mass transport feedback Flashcards
why would scientists use percentage change?
allows comparison which can be more accurate as starting points could be different
what is the cardiac output equation
CO=stroke volume x heart rate
why is the rise and fall in blood pressure greater in the aorta than smaller arteries?
- aorta is elastic and can stretch and recoil
- it needs a greater pressure to get oxygenated blood around the body
why does blood NOT accumulate in the arterioles?
there are many/more capillaries (than arterioles)
give one way on how sieve cells are adapted for mass transport? (in the phloem)
few organelles/little amount of cytoplasm so more/easier flow of organic substances in the tube (sieve tube?)
give one way on how companion cells are adapted for the transport of sugars between cells?
mitochondria releases ATP for active transport and has more organelles than sieve cells for metabolic processes/reactions
how does plasmodesmata help in the phloem?
The cytoplasm in the sieve tube elements and companion cells linked by gaps between the cells walls=plasmodesmata.Allows communication and flow of substances
what is the result of a steeper water potential gradient on the rate of transpiration?
a greater rate of transpiration
what is the effect of low humidity on the rate of transpiration?
fewer water vapour molecules outside the leaf so a steeper water potential gradient between the air spaces in the leaf and the air outside so higher rate of transpiration.
what is the effect of high wind speed on the rate of transpiration?
reduces layer of still air surrounding stomata so steeper water potential gradient between the air spaces in the leaf and the air outside therefore a higher rate of transpiration.
what is the effect of high temperature on the rate of transpiration?
kinetic energy of water molecules increases so rate of evaporation from mesophyll cells to air spaces in the leaf increases+increased saturation point of the air outside the leaf so steeper water potential gradient meaning higher rate of transpiration.
what is the effect of high light intensity on the rate of transpiration?
stomata opens so CO2 can be provided to plants for photosynthesis but opening increases rate of water vapour diffusing out so increases the rate of transpiration.
what is the effect of low rainfall/dry conditions on the rate of transpiration?
water potential gradient between inside of leaf and external air is steep BUT little amount of water in the soil so rate of transpiration exceeds water uptake so plant wilts and closes its stomata decreasing the rate of transpiration.
