Adaptations for Gas Exchange- Unit 2.2

Question 1

What do gill rakers do?

Answer 1

Remove debris

Question 2

Describe what is meant by diffusion.

Answer 2

The net movement of molecules from a higher concentration to a lower concentration. It occurs passively. (without energy)

Question 3

What is the capillary endothelium?

Answer 3

The single layer of cells of the capillary wall.

Question 4

Why do multicellular organisms need a specialised gas exchange mechanism?

Answer 4

They have a lower surface area to volume ratio so cells are further away from the surface, meaning diffusion has to occur over a greater distance.

Question 5

Why does the amoeba have adequate gas exchange?

Answer 5

• Large surface area to volume ratio
• Thin so short diffusion pathway
• Small

Question 6

How does a continuous supply of oxygen reach all tissues of an earthworm?

Answer 6

• Large surface area
• Skin is the respiratory surface which is moist
• Tubular structure

Question 7

What does the cartilage do in the lungs?

Answer 7

Keeps the trachea open as it’s made from rings of strong, bendy cartilage.

Question 8

What do goblet cells do?

Answer 8

Produce mucus to trap inhaled dust.

Question 9

What are cilia and what do they do?

Answer 9

Hairs on cells in the trachea, bronchi and bronchioles. They move to push mucus with trapped particles upwards. (away from lungs)

Question 10

What do elastic fibres do and where are they located?

Answer 10

Between the alveoli. They stretch lungs when inhaling, recoil when exhaling to push air out.

Question 11

What is and where is the pleural membrane?

Answer 11

Protective lining on the lungs.

Question 12

What is the alveolar epithelium?

Answer 12

The single layer of cells lining the alveoli.

Question 13

Describe the path that oxygen take across the alveoli.

Answer 13

• oxygen diffuses out of alveoli
• across alveolar epithelium
• across capillary endothelium
• then into haemoglobin in blood

Question 14

Describe the path of carbon dioxide across alveoli.

Answer 14

• Diffuses into alveoli from blood
• Then breathed out through lungs
• To trachea
• Then out of mouth and nose

Question 15

What liquid does alveoli secrete?

Answer 15

Surfactant

Question 16

What is an alveoli?

Answer 16

A microscopic air sac.

Question 17

What does surfactant of the alveoli do?

Answer 17

Stops alveoli collapsing by lowering surface tension of water layer lining alveoli.

Question 18

Name four adaptations the alveoli have to speed up the rate of diffusion.

Answer 18

• Thin exchange surfaces (alveolar epithelium)
• Short diffusion pathways (alveolar epithelium one cell thick)
• Large surface area to volume ratio
• Steep concentration gradient (between alveoli and capillaries)

Question 19

How does oxygen enter and travel though fish?

Answer 19

•Oxygenated water enters gills in one-way current that continually flows by pumping mechanisms.

Question 20

What are lamellae?

Answer 20

Thin plates in the gills that create a large surface area. They have lots of capillaries and a thin surface layer.

Question 21

What is counter-current flow?

Answer 21

Blood flowing over the lamellae in one direction with water flowing over in the opposite direction.

Question 22

Why is a counter-current flow beneficial?

Answer 22

A concentration gradient is maintained between water and blood. (as much oxygen as possible diffuses from water into blood)

Question 23

What is metabolic rate?

Answer 23

The rate of energy expenditure by the body.

Question 24

What are gill filaments?

Answer 24

Specialised respiratory area. Water is forced over them by a ventilating mechanism.

Question 25

How is ventilation in a bony fish achieved?

Answer 25

Pressure changes in the buccal and opercular cavities.

Question 26

What is the buccal in a fish?

Answer 26

The mouth.

Question 27

What are the opercular cavities in a fish?

Answer 27

The gills.

Question 28

Describe stage 1 of the ventilation mechanism of a bony fish. (4)

Answer 28

* Mouth opens & floor of buccal cavity lowers * Volume of buccal cavity increases & pressure decreases * Operculum remains closed * Water pulled into buccal cavity from outside due to pressure change

Question 29

Describe stage 2 of the ventilation mechanism in a bony fish. (3)

Answer 29

* Mouth closes * Buccal cavity contracts, raising floor of cavity * Water forced across gills

Question 30

Describe stage 3 of the ventilation mechanism of a bony fish. (2)

Answer 30

* Pressure in gill cavity increases & forces operculum open | * Water leaves via operculum

Question 31

What is the operculum?

Answer 31

The gill slit.

Question 32

Fish have haemoglobin and a circulatory system to do what?

Answer 32

Carry oxygen throughout the fish.

Question 33

How do insects reduce water loss?

Answer 33

Have evolved a rigid waterproof exoskeleton covered by a cuticle.

