organisms exchange substances with their environment TOPIC 3 Flashcards
Describe the relationship between the size and structure of an organism and its SA:V ratio.
-As size increases, SA:V decreases
-More thin/elongated structures have a higher SA:V.
Suggest an advantage of calculating SA:mass for organisms instead of SA:V
SA:mass is easier to find because it is hard to find volume of irregular shapes.
What is metabolic rate?
Amount of energy used by an organism within a given period of time.
How is metabolic rate measured?
By measuring oxygen uptake.
Explain the relationship between SA:V and metabolic rate.
As SA:V increases, metabolic rate increases because:
-rate of heat loss per unit body mass increases
-so organisms need a higher rate of respiration to release energy in the form of heat
-to maintain a constant body temperature.
Describe the 3 main components that make up the tracheal system of an insect.
- 𝗦𝗽𝗶𝗿𝗮𝗰𝗹𝗲𝘀: pores on surface that can open/close to allow diffusion.
2.𝗧𝗿𝗮𝗰𝗵𝗲𝗮𝗲: large tubes full of air that allow diffusion
3.𝗧𝗿𝗮𝗰𝗵𝗲𝗼𝗹𝗲𝘀: smaller branches from trachea, permeable to allow gas exchange with cells.
Explain how an insect’s tracheal system is adapted for gas exchange.
𝗧𝗿𝗮𝗰𝗵𝗲𝗼𝗹𝗲𝘀:
-Thin walls so short diffusion distance to cells
-Highly branched tracheoles so large surface area.
𝗧𝗿𝗮𝗰𝗵𝗲𝗮𝗲:
-provide tubes full of air so fast diffusion
𝗖𝗼𝗻𝘁𝗿𝗮𝗰𝘁𝗶𝗼𝗻 𝗼𝗳 𝗮𝗯𝗱𝗼𝗺𝗶𝗻𝗮𝗹 𝗺𝘂𝘀𝗰𝗹𝗲𝘀:
-changes pressure in body causing air to move in/out
-maintains concentration gradient for diffusion.
Describe both structural and functional adaptations in terrestrial insects which allow efficient gas exchange while limiting water loss.
𝘁𝗵𝗶𝗰𝗸 𝘄𝗮𝘅𝘆 𝗰𝘂𝘁𝗶𝗰𝗹𝗲: increases diffusion distance so less evaporation.
𝘀𝗽𝗶𝗿𝗮𝗰𝗹𝗲𝘀: can open to allow gas exchange AND close to reduce water loss. 𝗵𝗮𝗶𝗿𝘀 around spiracles: trap moist air, reducing water potential gradient so less water loss (evaporation).
Explain how gills of fish are adapted for gas exchange.
-Gills are made of many filaments covered with 𝗺𝗮𝗻𝘆 𝗹𝗮𝗺𝗲𝗹𝗹𝗮𝗲 increasing surface area for diffusion.
-𝘁𝗵𝗶𝗻 𝗹𝗮𝗺𝗲𝗹𝗹𝗮𝗲 𝘄𝗮𝗹𝗹: short diffusion distance between water/blood.
-Lamallae have 𝗹𝗮𝗿𝗴𝗲 𝗻𝘂𝗺𝗯𝗲𝗿 𝗼𝗳 𝗰𝗮𝗽𝗶𝗹𝗹𝗮𝗿𝗶𝗲𝘀- maintains a conc. gradient as O2 is removed quickly and CO2 is taken in.
Explain the counter current flow system in fish.
1.Blood and water flow in opposite directions through lamellae.
2.So oxygen conc. is always higher in water, to ensure that oxygen constantly diffuses into blood (high conc. to low)
3. This maintains a conc. gradient of O2 between water and blood.
4.For diffusion along the whole length of lamallae.
What would happen if both blood and water flowed in the same direction?
equillibrium would be reached so oxygen wouldn’t diffuse into the blood along lamellae.
Explain how the leaves of a dicotyledonous plant is adapted for gas exchange.
-𝗺𝗮𝗻𝘆 𝘀𝘁𝗼𝗺𝗮𝘁𝗮: large surface area for gas exchange.
-𝘀𝗽𝗼𝗻𝗴𝘆 𝗺𝗲𝘀𝗼𝗽𝗵𝘆𝗹𝗹: contains air spaces- large surface area for gases to diffuse through
-𝘁𝗵𝗶𝗻: short diffusion distance.
Describe adaptations in xerophytic plants for gas exchange while limiting water loss.
