mod 3.2 - adaptations Flashcards
What are adaptations?
An adaptation is a characteristic that has been inherited to make an organism more suited to it’s environment. These features have evolved in response to biotic and abiotic factors.
These adaptations aren’t directly dictated by the organism, but by it’s changing environment.
Why do adaptations occur?
Adaptations occur because of natural selection: where organisms that are best suited to the environment survive and reproduce, passing on their advantageous adaptations to their offspring.
What do adaptations allow organisms to do?
Adaptations result in variation, and sometimes it is beneficial, neutral or not beneficial at all.
Adaptations enable animals and plants to live in extreme environments, access resources and mates, defend themselves and others, and communicate within and with other species.
What are structural adaptations?
Structural adaptations are anatomical or morphological features that improve an organism’s ability to cope with abiotic and biotic factors in their environment, increasing their chances of survival and reproduction. These are physical characteristics relating to body size and shape.
What are some structural adaptations of plants?
Reduced leaf SA Fewer stomata Stomatal hairs that create a humid microclimate Sunken or protected stomata Thick, waxy cuticle Extensive root systems Rolled leaves Leaves oriented away from sunlight Leaf abscission (shedding)
Structural Adaptations to Hot, Dry Environments (plants):
Rolled leaves:
Marram grasses (seen in sand dunes) (Ammophila species) are xerophytes that grow well in salty, sandy soils of coastlines, and when conditions are hot and dry, their bubble-shaped (bulliform) cells partially collapse, resulting in the leaf to roll inward.
Hairs on the inside of the roll trap moisture, creating a humid microclimate, which reduces the concentration gradient between the interior and exterior of the cell, reducing transpiration.
Leaf orientation:
Eucalypt trees have hard leaves with waxy cuticles on both sides that reduce water loss.
They also hang vertically, reducing the amount of direct sunlight they receive, reducing transpiration and water loss.
What are xerophytes?
Xerophytes: plants that grow in hot, dry environments. eg: Cacti like the Prickly Pear Cactus.
They have adaptations that conserve moisture and prevent leaf temperature from rising too much. They also have an increased tolerance for desiccation (drying).
Structural Adaptations to Cold, Dry Environments (plants):
Reducing the SA of the leaf protects the leaf from water loss in cold climates.
Conifers, like pines, do this by growing their leaves as needles.
Deciduous trees shed their leaves entirely during winter, a process known as leaf abscission.
Other leaves have a waxy-cuticle to prevent water loss.
Structural Adaptations to Warm, Wet Environments (plants)
Thin bark: plants in tropical rainforests do not need thick bark to prevent water loss.
Thick, waxy leaves: water runs off these leaves to prevent fungal growth.
A drip-tip: on leaves, a pointed end that funnels water off the leaves also preventing fungal growth.
Buttressing, stilt roots and prop roots: buttresses are the large ridges at the base of rainforest trees and stilt and prop roots are a root system above the ground; both provide stability.
Epiphytes: plants that grow on other plants, like ivy and creepers; to climb to get light.
What are some structural adaptations of animals?
Thick fur/blubber to protect against cold Bright feathers to attract mates Large ears to increase heat loss Small ears to reduce heat loss Webbed feet and flippers for swimming Spines for protection against predators SA:V to conserve body heat or water Patterned body coverings for camouflage
SA:V and Structural Adaptations (animals):
Larger animals are usually found in cold environments, because they have a lower SA:V and radiate less body heat per unit than smaller animals. A low SA:V allows large animals to conserve heat in cold environments.
Eg: Alpine snow leopard’s large size allows it to conserve heat in its cold environment.
Smaller animals with a larger SA:V can cool down and heat up quickly, this strategy is well suited to hot, dry climates.
Eg: A tiny desert sand cat allows it to lose and gain heat quickly in it’s hot, dry environment.
Body Coverings (animals): Structural
Emperor penguins have four layers of thick, scale-like feathers that create a windproof coat, and they also have blubber to keep them warm while swimming.
Juvenile penguins have soft down for insulation, but are not effective whilst swimming, and they must moult (shed) before swimming).