Question 34

How does gas exchange occur in insects?

Answer 34

Through paired holes (spiracles) which lead into a system of branched, chitin lined air tubes (tracheae)

Question 35

What are the ends of the tracheae called in an insect?

Answer 35

Tracheoles

Question 36

Name 4 labels on an insect.

Answer 36

* Head * Thorax * Spiracle * Abdomen

Question 37

What ventilates the tracheal system in an insect?

Answer 37

Compression and expansion of the abdomen.

Question 38

When the abdomen expands in an insect, the thorax spiracles are… and the abdominal spiracles are…

Answer 38

Open | Closed

Question 39

As the abdomen is compressed in an insect, the thorax spiracles… and the abdominal spiracles…

Answer 39

Close | Open

Question 40

Does oxygen enter or exit the thorax spiracles in an insect?

Answer 40

Enter

Question 41

Does oxygen enter or exit the abdominal spiracles in an insect?

Answer 41

Exit

Question 42

What is a thorax in a human?

Answer 42

An airtight compartment.

Question 43

Order the path that oxygen takes from entering the body to the site of gas exchange in a human.

Answer 43

1• Trachea 2• Bronchi 3• Bronchioles 4• Alveoli

Question 44

Describe inspiration.

Answer 44

* Intercostal muscles contract, raising ribcage upwards and outwards. * Diaphragm contracts and flattens. * Volume of thorax increases and pressure decreases. * Air enters and lungs expand.

Question 45

Describe expiration.

Answer 45

* Intercostal muscles relax, moving ribcage inward and downward. * Diaphragm relaxes and curves upwards. * Volume of thorax decreases and pressure increases. * Air forced out of lungs.

Question 46

Why are surfactants often given to premature babies?

Answer 46

It prevents the alveoli of their immature lungs from sticking together.

Question 47

Why do plants need to exchange gases?

Answer 47

For respiration and photosynthesis.

Question 48

What is the main gas exchange surface on a plant?

Answer 48

Leaf.

Question 49

How is a leaf adapted for gas exchange?

Answer 49

* Thin * Flat * Large surface area * Short diffusion pathway

Question 50

Order each part of a flowering plants leaf from top to bottom.

Answer 50

``` 1• Waxy cuticle 2• Upper epidermis 3• Palisade mesophyll 4• Spongy mesophyll 5• Vascular bundle 6• Guard cell 7• Stomata ```

Question 51

Name the function of the waxy cuticle in a leaf.

Answer 51

Reduces water loss from leaf surface by evaporation.

Question 52

Name function of upper epidermis in a leaf. What are they?

Answer 52

Transparent cells which allow light to pass through mesophyll tissue. They synthesise and secrete the waxy cuticle.

Question 53

What does the palisade mesophyll do in a leaf? What do they contain?

Answer 53

Contain many chloroplasts for photosynthesis. This layer is the main photosynthetic tissue.

Question 54

What do the spongy mesophyll and air spaces do in a leaf?

Answer 54

Spongy palisade cells photosynthesise. Air spaces between cells allow for circulation of gases.

Question 55

Two examples of vascular bundles:

Answer 55

Xylem and phloem.

Question 56

What do the vascular bundles do in a plant?

Answer 56

Xylem- water and mineral transport. | Phloem- transport of products of photosynthesis. (sucrose and amino acids)

Question 57

Function of guard cells in a leaf:

Answer 57

They become turgid and flaccid due to changes in water potential. This opens and closes stomata pore.

Question 58

What does the stomata do in a plant?

Answer 58

Allows gas exchange.

Question 59

Why can chloroplasts rotate and move in mesophyll cells in a leaf?

Answer 59

To allow arrangement of the best possible position for light absorption.

Question 60

How many guards cells bound a pore/stoma in a leaf?

Answer 60

2

Question 61

Describe the structure of a guard cell in a leaf. (4)

Answer 61

* Have chloroplasts. * Thick inner wall and thin outer wall. * Thick inner wall causes cell to become curved when swelled, opening the stomatal pore. * Can change shape to open/close stomata, helping control gas exchange and water loss.

Question 62

Why are stomata found on the lower leaf surface?

Answer 62

To reduce water loss from evaporation. (sun hits top of leaf so being at the top would result in leaf becoming flaccid)

Question 63

Do most stomata close or open at night?

Answer 63

Close

Question 64

During the day when light intensity is sufficient, the stomata is…

Answer 64

Open

Question 65

How does water enter/exit the guard cells in a leaf?

Answer 65

Osmosis

Question 66

When the stomata closes, water potential…

Answer 66

Increases

Question 67

When the stomata opens, water potential…

Answer 67

Decreases

Question 68

What is parallel flow in a fish?

Answer 68

Blood and water flow in the same direction.