Module 3 - Exchange Surfaces , Transport In Animals And Plants Flashcards
Why do small organisms such as amoeba require simple diffusion?
They have a large surface area to volume ratio
Distance that needs to be crossed over is short
Why do larger organisms require adaptations to increase the efficiency of exchange across their surface?
they have a small surface area to volume ratio
The distance that needs to be crossed over is larger
Why do larger organisms have a high metabolic rate ?
They require more oxygen for respiration to create ATP
What are some examples of features of efficient exchange surface ?
Large surface area to volume ratio
Concentration gradient
Thin pathway
Example of large surface area
root hair cells
Folded membranes
example of concentration gradient
exchange surface requires good blood supply/ ventilation to MAINTAIN a STEEP GRADIENT ( example alveoli)
Example of thin pathway
The exchange surface should be thin to ensure the distance that needs to be crossed over by substance is short
How is the trachea supported
It contains C-shaped rings of cartilage
What is the feature of trachea ?
- ciliated epithelial cells to sweep away any mucus
- goblet cells produce mucus
-smooth muscle within walls as muscles contract if any harmful substances detected in air
How is the lumen in the trachea adapted to its function
When lumen contracts it constricts and reduce flow of air in lungs
When lumen relaxes it dilates
how is the lumen able to stretch and recoil?
Due to the elastic fibres in tracheal walls
How is both bronchi and bronchioles provide structural support ?
they have cartilage which keeps the tubes open
What is alveoli
site of gas exchange
how does alveoli work?
oxygen diffuses from the alveoli into blood into the capillaries and carbon dioxide diffuse from blood into capillaries into alveoli
How is alveoli adapted to its function?
Large SA as there is large no. Of alveoli in lungs
Short diffusion rate as the walls are very thin
Maintains concentration gradient as each alveolus is surrounded by network of capillaries to remove exchanged gases
what’s purpose of ventilation
to maintain the concentration gradient for gas exchange at the alveoli
what happens during inspiration?
Increased volume of the thorax and air pressure inside thorax reduces. Air flows in lungs
what happens during expiration?
decrease in volume of thorax and increase in air pressure within thorax . Forces air out of lungs
what provides larger volume when you inhale?
diaphragm contracts
External intercostal muscles contact
Internal intercoastal relax
What causes decrease in volume when you exhale ?
diaphragm relaxes
External intercostal muscles relax
Internal intercostal muscles contract
Pull rib cage inward and down
what’s use of spirometer
measures volume of air inhaled and exhaled
Why is it difficult for fish to maintain concentration gradient ?
There is less oxygen dissolved in water than in atmosphere
Explain ventilation in fish
Swim with mouth open , water flows over the gills.
- open their mouth and lower buccal cavity , increases volume of BC and decrease pressure
- water flows in BC
Why do fish need a specialised exchange surface ?
- small surface area to volume ratio
- impermeable membrane so gases don’t diffuse through their skin
