Topic 4 - Gas Exchange Flashcards
What is the insect exoskeleton made up of and why would this make gas exchange difficult?
Chitin and because chitin is impermeable to oxygen so the insect needs to have trachea in order for gas exchange
What is the tracheal system made up of?
A main trachea forming the main pathway along the length of the insect body then smaller branches called tracheoles which lead to the direct tissues. The tracheae is connected to outside valves called spiracles
What is the tracheae supported by in an insect and what does this help?
Rings of chitin, which helps support the tracheae as, it means it can cope with lots of pressure and also allows flexibility
What type of organism has efficient gas exchange?
Unicellular, they have a high surface area to volume ratio
What is a major factor in the efficiency of gas exchange?
Surface area to volume ratio
Does a large circular organism have fast or slow gas exchange and why?
Slow because they have a low surface area to volume ratio
How may spiracles been seen on an insect?
As 8 small holes on either side of the abdomen and two more pairs on the thorax
Why do spiracles have small hairs?
To prevent the entry of small molecules which may block the tracheoles
What is the order of the thorax?
Trachea branches into two bronchi which goes to each lung and then divides into bronchioles and then tertiary bronchioles and then respiratory bronchioles then alveoli
What supports the human trachea, bronchioles and bronchi?
Cartilage rings
What do the pleural membranes do and where are they found?
They secrete plural fluid which protects the lungs from friction during breathing
They are found in the inner layers of the thorax
What is pleural fluid made of?
Blood plasma
Why do bronchi and large bronchioles have a thin ring or tiny plates of cartilage around them?
To prevent collapse from sudden reductions in pressure
When is air taken into the alveoli?
When air pressure in the lungs is lower than atmospheric pressure
When is air forced out a human?
When the pressure in the lungs is higher than atmospheric pressure
Why would water logging be bad for a plant?
Because most a oxygen for root tissue respiration diffuses straight from soil to a plant through its permeable cell wall and membrane meaning if the soil becomes waterlogged the oxygen in the soil is restricted so the plants growth is stopped
What prevents water loss in a plant?
The leaves and stem being covered in a cuticle or a bark - also prevents diffusion of gases
Why does a plant need lenticels?
Because the waxy cuticle or bark prevents water loss and diffusion of gases it’s hard for diffusion to take place here therefore, the plant needs air spaces for direct diffusion to happen
What a lenticels?
Loosely packed cells (loosely packed so leave air spaces)
Where are lenticels found?
On the stem of a plant
Where on a plant is the place where most diffusion takes place and why?
The leaves as, co2 is used for photosynthesis
How do plant leaves diffuse easily even though they’re covered in a waxy waterproof cuticle?
On the epidermis there’s many thousand small pores called stomata (singular is stoma)
What is the epidermis?
The underside of leaves
What controls the opening and closing of the stomata?
Guard cells
