During phototropism, the plant hormone auxin<span> controls cell elongation.</span>
Explanation:
The length of the sperm in a few species is much larger or giant than the size of the animal-like observed in the <em>Drosophila bifurca.
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In this fruit-fly, the tails of the sperm are too long which could be accounted for many reasons:
1. The sexual selection prefers the long tails over the small tail.
2. The large sperms can displace the small sperms in the female reproductive organ.
3. The female reproductive organ increases the promiscuity of the large sperms that is favour the large sperms over the small sperms.
It does not include plant sources.
