Water regulation on land: plants
What is water regulation?
Wi = Wr + Wa - Wt - Ws
What is Wi?
internal water of plant
What are photosynthetic organisms?
- use CO2 for Carbon.
- Use sunlight for energy
- autotroph
What are Carnivores?
high risk of injury when obtaining their food because prey typically have adaptations to avoid predation.
What is C3 photosynthesis?
light + H2O + CO2 -> O2 + sugars
light reaction: photosynthetic pigments use light to create energy.
calvin cycle: use energy generated by the light reaction to create sugar.
use RUBISCO to take in CO2 when their stomata is open but their is low affinity for CO2. CO2 uptake happens slowly. inefficient, live in wet/cool environments.
Consequence: stomata are open for longer as a result, plants lose more water.
What is water aquisition on dry sites?
the plant grows a dense network of deeply penetrating roots to access moisture.
ex) deserts, prairies
What is Wr?
water absorbed by roots
What are chemosynthetic organisms?
use oxidation of inorganic molecules for Carbon and energy.
- autotroph
What are defences of plants?
physical: thorns, thick wax on surface, compound difficult to digest; cellulose, lignin compounds that strengthen plant tissue.
chemical: toxins, toxins (reduce digestion).
What is C4 photosynthesis?
light reaction and calvin cycle happen in different part of the plant.
advantage: can keep stomata open for less time = less water loss.
disadvantage: needs more energy
What is water acquisition on moist sites?
the plant grows a sparse network of shallow roots since there is so much water available.
ex) tropical rainforest.
What is Wa?
water absorbed from air
What are Autotrophs?
- produce own food and energy
- use inorganic sources of Carbon and energy
- able to take energy from surrounding resources and use it.
What are mixotrophs?
use more than one of the following categories to obtain nutrition.
- heterotrophic
- photosynthetic
- chemosynthetic
ex) carnivorous plants
what is CAM photosynthesis?
light reaction does not require CO2, so in CAM plants, the light reaction occurs during the day (stomata is closed).
Calvin cycle requires CO2 (stomata must be open). occurs at night when temps are cooler and less water loss will occur.
- disadvantage: slow.
What is water conversation by plants in desert environments?
some adaptations to conserve water are:
- reduced leaf area compared to roots size (Wt)
- dormant plants during dry conditions such as drought (Wt)
- physical changes reduce water loss (Wt): waxy cuticle, thick leaves, changed in timing of stomata opening. ex) only open at night when it's cold.
What is Wt?
What are heterotrophs?
- use organic sources for both Carbon and energy.
- need to consume because they cannot produce own energy
What is the comparison between animals and plants for water regulation?
in animals that have lungs, we lose water when we breathe.
- tradeoff: gain O2/release CO2 but lose H2O in the process (We).
In plants, they use opening in their leaves called stomata for gas exchange.
- tradeoff: gain CO2/release O2 but lose water in the process (Wt).
What is Ws?
Water lost through secretions
What are detritivores?
- feed on non-living organic matter.
- important in ecosystems because they break down dead organisms, this recycles those nutrients for other organisms.
- diet is typically limited in N, and rich in C.
- tend to be less active in cold temperatures and wet environments.