which is more likely to be the cause of down syndrome the egg or the sperm?
The egg
The three major clades of bilaterian animals are the <span>ecdysozoa, lophotrochozoa, and deiterstomia.
Ecdysozoa are organisms that include insects, crustaceans, chelicerata, and myriapods. Lophoytochozoa include fossil organisms. Deiterstomia include chordata, echinodermata, and hemichordata.
Bilaterian animals have bilateral symmetry, meaning that they have a head, and a tail, as well as back and belly.
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