Gas Exchange

Question 1

What are the features of an efficient gas exchange system?

Answer 1

-Large surface area
-Thin layers to speed up diffusion
-Rich blood supply to maintain concentration gradients
-Moisture surfaces to speed up diffusion
-Permeable surfaces to allow gases through

Question 2

What are the adaptations of the alveoli?

Answer 2

-Cell wall is one cell thick
-Elastic tissue holds the capillary to the alveoli which helps force air out
-Lung

Question 3

What is a mass transport system?

Answer 3

An arrangement of structures by which substances are transported in the flow of a fluid with a mechanism for moving it around the body

Question 4

What are spiracles?

Answer 4

The openings along the side of the thorax and abdomen of an insect that are the entry and exit of respiratory gases

Question 5

What are tracheae?

Answer 5

The largest tubes of the insect respiratory system which carry air directly into the body for gas exchange with the cells

Question 6

What are tracheoles?

Answer 6

Small tubes that are the site of gaseous exchange in insects

Question 7

What are gills?

Answer 7

The organs of gas exchange in a fish

Question 8

What is the operculum?

Answer 8

The bony protective flap that covers the gills of bony fish

Question 9

What is a countercurrent exchange system?

Answer 9

A system in which two fluid components flow in opposite directions and some properties are exchanged between the two fluids

Question 10

How is gas exchanged in fish?

Answer 10

-Water flows in through the mouth
-Water flows over the gills
-Water flows out through the operculum
-Fish without an operculum must continuously move

Question 11

How are fish adapted for efficient gas exchange?

Answer 11

-Gills have a good blood supply
-They have a countercurrent exchange system
-The countercurrent exchange system maintains the concentration gradient allowing the diffusion of oxygen into the blood
-Gills are made of overlapping gill filaments (lamelle) which have a large surface area and a good blood supply

Question 12

How is gas exchanged in insects?

Answer 12

-Air moves along the tracheae and tracheoles by diffusion
-The tracheae and tracheoles provide a large surface area
-The spiracles open and close to control the rate of gas exchange

Question 13

What ways can insects exchange gas?

Answer 13

-Mechanical pumping = insect moves its thorax in a muscular pumping motion which draws air in and out of the spiracles
-Collapsible tracheae = acts as air reservoirs and the movement of the thorax can inflate or deflate them

Question 14

What are lenticles?

Answer 14

A porous tissue with huge intercellular spaces
-it allows air to reach the remaining parts of the root system

Question 15

What are spongy mesophyll cells?

Answer 15

Cells inside the leaf where gas exchange takes place
-they have a high concentration of oxygen

Question 16

What are stomota?

Answer 16

Specialised pores found mainly in the epidermis on the underside of the leaf where gases diffuse into and out of the cell

Question 17

What are guard cells?

Answer 17

Cells that open and close the stomata pores which control the rate of gas exchange

Question 18

What is palisade mesophyll?

Answer 18

Packs many cells together meaning there is more chlorophyll so more photosynthesis can occur

Question 19

What is a xerophytic plant?

Answer 19

A plant adapted to survive in environments with little water
-they have structures which make gas exchange more efficient and limit water loss

Question 20

What are the adaptations of a xerophytic plant?

Answer 20

-Curled leaves and have hairs on their leaves to trap moisture to increase humidity and lower the rate of evaporation
-Thicker cuticle to trap the evaporating water
-Longer network of roots to access more water
-Sunken stomata to trap moisture to increase the humidity and lower the rate of evaporation

Question 21

Why are there gaps within the mesophyll layer?

Answer 21

Maintains a concentration gradient which allows gases to diffuse

Question 22

What is a guard cell?

Answer 22

Found on the underside of a leaf and control the opening and closing of the stomata
-open the stomata during the day
-close the stomata during the night