The crayfish have its nerve cord on the ventral side rather than on the dorsal side. The ventral side is under the Crayfishes' exoskeleton, as opposed to the dorsal side where the exoskeleton is . If it is attacked it will be from the dorsal side and the nerve cord would be snapped easier. The function of the nerve cord is that if it gets attacked by a predator they will go for the top and it will still be able to move.
Plant A would have one allele from each parent, so the leaf color will be the dominant one.
Plant B would have a more complex percentage for traits. And it'll probably "cancel-out" some alleles only showing the info given in one of them.
Hope it helped,
BioTeacher101
<span>systematic knowledge of the physical or material world gained through observation and experimentation.</span>