Exchange Flashcards
define surface area
the area outside of an object
define volume
the amount of space inside of an object
how do you calculate surface area : ratio
surface area / volume
how does size relate to surface area to volume ratio
the larger the object, the smaller the SA:V, theyre inversely proportional
how do you compare SA:V
make volume 1
define metabolic rate
the amount of energy used by that organism in a time period
define metabolic demand
how much oxygen and nutrients an organism needs to take in daily to respire enough to maintain the metabolic rate
what happens to the metabolic rate as mass increases
it increases
why do larger organisms have a harder time getting the oxygen and nutrients they need from the environment
larger SA:V ratio means there is a greater diffusion distance
what happens to metabolic rate as SA:V increases
it decreases
why do small organisms have a higher metabolic rate per unit of body mass
as they have a higher SA:V so they lose heat easier, more energy is needed to mantain body temp
how have small mammals with high SA:V addapted to survive cold environments behaviourally (2)
- by eating high energy foods like nuts and seeds to mantain body tem
- hibernating during colder months
how have small mammals with high SA:V addapted to survive cold environments physically (2)
- compact body shape gives it a smaller SA:V
- thick layers of fur to insulate and reduce heat loss
how have large organisms addapted to survive hot environments behaviourally (2)
- stay in water during the day to help them lose heat
- being nocturnal, most active in cooler temps
how have large organisms with low SA:V addapted to survive hot environments physically
- large ears allow them to increase their surface area to allow them to lose more heat
how have organisms adapted to survive dry environments behaviourally
- by being nocturnal so they’re active during the cooler temps
how have small mammals with high SA:V adapted to survive dry environments
- by having kidney structures that produce less urine to compensate for water loss through evaporation
what does it mean if muscles work antagonistically
they work in pairs where one contracts and the other relaxes
what is the muscle pair in the oesophagus
circular muscle (the outer one)
longitudinal muscle (inner one)
what is the start of the small intestines called
the duodenum
where is villi found, why is it useful
the illeums inner walls folding, gives it a larger surface area; useful for absorption
how is the large intestines also refered to
the colon
define digestion
the breaking down of food into smaller molecules
where does absorption of nutrients occur
the illeum
where are enzymes secreted in the small intestines
via the glands found in the ileums walls
what are the 7 components of villi
epithelium
goblet cells
endocrine cells
intestinal gland
microvilli
lacteal
blood capillaries
what do goblet cells (on villi) do
secrete mucus to lubricate the movement of food molecules, has no microvilli
what are the 4 adaptations of the small intestines to help with absorption
- internal walls are folded into projections called villi to increase surface area
- villi have a one cell thick epithileum to keep the diffusion pathway short
- villi have lots of capillaries to help maintain the concentration gradient
- villi contains muscles that can move to mix the contents of the ileum and maintain the concentration gradient
what lines the ileum
epithelial cells
how are epithelial cells adapted for absorption (4)
- by having microvilli to increase surface area for diffusion
- by having many mitochondria to release energy for active transport
- by having carrier proteins for active transport
- by having channel proteins for active transport
how are epithilal cells adapted for digestion and absorption
by having membrane bound disaccharidases, means monosaccharides are porduced close to the membrane for faster absorption
where is the enzyme amylase produced
the salivary glands and the pancreas
what does amylase do
breaks glycosidic bonds to hydrolyse starch into maltose
what do dissacharidases do
break glycosidic bonds to hydrolyse disaccharides into monosaccharides
what are the 3 membrane bound disaccharidase enzymes
maltase
sucrase
lactase
why is it important for disaccharides to be broken down into monosaccharides
so they are small enough to be transported across the epithelial cell membrane through transport proteins.
how does glucose and galactose get absorbed in digestion (3)
-they’re co-transported with sodium ions via active transport through the epithelial cells of the ileum
- inside the ileum there is a lower Na+ concentration due to a sodium pump which pushes them out the ileum against an active transport gradient
- glucose / galactose are then diffused into nearby capillaries via facilitated diffusion as there is a concentration difference
how is fructose absorbed in digestion
by facilitated diffusion with a transport protein.
