5 - Gas exchange (1)

Question 1

Gaseous exchange def

Answer 1

Uptake of oxygen (O2) from the surrounding environment and the release of carbon dioxide (CO2) which is a metabolic waste product of respiration

Question 2

Where does gas exchange usually occur in invertebrates?

Answer 2

Across the integument of the animal or via specialized structures

Question 3

(Cellular/ internal) Respiration def

Answer 3

Respiration is the energy-producing metabolic activities within cells

Question 4

Metabolism def

Answer 4

Consists of “all of the biochemical reactions involved in the uptake & use of energy & materials by organisms”

Question 5

Catabolic rxn def

Answer 5

Biochemical rxn where large molecules are broken down into small ones

Question 5

Catabolic rxn equation explained

Answer 5

The substrate (e.g. glucose) is broken down, which requires 6 molecules of oxygen O2 and several enzymes. The reaction releases 6 molecules of carbon dioxide (CO2) and 6 molecules of water (H2O), and generates energy in the process.

Question 6

Catabolic rxn equation

Answer 6

C6H12O2 + 6O2 —> 6CO2 + 6H2O

Question 7

Respiratory rates def

Answer 7

rates of oxygen uptake and/or carbon dioxide release

Question 8

What is metabolism estimated by?

Answer 8

Respiratory rates

Question 9

Skin/ integument def

Answer 9

Invertebrate will use the skin or integument as the structure for gas exchange and will typically lack other specialized structures.
- Propensity (natural tendency) to lose water

Question 10

Gas exchange structures

Answer 10

1. Skin/ integument
2. Gills
3. Lungs (book lungs)
4. Tracheae

Question 11

Skin/ integument examples

Answer 11

• Seaspiders (Order: Pantopoda)
• Micro-scorpions (Order: Palpigradi)
• Cnidarians (Phylum: Cnidaria)

Question 12

Ways of preventing water loss of skin

Answer 12

• Small body size - require less oxygen = less gas exchange demand = less water loss
• Large body size, soft-bodied forms (cnidarians & flatworms) = low surface-to-volume ratios = lose water at a lower rate per unit volume
• Inhabit aquatic habitats or damp terrestrial environments

Question 13

Tracheal system def

Answer 13

An open respiratory system composing of spiracles, trachea and tracheoles

Question 15

Spiracles def

Answer 15

The openings of the tracheae onto the body surface; there are closable and non-closable spiracles (depending on the organism)

Question 16

Trachea def

Answer 16

• A tube-like structure that conveys air (with needed oxygen) from external environment to tissues and vice-versa (also conveys carbon dioxide from tissues to the outside environment).
• They are invaginations of the cuticular exoskeleton and extend towards multiple tracheoles

Question 17

Tracheoles def

Answer 17

The smallest branches of the tracheal system where the transfer and diffusion of oxygen occurs into and out of the tissues and cells.

Question 18

Cambrian fossils (500Ma) name

Answer 18

Xenusians

Question 19

Ancestors of Onychophorans

Answer 19

Xenusians

Question 19

Xenusians are ancestors of who?

Answer 19

Onychophorans

Question 20

Earliest terrestrial ancestor of Onychophorans originated ?

Answer 20

In the upper carboniferous
300Ma

Question 21

Why do velvet worms have their name?

Answer 21

Their thin cuticle has numerous sensory papillae

Question 22

Onychophora structures & characteristics

Answer 22

• Terrestrial in moist habitats (leaf litter & rotten logs) - typically forests
• 1 pair of antennae, 2 eyes with spherical lenses
• 13 to 43 pairs of legs (also called ‘oncopods’)
• Thin cuticle has numerous sensory papillae
• Have malleable body and use hydrostatic muscle skeleton using pressurized fluid in the body to extend and contract their body and legs

Question 23

Oncopods def

Question 24

How do onychophora exchange gas?

Answer 24

Use multiple non-closable (continuous gas exchange) spiracles to exchange O2 and CO2 with environment.

Question 25

Continuous gas exchange def

Answer 25

Spiracles cannot open and close, we call this mode of gas exchange a “continuous” gas exchange

Question 26

Scientific name of velvet worm

Answer 26

P. capensis