OCRA Biology, OCR ALevel Biology OCR AS Level Biology. Module 3 (3.1) Exchange +Transport Summary notes. Revision notes.
H020 and H420. OCR, Breadth and depth of biology. Featured in Paper 1,2,3.
Chapter 5 – Breathing rate and gas exchange - Weaknesses per chapter.
In insects: have a head, thorax, and abdomen. Gas exchange that occurs in insects starts
with:
1) Spiracle: a hole which allows gases and water vapour to come in and out. They open when
active – allowing O2 into the insect and they close when they are at rest – allowing H2O out
of the spiracle.
2) Trachea: main tube about 1 mm wide and lined with chitin. Chitin is impermeable to gases
and is a tough chemical to support the trachea (stops trachea from collapsing)
3) Tracheoles: are individual elongated cells to increase the surface area. They are responsible
for gas exchange.
Other key definitions and involvements in the gas exchange system of an insect:
- Tracheal fluid: surrounds the tracheoles and limits the air penetration and no gas exchange
occurs here. This is because they are resting and so there is no major reason for O2. There is
very high water potential
Resting tracheal fluid Active tracheal fluid
Surrounds the tracheoles and limits the air Surrounds the tracheoles and due to the lack of
penetration. oxygen, anaerobic respiration occurs.
No gas exchange occurs here. Increasing respiration, increases lactic acid and
The insect is resting and so there is no major so decreases water potential of the tracheal
reason for O2. cells.
There is very high-water potential here. The tracheole fluid then moves into the cells
and leave the tracheoles by osmosis.
There is a higher SA for efficient diffusion of
gases.
This means more gases can then move in.
Gas exchange in bony fish:
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ariel3. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.41. You're not tied to anything after your purchase.
