7.4 Ventilation and gas exchange in other organisms

Question 1

gas exchange in insects

Answer 1

very active and have a high oxygen demand

tough exoskeleton through which very little gas exchange can take place

Don’t have blood pigments that carry O2

delivers O2 directly to the cells and removes CO2 the same way

Diffusion

Question 2

Spiracles

Answer 2

small openings. Air enters and leaves through them but water is also lost

to maximise gas exchange but minimise water loss the have spiracle sphincters, which open and close the spiracles. They are kept closed ad much as possible to reduce water loss

inactive- low O2 demands, they are closed. when demand is high or CO2 builds up they open.

Question 3

Tracheae

Answer 3

largest tube of the system, 1mm in diameter.

Run both into and along the body of the insect

Lined with spirals of chitin, which keeps them open if they are bent or pressed.

chitin makes up the cuticle and is impermeable to gases.

Question 4

tracheoles

Answer 4

0.6-0.8 micrometers in diameter

each one is a single elongated cell with with no chitin lining so is freely permeable to gases

They spread throughout the tissues of the insect, running between individual cells.

This is where most gas exchange takes place

vast number, small size means a large surface area

O2 dissolves in moisture of the walls of the tracheoles and diffuses into the surrounding cells.

Question 5

tracheal fluid

Answer 5

limits the penetration of air for diffusion

Question 6

lactic acid

Answer 6

builds up when O2 demand builds up

results in water moving out of the tracheoles by osmosis, exposing more surface area of gas exchange

Question 7

what insects have alternative types of gas exhange

Answer 7

larger beetles locusts, grasshoppers, bees wasps flies.

have higher energy demands so need more O2

Question 8

mechanical ventilation of the tracheal system

Answer 8

air is actively pumped into the systems by muscular pumping movements of the thorax and abdomen. These movements change the volume of the boddy, changing the pressure in the tracheal system. Air is drawn in or end depending on pressure changes

Question 9

collapsible enlarged tracheae or air sacs, which act as air reservoirs

Answer 9

to increase the amount of air moved through the gas exchange system. Inflated or deflated by the ventilating movements of the thorax and abdomen.

Question 10

Fish

Answer 10

water is more dense and more viscous than air and has a much lower oxygen content

Fish only move water in one dicrection to save energy

active, high oxygen demand, SA:V ratio means diffusion would not be enough to supply their inner cells with the O2 they need