Adaptations for Gas Exchange in Plants Flashcards
The features of the transfer section through a plant?
-Upper Epidermis
-Mesophyll
-Stoma
-Lower Epidermis
-Guard Cell
-Spongy Mesophyll
-Palisade Mesophyll
-Waxy Cuticle
what is the stoma covered by?
Each covered by two guard cells
What adaptations of leaves to gas exchange?
-Leaf blade=flat and thin—>short diffusion pathway
-Spongy, allows diffusion and circulation of gases to maintain diffusion gradients
-plant tissues permeated by airspaces
-The stomatal pores allow exchange of oxygen and carbon dioxide gases
why do plants (like animals) need to generate ATP?
-so they respire all the time (day and night)
what is required for the process of respiration in plants?
Oxygen
What do plants do during the day when the light is available?
Carry out photosynthesis using chloroplasts (requires carbon dioxide)
What are the functions of leaves?
-photosynthesis
-Cellular respiration
what are the adaptations of leaves for photosynthesis?
-Large SA to absorb as much light as possible
-Can orientate themselves towards the sunlight
-Thin to allow light to penetrate lower layers
-Cuticle and epidermis are transparent to allow light to pass to the mesophyll below
-Palisade cells are elongated and densely packed together and contain many chloroplasts
-chloroplasts rotate a move within the mesophyll cells to maximise the absorption
-Intercellular air spaces allow carbon dioxide to diffuse into the cells, oxygen and water vapour to diffuse away
where are the stomata (small pores) found in the leaf?
-Lower epidermis
what is the role of the stomata?
-Open to allow gas exchange in plants and close to control water loss (transportation)
how many guard cells surround each stomata (pore)?
2
what is unusual about Guard cells?
-They are the only epidermal cells that contain chloroplasts
-They have unevenly thickened walls (inner wall is thick, outer wall is thin)
Why is the inner cell wall thick and outer wall thin?
-so that if the guard cells become turgid the stomata pore opens and if the guard cells become flaccid the pore closes
what is the mechanism for opening?
-potassium ions are actively transported from the epidermal cells into the guard cells
-Stored starch (insoluble) in the guard cells is converted to malate (soluble) by enzymes in the cytoplasm
-Water potential in the garden cells is lowered (becomes more negative due to the increase in solutes) water enters by osmosis
-The guard cells become turgid and curve apart because the outer cell walls are thinner than the inner cell walls
What is respiratory pigment?
-molecule which increases the oxygen-carrying capacity of the blood (e.g. haemoglobin)
