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Adaptation of lenticels for gaseous exchange include;Cells are loosely arranged to facilitate air circulation.Cells have moist surfaces to dissolve respiratory gases.
Structural adaptation of a mammalian eye to it's function;Has sclera/sclerotic layer that contains inelastic (collagen) fibres to protect/maintain shape of the eye.Cornea is transparent to allow light to pass through or curved to reflect light toward retina.Conjuctiva, (thin) epithelium to protect the cornea.Has choroid which is rich in blood vessels/highly vascularized to supply the retina/eye with nutrients/ oxygen/remove metabolic waste.Has lens that is transparent to allow light to pass through.Iris has redial and circular muscles to alter the size of the pupil/control amount of light entering the eye.Retina contains cones and rods(photoreceptors) to perceive light/where the image is focused/formed.Has optic nerve sensory neurons/nerve cells that transmit impulses to the brain.Fovea has numerous cones (only) for accurate vision/high visual acuity.Pupils a hole/aperture/opening on the iris that lets in light.
Leaves of plants are adapted to carry out photosynthesis by having;Broad and flat to create surface area of carbon(iv)oxide and absorption of sunlight.Thin transparent upper epidermis to allow easier penetration to light to photosynthetic cells.Thin for faster diffusion of gases.Large/intercellular air space in the spongy mesophyll layer for storage of carbon (iv) oxide for easier gaseous exchange.Waxy water proof cuticle to reduce water loss.Palisade layer with numerous chloroplast to trap maximum amount of light for photosynthesis.Leaf mosaic/non-overlapping leaves for maximum exposure to light.Palisade cells placed next upper surface to trap maximum light for photosynthesis.Guard cells are modified to pen and close stomata to control amount of water loss from the leaf and allow gaseous exchange.
Adaptations of the guard cells to their function include;Have chloroplast (with chlorophyll) to photosynthesize.Thicker inner cell walls than outer wall to (allow for curvature to) form stoma.Bean shaped to allow formation of stoma.
Disadvantage of using seeds as a planting material are;Some have long dormancy and needs special treatment.Due to cross pollination you may experience variation which may be undesirableSoil born pests may damage seeds.Seeds may loose viability if stored for long.