Back to AI Flashcard MakerBiology /A-level Biology - 3.1.5 Gas Exchange and the Transport of Oxygen in Living Organisms Part 2
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 |