B6- Adaptations For Gas Exchange

Front 1

Why do large multicellular organisms require specialised gas exchange surfaces?

Back 1

When a cell increases in size the diffusion pathway gets longer so diffusion from the outer cell surface to the centre of the cell is slower so diffusion will not meet the cells needs.

Front 2

Define gas exchange

Back 2

The process by which oxygen reaches cells and carbon dioxide is removed from them

Front 3

Define ventilation

Back 3

The process of moving the respiratory medium over the respiratory surface to maintain a concentration

Front 4

Define respiration

Back 4

Respiration is a series of chemical reactions that result in the release of energy in the form ATP

Front 5

What is the surface area to volume ratio is an amoeba?

Back 5

Extremely large SA:V ratio

Front 6

Where does gas exchange occur in amoeba?

Back 6

Gas exchange occurs across the whole surface

Front 7

How are flatworms adapted to increase there SA:V?

Back 7

They have evolved a flattened shape, so that no cell in the body is far from the surface

Front 8

Where does gas exchange occur in flatworms?

Back 8

Across the flatworms permeable membrane

Front 9

Name 4 ways earthworms are adapted for gas exchange.

Back 9

- They have developed a tubular shape (which increases there SA:V) - They secrete mucus (moist surface allows gases to dissolve and diffuse) - There blood vessels are close to the body surface - Blood circulated in vessels to maintain a high concentration gradient

Front 10

Where does gas exchange occur in earthworms?

Back 10

Diffusion occurs across the surface, however the oxygen diffuses into blood that contains the respiratory pigment haemoglobin to carry oxygen to body cells.

Front 11

Name 4 key features of gas exchange surfaces

Back 11

Thin, moist, large surface area, permeable to gases

Front 12

Name two addition features that increase the efficiency of gas exchange in organisms which possess a circulatory system and a respiratory pigment.

Back 12

- Extensive blood supply and blood circulated to maintain a high diffusion gradient - Respiratory pigments such as Hb, increase the oxygen carrying capacity of blood

Front 13

Describe the process of gas exchange in insects.

Back 13

Air diffuses into the insect through paired holes called spiracles running along each side of the body. Spiracles lead to a system of branched chitin lines air tubes called trachea. The trachea branch repeatedly into tracheoles, oxygen diffuses directly from the ends of the tracheoles into cells.

Front 14

Why is it important that spiracles can open and close?

Back 14

Spiracles need to be able to open so air can diffuse in but it’s important they can close to prevent water evaporating out

Front 15

How can insects increase there ventilation during periods of activity?

Back 15

The movements of the abdomen ventilate the trachea

Front 16

Why are the ends of tracheoles fluid filled?

Back 16

Oxygen dissolved in the fluid and when the muscles contract this fluid is drawn into the muscle cells improving the efficiency of gas exchange

Front 17

Give 4 advantages of the tracheal system

Back 17

1. oxygen is supplied directly to the tissues 2. No respiratory pigment is needed 3. Oxygen gas moves faster than blood 4. Spiracles can close to reduce water loss

Front 18

Name 3 problems caused by living in water?

Back 18

Water contains less oxygen than air, the rate of diffusion is slower in water, water is a dense medium so it doesn’t flow freely.

Front 19

What type of Gill ventilation mechanism do cartilaginous fish have?

Back 19

Parallel flow, meaning the blood in the gill capillaries circulated in the same direction as water flowing over the gills

Front 20

Describe the ventilation mechanism in fish.

Back 20

Water is taken in through the bucks cavity, passed over the gills and is expelled via the operculum. Movements of the bucks cavity floor and operculum allow a one way current of water to flow through the gill.

Front 21

What happens to the mouth, operculum, floor of buccal cavity, volume and pressure during inspiration?

Back 21

The mouth opens, the operculum closes, the floor of the buccal cavity lowers, the volume increases and the pressure decreases

Front 22

What happens to the mouth, operculum, floor of buccal cavity, volume and pressure during expiration?

Back 22

The mouth closes, the operculum opens, the floor of the buccal cavity rises, the volume decreases and the pressure increases.

Front 23

How is the structure of gills in bonus fish adapted for gas exchange?

Back 23

Along each gill arch there are may thin filaments and on these filaments are lamellar. The gill filaments therefore have a large surface area for gas exchange. Blood circulated through the gill lamellae creating a concentration gradient.

Front 24

Why does counter current flow result in a higher blood oxygen saturation than parallel flow?

Back 24

Blood always meets water with a higher oxygen concentration, therefore the gradient for diffusion is maintained over the whole length of the gill.

