insects transport + ventilation + exchange surfaces

Question 1

open circulatory system definition

Answer 1

a transport system with a heart but few vessels to contain the transport medium

Question 2

haemolymph definition

Answer 2

the blood like fluid contained in insects body cavity

Question 3

haemocoel definition

Answer 3

an open cavity within insects

Question 4

dorsal definition

Answer 4

front/under side of an insect

Question 5

ventral definition

Answer 5

back/top side of an insect

Question 6

how are open and closed circulatory systems different

Answer 6

• in open systems blood is not enclosed in vessels
• in open systems the fluid fills body cavities and makes direct contact with organs + tissues
• open systems are less efficient

Question 7

what is an advantage of open circulatory systems

Answer 7

less vulnerable to pressure

Question 8

what is a disadvantage of open circulatory systems

Answer 8

requires a low metabolic rate so not possible for larger animals
lack of a transport system means it is only effective across small distances e.g. up to 1cm

Question 9

what kind of organisms have open circulatory systems

Answer 9

hard bodied insects

Question 10

what does haemolymph contain

Answer 10

water, salts, organic compounds e.g. lipids, carbohydrates, proteins

not oxygen or circulating oxygen carrying proteins as their gas exchange systems are sufficient to supply them with O2

Question 11

what colour is haemolymph

Answer 11

green or yellow
not red as no red blood cells as it does not carry O2

Question 12

outline the movement of haemolymph in a hard bodied insect

Answer 12

• haemolymph is pumped through the dorsal vessel along front side of insect
• it travels to the haemocoel
• it is then reabsorbed by the dorsal vessel

Question 13

what type of circulatory system do soft bodied insects have

Answer 13

closed circulatory systems

Question 14

what is the difference between blood/haemolymph in soft bodied insects and hard bodied insects

Answer 14

blood in soft bodied insects contains an O2 carrying pigment

Question 15

example of a closed circulatory system in a soft bodied insect

Answer 15

e.g. earthworms
- have a main heart and 5 other pumps that pump blood around
- their blood vessels distribute blood to all structures within each segment of the body

Question 16

how do insects obtain O2

Answer 16

they don’t breathe
insects survive by dissolving gas in and out

Question 17

outline what happens in inspiration in insects

Answer 17

nothing - passive diffusion

Question 18

outline what happens in expiration in insects

Answer 18

• muscles contract to flatten body
• this decreases volume of tracheal system
• pressure inside > pressure outside
• air is forced out

Question 19

what is the structure + function of the cuticle

Answer 19

an impermeable structure that forms a layer covering the insects body
it prevents water loss as well as too much O2 + CO2 dissolving in and out

Question 20

what is the structure and function of spiracles

Answer 20

these are small holes in the cuticle that allow gases to enter + leave the system
they can be closed using valves, which prevents water loss and stops excess O2 during rest periods

Question 21

what is the structure + function of tracheae

Answer 21

tracheae connect the insects internal organs + tissues to the spiracles
they are reinforced by chitin rings
they branch off into tracheoles

Question 22

what is the structure + function of tracheoles

Answer 22

they are smaller branches of tracheae
the tip of the tracheoles is the site of most gas exchange in insects - they make direct contact with cells with high metabolic activity to ensure they have adequate O2 supply for respiration

Question 23

why does O2 move into insect and CO2 move out

Answer 23

when cells are respiring actively O2 is used up, this decrease in [O2] creates a conc gradient causing O2 to diffuse towards cells

at the same time, CO2 production from respiration also creates a diffusion gradient, so CO2 diffuses out of insect

Question 24

how is gas exchange made more efficient

Answer 24

when insects have low activity levels, the tracheole ends contain fluid
as activity increases this fluid is removed as muscle cell walls produce lactic acid
this causes water potential of cell to decrease
this ensures gas exchange occurs faster and closer to cells

Question 25

what fluid is contained in the tracheoles of an insect + what is its purpose

Answer 25

tracheal fluid
this improves the efficiency of gas exchange

Question 26

outline the movement of oxygen in an insect

Answer 26

air - cuticle - spiracle - trachea - tracheole where it diffuses down to the ends and across to cells