-𝗧𝗵𝗶𝗰𝗸𝗲𝗿 𝘄𝗮𝘅𝘆 𝗰𝘂𝘁𝗶𝗰𝗹𝗲: increases diffusion distance for water so less evaporation
-𝗦𝘂𝗻𝗸𝗲𝗻 𝘀𝘁𝗼𝗺𝗮𝘁𝗮 𝗶𝗻 𝗽𝗶𝘁𝘀/ 𝗿𝗼𝗹𝗹𝗲𝗱 𝗹𝗲𝗮𝘃𝗲𝘀/ 𝗵𝗮𝗶𝗿𝘀: traps water vapour, so reduced water potential gradient between leaf/air, so less evaporation.
-𝘀𝗽𝗶𝗻𝗲𝘀/𝗻𝗲𝗲𝗱𝗹𝗲𝘀: reduces surface area to volume ratio.
What makes up the human gas exchange system?
-Trachea
-Bronchi
-Bronchioles
-Capillary network
-Alveoli
ALL found in lungs
What is the alveolar epithelium?
A single layer of cells that line the walls of the alveoli.
Describe how the alveolar epithelium is adapted for gas exchange.
-consists of flattened cells: short diffusion distance
-folded: large surface area
-permeable: allows diffusion of O2/CO2
-large network of capillaries: good blood supply which maintains conc. gradient.
Describe how gas exchange occurs in the lungs.
-Oxygen diffuses from alveolar air space into blood down its conc. gradient
-first across alveolar epithelium then across capillary endothelium.
(OPPOSITE FOR CARBON DIOXIDE: first capillary endothelium, then alveolar epithelium)
Explain the importance of ventilation.
-Brings in air containing a high conc. of O2 and removes air with lower conc. of O2.
-maintains conc. gradient
Describe the process of Inspiration (breathing in).
- External intercostal muscles contract
- Ribcage is pulled up / out
- Volume 𝗶𝗻𝗰𝗿𝗲𝗮𝘀𝗲𝘀 and pressure 𝗱𝗲𝗰𝗿𝗲𝗮𝘀𝗲𝘀 in thoracic cavity
- Air moves into lungs down pressure gradient.
Describe the process of expiration (breathing out).
- External intercostal muscles relax
- Ribcage moves down / in
- Volume 𝗱𝗲𝗰𝗿𝗲𝗮𝘀𝗲𝘀 and pressure 𝗶𝗻𝗰𝗿𝗲𝗮𝘀𝗲𝘀 in thoracic cavity
- Air moves out of lungs down pressure gradient.
Suggest why expiration (breathing out) is normally passive at rest.
-Internal intercostal muscles do not normally need to contract
-during expiration lungs naturally spring back to their original size (elastic recoil).
Suggest how different lung diseases reduce the rate of gas exchange. (3)
1.𝗧𝗵𝗶𝗰𝗸𝗲𝗻𝗲𝗱 alveolar tissue (e.g. fibrosis)- increases diffusion distance
2. Alveolar wall 𝗯𝗿𝗲𝗮𝗸𝗱𝗼𝘄𝗻- reduces surface area.
3. 𝗥𝗲𝗱𝘂𝗰𝗲𝗱 𝗹𝘂𝗻𝗴 𝗲𝗹𝗮𝘀𝘁𝗶𝗰𝗶𝘁𝘆- lungs expand / recoil less reducing conc. gradients of O2 / CO2.
Suggest how different lung diseases affect ventilation. (3)
- 𝗥𝗲𝗱𝘂𝗰𝗲𝗱 𝗹𝘂𝗻𝗴 𝗲𝗹𝗮𝘀𝘁𝗶𝗰𝗶𝘁𝘆- lungs expand / recoil less:
-reducing volume of air in each breath (tidal volume)
-reducing maximum volume of air breathed out in one breath. - 𝗡𝗮𝗿𝗿𝗼𝘄 𝗮𝗶𝗿𝘄𝗮𝘆𝘀 / 𝗿𝗲𝗱𝘂𝗰𝗲 𝗮𝗶𝗿𝗳𝗹𝗼𝘄 in and out of lungs (e.g. asthma)
-reducing maximum volume of air breathed out in 𝟭 𝘀𝗲𝗰𝗼𝗻𝗱 (forced expiratory volume)
3.𝗿𝗲𝗱𝘂𝗰𝗲𝗱 𝗿𝗮𝘁𝗲 𝗼𝗳 𝗴𝗮𝘀 𝗲𝘅𝗰𝗵𝗮𝗻𝗴𝗲- increased ventilation rate to compensate for reduced oxygen in blood.
What is tidal volume?
Volume of air in each breath.
