Exchange

Question 1

define surface area

Answer 1

the area outside of an object

Question 2

define volume

Answer 2

the amount of space inside of an object

Question 3

how do you calculate surface area : ratio

Answer 3

surface area / volume

Question 4

how does size relate to surface area to volume ratio

Answer 4

the larger the object, the smaller the SA:V, theyre inversely proportional

Question 5

how do you compare SA:V

Answer 5

make volume 1

Question 6

define metabolic rate

Answer 6

the amount of energy used by that organism in a time period

Question 7

define metabolic demand

Answer 7

how much oxygen and nutrients an organism needs to take in daily to respire enough to maintain the metabolic rate

Question 8

what happens to the metabolic rate as mass increases

Answer 8

it increases

Question 9

why do larger organisms have a harder time getting the oxygen and nutrients they need from the environment

Answer 9

larger SA:V ratio means there is a greater diffusion distance

Question 10

what happens to metabolic rate as SA:V increases

Answer 10

it decreases

Question 11

why do small organisms have a higher metabolic rate per unit of body mass

Answer 11

as they have a higher SA:V so they lose heat easier, more energy is needed to mantain body temp

Question 12

how have small mammals with high SA:V addapted to survive cold environments behaviourally (2)

Answer 12

• by eating high energy foods like nuts and seeds to mantain body tem
• hibernating during colder months

Question 13

how have small mammals with high SA:V addapted to survive cold environments physically (2)

Answer 13

• compact body shape gives it a smaller SA:V
• thick layers of fur to insulate and reduce heat loss

Question 14

how have large organisms addapted to survive hot environments behaviourally (2)

Answer 14

• stay in water during the day to help them lose heat
• being nocturnal, most active in cooler temps

Question 15

how have large organisms with low SA:V addapted to survive hot environments physically

Answer 15

• large ears allow them to increase their surface area to allow them to lose more heat

Question 16

how have organisms adapted to survive dry environments behaviourally

Answer 16

• by being nocturnal so they’re active during the cooler temps

Question 17

how have small mammals with high SA:V adapted to survive dry environments

Answer 17

• by having kidney structures that produce less urine to compensate for water loss through evaporation

Question 18

what does it mean if muscles work antagonistically

Answer 18

they work in pairs where one contracts and the other relaxes

Question 19

what is the muscle pair in the oesophagus

Answer 19

circular muscle (the outer one)
longitudinal muscle (inner one)

Question 20

what is the start of the small intestines called

Answer 20

the duodenum

Question 21

where is villi found, why is it useful

Answer 21

the illeums inner walls folding, gives it a larger surface area; useful for absorption

Question 22

how is the large intestines also refered to

Answer 22

the colon

Question 23

define digestion

Answer 23

the breaking down of food into smaller molecules

Question 24

where does absorption of nutrients occur

Answer 24

the illeum

Question 25

where are enzymes secreted in the small intestines

Answer 25

via the glands found in the ileums walls

Question 26

what are the 7 components of villi

Answer 26

epithelium goblet cells endocrine cells intestinal gland microvilli lacteal blood capillaries

Question 27

what do goblet cells (on villi) do

Answer 27

secrete mucus to lubricate the movement of food molecules, has no microvilli

Question 28

what are the 4 adaptations of the small intestines to help with absorption

Answer 28

- 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

Question 29

what lines the ileum

Answer 29

epithelial cells

Question 30

how are epithelial cells adapted for absorption (4)

Answer 30

- 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

Question 31

how are epithilal cells adapted for digestion and absorption

Answer 31

by having membrane bound disaccharidases, means monosaccharides are porduced close to the membrane for faster absorption

Question 32

where is the enzyme amylase produced

Answer 32

the salivary glands and the pancreas

Question 33

what does amylase do

Answer 33

breaks glycosidic bonds to hydrolyse starch into maltose

Question 34

what do dissacharidases do

Answer 34

break glycosidic bonds to hydrolyse disaccharides into monosaccharides

Question 35

what are the 3 membrane bound disaccharidase enzymes

Answer 35

maltase sucrase lactase

Question 36

why is it important for disaccharides to be broken down into monosaccharides

Answer 36

so they are small enough to be transported across the epithelial cell membrane through transport proteins.

Question 37

how does glucose and galactose get absorbed in digestion (3)

Answer 37

-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

Question 38

how is fructose absorbed in digestion

Answer 38

by facilitated diffusion with a transport protein.