Answer:
gills
Explanation: A fish without a jaw was the first vertebrate to evolve. These fish used filtration to capture their food and sucked water and debris from the sea through their mouths and then released the water and trash through their gills. Some features are as follows:
1. They have a notocorda that serves as support through the back of the fish.
2. Gill bags. These organs are responsible for filtering the oxygen in the water.
3. A pineal eye that is sensitive to light
4. A cartilaginous skeleton
Answer:Biological structures are able to adapt their growth to external mechanical stimuli and impacts. For example, when plants are under external loads, such as wind force and self-weight, the overloaded zones are reinforced by local growth acceleration and the unloaded zones stop growing or even shrink. Such phenomena are recorded in the annual rings of trees. Through his observation of the stems of spruce, K. Metzger, a German forester and author, realized that the final goal of the adaptive growth exhibited by biological structures over time is to achieve uniform stress distribution within them. He published his discovery in 1893.12 A team of scientists at Karlsruhe Research Centre adopted Metzger's observations and developed them to one single design rule: the axiom of uniform stress. The methods derived from this rule are simple and brutally successful like nature itself. An excellent account of the uniform-stress axiom and the optimization methods derived from it is given by Claus Mattheck in his book ‘Design in Nature’.13 The present study utilizes one of these methods, stress-induced material transformation (SMT), to optimize the cavity shape of dental restorations.
Explanation:
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