Surface Area To Volume Ratio Flashcards
what is the surface area and volume of rectangular/cubes ,cylindrical and spherical prisms and give examples of things with each shape.
rectangular /cubes prisms
volume=widthlength/breadthheight
SA=(baseheight)6
-used to simplify calculations for organs with weird shapes
cylindrical prisms
V=2piersquared * height
SA=piersquaredheight
phloem,tubes,arteries,veins.vessle
sphere
V=4/3piercubed
SA = 4 piersquaed
-cells
1)what is surface area to volume ratio?
2)work out the SA:V ratio of cube a with a side length of 15.
3)what are some rules you must abide to ,when using surface area to volume ratio?
1)it is the surface area divided by the volume of the object.
Its used as a way to describe how close every internal part of the object is to its surface area.
2)V=3375
SA=1350
SA:V = 0.4:1
3)you must always represent to a ratio of 1 .
you must always represent ratio in the requested form.e.g SA:V not the other way around.
what is the relationship between size and SA:volume.
what does a higher and lower SA:V mean?
as the size of an organism increases SA:V ratio decreeases
lower=means it is a large organisms so diffusion of substances is lower
higher=(parts of the object are closer to the edge) means it is a smaller organism so diffusion is faster as the distance from the edge to the middle is short.
size determines SA:V so that determines diffusion distsnce
what is the relationship between surface area to volume ratio and metabolic rate?
organisms small is size have a large surface to volume ratio so they loose heat faster so they must respire more for so can do more reactions using the energy from respiration
when cells grow to a certain size diffusion becomes a limiting factor so what do they require?
what do thin structures with the same volume as thicker structures have?
larger organisms require more complex gas exchange surface to provide required oxygen.so they have evoloved to become multicellular they also need to provide adaptions for gas exchange.
faster diffusion
what is Ameoba and does it have a high or low SA:V ratio
unicellular(made up of a single cell) organism multicellular(made up of many cells)
Their small size means they have a high surface area to volume ratio so can rely on soley on simple diffusion as their diffusion pathway are short for substances to difffuse quickly.
Explain gas exchange in insects.
what is the tracheal system?
1)O2 enters through holes (spiracle) on the sides of the body (abdomen) down the concentration gradient. the spiracles open and close to control ventialtion.
2)these spiracles lead to tubes called tracheae which branch to become smaller tubes know as tracheoles.
3)at the end of the tracheoles are thin exchange surfacaes so oxygen can diffuse down the concetnration gradient from the air in the tracheoles into the body cells/muslces for movement.
tracheal system-a network of tubes which spread between the insects body cells
A)in what ways is an insects tracheal system adapted for effiecient gas exchange?
B)what can bigger insects do for faster diffusion rate?
1)tracheoles have thin walls and are highly branched so short diffusion distance to cells
2)higly branched so large surface area
trachea provides tubes full of air so fast diffusion
B)body can be moved by muscles to move air so maintains diffusion concentration for oxygen and carbon dioxide.
what issues must we consider when assesing uncertainty?
every measurement has some inherited uncertainity
1)the resolution of the instrument used e.g.mm or cm (mm has a better resolution as it has smaller divisions since 1cm =10 mm )so reduces rounding errors and allows for smaller changes in length
2)the size of increments available e.g the size of drops from a pippete
3)the judgement made by the experimenter
4)the procedure adopted e.g. repeated readingd
what is uncertainty?
what is uncertainty equal to?
a small diffrence between the measured value and the true value.
The uncertaintiy is equal to half of the smallest division on the scale being used.E.g scale goes up by 2 so its uncertainty is 1.
1)when measuring a potato how many points of error might there be in your measuremt?(length)
2)in temprature ?
3)when measuring the time taken to complete a race?
EDITTTTTTTNFROM POWERPOINTT
1) 2 (uncertainity may be between markings of the start and the end point)
2)1 (only at the end becouse it is a scaler quanity only has magnitude not direction and is measured at one single point )
3)2 (same as the length one )
How do insects ventilate ?
They open their spiracles
