Gas exchange

Question 1

What is the tissue fluid?

Answer 1

The environment around the cells of multicellular organisms

Question 2

How have organisms evolved to improve exchange?

Answer 2

A flattened shape (leaf) or specialised exchange areas (lungs/gills)

Question 3

What are the features of specialised exchange surfaces?

Answer 3

Large SA relative to the volume of the organism, very thin to decrease diffusion distance, selectively permeable, movement of environmental medium (air) to maintain diffusion gradient and transport system (blood) to move internal medium

Question 4

What are the tracheae or insects?

Answer 4

Internal network of tubes

Question 5

How does the tracheae prevent from collapsing?

Answer 5

Strengthened rings

Question 6

What does the tracheae divide into?

Answer 6

Tracheoles

Question 7

Where do the tracheoles extend to?

Answer 7

All the body tissue of the insects

Question 8

How do respiratory gases move in and out of the tracheal system?

Answer 8

Along a diffusion gradient, mass transport and the ends of tracheoles are filled with water

Question 9

How does the contraction of respiratory muscles aid mass transport?

Answer 9

Squeezes the trachea enabling mass movements of air

Question 10

How does anaerobic respiration affect the muscle cells?

Answer 10

Produces lactate which lowers the water potential of the cells, so water moves into the cells from tracheoles by osmosis.

Question 11

Why does the tracheoles being filled with water benefit the insect?

Answer 11

When the water level drops due to anaerobic activity, more air is drawn into the insect, the air diffuses quicker than the liquid

Question 12

How does gas enter the insects?

Answer 12

Spiracles on the body surface

Question 13

How are spiracles opened?

Answer 13

A valve

Question 14

What are the limitations of insect gas exchange?

Answer 14

Small insects for short diffusion pathway

Question 15

Why do fish require require a specialised gas exchange surface?

Answer 15

They are too large for SA:V and waterproof skin

Question 16

Where are the gills located?

Answer 16

Within the body of the fish behind the head

Question 17

How are gill filaments structured?

Answer 17

Stacked up in a pile

Question 18

Where are the gill lamellae?

Answer 18

At right angles to the gill filaments to increase the surface area of the gills

Question 19

How does water travel through the fish?

Answer 19

It moves in through the mouth and is forced over the gills before leaving through opening at either side of the fish

Question 20

What is the countercurrent flow?

Answer 20

Flow of water over the gill lamellae and the flow of blood within them are in opposite directions

Question 21

How is the countercurrent exchange system beneficial?

Answer 21

Blood well-loaded with oxygen meets water with the maximum amount of oxygen, therefore diffusion into the blood can still occur

Question 22

How much of the oxygen in the water is transferred to the blood?

Answer 22

80%

Question 23

How is gas exchange in plants similar to that of insects?

Answer 23

No living cells are far from external air and diffusion takes place in the gas phase

Question 24

How are leaves adapted for efficient gas exchange?

Answer 24

Many stomata (short diffusion pathway)
Numerous interconnected air spaces
Large SA of mesophyll cells (rapid diffusion)

Question 25

What are stomata?

Answer 25

Minute pores

Question 26

Where are the stomata mainly found?

Answer 26

Mostly, but not exclusively, on the underside

Question 27

How does a stoma open and close?

Answer 27

Has a pair of guard cells that swell to close and control gas exchange

Question 28

What is a dicotyledonous plant?

Answer 28

A plant that has seeds made of two parts

Question 29

How have insect evolved to reduce the water loss?

Answer 29

Small SA:V, waterproof covering and spiracles

Question 30

What is the waterproof covering in insects?

Answer 30

Rigid outer skeleton of chitin that is covered with a waterproof cuticle

Question 31

What are plants with restricted water supply called?

Answer 31

Xerophytes

Question 32

How are leaves modified for limiting water loss?

Answer 32

A thick cuticle, rolling up of leaves, hairy leaves, stomata in pits or grooves and reduced SA:V

Question 33

How much water loss occurs through the waxy cuticle?

Answer 33

10%

Question 34

What grass rolls its leaves?

Answer 34

Marram grass

Question 35

What is the benefit of plant leaves rolling?

Answer 35

Traps air and becomes saturated with water vapour to give a high water potential and stop diffusion

Question 36

How do hairy leaves benefit the plant?

