gas exchange in plants Flashcards
1
Q
what is the adaptation of dicotyledonous plans?
A
broad leaves
2
Q
what does the adaptation allow in dicot plants ?
A
broad leaves give a large SA
3
Q
what is meant by transpiration ?
A
the evaporation of water from the surface of the leaf
4
Q
transpiration rate in terms of fick’s law ?
A
transpiration is proportional to SA x humidity gradient / transpiration distance
5
Q
state the factors that affect the rate of transpiration in a broad leaf ? (12)
A
- number of leaves - SA
- temperature - humidity gradient to do with kinetic energy
- thin / thickness of leaves = distance
- diameter f stomata = distance
- humidity in the air = humidity
- wind speed = humidity
- size of leaf / width = SA
- light intensity = the lighter it is the faster the rate of photosynthesis so stomata will open up more
- size of stomata
- density of stomata
- availability of water in the soil = humidity
6
Q
why do most stomata begin to close around noon ?
A
- because it is the hottest part of the day so there is a high transpiration rate and they want to minimise water loss
7
Q
what are xerophytes ?
A
plants that are adapted to live in very dry environments
8
Q
cacti adaptations to minimise water loss ?
A
- spines = discourages feeding
- thick waxy cuticle = distance
- succulent stem = store of water
- low stomata density = distance
- deep roots / wide roots = to absorb water faster
- no leaves = reduces SA
9
Q
Maram grass adaptations to minimise water loss?
A
- schlerenchyma tissue = prevents willting
- sunken stomata = trap humid air which reduces the effect of wind
- hinge cells = enable leaf to roll
- rolling of the leaf = reduces exposed SA ,
- layer of humid air = traps water molecules
10
Q
A
