Chapter 6 - Exchange Flashcards
Who has a larger surface area to volume ratio out of a mouse and an elephant?
Mouse
What are the 2 possible scenarios that might be asked about in relation to surface area to volume ratio
- The absorption of oxygen in single celled organisms
- Heat conservation/loss between mammals
How does extreme enter a single celled organism or a flatworm
Direct diffusion
What is a single celled organisms SA:VOL like
And how does oxygen diffuse into it
Very high SA:VOL
O2 observed through membrane
What does it mean if a mammal has a higher SA:VOL than another?
They lose more heat per gram of body weight
What does a mammal have to do if it loses more heat per gram of body mass
- Requires a faster rate of respiration
- As it needs more oxygen to maintain body temperature
How does an elephants rate of respiration differ to a mice?
Elephants is slower as they don’t need as much oxygen to maintain body temperature due to a smaller SA:VOL
What does the rate of diffusion for gas exchange depend upon? (Fick’s law)
Surface area of membrane
Diffusion distance (thickness)
Concentration gradient
What is fick’s law
Rate of diffusion is proportional to
Surface area x concentration difference/diffusion distance
Explain how gas exchange occurs in insects
- Air enters through spiracles into trachea
Trachea divide into tracheoles - Oxygen diffuses does concentration gradient along tracheoles
- Tracheoles are closely surrounded by cells so oxygen diffuses into cells
- Ventilation occurs, where air in trachea and tracheoles is replaced to maintain concentration gradient of oxygen between air and cells
What are examples of water loss adaptations in insects
- Body is covered by waxy cuticle to reduce evaporation
- Insects can close spiracles
Why are insects not able to grow to a large size?
Insects rely on diffusion to exchange gases directly between the environment and its cells, therefore a short diffusion pathway is needed
This means that they can’t grow to a much larger size
What is the way in which gas exchange in fish occurs referred to as
Counter current flow
What is meant by counter current flow
Water and blood moving in opposite directions
What is the purpose of counter current flow
- A high concentration gradient can be maintained across the entire surface, water is always next to blood with a low oxygen concentration
What are some adaptations that increase efficiency of diffusion in fish
- Filaments and lamellae have a large surface area
- Thin epithelium(short diffusion distance
- Circulation of blood, means that deoxygenated blood replaces oxygenated blood to maintain concentration gradient
- Ventilation of water means that oxygen is not lost by diffusing back into water
What are dicotyledonous plants
Plants with leaves
Explain gas exchange in dicotyledonous plants
- Air enters through stomata
- Gas exchange of CO2 and O2 occurs in mesophyll
What is an adaptation of mesophyll and why is this
They are spongy, so can increase surface area
How are dicotyledonous plants adapted to reduce water loss and how does this happen
- Guard cells can open and close stomata
- If a plant has a lot of water, cells are hard
- If it has a lack of water, cells are flacid, and if guard cells are flacid they close the stomata
What is a xerophytic plant
A plant in dry conditions eg cacti
What are 5 adaptations of xerophytic plants
- Curled leaves (spikes)
- Stomata sunken in pits
- Hairs on epidermis of leaf (bottom)
- Thick waxy cuticle
- Few stomata
How do curled leaves, sunken stomata and hairs on epidermis help to reduce water loss
- Reduces ventilation of air
- Therefore water vapour accumulates within the leaf (outside stomata)
- This decreases diffusion gradient for water vapour
- Reduces water loss
How does a thick waxy cuticle reduce water loss in xerophytic plants
- Reduces evaporation of water from leaf, thus reduces water loss
How does having fewer stomata reduced water loss for xerophytic plants
Fewer stomata mean there is less opportunity for water loss via stomata
What are the adaptations for efficient gas exchange in humans? (Surface area)
- Alveoli at end of bronchioles
- Large number of them
- They have a folded membrane to increase surface area
- Many small capillaries to increase surface area
What are the adaptations for efficient gas exchange in humans? (Concentration gradient)
- Ventilation through breathing replaces air with high CO2 and low O2 concentration
- Circulation of blood, deoxygenated blood is replaced by blood with high CO2 and low O2 concentration
- Both increase concentration gradient
What are the adaptations for efficient gas exchange in humans? (Diffusion distance)
- Thin epithelia In alveoli and capillaries
- One cell thick
- Short diffusion pathway
What is meant by tidal volume
Volume of air breathed in or out per breath at rest
What is meant by ventilation/breathing rate
Number of breaths per minute
What is meant by pulmonary ventilation
Total volume of air breathed in per minute
Calculation for pulmonary ventilation
Tidal volume x breathing rate
What is meant by oxygen consumption
Volume of oxygen used per min
What is meant by vital capacity
Maximum volume of air that can be exhaled after maximum volume of air inhaled
What is meant by residual volume
Volume of air that can’t be breathed out after maximum inhale and exhale
What is the effect of exercise on tidal volume
Increases, deeper breaths
What is the effect of exercise on breathing rate
Increase, faster breaths
What is the effect of exercise on pulmonary ventilation
Increase, more breaths per min
What is the effect of exercise on oxygen consumption
Increases, due to more respiration
Draw a spirometer trace and label it with vital capacity, residual volume and tidal volume
Snapchat memories 14 nov
Explain the mechanics of breathing for inspiration
- Diaphragm contracts (flattens)
- External intercostal muscles contract, rib cage moves up and out
- Increasing volume of thorax (chest cavity)
- Decreases air pressure in thorax, so air moves in from high to low pressure
Explain the mechanics of breathing for expiration
- Diaphragm relaxes (becomes domed)
- External intercostal muscles relax
- Rib cage moves down and in
- Decreases volume of thorax
- Increases air pressure in thorax
- Air moves out from high to low pressure
Explain the mechanics of breathing for forced expiration
- Internal intercostal muscles contract
- Pulls rib cage down more and faster
- Internal and external intercostal muscles are an antagonistic pair
What is meant by digestion
Large biological molecules are hydrolysed (broken down) by enzymes into smaller molecules that can be absorbed across a cell membrane
Explain digestion of carbohydrates
- Amylase hydrolyses glycosidic bonds in starch (polysaccharide)
- Form maltose (disaccharide)
- Maltase hydrolyses glycosidic bonds in maltose
- Form 2 glucose molecules
How are carbohydrates absorbed
After being digested into glucose, they are absorbed by co-transport with sodium ions
Where is amylase found and where is it made
Found in saliva
Made in pancreas
Where is maltase made
Small intestines
What is sucrose broken down into
Glucose and fructose
What is lactose broken down into
Glucose and galactose
Explain the digestion of lipids
- A lipid droplet (triglyceride) is emulsified by bile salts
- Emulsified means make them smaller, thus increase SA:VOL
- Lipase (enzyme) breaks the emulsified lipid droplets down into a monoglyceride and 2 fatty acids
What are micelles
Tiny droplets of monoglycerides and fatty acids
Where are bike salts produced
Liver
What are the three ways that proteins are broken down
Endopeptidase
Exopeptidase
Membrane bound dipeptase
What does endopeptidase do
Hydrolyses peptide bonds within a polypeptide
What does exopeptidase do
Hydrolyses peptide bonds at the end of polypeptides
What does membrane bound dipeptase do
Hydrolyse the peptide bonds between dipeptides
Explain how amino acids are absorbed
- Co-transport with sodium
- sodium pumped out
- Low concentration of sodium
- Sodium diffuses in via carrier protein
- Amino acids are also absorbed via co-transport (against concentration gradient)
How are lipids absorbed
- Once broken down into micelles, these release monoglycerides close to surface of the cell
- These are small non-polar molecules so diffuse in to epithelium of cell