Answer 36

Traps moisture to decrease potential gradient

Question 37

What plant type has hairy leaves?

Answer 37

One type of heather plant

Question 38

What plant has stomata in pit or grooves?

Answer 38

Pine trees

Question 39

Why are the volumes of CO2 and O2 that have to be exchanged in mammals large?

Answer 39

Relatively large organisms with a large volume of living cells and they maintain a high body temperature which is related to them having high metabolic and respiratory rates

Question 40

What are the lungs?

Answer 40

A pair of lobed structures made up of a series of tubules, called bronchioles, which end in tiny air sacs called alveoli

Question 41

What supports the trachea?

Answer 41

Rings of cartilage, that prevent it collapsing when the air pressure falls inside the lungs when breathing in

Question 42

What are the tracheal walls made up of?

Answer 42

Muscle tissue, lines with ciliated epithelium and goblet cells

Question 43

What does the mucus and cilia in the bronchi do?

Answer 43

Mucus traps dirt and cilia moves the dirt-laden mucus towards the throat

Question 44

How does the support of bronchi differ from trachea?

Answer 44

The cartilage is reduced ass the bronchi gets smaller

Question 45

What are the bronchioles walls made of?

Answer 45

Muscle lined with epithelium cells

Question 46

How does the muscle benefit the bronchioles?

Answer 46

They can constrict to control the flow of air into and out of the alveoli

Question 47

What is the diameter of alveoli

Answer 47

100-300 micrometers

Question 48

What exists between the alveoli?

Answer 48

Collagen and elastic fibres

Question 49

What are the alveoli lined with?

Answer 49

Epithelium

Question 50

What do the elastic fibres between alveoli do?

Answer 50

Allow the alveoli to stretch as they fill with air when breathing in, they then spring back to breathe out and force CO2 out

Question 51

What is ventilation?

Answer 51

Constant moving of air in and out of the lungs

Question 52

What causes inspiration?

Answer 52

When the atmospheric pressure of air is greater than that in the lungs

Question 53

What causes expiration?

Answer 53

When the atmospheric pressure is lower than that of the lungs

Question 54

What is the diaphragm?

Answer 54

A sheet of a muscle that separates the thorax and abdomen

Question 55

What contractions cause inspiration?

Answer 55

External intercostal muscles and diaphragm

Question 56

What contractions cause expiration?

Answer 56

Internal intercostal muscles

Question 57

Is inspiration active or passive?

Answer 57

Active

Question 58

How does expiration differ?

Answer 58

During normal quiet breathing the elastic tissue is the main cause, however under strenuous conditions such as exercise do the various muscles play a major part

Question 59

What is the calculation for pulmonary ventilation rate?

Answer 59

Tidal volume x breathing rate

Question 60

How are the lungs adapted to enable efficient transfer of materials?

Answer 60

Thin, partially permeable membrane and have a large SA

Question 61

How are we adapted to maintain a diffusion gradient?

Answer 61

Capillary network (rich blood supply) and ventilation

Question 62

How many alveoli are there in each human lung?

Answer 62

About 300 million

Question 63

What is the total SA of all the alveoli in each human lung?

Answer 63

70m2

Question 64

How thick are the epithelial cells lining the alveoli?

Answer 64

0.05- 0.3 micrometers

Question 65

What is the lumen diameter of the surrounding cappilaries?

Answer 65

7-10 micrometers

Question 66

How thick are capillaries?

Answer 66

0.04-0.2 micrometers

Question 67

How is diffusion into capillaries rapid?

Answer 67

RBC are slowed, allowing more time Distance reduced as RBC are flattened against capillary walls Thin walls Very large total SA Steep concentration gradient

Question 68

What are the risk factors of lung disease?

Answer 68

Smoking, air pollution, genetic makeup, infections and occupation

Question 69

How is an insect's tracheal system adapted for efficient gas exchange?

Answer 69

Tracheoles have thin walls so short diffusion distance to cells Highly branched/large number of tracheoles so short diffusion distance to cells and large surface area Tracheae provide tubes full of air so fast diffusion Fluid in the end of the tracheoles that moves out into tissues, during exercise so faster diffusion through the air to the gas exchange surface and larger surface area Body can be moved (by muscles) to move air so maintains diffusion/concentration gradient for oxygen/carbon dioxide;