Maintaining a Balance Flashcards
(50 cards)
1
Q
What are enzymes and their roles in metabolism?
A
- biological catalysts that regulate the rate of reactions within the body.
- lower activation energy needed for a reaction to progress
- speed up reactions
- work on only one specific substrate molecule.
- globular proteins
- function at a specific temperature and pH range
2
Q
What is the lock and key theory?
A
The theory, proposed by German scientist Emil Fischer, assumes that only one substrate (key) can fix into an enzyme’s active site (lock), forming an enzyme-substrate complex.
An enzyme will not work unless the substrate matches its active site.
3
Q
What are cofactors and coenzymes?
A
They are molecules that assist enzymes to function.
Coenzymes are organic and can be vitamins. Cofactors are inorganic, and include minerals.
They are easily separated from the protein part of an enzyme, and their presence is essential for enzyme reaction to occur.
4
Q
What is the induced fit theory?
A
The theory assumes that the substrate plays a role in determining the final shape of the enzyme substrate complex, and the active site is more flexible than first thought.
The substrate enters in and binds to the enzyme, shaping the active site and properly aligning the enzyme for the reaction to take place.
Other substrates may fit into the active site, but unless they are able to properly shape the enzyme, a reaction will not be catalysed.
5
Q
How does pH describe the acidity of a substrate?
A
- pH scale measures how acidic/basic a substance is (less than 7 is acidic, more than 7 is alkaline).
- pH scale is logarithmic, with each pH value 10x more acidic/alkaline than the next
- pH scale measures changes in environment, and it is important to know if the body is too acidic/alkaline, as it affects rate of enzyme activity
6
Q
Why is it important to maintain a constant internal environment?
A
- Cells in a multicellular organism require a relatively constant environment to function
- need relatively stable internal state regardless of changes to external enviro
- metabolic efficiency and optimal efficiency of enzymes are sensitive to factors including pH, temp, water and salt conc.
7
Q
What is homeostasis?
A
the maintenance by an organism of a constant or almost constant internal state, regardless of external enviro change
8
Q
How can temperature impact metabolic efficiency?
A
- variations can decrease activity of enzymes, or can denature enzymes
- very low temps can cause water in cells to freeze, and can rupture of freezing expands
- very high temps can cause both enzymes and other proteins to denature
9
Q
Why do we need to keep a constant concentration of metabolites?
A
- metabolites are chemicals that participate in chemical reactions in cells
- many metabolic reactions rely on ATP in cells
- if this cannot be produced, other metabolic activity will be affected
- so a lack of metabolites can stop/slow chemical respiration and other reactions, thus affecting overall metabolic efficiency
10
Q
Why do we need to keep water and salt concentration constant?
A
- all chemical reactions in living organisms take place in water as reactants dissolve in water
- dissolved substances affect osmotic balance of fluids, so concentration of salts/other dissolved substances must be maintained in narrow range
11
Q
Why do we need to remove toxins in cells?
A
- build up of Co2 and other wastes is toxic to cells
- it can directly block active site of enzymes, or alter optimal conditions
- to remove means to enable metabolic efficiency
12
Q
Describe homeostasis in stages
A
- detecting the change:
- sensory cells/receptors detect a change in temp or chemical composition of body, known as a stimulus - counteracting the change:
- effector organs work to reverse change
- appropriate response will reverse change and return body to homeostasis
13
Q
What is the role of the nervous system in detecting and responding to environmental change?