Front 25

Why does parallel flow result in a lower blood saturation level than counter current flow?

Back 25

Gas exchange is very efficient at first as there is a very steep concentration gradient. However about halfway along the gill lamellae equilibrium is reached so diffusion of carbon dioxide and water is no longer possible.

Front 26

Describe the lung structure of an amphibian.

Back 26

Amphibians lunch have a simple structure with little infolding to Increase the surface area for gas exchange

Front 27

Why is the pleural cavity filled with a small amount of fluid?

Back 27

To lubricants the lungs and adhere the lungs to the thoracic cavity

Front 28

Why what proceeds do humans ventilate there lungs?

Back 28

Negative pressure breathing

Front 29

What happens to the external intercostal muscles and ribs, the diaphragm, volume of the thorax, the pressure in the thorax and the outside atmospheric pressure during inspiration?

Back 29

The external intercostal muscles contract and the ribs swing out and upwards. The diaphragm contracts and flattens, the volume of the thorax increases, the pressure in the thorax decreases therefore the outside atmospheric pressure is higher in the alveoli therefore air moves in.

Front 30

Why does parallel flow result in a lower blood saturation level than counter current flow?

Back 30

Gas exchange is very efficient at first as there is a very steep concentration gradient. However about halfway along the gill lamellae equilibrium is reached so diffusion of carbon dioxide and water is no longer possible.

Front 31

Give 7 ways leaves are adapted for photosynthesis.

Back 31

Large surface area, leaves can orientate themselves towards the sun, leaves are thin, cuticle and epidermis are transparent, palisade cells are elongated and densely packed together and contain mainly chloroplasts, chloroplasts can rotate and move within the mesophyll cells, intercellular air spaces allow for diffusion

Front 32

Where are stomata found?

Back 32

Bottom on the lower epidermis

Front 33

Name two unusual things about guard cells.

Back 33

They are the only epidermal cells that contain chloroplasts and they have unevenly thickened cell walls.

Front 34

What is the structure of the stomatas cell walls?

Back 34

The inner cell wall is thick and the outer wall is thin, so if the guard cell becomes turgid the pore opens and if it becomes flaccid the pore closes

Front 35

Describe the mechanism for stomatal opening.

Back 35

Potassium ions are actively transported from the epidermal cells into the guard cells. Stored stars is converted to malware by enzymes in the cytoplasm. The water potential is lowered so water enters by osmosis. The guard cells become turgid and curve apart.

Front 36

Why are stomata usually open during the day?

Back 36

Because during the day light triggers stomatal opening to allow carbon dioxide to diffuse into the leaf for photosynthesis

Front 37

Describe the lung structure of an amphibian.

Back 37

Amphibians lunch have a simple structure with little infolding to Increase the surface area for gas exchange

Front 38

Why is the pleural cavity filled with a small amount of fluid?

Back 38

To lubricants the lungs and adhere the lungs to the thoracic cavity

Front 39

Why what proceeds do humans ventilate there lungs?

Back 39

Negative pressure breathing

Front 40

What happens to the external intercostal muscles and ribs, the diaphragm, volume of the thorax, the pressure in the thorax and the outside atmospheric pressure during inspiration?

Back 40

The external intercostal muscles contract and the ribs swing out and upwards. The diaphragm contracts and flattens, the volume of the thorax increases, the pressure in the thorax decreases therefore the outside atmospheric pressure is higher in the alveoli therefore air moves in.

Front 41

What happens to the external intercostal muscles and ribs, the diaphragm, volume of the thorax, the pressure in the thorax and the outside atmospheric pressure during expiration?

Back 41

The external intercostal muscles relax and the ribs move down and inwards. The diaphragm relaxes and the volume in the thorax decrease and the pressure increases therefore the outside atmospheric pressure is lower than in the alveoli therefore air moves out.

Front 42

Give 5 ways the alveoli are a suitable gas exchange surface.

Back 42

Lined with squamous epithelium (provides a short diffusion pathway), moist surface (makes diffusion easy as gases can dissolve), each alveolus has an extensive capillary network (circulation maintains a high concentration gradient), permeable (so oxygen and carbon dioxide can diffuse easily), small and many of them (so large surface area for diffusion of gases)

Front 43

What is a surfactant and what is it’s purpose?

Back 43

A Surfactant is a chemical substance which covers the surface of the alveoli, it reduces surface tensions and prevents the alveoli sticking together and collapsing when breathing out.

Front 44

What is the epiglottis?

Back 44

A flap of skin that stops food entering the trachea when swallowing.

