enzymes and digestion

Question 1

define digestion

Answer 1

the hydrolysis of large, insoluble molecules into smaller molecules that can be absorbed across cell membranes

Question 2

where are lipids digested?

Answer 2

the small intestine

Question 3

what needs to happen before lipids can be digested?

Answer 3

they must be emulsified by bile salts produced by the liver. this breaks down large fat molecules into smaller, soluble molecules called micelles, increasing surface area.

Question 4

how are lipids digested?

Answer 4

lipase hydrolyses the ester bond between the monoglycerides and fatty acids

Question 5

name three features of an efficient gas exchange

Answer 5

1. large surface area
2. short distance
3. steep concentration gradient

Question 6

name and describe the three main features of an insects gas transport system

Answer 6

• spiracles= holes on the body surface which may be opened or closed by a valve for gas or water exchange
• trachea= large tubes extending through all body tissues, supported by rings to prevent collapse
• tracheoles= smaller branches dividing off the tracheae

Question 7

explain the process of gas exchange in insects

Answer 7

• gases move in and out of the tracheae through the spiracles
• a diffusion gradient allows oxygen to diffuse into the body tissue while waste carbon dioxide diffuses out.
• contraction of muscles in the tracheae allows mass movement of air in and out.

Question 8

name and describe the two main features of a fish’s gas transport system

Answer 8

gills= located within the body, supported by arches, along which are multiple projections of gill filaments, which are stacked up in piles
lamellae= at right angles to the gill filaments, give and increased surface area. blood and water flow across them in opposite directions (countercurrent exchange system)

Question 9

name and describe three adaptations of a leaf that allow efficient gas exchange

Answer 9

1. thin and flat to provide short diffusion pathway and large surface area to volume ratio
2. many pores in the underside of the leaf (stomata) allows gases to easily enter.
3. air spaces in the mesophyll allow gases to move around the leaf, facilitating photosynthesis

Question 10

how do plants limit their water loss while still allowing gases to be exchanged

Answer 10

stomata regulated by guard cells which allows them to open and close when needed.
most stay closed to prevent water loss while some open to let oxygen in.