B2.2 Flashcards
starting at the roots describe the path a water molecule will travel in the transpiration stream
-water enters roots by root hairs
-water is drawn up the leaf stem
-water moves into leaf
-water escapes stomata
how does water enter the root hair cells?
through osmosis
how do mineral ions enter the root hair cells?
through active tranport
surface area
the total area that the surface of the object occupies
volume
quantity of space that a substance occupies or contains
surface area to volume ratio
ratio used to compare the volume of an object with the surface area of an object
arteries
takes blood away from the heart
properties of arteries
-small lumen
-thick walls as blood in arteries are high pressure so walls don’t burst
-stretchy elastic fibres to keep pressure constant
veins
take blood towards the heart
properties of veins
-thin walls
-large lumen
-valves so blood doesn’t flow the wrong way as it’s low pressure
capillaries
small vessels that take blood to the body
properties of capillaries
-single cell thick walls
-small lumen so diffusion is quicker
what are the 4 components of blood?
-red blood cells
-white blood cells
-plasma
-platelettes
what is the acronym for the flow of blood around the heart?
Left
Oxygentated
Right
Deoxygenated
adaptions of alvoeoli
-thin walls so diffusion can occur quickly
-single layer of flat cells for diffusion to occur through
-moist for solution of gases
-network of capillaries around each alveolus to maximise gas exchange
-there are lots of them
adaptations of villi
-thin walls so diffusion can occur quickly
-single layer of flat cells for diffusion to occur through
-network of capillaries around each alveolus to maximise absorption of nutrients
-there are lots of them and intestine is very long
Why’s surface area to volume ratio important?
-large surface area : volume ratio means nutrients can diffuse directly into the organism quickly enough to sustain life, as diffusion distances are small
-the larger the organism, the lower the surface area : volume ratio
can multicellular organisms use just diffusion to survive?
most multicellular organisms cannot use simple diffusion to survive as diffusion over the greater distance cannot occur fast enough to meet the cells demands
how have multicellular organisms adapted to increase the surface area : volume ratio at exchange surfaces?
to maximise the rate of diffusion of oxygen into the bloodstream, lungs contain many alveoli
describe the flow of blood around the body?
- deoxygenated blood is pumped from the right side of the heart to the lungs
- in the lungs CO2 diffuses out of the blood and oxygen diffuses into it (gas exchange)
- oxygenated blood travels from the lungs to the left side of the heart and is pumped to the body
- oxygen diffuses out of the blood and into the tissues and CO2 diffuses into the blood
- deoxygenated blood returns to the heart
vena cava
carries blood into the heart from the body
aorta
carries blood around the body
pulmonary artery
carries blood to the lungs
pulmonary vein
carries blood into the heart from the lungs
left atrium
has thin walls
left ventricle
has very thick walls; pumps blood to the body
right ventricle
has thick walls; pumps blood to the lungs
right atrium
has thin cell walls
xylem
transports water and mineral ions upwards
phloem
transports sugars upwards and downwards
translocation
movement of sugars from where they are produced to where they are needed
where does translocation take place?
in the phloem
transpiration
the loss of water from the leaves of a plant
transpiration stream
constant flow of water from the roots, through the xylem and out the leaves
what piece of equipment is used to estimate transpiration rates?
potometer
properties of the xylem
-carries chemicals needed for photosynthesis
-consists of dead cells
properties of the phloem
-carries chemicals made during photosynthesis
-consists of living cells
where will sugars be needed in a plant?
-all cells for respiration
-growing parts of the plant
-storage parts of the plant
-developing seeds
what are the stomata?
pores in a leaf, mostly on the undersurface
how do stomatas work?
each pore is surrounded by a pair of guard cells which can change shape to open or close stomata:
-stomata open = guard cells swollen / turgid
-stomata closed = guard cells shrunken / flaccid
what equation is used for the rate of transpiration?
rate of movement = distance / time
factors affecting the rate of transpiration
-light
-temperature
-wind
-humidity
how does light affect the rate of transpiration?
it increases it because the stomata open wider to allow more CO2 into the leaf for photosynthesis
how does temperature affect the rate of transpiration?
it increases it because evaporation and diffusion are faster at higher temperatures
how does wind affect the rate of transpiration?
it increases it because water vapour is removed by air movement, speeding up diffusion of more water vapour out of the leaf
how does humidity affect the rate of transpiration?
it decreases it because diffusion of water vapour out of the leaf slows down if the leaf is already surrounded by moist air
