Under the leadership of Mikhail Gorbachev, the doctrine of perestroika called for "<span>A. Openness in communication", since the "closed off" Soviet Tactics of the past were clearly not working by the 1980s.</span>
<span>There are numerous proteins in muscle. The main two are thin actin filaments and thick myosin filaments. Thin filaments form a scaffold that thick filaments crawl up. There are many regulatory proteins such as troponin I, troponin C, and tropomyosin. There are also proteins that stabilize the cells and anchor the filaments to other cellular structures. A prime example of this is dystrophin. This protein is thought to stabilize the cell membrane during contraction and prevent it from breaking. Those who lack completely lack dystrophin have a disorder known as Duchene muscular dystrophy. This disease is characterized by muscle wasting begininng in at a young age and usually results in death by the mid 20s. The sarcomere is the repeating unit of skeletal muscle.
Muscle cells contract by interactions of myosin heads on thick filament with actin monomers on thin filament. The myosin heads bind tightly to actin monomers until ATP binds to the myosin. This causes the release of the myosin head, which subsequently swings foward and associates with an actin monomer further up the thin filament. Hydrolysis and of ATP and the release of ADP and a phosphate allows the mysosin head to pull the thick filament up the thin filament. There are roughly 500 myosin heads on each thick filament and when they repeatedly move up the thin filament, the muscle contracts. There are many regulatory proteins of this contraction. For example, troponin I, troponin C, and tropomyosin form a regulatory switch that blocks myosin heads from binding to actin monomers until a nerve impulse stimulates an influx of calcium. This causes the switch to allow the myosin to bind to the actin and allows the muscle to contract. </span><span>
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This change best illustrates the 3rd answer choice, Loss of Habitat.
The plants aren't migrating, but are rather only surviving in areas where there is enough moisture to support life. The wildflowers are not adapting to grow in dryer conditions, and the species is not going extinct, as there are still some areas where the plants can get enough moisture.
Hope this helped!
Answer:
Option (D)
Explanation:
Dinosaurs are the extinct species that were very well structured and developed and were enormous. They existed on earth during the Mesozoic era, which includes the Triassic, Jurassic and Cretaceous period and the rocks of this age are found to comprise of their fossils at different places on earth. They were extinct about 65 million years back i.e. by the end of the Cretaceous.
They were Archosaurs, which belongs to the group of diapsid amniotes and are mainly classified as reptiles. They also had some property of endothermy, where an organism can maintain their body temperature by carrying out the processes related to metabolism. So, they were able to control their body temperature.
Thus, the correct answer is option (D)- all of these.
