3.3 Exchange With The Environment Flashcards
How do you calculate the perimeter of a square?
4 x side length
How do you calculate the perimeter of a rectangle?
2 x (length + width)
How do you calculate the circumference of a circle?
2 x pi x radius
How do you calculate the area of a square?
side^2
How do you calculate the area of a rectangle?
Length x width
How do you calculate the area of a circle?
Pi x radius squared
How do you calculate the surface area of a cube?
6 x side squared
How do you calculate the surface area of a sphere?
4 x pi x radius squared
How do you calculate the surface area of a cylinder?
2(pi x radius squared) + 2 x pi x radius x height
How do you calculate the volume of a cube?
Side^3
How do you calculate the volume of a rectangular prism?
Side 1 x side 2 x side 3
How do you calculate the area of a sphere?
(4/3) x pi x radius ^3
How do you calculate the volume of a cylinder?
Pi x r^2 x height
how can single celled organisms provide their nutrients?
they can use diffusion and diffusion alone as the diffusion pathway is short
how do multicellular organisms provide all of their cells with the nutrients they need?
they require transport systems and specialised exchange surfaces
why do organisms with a high metabolic rate need an increased diffusion rate?
they exchange more nutrients
as size increases, what happens to the SA:V ratio?
it decreases
what is exchange like in small organisms?
large SA:V ratio, exchange directly with the environment
what is exchange like in large organisms?
smaller SA:V ratio, specialist exchange surfaces to meet the organisms demands, mass transport system to deliver and remove material
describe how single celled organisms are adapted for gas exchange (3 marks)
they have a large surface area to volume ratio so there is more space for the gas to diffuse across, they are only one cell thick therefore there is a short diffusion pathway to allow for quicker gas exchange, only have a cell surface membrane, no cell wall, so no additional barrier to diffusion
why can insects not use their body for gas exchange?
this would result in water loss, increasing their surface area for gas exchange conflicts with water conservation, they need to balance the needs to exchange gases with the need to conserve water as they are terrestrial they have mechanisms to conserve water
how do insects limit water loss?
have exoskeletons/shells to stop water loss (rigid exoskeleton made of chitin, waterproof cuticle), small SA:V ratio minimises water loss area, spiracles open and close to limit water loss
what are the limitations of the tracheal system in insects?
relies on diffusion rather than a transport system, diffusion distance must be short, limits the size that insects can grow to
are fish adapted to exchange materials via their surface?
no, relatively large so small SA:V ratio, waterproof, gas tight outer coating, surrounded by water, less dissolved gas, specialised internal gas exchange surface/system via the gills
how are the gills adapted for gas exchange?
large surface area provided by gill lamellae on the gill filaments at right angles, rich blood supply, counter current flow, blood passes opposite way to water
how does counter current flow optimise gas exchange at the gills?
the flow of water over the gill lamellae and the flow of blood within them are in opposite directions, maintains a favourable concentration gradient across the whole gill, the blood is always next to water with higher level of oxygen, blood already loaded with O2 meets water which has maximum concentration of oxygen, therefore oxygen diffuses into the blood, blood with low O2 concentration meets water that has had most of its O2 removed so diffusion still happens. 80% of the available O2 is absorbed compared to 50% in parallel flow
How do insects use the tracheal system to exchange gases?
They have microscopic air filled pipes called tracheae which they use for gas exchange, air moves into the tracheae through pores on the surface called spiracles, oxygen travels down the concentration gradient toward the cells, the tracheae branch off into smaller tracheoles which have thin, permeable walls and go to individual cells meaning oxygen diffuses directly into the respiring cells, the insects circulatory system doesn’t transport O2. Carbon dioxide from the cells moves down its concentration gradient towards the spiracles to be released into the atmosphere, they ie rhythmic abdominal movements to move air in and out of the spiracles,
Why are the end of the tracheoles filled with water?
anaerobic respiration produces lactate, lactate is water soluble so lowers WP of muscle cells, water moves into muscle cells from tracheoles, volume in tracheole ends decreases, drawing air in
how do spiracles open and close?
by a valve
what are dicotyledonous plants?
flowering plants, the seed bears two cotyledons (seed leaves)
what is the symbol equation for aerobic respiration?
6O2 + C6H12O6 -> 6CO2 + 6H2O + energy
what is the symbol equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
how is a large surface area beneficial for diffusion?
greater surface for diffusion to take place
how is being thin beneficial for diffusion?
one cell thick, short diffusion pathway
how is being selectively permeable beneficial for diffusion?
control what goes into and out of the cell
how is a steep diffusion gradient beneficial for diffusion?
increased rate of diffusion
what are the structures found in a leaf?
upper epidermis; cuticle, upper epidermis cells. upper mesophyll; palisade mesophyll cells. lower mesophyll; xylem. phloem, sheath, spongy mesophyll cells, sub-stomatal air space. lower epidermis; lower epidermis cells, guard cells, stoma
what sub cellular structures are found in a palisade cell?
ribosomes, Golgi apparatus, chloroplasts, mitochondria, cell membrane, vacuole, amyloplast, SER, nucleus, RER, cell wall
what is the function of the stomata?
small pores, allow gases in and out, all cells are close to the stomatal pore therefore there is a short diffusion pathway
what is the function of sub stomatal air spaces?
interconnected air spaces throughout the mesophyll layer so gases can move around mesophyll cells
what is the function of the spongy mesophyll layer?
large surface area of mesophyll cells allows for maximum diffusion
what is the transpiration stream?
transports water from the roots to the leaves, created as water is evaporated from the surface of the leaf
what are xerophytes?
plants adapted to living in areas with a short supply of water
why do xerophytes need a thick cuticle?
acts as a waterproof barrier
why do xerophytes need rolled up leaves?
stomata on lower epidermis protected/ trap still air, traps water vapour = high WP so no WP gradient
why do xerophytes need a sunken stomata?
traps still, moist air, lower water potential gradient
why do xerophytes need hairs on leaves?
traps still, moist air, lower WP gradient
why do xerophytes need non typical leaves to reduce SA:volume ratio?
slower rate of diffusion, still able to photosynthesise