biology 3.1

Question 1

What are factors that affect the need for a transport system?

Answer 1

-Small organisms have a short distance between cytoplasm and environment whereas multicellular organisms have lots of layers of cells so simple diffusion isn’t enough to supply all the cells
-Small organisms have a small surface area and volume so surface area to volume ratio is high however as organism size increases volume increases quicker than surface area.
-Organisms that are larger, more active, and mammals tend to have a higher metabolic rate so need more oxygen for aerobic respiration

Question 2

What are the adaptations of the alveoli?

Answer 2

-Made of squamous epithelial cells which are flattened cells one cell thick for short diffusion distance
-Large number of small alveoli for high surface area
-Good blood supply to maintain steep concentration gradient
-Ventilated so oxygen is constantly supplied and co2 removed
-Warm so diffusion rate is high
-Contain elastic fibres to stretch and recoil

Question 3

What is the route of oxygen from outside body into blood

Answer 3

Nose/mouth-trachea-bronchi-bronchioles-alveoli-cappilary

Question 4

What is the double membrane that encloses the lungs?

Answer 4

-Pleural membrane, the space between the two membranes is called the pleural fluid which lubricates the lungs
-It also adheres to the outer walls to the thoracic(chest) cavity by water cohesion, so that the lung expands when the chest is breathing

Question 5

Why do land animals face a constant struggle between retaining water and gas exchange?

Answer 5

-Inner surface of alveoli is covered in thin layer of water, salts and lung surfactant, lung surfactant reduces cohesive forces so alveoli can stay deflated and oxygen dissolves in the water and diffuses into the blood.
-Water also however evaporates and leaves as we breath

Question 6

What is the trachea? and how is it adapted?

Answer 6

-The airway from the mouth/nose to the bronchi
-Supported by a layer of cartilage that holds the trachea open however the rings are incomplete to allow for it to bend when food is swallowed, gaps between the cartilage are filled with elastic fibres and smooth muscle
-The trachea is lined with goblet cells, which secrete mucus and ciliated epithelial cells which move the mucus away from the lungs

Question 7

What are the bronchus?

Answer 7

-Bronchi are extensions of the trachea which split off into two for the left and right
-Very similar structure to trachea but smaller

Question 8

What are the bronchioles?

Answer 8

-Bronchus split into bronchioles which are 1mm in diameter or less, have no cartilage and are held open by smooth muscle
-Lined with thin layer of epithelial tissue

Question 9

Explain inspiration/inhalation?

Answer 9

-Diaphragm contracts and flattens, external intercostal muscle contracts moving ribcage up and out
-Thoracic volume increases and pressure decreases
-Air flows into the lungs to equalize pressure

Question 10

Explain active and passive exhalation/expiration?

Answer 10

Passive: diaphragm relaxes and curves up and intercostal muscles relax pulling ribcage down and in, thoracic volume decreases and pressure increases forcing air out of the lungs

Active: Instead of intercostal muscles relaxing they contract

Question 11

What are three ways you can measure Lung capacity?

Answer 11

-Peak flow metre: measure rate at which air can be expelled from lungs
-Vitalograph: More sophisticated version of peak flow metre, produces a graph as the patient breathes out as quickly as they can
-Spirometer: lower half of the tank is filled with water and upper air, as the patient breathes out volume of air in the tank increases so upper half rises, marker is attached to upper half which produces a graph

Question 12

What is tidal volume and Vital lung capacity?

Answer 12

-Tidal volume: volume of air that moves into and out of lungs with every breath
-Vital lung capacity: largest volume of air that can be breathed out

Question 13

What is inspiration and expiration reserve volume?

Answer 13

-Inspiration reserve volume: maximum volume of air you can breath in above normal inhalation
-Expiration reserve volume: maximum volume of air you can force out over and above the normal tidal volume of air.

Question 14

What is residual volume?

Answer 14

-The volume of air remaining in lungs after forceful expiration

Question 15

What are spiracles?

Answer 15

-Small openings found along the thorax of insects
-Open (when they need oxygen and co2 builds up) and closed(oxygen demands are lower and environment is dry) by sphincters
-Lined with bristles that trap unwanted particles out of the air and trap moist air to reduce water loss

Question 16

What are trachea in insects?

Answer 16

-Run from spiracles into tissue, 1mm in diameter
-Covered in chitin to support it keeping airway open and preventing any gas exchange

Question 17

What are the tracheoles in insects and how are they adapted to carry out their function?

Answer 17

-Trachea Branch into a series of tracheoles which divide until their microscopic ends penetrate an individual body cell
-tracheal system supplies all the oxygen needed by the cells of the insect
-Adaptations: no chitin so gas exchange is possible, many branches so there is a large surface area, walls are thin to reduce the diffusion distance and walls are moist

Question 18

What is tracheal fluid and how does it help the cell during high oxygen demands?

Answer 18

-Towards the ends of the tracheoles is the tracheal fluid, during strenuous activity anaerobic respiration occurs which causes a build-up of lactic acid in cells lowering water potential of tissues.
-This causes tracheal fluid to move into cells by osmosis and more of the tracheal is now exposed for more efficient gas exchange

Question 19

How do some insects meet high oxygen demands?

Answer 19

-When some insects are flying they use wing movements to pump thoraxes to move oxygen in and out
-Some insects have air sacs which are squeezed by flight muscles to pump oxygen around the gas exchange system

Question 20

Why won’t mammalian ventilation work in fish?

Answer 20

-Water is more dense so requires more energy to move
-Water has a lower O2 concentration

Question 21

What are the adaptations of the fish gas exchange surface?

Answer 21

-Water causes gil filaments to separate, this increases the surface area of gas exchange
-Secondary gil lamellae on the ends of gil lamellae are one cell thick to reduce diffusion distance
-Lots of blood capillaries so there is a low concentration of oxygen in lamellae so there is a steep concentration gradient

Question 22

How does countercurrent flow work?

Answer 22

-Blood flows in opposite direction to water, blood(operculum-mouth) and water (opposite)
-Blood at the operculum is deoxygenated from the cells and gets reoxygenated up to the mouth by the steep concentration gradient of O2 between water and blood.

Question 23

How do fish inspire and expire?

Answer 23

-Inspiration: fish opens buccal cavity(mouth) and lowers floor of buccal cavity so volume increases and pressure decreases forcing water into mouth
-Expiration: fish raises floor of buccal cavity decreases volume and increases pressure forcing water into gil cavity as water enters gil cavity pressure increases forcing water out operculum