6.5 Limiting water loss
- Created by: germaineconroy
- Created on: 08-02-18 11:46
View mindmap
- 6.5 Limiting water loss
- Terrestrial org - problem btwn needs efficient GE system & conserve water.
- Feat make good GE system = ^ water loss.
- Must limit water loss w/o compromise GE
- Feat make good GE system = ^ water loss.
- GE surf of terrestrial org inside body. Air at exchange surface +/- 100% sat w/ water vapour = less evap water from ES
- Limiting water loss in insects
- Most insects terrestrial. Water easy evap surf body = dehydrated
- Efficient GE req...
- Thin
- Permeable
- All conflict w/ conserve water. Organism needs a balance
- Thin
- Large SA
- All conflict w/ conserve water. Organism needs a balance
- Large SA
- Insects evolved: small SA:V - minimise area water loss.
- Waterproof coverings
- Rigid outer skeleton of chitin covered w/ waterproof cuticle
- These feat mean insects cannot use body surf to diffuse resp gases in way signle-celled org does.
- Spiracles - opening trachea @ body surf - reduce water loss. Conflicts w/ need for O so occurs when insect resting.
- Instead have internal network tubes called tracheae - carry air cont oxygen directly 2 respiring tiss.
- These feat mean insects cannot use body surf to diffuse resp gases in way signle-celled org does.
- Rigid outer skeleton of chitin covered w/ waterproof cuticle
- Spiracles - opening trachea @ body surf - reduce water loss. Conflicts w/ need for O so occurs when insect resting.
- Limiting water loss in plants
- Also have waterproof coverings
- Cannot have small SA:V bc photosynthesis require opposite to abs light
- terrest plants have waterproof covering over parts of the leaves + ability to close stomata when nec
- Certain plants w/ restrict water supply evolve limit water loss thro transpiration - xenophytes
- Main way surviving = reduce water loss thro evap
- Leaves have thick cuticle, less water escape.
- Leaves roll up bc stomata largely confined to lower epidermis. Traps region still, moist air (saturated w/ water vapour ^ WP. No water potential gradient btwn out & in = no water loss
- Hairy leaves - thick layer on leaves - esp lower epidermis, traps still, moist air next 2 leaf surf. WP grad btwn in & out reduced so less water lost by evap
- Main way surviving = reduce water loss thro evap
- Stomata in pits or grooves - trap air next 2 surf - reduce WP gradient
- Reduced SA:V. Smaller the SA:V slower the rate diffusion.
- Having leaves small, roughly circular in cross-section (pine needles) rather than broad & flat.
- Terrestrial org - problem btwn needs efficient GE system & conserve water.
Comments
No comments have yet been made