Back to AI Flashcard MakerBiology /A-level Biology - 3.1.5 Gas Exchange and the Transport of Oxygen in Living Organisms Part 2
A-level Biology - 3.1.5 Gas Exchange and the Transport of Oxygen in Living Organisms Part 2
This deck covers key concepts in gas exchange and oxygen transport in living organisms, focusing on insects, plants, and human respiratory processes.
Why do insects have to be small in size?
∵ insects mainly rely on diffusion to exchange gases
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Key Terms
Term
Definition
Why do insects have to be small in size?
∵ insects mainly rely on diffusion to exchange gases
What is tracheae supported by to prevent them from collapsing?
Strengthened rings
Name 4 adaptations of dicotyledonous plants that enable efficient gas exchange
Many stomata Thin, flat shape = provides large SA:volume ratio Numerous interconnection air spaces throughout mesophyll Leaf is flattened so no living...
Exchanging gases ____ water
loses
Name 2 adaptations that insects have to minimise water loss (without reducing gas exchange too much)
If insects are losing too much water = close their spiracles using muscles Have waterproof, waxy cuticle over their body & tiny hair around their spir...
Name an adaptation of dicotyledonous plants to minimise water loss without reducing gas exchange too much
If plants gets dehydrated = guard cells lose water & become flaccid = closes stomata
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| Term | Definition |
|---|---|
Why do insects have to be small in size? | ∵ insects mainly rely on diffusion to exchange gases |
What is tracheae supported by to prevent them from collapsing? | Strengthened rings |
Name 4 adaptations of dicotyledonous plants that enable efficient gas exchange | Many stomata Thin, flat shape = provides large SA:volume ratio Numerous interconnection air spaces throughout mesophyll Leaf is flattened so no living cell is far from external air |
Exchanging gases ____ water | loses |
Name 2 adaptations that insects have to minimise water loss (without reducing gas exchange too much) | If insects are losing too much water = close their spiracles using muscles Have waterproof, waxy cuticle over their body & tiny hair around their spiracles = reduce evaporation |
Name an adaptation of dicotyledonous plants to minimise water loss without reducing gas exchange too much | If plants gets dehydrated = guard cells lose water & become flaccid = closes stomata |
How are plants' stomata kept open during day (for gaseous exchange)? | Water enters guard cells = making them turgid = opens stomatal pore |
What type of process is inspiration (breathing in)? | Active process – uses energy |
What type of process is expiration (breathing out)? | Passive process |
Describe the process of inspiration | |
Describe the process of expiration | Passive Expiration (Normal Breathing) Diaphragm relaxes → moves upward into a dome shape. External intercostal muscles relax → rib cage moves down and inward. Thoracic cavity volume decreases. Pressure inside the lungs increases (Boyle’s Law: ↓ volume = ↑ pressure). Air is pushed out of the lungs into the atmosphere. Active Expiration (Forceful Breathing) Internal intercostal muscles contract → further compress the rib cage. Abdominal muscles contract → push diaphragm even higher. This creates greater pressure in the thoracic cavity, forcing air out more rapidly. |
Describe what happens during forced expiration (e.g. when you want to blow out candles) | External intercostal muscles relax & internal intercostal muscles contract = pulling ribcage further down and in During this time, movement of 2 sets of intercostal muscles is said to be antagonistic (opposing) |
What mainly causes the air to be forced out during normal quiet breathing (e.g. sleeping)? | Recoil of the elastic lungs |
Describe how oxygen gets from the alveoli to the blood | O2 diffuses out of alveoli, across the alveolar epithelium and capillary endothelium (type of epithelium that forms the capillary wall) & into haemoglobin in blood |
Oxygen from the air moves down the trachea, bronchi and bronchioles into the alveoli down a _______ | pressure gradient |
Once in alveoli, oxygen diffuses across alveolar epithelium, then capillary endothelium, into the capillary, down a ____ _______ | diffusion gradient |
Name 3 adaptations alveoli have for gaseous exchange | Thin exchange surface Alveolar epithelium = one cell thick Short diffusion pathway Large SA Large no. of alveoli = large SA for gas exchange Steep concentration gradient (of O2 & CO2 between alveoli and capillaries) Maintained by flow of blood and ventilation |
Name 2 things red blood cells do to enable efficient gas exchange | RBC are slowed as they pass through pulmonary capillaries = allow more time for diffusion RBCS are flattened against capillary walls = reduces diffusion distance |
Describe the structure of haemoglobin | Haemoglobin = large protein with quaternary structure Made up of 4 polypeptide chains Coiled into a helix Chains linked together to form spherical molecule Each chain contains a haem group Which contains a iron ion (Fe2+) |
How many oxygen molecules can each haem group combine with? | 1 oxygen molecule |