A
The nervous system works to regulate and maintain an animal’s internal environment and respond to the external environment by coordinating the body’s response to environmental changes.
the central nervous system consists of the brain and spinal cord:
- spinal cord transmits messages from receptor organs to regions in brain
- receives stimuli from sensory neurons, coordinates necessary response to counteract change
the peripheral nervous system consists of nervous outside CNS:
- sensory neurons transmit messages from receptor organs to CNS
- motor neurons transmit messages from CNS to effector organs to activate a response
14
Q
Describe a feedback mechanism
A
- heat gain may be a result of exercise
- thermoreceptors in skin and brain detect the change and send messages to hypothalamus
- hypothalamus stimulates sweating - liquid sweat secreted through sweat pores, heat is removed from body to evaporate liquid
- body temperature returns to ~ 37
or
- heat loss may be a result of cold external temperatures
- thermoreceptors in skin and brain detect change and send messages to hypothalamus
- hypothalamus stimulates shivering, where rapid small muscle contractions generate heat
- body temperature returns to ~ 37
15
Q
Identify the broad range of temps which life is found compared with narrow limits for individual species
A
- some life forms can be found at temps ranging from 40-120
- thermoacidiphiles in hot springs can live as high as 110 because their enzymes can catalyse reactions in this temp range
- great majority of living organisms found in 0-40 range, and each individual species’ range is even narrower (each species has a tolerance range)
- below 0, ice crystals may form in cells, and above 45, proteins and enzymes denature
16
Q
What is an endotherm and ectotherm?
A
Endotherms:
- use internal metabolic processes to control body temp
- produce own body heat through metabolism
- ability to adjust metabolic rate to control heat loss/gain
Ectotherms:
- depend on external source for heat energy
- body temps tend to fluctuate over wider range of temps, organism has limited ability to control body temp
17
Q
What is ambient temperature?
A
temperature of the environment, immediate surroundings
18
Q
What are physiological adaptations?
A
focuses on inner body functions, e.g. increased metabolic activity to generate heat to maintain body temp
19
Q
What are structural adaptations?
A
physical body features, e.g. insulation through hair/fur/scales/blubber
20
Q
What are behavioural adaptations?
A
physical movement of organisms, e.g. positioning of body to increase/decrease SA of body exposed to sunlight
21
Q
Describe the response of an Australian ectothermic organism to assist temp regulation.
A
Diamond python:
- in cold conditions, it has a structural adaptation of being dark in colour so it can absorb heat. thus, can tolerate colder temps than most snakes
- in warm conditions, it has a behavioural adaptation of being nocturnal - hunting at night to escape heat during day.
22
Q
Describe the response of an Australian endothermic organism to assist in temp regulation.
A
Red Kangaroo:
- in cold conditions, its physiological adaptation enables it to increase metabolic rate to generate more heat
- in warm conditions, it licks its forelegs to increase evaporation from skin
23
Q
What are some responses of plants to high temps?
A
- leaves hang vertically or at different angles to reduce SA exposed to sun and thus reduce heat absorption, minimising transpiration (eucalypts)
- some Australian native plants rely on high temps, such as a fire, to germinate their seeds (Banksia seeds only able to open seed coats when exposed to fire).
24
Q
What are some responses of plants to low temps?
A
- organic anti-freeze: water between cells can potentially freeze, posing great risks, so some plants produce an organic compound that acts as antifreeze, reducing temp at which cytoplasm freezes
- plants can enter a period of dormancy and exhibit little to now growth and await favourable environmental conditions (Nothofagus gunnii, deciduous beech in Tasmania, loses leaves in late April and May to reduce water shortage during winter)
25
How is oxygen carried in blood?
In RBCs in the form of oxyhaemoglobin
26
How is carbon dioxide carried in blood?
```
In the plasma, approx:
70% as hydrogen carbonate ions
23% as carbaminohaemoglobin
7% dissolved directly in plasma
(as Co2 and water forms carbonic acid, not ideal as it affects pH of blood)
```
27
How is water carried in blood?
In the plasma as water molecules
28
How are salts carried in blood?
In the plasma as ions
29
How are lipids carried in blood?
In the plasma in the form of chylomicron (package of digested lipids, phospholipids and cholesterol)
30
How are nitrogenous wastes carried in blood?
In plasma, mostly in the form of urea - NW are harmful substances so need to be transported in diluted form in plasma
31
How are other products of digestion carried in blood?
In the plasma in the form of whole molecules
32
What is the adaptive advantage of haemoglobin?
