Exchange And Transport

Question 1

Small and large organism in relation to SA:V ratio

Answer 1

• Smaller organisms=Larger SA:V ratio.

- Larger organisms=Smaller SA:V ratio.

Question 2

How to single-celled organisms exchange substances?

Answer 2

• Substances can diffuse directly into the cell across the cell surface membrane.
• Diffusion rate is quick because of the short distances and because they tend to have a high SA:V ratio.

Question 3

Why is gas exchange slow in multicellular organisms?

Answer 3

• Some cells are deep within the body. (Big distance between them and the outside environment).
• Large animals have low surface area to volume ratio.
• Multicellular organisms have a high metabolic rate, so they use up oxygen and glucose faster.

Question 4

Special features on exchange surfaces

Answer 4

• A large surface area.
• Thin cell walls.
• Good blood supply.

Question 5

How does a large surface area improve gas exchange efficiency?

Answer 5

• Provides the area needed for exchange.
• Overcomes the limitations of the SA:V ratio of larger organisms.
  E.g root hair cells (branches are covered in hairs).

Question 6

How do thin cell walls improve gas exchange efficiency?

Answer 6

• Provides a shorter pathway for diffusion.

- E.g alveoli in the lungs.

Question 7

Good blood supply

Answer 7

• Ensures substances are constantly delivered to and removed from the exchange surface.
• Maintains a steep concentration gradient for diffusion.
• E.g alveoli in the lungs and gills of a fish.

Question 8

What are the key feature of the gaseous exchange system?

Answer 8

• Cartilage.
• Ciliated epithelium.
• Goblet cells.
• Smooth muscle.
• Elastic fibres.

Question 9

Cartilage function

Answer 9

• supports the trachea and bronchi

- prevents the lungs from collapsing in the event of pressure drop during exhalation

Question 10

Where is the Ciliated epithelium found and what is its function?

Answer 10

• present in bronchi, bronchioles and trachea,

- moves mucus along to prevent lung infection by moving it towards the throat

Question 11

Where are goblet cells found and what is their function?

Answer 11

• present in the trachea, bronchi and bronchioles
• involved in mucus secretion to trap bacteria and dust to reduce risk of infection with the help of lysozyme which digests bacteria

Question 12

Smooth muscle function

Answer 12

• Constricts the airway.

- Controls the flow of air to and from alveoli.

Question 13

Elastic fibres function

Answer 13

stretch when we inhale and recoil when we exhale thus controlling the flow of air

Question 14

Which features are present in the trachea and in what form?

Answer 14

• Cartilage present (large C-shaped pieces).
• Smooth muscle present.
• Elastic fibres present
• Goblet cells present.
• Ciliated epithelium present.

Question 15

Which features are present in the Bronchi and in what form?

Answer 15

• Cartilage present (smaller pieces).
• Smooth muscle present.
• Elastic fibres present.
• Goblet cells present.
• Ciliated Epithelium present.

Question 16

Which features are present in the larger bronchiole and in what form?

Answer 16

• Cartilage not present.
• Smooth muscle present.
• Elastic fibres present.
• Goblet cells present.
• Ciliated epithelium present.

Question 17

Which features are present in smaller bronchioles and in what form?

Answer 17

• Cartilage not present.
• Smooth muscle present.
• Elastic fibres present.
• Goblet cells not present.
• Ciliated epithelium present.

Question 18

Which features are present in the smallest bronchioles and in what form?

Answer 18

• Cartilage not present.
• Smooth muscle not present.
• Elastic fibres present.
• Goblet cells not present.
• No Ciliated epithelium.

Question 19

Which features are present in alveoli and in what form?

Answer 19

• Cartilage not present.
• Smooth muscle not present.
• Elastic fibres present.
• Goblet cells not present.
• No Ciliated epithelium.

Question 20

What happens during inspiration?

Answer 20

• The external intercostal muscles and diaphragm muscles contract.
• This causes the ribcage to move upward and outward and the diaphragm to flatten, increases the volume of the thorax.
• As the volume of the thorax increase, the lung pressure decreases (to below atmospheric pressure).
• This causes air to flow into the lungs.
• Inspiration is an active process (requires energy).

Question 21

What happens during expiration?

Answer 21

• The external intercostal muscles and diaphragm muscles relax.
• Ribcage moved downwards and inwards.
• Volume of thorax decrease, causing the air pressure to increase (to above atmospheric pressure).
• Air is forced out of the lungs.
• Expiration is a passive process (doesn’t require energy).

Question 22

What does a spirometer give readings of?

Answer 22

• Tidal volume.
• Vital capacity.
• Breathing rate.
• Oxygen uptake.

Question 23

What is tidal volume?

Answer 23

• The volume of air in each breath. (Usually about 0.4dm cubed).

Question 24

What is vital capacity?

Answer 24

• The maximum volume of air that can be breathed in our out.

Question 25

What is breathing rate?

Answer 25

• How many breaths are take per unit time. (Usually per minute).

Question 26

What is oxygen uptake?

Answer 26

• The rate at which a person uses up oxygen.

Question 27

How do you use a spirometer?

Answer 27

• A spirometer has an oxygen-filled chamber with a moveable lid.
• The person breathes through a tube connected to the oxygen chamber.
• As the person breathes in and out, the kid of the chamber moved up and down.
• These movement are recorded by a pen attached to the lid of the chamber.
• This creates a spirometer trace.
• The soda lime in the tube absorbs carbon dioxide so the person doesn’t breathe it back in.

Question 28

Why is a counter-current exchange system important?

Answer 28

• Means that water with a high oxygen concentration always flows next to the blood with a low oxygen concentration.
• This means that a steep concentration gradient is maintained.

Question 29

Fish adaptations

Answer 29

• Gill filaments give a big surface area for gas exchange.

- Gill filament are covered in Gill plated which increases the surface area even more.

Question 30

How to fish ventilate?

Answer 30

• Fish opens its mouth, which lowers the floor of the buccal cavity.
• Volume of buccal cavity increases, deceasing the pressure inside the cavity.
• Water is sucked into the cavity.
• The fish closes its mouth and the floor of the buccal cavity is raised again.
• The volume inside the cavity decreases, and the pressure increases.
• Water is forced out of the cavity and across the Gill filaments.
• Each Gill is covered by a operculum.
• The Increase in pressure caused the operculum to open allow water to leave the gills.

Question 31

How do insects exchange gases?

Answer 31

• Air moves into the trachea through spiracles.
• Oxygen travels down the concentration gradient toward the cells.
• Co2 from the cells move down its own concentration gradient toward the spiracles to be released.
• Trachea branches off into tracheoles which have thin permeable walls and go into individual cells.
• Tracheoles contain a fluid which oxygen dissolved in.
• Oxygen diffuses from the fluid into body cells.
• Co2 diffuses in the opposite direction.
• Insects use rhythmic abdominal movements to change the volume of their bodies and move air in and out of their spiracles.

Question 32

How to dissect fish gills

Answer 32

• Place the fish on a cutting board.
• Push back the operculum and uses scissors to remove the gills.
• Cut each Gill arch through the bone at the top and bottom.
• Draw the Gill and label it.
• Wear an apron and gloves.

Question 33

How to dissect an insect.

Answer 33

• Fix the legs to a dissecting board.
• Cut and remove a pieced of exoskeleton.
• Use a syringe to fill in the abdomen with saline solution.
• Mount the trachea on a wet mount microscope slide and examine it under a light microscope.
• Trachea will appear silver or grey because they are filled with air.
• Can also see rings of chitin in the walls of the trachea (used for support).