Pack 7 - Exchange Flashcards
List 4 factors affecting diffusion
Surface area
Diffusion distance
Concentration gradient
Temperature
How do you calculate the surface area of a cube?
6side²
How do you calculate the volume of a cube?
side³
As an object gets larger which is happening to its surface area to volume ratio?
Decreases
What structures are present in the small intestine that help absorption?
Villi
Why do elephants need large ears?
To have a larger surface area:volume ratio for increased heat loss
Do animals with a larger SA:Vol require a higher or lower rate of metabolism?
Higher: higher SA:Vol leads to more heat loss
More respiration is therefore required to maintain the animal’s temperature
Define respiration
The release of energy (ATP synthesis) from food
eg. glucose/fats and proteins if desperate
What is respiration with O2 called?
Aerobic respiration
What is respiration without O2 called?
Anaerobic
What is the word equation for aerobic respiration?
Glucose + oxygen -> CO2 + H20 + Energy (ATP and heat)
What is the word equation for anaerobic respiration?
Glucose -> lactate + energy (ATP and heat)
Which type of respiration produces more ATP?
Aerobic
Aerobic Anaerobic
38 ATP : 2 ATP
Do all organisms need to respire?
Yes
List 6 features of an effective gas exchange surface
And why (think Fick’s law)
- Moist - To dissolve gases
- Large SA:Vol - SA
- Thin - DD
- Permeable to gases - To allow gas exchange
- Ventilation - CG
- Movement of internal medium - CG
What will happen to the rate of diffusion if diffusion distance is increased?
It will fall
What will happen to the rate of diffusion if SA:Vol is increased?
It will increase
What will happen to the rate of diffusion if the concentration gradient is decreased?
It will fall
Give an example of a single-celled protoctista?
Amoeba
How do amoeba get their O2 in and CO2 out?
Simple diffusion
Why do amoeba not need a specialised gas exchange system?
They are single-celled and therefore have a small diffusion distance for gases to travel
Why do bigger animals develop specialised respiratory surfaces/transport systems?
Most cells are far from the surface and so receive inadequate oxygen
Many larger animals have an increased metabolic rate, increasing oxygen demand
Give an example of a respiratory pigment
Haemoglobin
Give an example of a ventilation movement
Breathing
Why is spongy mesophyll made up of irregular cells?
Increased surface area due to more exposed CSM
Therefore a faster rate of diffusion
Do plants photosynthesise or respire at a higher rate at night?
Respire
Lack of sunlight means ineffective/no photosynthesis
Do plants photosynthesise or respire at a higher rate at in the day?
Photosynthesise
What is the function of stomata?
Open in light/close in dark
When open gas exchange is able to occur through them
-For metabolic needs eg. photosynthesis, respiration
Close (shrunken guard cells) if the plant looses too much water
-Reducing water loss through transpiration through open stomata
If a leaf is losing too much water, what will it do and how will this affect gas exchange in the leaf?
Close the stomata
Reduce gas exchange
-lower volume of gases diffusing in and out of the leaf
What is transpiration?
Evaporation of water from a plant leaf
Give 4 factors that will increase transpiration rate
Hot
Windy
Dry
Sunny
Define hydrophyte
Live in environment with LOTS of water availability
Define mesophyte
Live in environment with MODERATE water availability
Define xerophyte
Live in environment with LOW water availability
How does water potential gradient affect water loss from stomata?
More water is lost when there is a greater water water potential gradient between the inside and outside of the stomata
List 5 ways xerophytic plants are adapted to reduce water loss
And link to Fick’s law
Thick cuticle - DD
Rolled up leaves - CG (traps moist air on inside)
Hairy leaves - CG (traps moist air)
Stomata on pits/grooves - CG
Reduced SA:Vol of the leaves - SA (traps moist air)
Trapping moist air lowers the ψ gradient, lowering rate of diffusion, reducing water loss from the plant
Why do insects have a waterproof cuticle?
Water evaporates from their surfaces as they live on land and can become easily dehydrated
They conserve water by having waterproof coverings
How do insects respire?
Spiracles (pores) on their thorax and abdomen lead to
Tracheae (strengthened rings of chitin) dividing into
Tracheoles which bring atmospheric air directly into respiring cells
The spiracles can be opened and closed by valves which allow the insects to control water loss
What feature of respiratory surfaces is missing in an insect?
Permeable surface (exoskeleton)
How does oxygen enter the tracheal system?
Moving down the concentration gradient
Ventilation - moving muscles means air is taken in via the spiracles in the abdomen
Why are insects small?
To have short diffusion pathways for efficient respiration
What is the effect of exercise on the gas exchange of insects?
- Anaerobic respiration takes place
- Lactate increases
- Ψ decreases in muscle
- Water enters muscle via osmosis
- Air drawn into tracheoles
- Increases SA for gas exchange
- O2, CO2 diffuse faster through gases than liquids
- Increased respiration
What is the advantage of water entering insect’s muscle cells from the tracheoles?
O2, CO2 diffuse faster through gases than liquids, increasing respiration
How do insects limit water loss?
Hard, impermeable exoskeleton - reduces water loss from the whole body
Small SA: Vol - lower rate if diffusion of water
Valves around the spiracles - shut to reduce water loss from spiracles SA:Vol
Setae around the spiracles - hairs that trap most air reducing the concentration gradient therefore slower evaporation of water
What is Fick’s Law?
Diffusion rate ∝ Conc. Grad. × Surface Area
Diffusion Distance
Which areas of Fick’s Law do you want to keep large and small?
Big × Big
Small
How do fish move water over the gill?
Bony fish have four pairs of branchial arches supporting gill lamellae. These are covered by a muscular flap - the operculum.
- Fish open their mouth and lower the floor of the buccal cavity
- This increases the volume and decreases the pressure in the mouth, compared to outside, and so water enters down the pressure gradient
- The operculum is closed at this stage
- Then the fish closes its mouth and raises the floor of the mouth
- This has the effect of decreasing the volume and increases the pressure compared to outside and so forces water through the gills and out through the operculum