- Hb is a protein made up of 4 polypeptide chains each bonded to a haem that carries oxygen
1. Hb can increase the oxygen-carrying capacity of blood - each Hb molecule contains 4 haem units, so one Hb molecule has the ability to bond 4 oxygen molecules.
2. Once the first oxygen molecule is bound to a hb molecule, the hb molecule changes shape slightly and makes it easier for each following oxygen molecule to bind to it. this increases the rate & efficiency of oxygen update - a small increase in oxygen concentration in lungs = large increase in oxygen saturation of blood.
3. the capacity to release oxygen increases when co2 is present. hb has a reduced affinity for o2 at lower ph, meaning it releases oxygen readily in tissues that are low in pH (bohr effect)
33
Describe the structure and function of arteries
- carry blood away from the heart
1. thick muscular walls enable high pressure blood to flow through, and they hold artery in place
2. elastic fibres in inner and middle layers enable arteries to expand and contract to adjust amount of blood travelling through
3. smooth inner layer to ensure easy blood flow.
34
Describe the structure and function of veins
- blood towards heart
1. thin walls as the blood pressure is lower
2. wide lumen for easier blood flow
3. valves at regular intervals along inside of vein ensures blood flow is towards the heart - they prevent backflow by closing
35
Describe the structure and function of capillaries
1. one cell thick endothelium maximises opportunity for exchange of substances between blood and cells through diffusion
2. small lumen forces RBCs to pass through single file, slowing down flow and increasing exposed SA for gaseous exchange.
36
Describe the changes in chemical comp. of blood in the lung, small intestine, kidneys and other body tissues
1. lungs increase in oxygen, decrease in co2
2. small intestine increase in glucose and other products of digestion
3. kidneys decrease in nitrogenous wastes
4. other body tissues decrease in oxygen and glucose, but increase in co2
37
Why is oxygen necessary in living cells, and why do we need to remove co2 from cells?
1. oxygen is needed for cellular respiration, which enables metabolic processes such as protein synthesis. oxygen combines with glucose during cellular respiration to release ATP which is needed by cells by metabolism.
2. co2 is produced as result of cellular respiration. it must be removed to prevent change in pH in cells, blood and body because when co2 combines with water, it forms carbonic acid, which dissociates into hydrogen and bicarbonate ions - extra hydrogen ions make pH more acidic. it is removed to maintain homeostasis.
38
What is arterial blood gas analysis and how does it work?
- invasive technique only carried out if abnormalities show up in the pulse oximeter readings, or severe cases of breathing disturbance
- small sample of arterial blood withdrawn from patient, or probe inserted for measurement (o2 and co2 levels measured directly)
- uses sensor that translates chemical properties into electrical signal to be measured
- measures oxygen levels and saturation, and carbon dioxide levels, ph, bicarbonate ions
39
What is a pulse oximeter and how does it work?
- non-invasive technique: a probe attached to patient's finger or earlobe
- oxygen level measured indirectly
- a sensory translates the light absorption caused by arterial blood into an electrical signal that can be measured
- measures oxygen levels and pulse rate
40
Blood products and their uses
1. red cell concentrate - patients with anaemia or severe blood loss
2. platelet concentrate - patients who need extra blood-clotting capability, such as leukaemia sufferers, or severe blood loss
3. plasma - in emergencies to boost volume of blood following severe blood loss
4. cryoprecipitate - treat severe haemorrhaging
5. factor viii - treat ppl who have haemophilia or where blood is not able to clot properly
41
Describe the transpiration stream theory (cohesion-adhesion-tension)
- movement
- evidence
- describes movement of water through xylem
- stomates open, water constantly evaporates = TENSION on remaining water to draw up xylem tubes
- once water absorbed into roots by osmosis, and mineral ions by diffusion and AT, these substances move across root into xylem
- small amount of ROOT PRESSURE bc of water moving across cells into xylem
- COHESION between water molecules causes them to move further up, attracting molecules below to fill space left by water lost by transpiration
- ADHESION between cellulose in xylem walls and water in contact with it (known as capillarity in narrow tubes)
Evidence:
- 1893 Eduard Strasburger's experiment
- placed tree trunks into buckets of poisonous solutions
