Topic 3A & 3B - Exchange and Transport Systems Flashcards
What are advantages of large organisms being multicellular?
Many cells allow them to be less vulnerable to death as cells can be readily replaced if they have died or been damaged
Why can’t certain cells get to the size of small fish?
They’re prokaryotes (as a side note so dont have specialised cells, but main point…): their surface area to volume ratio would be too small and so waste products would build up.
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Read over.
Before you do, think about what mass transport is and why its needed.
Mass transport iswhen the bulk movement of gases or liquids in one direction occurs, usually via a system of vessels in animals.
(FOR CONTEXT: small organisms have a large surface area to volume ratio. This allows sufficient gas exchanges across their membranes to supply their relatively small number of cells (or volume)).
- larger organisms have a smaller surface area to volume ratio
Gas exchange across that body alone would only allow the first few layers of cells to receive oxygen. SO, large organisms rely on mass transport systems which are adapted to provide large SA:V needed.
- Such as circulatory system with networks of capillaries or respiratory system with loads of alveoli.
Features a gas exchange surface must gave in order to be efficient, to increase rate if diffusion.
- steep concentration gradient (maintaining it, so that diffusion occurs constantly at a high rate).
- thin exchange surface (one epithelium/ endothelium cell layer thick) for a short diffusion pathway.
- large surface area for more diffusion to occur at once (many possible areas for diffusion to occur across)
NB that a large SA:V ratio is for organisms as a whole, not their systems.
Explain how air moves in to terrestrial insects and how they exchange gases.
- Air enters the tracheae through the spiracles (pores on the outside)
- Tracheae branch into smaller tracheoles WHICH have thin permeable walls
- This allows oxygen to diffuse down a concentration gradient directly into repairing cells and waste CO² diffuses out.
- These insects also “pump” their abdomens rhythmically to move air in and out (maintaining steep concentration gradient).
How are terrestrial insects adapted to exchange gases efficiently?
- large SA: there are very many tracheoles, increasing the area over which diffusion can take place.
- short diffusion pathway: tracheal lines with single layer of cells to minimise distance travelled by gases.
- Maintenance of a steep conc. gradient: rhythmic abdominal movements (pumping), removing air low in O² out and allowing air high in O² in through spiracles.
- Also fluid in the end of tracheoles are removed/ moves outwards during abdominal pumping and exercise.
How do insects prevent water loss through water evaporating out and escaping?
- They close their spiracles as a preventative method; H²O vapour can’t diffuse out down concentration gradient for a (short?) period of time
- Waxy cuticle on surface; its impermeable to water so it can’t escape (no diffusion out of epithelial cells, same in plants)
- Hairs around spiracles; traps H²O vapour, decreasing the steepness of the conc. gradient, hence slowing the rate of diffusion.
How is the gill structure in a fish adapted for efficient gas exchange?
- large surface area: very many hill filaments that then have further lamellae structures.
- short diffusion pathway: lamellae have a thin exchange surface, short distance (see diagrams).
- steep oxygen concentration gradient: counter current AND flow of O² rich water outside and many blood capillaries.
what is the counter current principle?
This is where blood flows over the gill lamellae (that stick up) in the opposite direction to the flow of the fish’s blood.
Why is the counter current principle useful?
The counter current system helps maintain an oxygen diffusion gradient between the water and the blood ACROSS THE WHOLE LENGTH OF THE GILL LAMELLAE; so a maximum volume of oxygen can reach the cells, for respiration.
Read over
Food compounds such as starch, proteins and lipids are large and insoluble molecules, unable to be absorbed directly into blood. Must first be digested intibsmall soluble molecules.
- Digestion is catalysed by enzymes secrete6into the lumen of the digestive system.
Which enzymes are responsible for the complete hydrolysis of starch
amylase and then maltase
What are disaccharidases?
These are membrane bound enzymes that are attached to the cell membranes of epithelial cells lining the ileum and they hydrolyse disaccharides into monosaccharides.
