I believe this is survival of the fittest. so because of the drought there was no more food supply for the long necked tortoises thus causing them to die off and not be able to reproduce and pass of their gene for long neck. where as for the short neck tortoises there was enough food for them to survive and thus being able to reproduce and pass on their gene for short necks.
Answer:
Part-A will lead toward the head development of Drosophila.
Explanation:
A morphogen is a substance that governs the pattern of tissue development in the process of morphogenesis or pattern formation, Pattern formation is one of the core processes in the development of Drosophila's body. Bicoid was the first protein demonstrated to act as a morphogen. Bicoid is a gene whose protein concentration gradient patterns the anterior-posterior (A-P) axis during Drosophila embryogenesis. Although Bicoid is important for the development of Drosophila's head. Bicoid concentration is high in the anterior side or in part-A of the Drosophila that will become the head. Bicoid concentration is low at the posterior side or part-E of the Drosophila that will become the tail.
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1)Bilaterally symmetrical, and vermiform.
2)Body has more than two cell layers, tissues and organs.
3)Body cavity is a pseudocoel, body fluid under high pressure.
4)Body possesses a through gut with a subterminal anus.
5)Body covered in a complex cuticle.
6)Has a nervous system with pharyngeal nerve ring.
7)Has no circulatory system (no blood system)
8)Reproduction normally sexual and gonochoristic.
9)Feed on just about everything.
10)Live just about everywhere, many species are endoparasites.</span></span>
Answer The gravity and the sun
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