- solutions rose in xylem even tho tissues down trunk were dead, stream continued until leaves were killed
- indicates that living cells pumping substances up xylem not responsible for upward movement, as they were already dead
- leaves had crucial role in transporting up xylem
- transport not due to root pressure alone, as roots had been cut off
42
Describe the pressure flow theory (source-path-sink)
- movement
- theories of mechanism that materials are loaded
- evidence
- describes two-directional movement of materials in phloem tissues
- flow driven by osmotic pressure gradient
- sugar actively loaded into phloem at source, causing high conc. of solutes
- attracts water to flow by osmosis, causing region of high pressure
- sugar forced away from source along phloem to sink due to difference in pressure
theories for mechanism that materials are loaded:
1. symplastic loading: materials move in cytoplasm from mesophyll cells to sieve elements through plasmodesmata
2. apoplastic loading: materials move between cell walls (apoplast) of cells until reach sieve element. then cross cell membrane to enter phloem tube. these sugars pass into sieve cell by AT
Evidence:
- aphids feed on phloem sap by inserting a needle-like mouth (stylet) into phloem
- pressure in phloem forces spa into aphids body, swelling it up
- scientists use stylet as tap to drip phloem sap for analysis
- closer stylet, faster the sap drips out and greater the sugar conc.
43
Phloem structure and function
1. sieve plates - perforated cell walls between cells that enable each cell to open into the next to form a continuous tube
2. companion cell - maintain sieve cells by performing their metabolic functions, as sieve cells do not have a nucleus
3. sieve cell - main conducting cells of the phloem. they are elongated cells that join to form vertical columns called sieve tubes. sieve tubes are used for longitudinal transmission of prepared food materials from source to sink.
44
Xylem structure and function
1. dead hollow cells - form a continuous tube from root to leaf to enable flow of water and dissolved materials.
2. walls of tracheids reinforced with lignin - prevents tracheids from collapsing, assists in continuous movement of water.
45
Haemoglobin provides an adaptive advantage to an endotherm in a cold environment because it allows
- more energy to be available to the organism
- endotherms generate their body heat from their own metabolic activity
- aerobic respiration releases much energy
- oxygen is required for aerobic respiration
- oxygen is transported to cells bound to haemoglobin therefore hb increases the supply of oxygen to cells
- this increases the release of energy from aerobic respiration
46
How does a plant respond to keep cool on an extremely hot day?
- it opens stomata in the leaves
- transpiration is the evaporation of water from leaf surface and this cools the plant
- about heat loss, NOT water loss
47
An experiment was conducted to test the effect of dissolved co2 on ph of water. it was found that the ph of water decreased as co2 was added. how do these findings relate to the acidity of blood as it circulates in the body?
- blood in the capillaries of the lungs become less acidic
- capillaries are the site where gases are exchanged
- capillaries in the brain pick up carbon dioxide from the tissue, therefore the blood in capillaries will become more acidic.
- capillaries in the lungs lose carbon dioxide therefore blood becomes less acidic.
48
Why do insects primary excrete uric acid?
Many insects live on land where water availability is low. Uric acid is a form of nw that has low toxicity and doesn't require water for excretion.
49
Limitations of pulse oximeters in determining health
| particular question scenario w/ image
- many other factors determine health, e.g. presence of infection, cancer, mental wellbeing, levels of toxic substances in the body and diet
- no info is given about the person or environmental conditions when recording was taken - age, gender, at rest or exercising
50
Advantages of pulse oximeters to measure oxygen saturation compared to using another named technology in a specific setting.
- immediate results
- continuous data recording
- portable/battery operated/small/easy to attach/non invasive
- o2 saturation can also be measured using arterial blood gas analysis. in this method, arterial blood extracted from person and analysed in lab. recording is not continuous nor immediate.
- at site of accident/in ambulance, pulse oximeter gives continuous readings
- enables any abnormalities to be quickly identified and monitored, allowing treatment to be given
- risk of infection is reduced as blood sample is not required
