Answer:
A
Explanation:
I'm quite sure its a, might be wrong.
Answer:
C)radial symmetry.
Explanation:
The central nervous system (CNS) is a part of the nervous system, it comprises the spinal cord and the brain. The brain plays in an important role in controlling most functions in the body such as movement, memory, speech etc.
Animals that have bilateral symmetry have a central nervous system because of the presence of the brain. But animals with radial symmetry such Cnidarians which include corals and jelly fish, do not have a central nervous system. Instead of the presence of neurons, they possess nerve nets.
Answer:
Principal Cell
Explanation:
The main sodium ion absorption cells are the principal cell. These cells are also the site for the action of aldosterone.
Answer:
We have just seen that pathogens constitute a diverse set of agents. There are correspondingly diverse ranges of mechanisms by which pathogens cause disease. But the survival and success of all pathogens require that they colonize the host, reach an appropriate niche, avoid host defenses, replicate, and exit the infected host to spread to an uninfected one. In this section, we examine the common strategies that are used by many pathogens to accomplish these tasks.
Explanation:
The first step in infection is for the pathogen to colonize the host. Most parts of the human body are well-protected from the environment by a thick and fairly tough covering of skin. The protective boundaries in some other human tissues (eyes, nasal passages and respiratory tract, mouth and digestive tract, urinary tract, and female genital tract) are less robust. For example, in the lungs and small intestine where oxygen and nutrients, respectively, are absorbed from the environment, the barrier is just a single monolayer of epithelial cells.
Skin and many other barrier epithelial surfaces are usually densely populated by normal flora. Some bacterial and fungal pathogens also colonize these surfaces and attempt to outcompete the normal flora, but most of them (as well as all viruses) avoid such competition by crossing these barriers to gain access to unoccupied niches within the host.
Answer:
Identical twins are also known as monozygotic twins. They result from the fertilization of a single egg that splits in two. Identical twins share all of their genes and are always of the same sex. In contrast, fraternal, or dizygotic, twins result from the fertilization of two separate eggs during the same pregnancy.
Explanation:
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