Adaptations of Gas Exchange Surfaces

Question 1

Effective exchange surfaces in organisms have…? (3 things)

Answer 1

a large surface area
short diffusion distance
maintained concentration gradient

Question 2

What is chlamydomomas and give 3 features

Answer 2

A single celled organism that is found in fresh water ponds. It is spherical in shape and has a diameter of 20um. Oxygen can diffuse across the cell wall and cell surface membrane.

Question 3

Is diffusion an efficient exchange mechanism for chlamydomomas?

Answer 3

yes

Question 4

What type of skeleton do all insects have and what coating does it have, what is the coating impermeable to?

Answer 4

A rigid exoskeleton with a waxy coating that is impermeable to gases

Question 5

Where does insects breathing system deliver oxygen directly to in their bodies?

Answer 5

all the organs and tissues

Question 6

What is a spiracle and what is its function?

Answer 6

An opening in the exoskeleton of an insect which has valves. It allows air to enter the insect and flow into the system of tracheae.

Question 7

Why are the spiracles closed most of the time?

Answer 7

To reduce water loss

Question 8

What are tracheae?

Answer 8

Tubes within the insect breathing system which lead to tracheoles.

Question 9

Why do tracheae walls have reinforcements that keep them open?

Answer 9

Because the air pressure inside them fluctuates

Question 10

Why can a concentration gradient be created in insects?

Answer 10

As oxygen is used by respiring tissues allowing more to move in through the spiracles by diffusion.

Question 11

What happens to the carbon dioxide produced by the respiring tissues in insects?

Answer 11

Moves out through the spiracles down a concentration gradient

Question 12

What do very active, flying insects need?

Answer 12

a more rapid supply / intake of oxygen

Question 13

How do insects create a mass flow of air into the tracheal system?

Answer 13

closing the spiracles, using muscles to create a pumping movement for ventilation

Question 14

What happens during flight of an insect?

Answer 14

The production of lactate in the respiring muscles lowers the water potential of muscle cells. Water found at the narrow ends of the tracheoles is then drawn into the respiring muscle by osmosis. This allows gases to diffuse across more quickly.

Question 15

A given volume of our air contains how many times more oxygen than the same volume of water?

Answer 15

30

Question 16

What are fish adapted to do?

Answer 16

directly extract oxygen from water

Question 17

What is the structure of fish gills in bony fish?

Answer 17

series of gills on each side of the head, each gill arch is attached to two stacks of filaments, on the surface of each filament there are rows of lamellae, the lamellae surface consists of a single layer of flattened cells that cover a vast network of capillaries.

Question 18

What does the capillary system within the lamellae ensure?

Answer 18

that the blood flow is in the opposite direction to the flow of water - it is a counter-current system

Question 19

What does the counter current system ensure?

Answer 19

the concentration gradient is maintained along the whole length of the capillary

Question 20

Where is the water with the lowest oxygen concentration found?

Answer 20

adjacent to the most deoxygenated blood

Question 21

In order to carry out photosynthesis, plants must have an adequate supply of what?

Answer 21

carbon dioxide

Question 22

How have leaves evolved?

Answer 22

They have adaptations to aid the uptake of carbon dioxide

Question 23

What are the components of a leaf? (7)

Answer 23

waterproof cuticle, upper epidermis, palisade mesophyll layer, spongy mesophyll layer, stomata, guard cells, lower epidermis

Question 24

What is the upper epidermis?

Answer 24

a layer of tightly packed cells

Question 25

what is the palisade mesophyll layer?

Answer 25

a layer of elongated cells containing chloroplasts

Question 26

what is the spongy mesophyll layer?

Answer 26

a layer of cells that contains an extensive network of air spaces

Question 27

What is the stomata?

Answer 27

pores (usually) on the underside of the leaf which allows air to enter

Question 28

What are the guard cells?

Answer 28

pairs of cells that control opening and closing of stomata

Question 29

What is the lower epidermis?

Answer 29

a layer of tightly packed cells

Question 30

What happens when the guard cells are turgid?

Answer 30

the stomata remains open allowing air to enter the leaf

Question 31

What do the air spaces within the spongy mesophyll layer allow?

Answer 31

CO2 to rapidly diffuse into cells

Question 32

What cells quickly use up CO2 in leaves, what is it used for?

Answer 32

Cells containing chloroplasts, used for photosynthesis

Question 33

What is maintained by CO2 being used up quickly in photosynthesis?

Answer 33

A concentration gradient

Question 34

Why is no active ventilation required in leaves?

Answer 34

As the thinnest of the plant tissues and the presence of stomata help to create a short diffusion pathway