Organisms exchange with environment Flashcards
Surface are to vol ratio gas exchange digestion and absorption mass transport
Describe the internal structure of a leaf
wax cuticle
thin upper epidermis layer
palisade mesophyll
spongy mesophyll
within mesophyll layers are air spaces
lower epidermis, contains stomata and guard cells
Explain how the structure of a leaf is adapted to allow efficient gas exchange
-air spaces within spongy mesophyll, creates a large surface area for gas exchange
-chloroplasts are close to the membrane as vacuole of palisade cells push
-palisade cells are long + thin so large surface area for diffusion
-thin so short diffusion pathway
what is a xerophytic plant
a plant living where water is in short supply with adaptions for this condition
Explain the adaptions of a xerophytic plant
-thick waxy cuticle to increase diffusion pathway, reducing evaporation
-hairs on leaf to trap water vapor, reducing water potential gradient
-curled leaves reduces surface area, reduces SA:V , increases local humidity so reduces water potential gradient
-sunken stomata to increase local humidity, reduces water potential gradient
-thick stems
-widespread root system
Describe the structure of an insects tracheal system
spiracles, trachea, air sac, tracheole, muscle cell
Explain how the tracheal system is adapted for sufficient gas exchange in insects
-spiracles so gas exchange can take place through impermeable -exoskeleton
-tracheae are highly branched helping to increase the Surface area : volume ratio available for gas exchange
-trachea straight into muscle cells, increases rate since no time is lost in circulation
Explain how the tracheal system of insect balance the need for gas exchange but minimizes water loss
-sunken spiracles
-waterproof exoskeleton that prevents water loss
Describe the structure of fish gills
gills on each side of the head
Each gill arch is attached to two stacks of filaments
On the surface of each filament, there are rows of lamellae
The lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries
Explain how fish gills are adapted to maximizing gas exchange
-counter current mechanism-blood and water flows in opposite directions, ensures the concentration gradient is maintained along the whole length of the capillary, water with the lowest oxygen concentration is found adjacent to the most deoxygenated blood
-large surface are due to many filaments
-constant blood supply
-Epithelium covering gills is only one cell thick
-thin lamellea, short diffusion distance
Explain the role of cartilage in the trachea and bronchi
c shaped rings for flexibility and strength
Explain the purpose of the ciliated epithelial cells in the trachea
cilia are hair like projections captures pathogens + particles
contains goblet cells which produce mucus to trap particles and cilia remove mucus
Explain the process of inspiration
External intercostal muscles contract, air enters the lungs, diaphragm contracts/flattens, thorax volume increases, pressure inside lungs is lower than atm pressure
Explain the process of expiration
Internal intercostal muscles contact, air enters the lungs, diaphragm relaxes/domes, thorax volume decreases, pressure inside the lungs is higher than atm pressure
What is the equation of Ficks Law
Rate of diffusion= (surface area x difference in conc) / length of the diffusion pathway
explain Fick’s law in terms of rate of photosynthesis
more co2 = more photosynthesis= more glucose formed= more growth of cell, cellulose
Explain the adaption of the tracheal system of an insect in flight
water accumulates at end of tracheole, move in to muscle cells by osmosis during anaerobic respirations, this produces lactic acid which lowers the water potential, gas exchange more efficient as increases concentration gradient for oxygen in air v cells water
give brief adaptations of gas exchange surface
* across the body surface of a single-celled organism
* in the tracheal system of an insect (tracheae, tracheoles and
spiracles)
* across the gills of fish (gill lamellae and filaments including
the counter-current principle)
* by the leaves of dicotyledonous plants (mesophyll and
stomata).
- thin so short dp incrs rate of simple diffusion, large sa:vol incr rate across whole body cell
-spiracles allow o2 to pass through exoskeleton, many tracheoles incr sa
-counter current incr exchange accross whole length, many lamelle incr sa, thin decr dp
-spongy mesophyl incr sa, thin short dp, palisade mesophyl long so large sa