Vascular Body Parts (animals):
Structural
Animals in hot dry climates have big ears, long tails or a long body to release body heat to keep their bodies cool; these extremities being considered highly vascular (they contain many blood vessels. Eg: the fennec fox in the desert has highly vascularised ears.
Thermoregulation: when the body is overheated, blood vessels expand, allowing blood to flow closer to the surface, and when cold they restrict themselves to conserve heat.
Tearers and Crushers: Dental Adaptations (animals):
Structural
Many structural adaptations are linked to diet; the arrangement and structure of teeth (dentition).
The molars of a koala are flat and wide and sit directly on top of each other when the jaw is closed, allowing for them to grind and crush tough eucalypt with high cellulose.
The molars of a Tasmanian devil are sharp and arranged so that one set sits inside the other when the jaw is closed, perfect for tearing meat.
What are physiological adaptations?
Physiological adaptations affect the functioning at different levels of organisation, ranging from the biochemical reactions in organelles and cells to the tissue, organ, system or even the organism as a whole.
Crassulacean Acid Metabolism - CAM (plants):
Physiological
CAM photosynthesis is a physiological adaptation that reduces water loss in plants living in dry areas. Eg: succulent plants in deserts
The stomata only open at night to collect CO2 that is not used immediately (like normies) but stored in cell vacuoles as the organic compound: malic acid.
Frost Tolerance (plants): Physiological
A high concentration of solutes (sugars and salts) lowers the freezing point of water; plants that can accumulate high levels of these solutes in their leaves are less likely to be damaged by freezing temperatures (which can burst cell membranes and slow enzymes otherwise).
Other plants produce antifreeze proteins that inhibit the growth and recrystallisation of ice crystals by binding to them; dehydrin proteins bind to water molecules inside the cell, changing the structure of the water and stabilizing the cell membrane.
Plants can also change the lipid composition of their cell membranes to survive cold temperatures.
Regulation of Salinity (plants):
Physiological
Plants can exclude salt by:
Shedding leaves that are overloaded with salt
Excreting salt from salt glands
Pumping salt out of the roots
Controlling transpiration to avoid excess salt being delivered from the soil to the shoots
Balancing the rate of growth with the uptake of soluble ions to maintain a constant salt concentration in tissues
Increasing water uptake to dilute salt concentrations in tissues
Camouflage (animals):
Physiological
Enable organisms to blend with their environment; to avoid predators or capture prey.
Eg: the common octopus, Octopus vulgaris has specialised colour-changing cells, chromatophores, which move pigment to and from the cells and change their reflective characteristics to produce camouflage, they also have tissues that can create textures to mimic its environment.
Evaporative Cooling (animals) Physiological
Sweating plays an important role in thermoregulation through evaporative cooling; when warm sweat comes into contact with cooler air, it evaporates, carrying the heat away and lower body temperature.
Heat Exchange for Cooling (animals)
Physiological
The Oryx gazelle in the Kalahari desert (South Africa) keeps the brain cool through a network of veins and smaller arteries that are so close to one another that they can exchange heat, called a carotid rete system.
The venous blood in this system travels through the nasal sinuses and cools during evaporative cooling in the nostrils, through countercurrent heat exchange, where the cooler blood from the nostrils passes in the opposite direction to the warmer blood from the body; heat flows from hotter blood to cooler blood.
Heat Exchange for Heating (animals)
Physiological
Penguins have heat exchangers in their flippers, feet and tails. Vasoconstriction occurs to decrease blood flow to these extremities and reduce heat loss; so cells in the feet receive oxygen and nutrients and remain warm enough to function, but less heat is lost. → also countercurrent heat exchange.
Antifreeze Proteins (animals) Physiological
Fish like the Antarctic cod construct antifreeze proteins that prevent the growth of ice-crystals and keep the blood a liquid.
Deep Diving (animals) Physiological
The crab-eater seal must store oxygen in their blood to allow for them to be submerged under water for a long time and at a deep depth.
Other diving mammals also carry out anaerobic respiration.
