Environmental Constraints: Water

Question 1

What are Water Budgets

Answer 1

organisms way of regulating their internal water concentration by balancing water inputs with water outputs

Question 2

Diffusion

Answer 2

movement of soluble salts or water due to random of particles
- as a result, salt concentrations are equalized in a solution

Question 3

Osmosis

Answer 3

a process similar to diffusion but involves movement through a semipermeable membrane

Question 4

Osmolarity in aquatic animals

Answer 4

• isosmotic: organism has the same water concentration as environment
• hyperosmotic: organism has lower water concentration as environment
• hypoosmotic: organism has higher water concentration than environment

Question 5

Water Potential

Answer 5

water’s potential or its capacity to do work
- water moves from high to low water potential
- in general water potential is negative

Question 6

Why do the water loss rates of organisms differ?

Answer 6

evolution and adaptation
- species evolve in environments that differ in water availability
- selection therefore is more intense for water conservation in some environment vs. others

Question 7

How do terrestrial organisms conserve water?

Answer 7

behavioural modifications
- exploiting microclimates that are cooler than surroundings
- nocturnal
-thick, waxy cuticle
- storing water
- conservation of urine, feces and sweat
- small leaves or thorns in arid environments
- restrict stomatal opening during the hottest, driest parts of the day
- plants wilt to conserve water