2 locations where maltase is produced
salivary glands and pancreas
Give the name of the membrane bound enzymes located in epithelial cells lining the ileum
sucrase importantly
maltase
lactase
word equation for hydrolysis of maltase
Maltose»_space; (H²O + maltase)»_space; glucose + glucose
In the digestive system, what type of Bond is hydrolysed during the digestion of disaccharides into monosaccharides? what type of reaction?
glycosidic, hydrolysis; using water to break bonds
Suggest how the two monosaccharides of glucose and fructose individually might be transported across the cell membrane of the cells lining the ileum
Glucose is transported via co transport and fructose by facilitated diffusion
Which enzyme is responsible for hydrolyzing down triglycerides aka lipids
lipase
Where is lipase produced and where does it work?
Produced in the pancreas and works in the small intestine
word equation for hydrolysis of lipids
triglyceride»_space;(H²O + lipase)» monoglyceride and (2) fatty acids
What is a monoglyceride
A type of fatty acid consisting of one glycerol and one fatty acid chain attached to it
What bond is broken in the digestion of a triglyceride
ester
What effect would you expect the products of lipid digestion to have on the pH of the small intestine, explain.
To lower pH as fatty acids are acidic
Give two ways in which bile salts aid lipid digestion: technically the one way.
(The neutralize the pH - this is a side note, as it helps general digestion) and emulsify large lipids to increase the surface area for lipase to act on AND increase the rate of hydrolysis (before digestion).
Where is bile made and where is it secreted from
made in the liver and stored in the gallbladder secreted via the bile duct
What is a micelle and how is it formed
Micelles are formed after emulsification has taken place to create smaller lipid droplets. Then lipase hydrolyses the small lipid droplets to create micelles, which, are simply a structure of monoglycerides and fatty acids stuck to bile salts.
Hydrophobic inside, hydrophilic outside which allows it to dissolve (it’s water soluble)
how does a micelle aid lipid absorption and how the contents pass through the cell membrane?
Micelles allow for many monoglycerides and fatty acids to be transported at once with ease to where they need to be absorbed.
Hydrophobic inside, hydrophilic outside which allows it to dissolve (it’s water soluble)
-At the site of absorption, micelle breaks down and components are absorbed into the small intestine by simple diffusion BECAUSE phospholipid bilayer allows lipid soluble molecules (which are then taken away by chylomicrons)
General name for enzymes that break down on proteins, and then the 2 specific types
peptidases: endopeptidases and exopeptidases
Bond between amino acids of proteins that is hydrolysed (using water)
peptide bond
Main difference between endo and exopeptidases?
Exo: removes one amino acid off of the ends of polypeptide chain.
Endo: Produces polypeptide fragments from within the original polypeptide chain (in the middle)
Name of final product of protein digestion
amino acids
How does the action of endopeptidases affect the overall rate of protein digestion?
Rate increases and the surface area increases: which also allows for both endo/exopeptidases to work more efficiently
Which endopeptidase enzyme might have an optimum pH of around 2-3 and why?
Pepsi: works in the stomach where the HCl is present, so an acidic pH.
— Enzyme is produced in stomach and released into stomach by cells in the stomach lining.
State the 2 types (examples) of endopeptidases you have to know, and where they are produced
Trypsin and chymotrypsin
- fairly easy to remember due to trypsin common origin.
Produced in pancreas
What are dipeptides and dipeptidases? Where are these found?
2 amino acids
Enzyme that hydrolyses dipeptides and their peptide bond
Dipeptidases are membrane bound enzymes found in the ileum of the small intestine (on the epithelial cells?)
What is the role of water in protein digestion?
Hydrolyse peptide bonds in between amino acids
How are the following monosaccharides absorbed across the cell membrane:
1. glucose
2. galactose
3. fructose
- glucose absorbed by active transport/ co-transport with sodium ions via a co-transporter protein.
- galactose absorbed in same way via a co-transporter protein.
- fructose: facilitated diffusion through a different transporter protein
Intracellular enzyme
one working inside cells
how are monoglycerides and fatty acids absorbed across the cell membrane
Micelles help to move monoglycerides and fatty acids across the epithelium. This is because micelles constantly break up and reform so they can release the monoglycerides and fatty acids allowing them to then be absorbed, whole micelles are NOT taken up across the epithelium.
The contents are lipid soluble so can diffuse directly across.
how are amino acids absorbed across the cell membrane?
Amino acids are absorbed via co-transport in a similar way to glucose and galactose. Sodium ions are actively transported out of the ileum epithelial cells into the blood. Then this can create a Sodium Ion concentration gradients as the sodium ions can then diffuse from the lumen of the ileum into the epithelial cells through sodium dependent transporter proteins, carrying the amino acids with them
Would a mouse or an elephant lose heat quicker?
