20. Three common characteristics of adult vertebrates are
a. skull, notochord, and complex organ system
b. backbone, segmentation, and open circulatory system
c. two pairs of jointed appendages, cephalization, and internal skeleton
d. hydrostatic skeleton, bilateral symmetry, and true coelom
A?
-MC
I hope when you are an adult, you do not have a notochord.
Not a.
D?
-MC
To determine the correct answer, we need to understand the characteristics of adult vertebrates. Let's analyze each option:
a. Skull, notochord, and complex organ system: The skull is indeed a common characteristic of adult vertebrates, as it encloses and protects the brain. However, the notochord is a defining feature of chordates, which includes vertebrates. However, in adult vertebrates, the notochord is usually replaced by the vertebral column (backbone). The presence of a complex organ system is also a characteristic of adult vertebrates. So, this option seems partially correct.
b. Backbone, segmentation, and open circulatory system: The backbone (vertebral column) is a key characteristic of vertebrates. Segmentation is not a universal trait among vertebrates but is present in some groups (e.g., fish). An open circulatory system, where blood is pumped into a body cavity, is not a common characteristic of adult vertebrates. Therefore, this option is not entirely correct.
c. Two pairs of jointed appendages, cephalization, and internal skeleton: Adult vertebrates do not typically have two pairs of jointed appendages. Instead, they generally have paired limbs with multiple joints. Cephalization, which is the concentration of sensory organs in the head region, is a characteristic of some bilaterally symmetrical animals, including vertebrates. And an internal skeleton is indeed a defining feature of vertebrates. Therefore, this option is not entirely correct.
d. Hydrostatic skeleton, bilateral symmetry, and true coelom: Vertebrates do not have a hydrostatic skeleton, which is a type of skeleton found in some invertebrates (e.g., worms). Bilateral symmetry, where the body is divided into two mirror-image halves, is a characteristic of many animals but not unique to vertebrates. True coelom, which is a fluid-filled body cavity completely surrounded by mesoderm, is a characteristic of many animals, including vertebrates. So, this option is not entirely correct either.
Considering the explanations above, option A, "skull, notochord, and complex organ system," is the most accurate choice out of the given options.