Answer:
Sarcomere
Explanation:
The muscle fiber / myofibrils consist of 2 types of filaments - actin and myosin. The myosin filaments are thick filament whereas the actin filaments are the thin filament.
In addition to this, the muscles have A-band and I-bands. These bands give the muscles alternate light and dark colour band structure. In the A-band, myosin filaments are present, whereas in the I - band the actin filaments are found.
In I-band 2 Z-lines are located. The area between the Z-lines is called sarcomere. In this sarcomere region both actin and myosin filaments present.
When muscles get contracted the length of the sarcomere shorten. The actin and myosin filaments overlap in this area. A cross-bridge form between them, with the help of filamentous protein titin.
<h2>What is the atmosphere attracted by earth</h2>
<h3> Let's begin.</h3>
Our Earths magnetic field may be to blame.
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Answer: The correct answer is -
D) giraffes having increasingly longer necks over time.
Natural selection is an evolutionary mechanism that was proposed by Darwin.
According to this mechanism, organisms that are better capable of adapting to their changing environmental conditions, survive and increase their number through reproduction whereas other are eliminated from the population.
Example - Long neck of Giraffe, which is much elongated, lofty stature, that was beautifully adapted for browsing on the higher tree branches. This was an adaptation with slow and gradual change in the gene frequency as the lower vegetation was eaten by other animals. Due to this, giraffes had to search for other source (that was higher tree branches).
This is considered as a peculiar example of natural selection.
