What change must have occurred during the evolution from invertebrate chordates to vertebrate chordates

vertebrate chordates are believed to have evolved from invertebrate chordates, which were similar to modern-day tunicates. what change must have occurred during the evolution from invertebrate chordates to vertebrate chordates? a. an endoskeleton evolved to enclose the spinal cord, which develops from the notochord.

Explanation:

"do a testcross with a homozygous recessive plant."

ecological efficiency: % of usable energy transferred as

biomass from one trophic level to the next typical is 10% efficient (90% of

energy is lost),is diagramed as the pyramid of energy flow. then osprey eagle

are tertiary consumer and the shrimp are primary consumer, so to balance

mass of shrimp (1/0.1) / 0.1 = 100 kg