Gas exchange in insects

Question 1

what do insects have in terms of their skeleton ?

Answer 1

an exoskeleton made of hard fibrous material (chittin) for protection

Question 2

what layer of skin do they have and what is it for ?

Answer 2

a lipid layer
- to prevent water loss

Question 3

what do insects have instead of lungs ?

Answer 3

a tracheal system

Question 4

how is water lost from an insect ?

Answer 4

water evaporates off the surface of terrestrial insects

Question 5

what provides ideal conditions for gas exchange ?

Answer 5

adaptations of gas exchange surfaces

Question 6

what are the adaptations of insects that prevent water loss?

Answer 6

• insects have a small surface area to volume ratio where water can evaporate from
• insects have a waterproof exoskeleton
• spiracles, where gases enter and water can evaporate from so they can open and close to reduce water loss

Question 7

what do insects use to exchange gases ?

Answer 7

a trachea, tracheoles and spiracles

Question 8

what are spiracles ?

Answer 8

round, valve like openings that run along the length of the abdomen. oxygen and carbon dioxide enter and leave via the spiracles. and the trachea attatch to these openings

Question 9

what is the trachea ?

Answer 9

a network of internal tubes which have rings within them to strengthen the tubes and keep them open

Question 10

what does the trachea branch into ?

Answer 10

tracheoles

Question 11

what are tracheoles ?

Answer 11

smaller tubes with thin permeable walls which are deep into the abdomen and extend throughout all tissues in the insect and terminate at individual cells to deliver oxygen to all respiring cells

Question 12

what does the circulatory system in insects NOT do ?

Answer 12

transport oxygen

Question 13

what happens to carbon dioxide in an insect ?

Answer 13

CO2 diffuses from cells and into the spiracles as it travels down its own conc gradient out of the insect

Question 14

what do some larger insects have ? and what does it do ?

Answer 14

muscles in their abdomen which contract rhythmically to move air in and out of the spiracles

Question 15

what is the exoskeleton made out of and what is its properties ?

Answer 15

made from chittin
- strong, waterproof and airtight

Question 16

explain the movement of oxygen into the gas exchange system of an insect at rest ? (3)

Answer 16

air firstly moves into the insects trachea through the spiracles which are pores on the insects exoskeleton. The air then moves into tracheoles which have thin permeable walls that terminate at each cell and so the oxygen will diffuse directly into the cells. Oxygen is used in aerobic respiration and oxygen moves along a concentration gradient