Front 45

Name 4 ways leaves are adapted for gas exchange?

Back 45

The lead blade is flat (this provides a short diffusion pathway and increases the SA:V), the spongy mesophyll is permeated with air spaces (to allow diffusion and circulation of gases which maintains diffusion gradients), stomatal pored opens and close (to allow gas exchange and reduce water loss), mesophyll cells have partially permeable membranes (to allow diffusion of gases)

Front 46

Why does parallel flow result in a lower blood saturation level than counter current flow?

Back 46

Gas exchange is very efficient at first as there is a very steep concentration gradient. However about halfway along the gill lamellae equilibrium is reached so diffusion of carbon dioxide and water is no longer possible.

Front 47

Give 7 ways leaves are adapted for photosynthesis.

Back 47

Large surface area, leaves can orientate themselves towards the sun, leaves are thin, cuticle and epidermis are transparent, palisade cells are elongated and densely packed together and contain mainly chloroplasts, chloroplasts can rotate and move within the mesophyll cells, intercellular air spaces allow for diffusion

Front 48

Where are stomata found?

Back 48

Bottom on the lower epidermis

Front 49

Name two unusual things about guard cells.

Back 49

They are the only epidermal cells that contain chloroplasts and they have unevenly thickened cell walls.

Front 50

What is the structure of the stomatas cell walls?

Back 50

The inner cell wall is thick and the outer wall is thin, so if the guard cell becomes turgid the pore opens and if it becomes flaccid the pore closes

Front 51

Describe the mechanism for stomatal opening.

Back 51

Potassium ions are actively transported from the epidermal cells into the guard cells. Stored stars is converted to malware by enzymes in the cytoplasm. The water potential is lowered so water enters by osmosis. The guard cells become turgid and curve apart.

Front 52

Why are stomata usually open during the day?

Back 52

Because during the day light triggers stomatal opening to allow carbon dioxide to diffuse into the leaf for photosynthesis

Front 53

Why are stomata usually closed at night?

Back 53

To reduce the loss of water vapour as there is insufficient light for photosynthesis.

Front 54

What is the effect of cyanide on stomatal opening?

Back 54

Cyanide prevents stomatal opening as it prevents the production of ATP

Front 55

Describe the lung structure of an amphibian.

Back 55

Amphibians lunch have a simple structure with little infolding to Increase the surface area for gas exchange

Front 56

Why is the pleural cavity filled with a small amount of fluid?

Back 56

To lubricants the lungs and adhere the lungs to the thoracic cavity

Front 57

Why what proceeds do humans ventilate there lungs?

Back 57

Negative pressure breathing

Front 58

What happens to the external intercostal muscles and ribs, the diaphragm, volume of the thorax, the pressure in the thorax and the outside atmospheric pressure during inspiration?

Back 58

The external intercostal muscles contract and the ribs swing out and upwards. The diaphragm contracts and flattens, the volume of the thorax increases, the pressure in the thorax decreases therefore the outside atmospheric pressure is higher in the alveoli therefore air moves in.

Front 59

What happens to the external intercostal muscles and ribs, the diaphragm, volume of the thorax, the pressure in the thorax and the outside atmospheric pressure during expiration?

Back 59

The external intercostal muscles relax and the ribs move down and inwards. The diaphragm relaxes and the volume in the thorax decrease and the pressure increases therefore the outside atmospheric pressure is lower than in the alveoli therefore air moves out.

Front 60

Give 5 ways the alveoli are a suitable gas exchange surface.

Back 60

Lined with squamous epithelium (provides a short diffusion pathway), moist surface (makes diffusion easy as gases can dissolve), each alveolus has an extensive capillary network (circulation maintains a high concentration gradient), permeable (so oxygen and carbon dioxide can diffuse easily), small and many of them (so large surface area for diffusion of gases)

Front 61

What is a surfactant and what is it’s purpose?

Back 61

A Surfactant is a chemical substance which covers the surface of the alveoli, it reduces surface tensions and prevents the alveoli sticking together and collapsing when breathing out.

Front 62

What is the epiglottis?

Back 62

A flap of skin that stops food entering the trachea when swallowing.

Front 63

Name 4 ways leaves are adapted for gas exchange?

Back 63

The lead blade is flat (this provides a short diffusion pathway and increases the SA:V), the spongy mesophyll is permeated with air spaces (to allow diffusion and circulation of gases which maintains diffusion gradients), stomatal pored opens and close (to allow gas exchange and reduce water loss), mesophyll cells have partially permeable membranes (to allow diffusion of gases)