The answer is D. Chordata.
There are three domains of life - Archaea, Bacteria, and
Eukarya. All organisms that belong to the domains Archaea or
Bacteria have cell walls. In the domain Eukarya, there are some groups
that have cell walls and others that do not.
Chordata is phylum of the kingdom Animalia which belongs to the domain Eukarya. So, Chordata cannot be a domain.
<span>Aplysia is a marine gastropod mollusc which is an often used model organism in neuroscience, especially on the cellular biology of learning and memory. What makes them easy to work with are their giant neurons, which are one of the largest. Aplysia neurons are suitable for studies of how neurons and neural circuits control behaviours. Its defensive reflex has been studied because it is mediated by electrical synapses, which allow several neurons to fire synchronously.</span>
Answer:
The correct option is B.
Explanation:
Muscle tissues of the heart refers to a group of cells that are carrying out similar functions in the heart. There are three different types of muscles, these are skeletal, cardiac and smooth muscles. The cardiac muscles are found in the heart, they form the contractile wall of the heart. These muscle contract involuntarily ( that is, without any external stimulation) and they are single nucleus, striated and short.