Mice = large SA: V and lose heat quickly due to this.
The mouse is very active so has a high metabolic (respiration) rate, releasing lots of heat energy, keeping the mouse warm.
- They also eat high energy foods like grains (and fur to reduce hear loss).
- Also as a note, it’s warmer underground, good for small animals
How do guard cells open and close stomata?
- photo synth. produces glucose, lowering the water potential within the guard cells
- hence, water molecules move from nearby epidermal cells into guard cells by osmosis down the water potential gradient.
- this makes them turgid; causing the stomata to open
What kind of environment do zerophytes live in?
- when writing exam Qs, you must try to link this to any adaptation you mention
These are plants adapted to their warm, windy, and dry habitats - where water loss by transpiration is often a problem.
NOTE THAT an increase in humidity can decrease the rate of diffusion.
Adaptations of zerophytic plants
- Sunken stomata trap water vapour, reducing evaporation rate by reducing concentration
- ‘Hairs’ on (lower) epidermis to trap water vapour near stomata
- Curled leaves w/ stomata inside - protects from wind that increase diffusion / evaporation by conc. gradient
- Less stomata to stop water escaping
- Thick waxy, Waterproof cuticles on leaves and stem epidermises, reduce evaporation.
Extra explanation on why curved leaves benefit xerophytic
prevents air high in water concentration from being swept away and replaced w/ low water concentration air.
Reducing evaporation from diffusion by having a shallow gradient.
remember
comparative language
relationship between internal and external intercostal muscles
antagonistic, move opposite
Events that happen when you exhailing - including pressure, volume, and muscles.
- the opposite for inhailing
- internal intercostal contract, external relax - antagonistic action.
- volume decreases (of thorax), gas pressure ^
- pressure gradient causes gas to move out (think due to build-up of pressure).
- diaphragm muscle relaxes & rises to cone shape, ribs move down and in
- THINK WHEN YOU EXHALE, YOU RELAX ON THE INSIDE, relax internal intercostal muscles.
Briefly describe inhalation in terms of thoracic/ lung volume and the diaphragm
diaphragm contracts & flattens, opening up lungs, which increases volume, and this change decreases the pressure.
Then, as a result, the pressure in the lungs is lower than the atmospheric pressure, so air can enter down the pressure gradient.
How does the oxygen diffuse in the final stages of breathing.
The alveoli are covered in a network of capillaries.
Oxygen enters by diffusing across alveolar epithelium and then, through capillary endothelium.
Adaptations for alveoli (explanations to do in your head)
- MANY networks of capillaries (maintain conc. gradient, blood brought to lungs is low in O2.
- Alveolar epithelium and capillary endothelium, diffuses across one cell layer of thickness AND flattened (or just thin), short d. pathway.
- MANY alveoli, large SA, ^ diffusion
- Ventilation ensures air high in O2 comes in, exchanges low O2 air, maintaining gradient
What lungs structures cause the pressure gradient?
What maintains the diffusion gradient?
the diaphragm and intercostal muscles (may want to watch a video on pressures)
ventilation by lungs and circulation of blood
A mountain climber is climbing at altitude, where there’s less O². Suggest how this will affect gas exchange in alveoli.
(note that less oxygen means that’s there’s higher pressure higher up)
Less air means less O² inhaled in each breath, so the concentration gradient between the alveoli and capillaries is less steep, so there’s a decreasing RATE of diffusion.
A mountain climber is climbing at altitude, where there’s less O². Suggest how this will affect gas exchange in alveoli.
(note that less oxygen means that’s there’s higher pressure higher up)
Less air means less O² inhaled in each breath, so the concentration gradient between the alveoli and capillaries is less steep, so there’s a decreasing RATE of diffusion.
Tidal volume
vol of air in each breath at rest
Ventilation rate
Number of breaths per min
Forced expiratory volume ¹ (FEV¹)
Max volume of air breathed out in one second
Forced viral capacity (FVC)
Max volume of air that’s forcefully breathed out after really deep breath in
What’s a spirometer?
A machine to measure lung function through the volume of air breathed in and out. You can figure out many measures through a graph produced from machine.
