusion. In freshwater fish, constant receiving of water dilutes urine and thus slows down excretion by diffusion

89

Define: Passive transport

Relies on the concentration gradient and is too slow for body processes as it stops at equilibrium. Requires no energy

90

Define: Active transport

Moves substances against the concentration gradient and requires energy

91

Explain the processes used in amino acid and glucose reabsorption

Facilitated diffusion and active transport in proximal tubule

92

Explain the processes used in salt reabsorption in the kidney

Active transport in the ascending limb of LOH and distal convoluted tubule

93

Explain the processes used in water movement in the kidney

Osmosis throughout tubules (dependent on the body's needs)

94

Identify the function of ADH and what it responds to in the body

Anti-Diuretic Hormone is released in response to a high osmolarity in blood. ADH is secreted from the pituary gland to kidneys to increase water reabsorption. Osmoreceptors in hypothalamus monitor osmolarity of blood

95

Identify the function of Aldosterone and what it responds to in the body

Aldosterone is released in response to a decrease in blood pressure, volume or an excess loss os salt. It acts on the tubules in nephron to increase the reabsorption go sodium ions.

96

Describe aldosteronism

Condition where adrenal glands do not produce enough aldosterone - can lead to excess loss of sodium ions and water in kidney. Treatment involves HRT using synthetic fludrocortisone

97

What to ADH and aldosterone both respond to?

Osmoregulatory problems

98

Define: Estuary

Ecosystem where freshwater merges with the ocean. It is a transition zone of constant chemical and physical changes

99

Identify some adaptation of estuarine organisms to survive sudden changes in salinity

Burrowing in mud where salinity is stable (crabs)
Seek refuge in closed shell (muscle)
Reverse the direction of salt transport across gills and kidneys change the concentration of urine (salmon)

100

Define: Enantiostasis

Maintenance od metabolic and physiological functions in repose to variations in the environment. They are osmoconformers or osmoregulators

101

Define Osmoconformers with example

Osmoconformers allow the osmolarity of blood and interstitial fluid to follow the environment and depends on ability to cells to tolerate changes in osmolarity of body fluids. This means that the osmotic pressure is similar inside the organism to outside. Fiddler crabs accumulate salt in tissues or pump excess salt from gills.

102

Define Osmoregulators with example

Osmoregulators regulate osmolarity of blood and interstitial fluid despite variations in external environment by some form of active transport. Cell metabolism can not tolerate wide range of salinity. Salmon drinks excessively in marine water and eliminates salt in gills. In freshwater, salmon stop drinking and absorbs water in gills, excretes dilute urine

103

Identify some of the adaptations that native Australian plants have to minimise water loss

Sclerophyllous leaves (rigid, hard, spiny): Hakea
Thick cuticle: Acacia, Banksia
Stomates in pits/grooves or trichomes
Small scales are leaves: Casurina
Leaves hang vertically: Eucalyptus
Leaves roll up: Spinifes
High shoot:root ratio

104

Identify the regions of excretion in the kidney

Cortex (glomeruli)
Medulla (LOH)
Renal Pelvis (collecting ducts)

105

Describe the use of renal dialysis

To treat patients with kidney failure by filtering blood to remove wastes (can only filtrate, not secrete or reabsorb).

106

Describe the process of renal dialysis

Blood is drawn from an artery and processed through the renal dialysis machine and returned to a vein. The process relies on diffusion through a selectively permeable membrane in the machine. On one side of the membrane, is dialyse fluid, which contains plasma, glucose and bicarbonate ions, so that these will no diffuse from the blood. The patient's blood is on the other side of the membrane. Diffusion of wastes and some nutrients occurs and moves from the blood into the dialyse fluid.

107

Identify the disadvantages of renal dialysis

- Sit my machine for 15hrs/week
- Decreased blood pressure
- Anaemia
- Risk of infection and embolism
- Limited amounts of wastes are removed as process relies on concentration gradient (passive transport)
- Nutrients can not be reabsorbed.
- Invasie

108

Outline the use of HRT in people who cannot excrete aldosterone

Importance of aldosterone: regulates blood pressure by increasing the salt reabsorbed from kidneys.
An inability to excrete aldosterone can lead to Addison's disease (adrenal cortex cannot secrete adequate aldosterone), a decrease in Sodium and increase in Potassium (K leads to heat failure).
HRT involves restoring the balance of hormones by giving patients artificially engineered hormones (i.e. fludrocortisone), allowing them to manage symptoms. HRT allows individuals to overcome complications of hormone-deficient diseases (i.e., fatigue, water loss, heat failure)

109

Compare the type of nitrogenous waste excreted in freshwater fish, marine fish and terrestrial mammals and explain way

Freshwater fish: ammonia - excess waster can excreted
Maine fish: urea - conserves water, less need to dilute
Mammals: urea - conserves water, less need to excrete

110

Compare the urine concentration of marine fish, freshwater fish and mammals

Freshwater fish: copious amounts of dilute urine
Marine fish: small amounts of concentrated urine
Terrestrial mammals: varies depending on the needs of the body at the time

111

Identify any characteristics of the nephron that assist the freshwater fish, marine fish or terrestrial mammals in producing need concentration of urine

Freshwater fish: large glomeruli to increase rate of filtration and excrete large amounts of urine
Marine fish: small glomeruli to decrease rate of filtrate as part of conserving water
Mammals: many nephrons and long tubules to increase surface area for secretion and reabsorption

112

Describe the movement of salts in marine and freshwater fish

Freshwater: salts are actively transported into the fish from the water as the fish has a higher concentration of salt than the water
Maine fish: actively transports salt out of the fish into the water as fish has lower concentration of salt than water

113

Compare the nitrogenous wastes produced by an invertebrate and a vertebrate in relation to water conservation

Blowfly: uric acid - lives in arid conditions so water conservation is important. Requires little water for dilution
Meal worm: ammonia - excretes ammonia as a vapour to conserve water (large SA:V ratio increases water lost as vapour)
Human: urea - arid conditions
Hopping Mouse: urea - less water needed to dilute than ammonia

114

Identify any adaptations or characteristics of a invertebrate and a vertebrate in relation to water conservation in urine production

Blowfly: excretes urine as uric acid to conserve water as large amounts of water is evaporated due to large SA:V ratio. Excretes dry faeces
Meal Worms: excretes ammonia as vapour as water is lost be evaporation
Humans: long LOH to increase reabsorption of water
Hopping Mouse: long LOH to increase reabsorption of water

115

Identify and describe the four process which estuarine organisms use to maintain osmolarity.

Ion exclusion - actively resists uptake of salt
Ion accumulation - accumulates and stores salt in parts of plant
Ion dilution - small SA:V ratio in leaves
Ion extraction - salts are excreted

116

Identify the processes used by mangroves to maintain a constant osmolarity

Ion exclusion - actively resists uptake of salts in roots
Ion extraction - accumulates and stores salts in vacuoles of bladder cells (extension of epidermal cells), where it ruptures
Ion accumulation - salt is actively transported and stored in dying leaves

117

Identify three structures of plants which assist in the conservation of water

Waxy cuticle: reduces water loss by acting as a 'waterproof seal' to prevent evaporation
Reduced leaves: small SA:V ration decreases surface and amount of stomates exposed to the sun
Leaves hanging vertically: less SA exposed to the sun