Adaptations for gas exchange.

Question 1

factor affecting sa:v ratio

Answer 1

smaller organisms=large ratio

Question 2

rate of o2 absorption

Answer 2

proportional to size of organism/surface are and requirments proportional to volume=higher activity level for organism with higher ratio.

Question 3

Amoeba gas exchange

Answer 3

single celled
large sa:v ratio
diffusion through outer membrane meets needs for o2.

Question 4

Flatworm gas exchange

Answer 4

small sa:v ratio
flat to reduce diffusion distance
so external surface is satisfactory

Question 5

earthworms gas exchange

Answer 5

rely on external surfaces
low oxygen needs because slow and low metabolism
mucus to keep skin moist

Question 6

Cartilaganous fish gas exchange

Answer 6

-\keep swimming for ventilationm
-parallel flow=blood same direction as water travels
-o2 in water to blood but only till 50%
-until o2 conc in blood and water is equal across part of gill lamella

Question 7

Bony fish gas exchange

Answer 7

-mouth opens
-operculum closes
-floor mouth lowers
-volume in cavity increases
-pressure decreases
-water flows in as goes down pressure gradient
-reversed for expiration

Question 8

why is ventilation importance in animals with high metabolic rates

Answer 8

to provide a constant flow of oxygen and a steep concentration gradient across respiraory surfaces

Question 9

Counter current flow

Answer 9

blood and water flow in opposite directions at gill llamelae
maintains conc grad as diffusion can occur across entire length
water always has higher o2 conc
more efficinet than parallel flow
constant supply of fresh oxygenated water to diffuse into blood.

Question 10

Gill structure.

Answer 10

arch-backbone of gills
gill rakers-protect gills from debris
lamella-site of gas exchange
gill filaments-have lamellae in them
4 pairs of gills in bony fish

Question 11

Structure of human breathing system and locations

Answer 11

-Lungs in the thorax
-Pleural membranes line thorax and cover lungs, fluid prevents friction between lungs and chest cavity as we move.
-Diaphragm at base of thorax, muscle seperating thorax and abdomen.
-Ribs around thorax, protect lungs
-Intercostal muscles between ribs
-Trachea,flexible airway brings air to lungs
-2 bronchi, branches of the trachea
-bronchioles, branching tube network arise from bronchi
-alveoli at end of bronchioles
-pleural cavity, in membranes
-larynx, just above trachea

Question 12

human breathing system elements functions.

Answer 12

Larynx-protects lower respiratory tract from aspirating food into the trachea while breathing, air passes from throat to trachea.
Trachea-passage of air in and out the lungs.
Bronchi-air from trachea to lungs during inspiration and vice versa for expiration.
Bronchioles-small branches of bronchi, carry air to the alveoli.
Alveoli-fill w air when breathe in, site of gas exchange.
Pleural membranes-reduce friction during breathing and prevent lung collapse.
Pleural cavity-has pleural fluid, prevents friction.
Intercostal muscles-contract to move ribs.
Diaphragm-contracts and flattens to enlarge chest cavity.

Question 13

Trachea adaptations.

Answer 13

Cartilage rings to help keep open/prevent collapse.

Question 14

Bronchi adaptations.

Answer 14

Lined with cilia to help waft mucus out of throat and keep particles out of lungs.

Question 15

Alveoli adaptations.

Answer 15

Large surface area to volume ratio/SA.
Thin walls for short diffusion distances.
Permeable walls.
Lined with surfactant to reduce surafce tension and prevent collapse on exhalation.
Moist walls to help gases dissolve.
Capillary network maintains diffusion gradient (one cell thick).

Question 16

Ventilation in humans(inspiration).

Answer 16

External intercostal muscles contract and pull the rib cage up and out.
Outer pleural membrane is pulled out.
Pressure in pleural cavity is reduced.
inner pleural membrane pulled outwards.
This pulls on lungs surface and increases volume of alveoli.
Alveolar pressure decreases to below outside pressure so air is drawn/forced into lungs.

Question 17

Expiration.

Answer 17

Same as inspiration but opposite.

Question 18

Gas exchange in the alveoli process.

Answer 18

De-ox blood enters capillaries around alveoli.
Oxygen diffuses out of air in alveoli into red bloods cells in the capillary.
CO2 diffuses out of plasma in capillary into air in alveoli, then exhaled.

Question 19

Insect adaptations.

Answer 19

Impermeable cuticle to reduce water loss by evaporation.
Spiracles on trachea where gas exchange occurs/ air enters.
Whole body contractions aid ventilation, speeds up air movement through spiracles.
Spiracles open and close to conserve water.

Question 20

Insect gas exchange process.

Answer 20

Spiracles pairs on thorax and abdomen.These holes lead to trachea and trachioles.
Enter muscle cells directly.
Fluid at end for dissolving and diffusing O2.
In flight, more O2 needed so fluid decreases to reduce distance/path and whole body contractions.

Question 21

Structure of leaf.

Answer 21

Look at picture.

Question 22

Functions/adaptations of leaf structures.

Answer 22

Cuticle-waxy, transparent to let light through and reduce water loss by evaporation.
Upper epidermis-transparent so light can reach photosynthetic layers.
Palisade mesophyll-packed with chloroplasts for photosynthesis and light absorption.
Vascular bundle-contains xylem and phloem and bundle sheath parenchyma.
Spongy mesophyll-air spaces for easy gas diffusion , cell membranes are gas exchange site.
Stomata-allow exchange of gases in and out leaf, open during day for CO2 and closed at night to reduce water loss, controlled by guard cells.
Large surface area-room for chloroplasts/stomata.
Thin-short pathway and light gets through.
Chloroplasts-move to best position in mesophyll for more light.

Question 23

Stomata opening process.

Answer 23

In light, chloroplasts in guard cells produce ATP by photosynthesis.
ATP used in active transport of K+ ions into guard cells.
Starch is converted to malate ions.
K+ and malate ions reduce water potential so lower than surroundings.
Water moves in by osmosis.
Inner wall of guard cells thick than outer wall so as cell increases in size stomatal pores open.

Question 24

Stomata closing process.

Answer 24

Reverse of opening when conditions are dark.

Question 25

When are the stomata closed?

Answer 25

Night- prevents water loss when not enough light for photosynthesis.
Very bright light- intense heat increases evaporation.
If there is excessive water loss.