Answer:
Most cells within planarians tend to be very close to their gastrovascular cavity, in addition to their external environments. Also, planarians have the ability for oxygen and carbon dioxide to diffuse through the cells on their body walls: this makes it unnecessary for these varieties of flatworms to need a dedicated bodily system.
I think the deficiency of dedicated respiratory and circulatory systems in Planarians does not cause a problem because none of their cells are far removed from the gastrovascular cavity or from the external environment. Planarians are free-living flatworms and form the class Turbellarians in the Phylum Platyhelminthes. Flatworms have three tissue layers, that is the ectoderm, mesoderm, and endoderm.
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Explanation:
The four major organic compunds are lipids, carbohydrates, proteins, and nucleic acids.
Lipids are used to store energy, insulate insulate, and they help build cell membranes. Examples of lipids are fats, oils, and waxes.
Carbohydrates are used to give us quick energy and they help build cell walls. Examples of carbohydrates include bread, pasta, cereal, and rice.
The role of proteins is to build our bodies, help our immune system, and help cells communicate. Such examples include meat, beans, eggs, fish, nuts, soy, and dairy.
Finally, Nucleic acids are used to store gentetic info. Anything plant or animal based is considered a nucleic acid.
Answer:
<h3>Viruses can only replicate themselves by infecting a host cell and therefore cannot reproduce on their own.</h3>
<h3>At the most basic level, viruses consist of genetic material contained within a protective protein coat called a capsid; the existence of both genetic material and protein distinguishes them from other virus-like particles such as prions and viroids.</h3>
<h3>They infect a wide variety of organisms: both eukaryotes (animals, fungi and plants) and prokaryotes (bacteria).</h3>
<h3>A virus that infects bacteria is known as a bacteriophage, often shortened to phage.</h3>
<h3>The study of viruses is known as virology, and those who study viruses are known as virologists.</h3><h3 /><h3>It has been argued extensively whether viruses are living organisms.</h3>
<h3>Most virologists consider them non-living, as they do not meet all the criteria of the generally accepted definition of life.</h3>
<h3>They are similar to obligate intracellular parasites as they lack the means for self-reproduction outside a host cell, but unlike parasites, viruses are generally not considered to be true living organisms.</h3>
<h3>A primary reason is that viruses do not possess a cell membrane or metabolise on their own - characteristics of all living organisms.</h3>
<h3>Examples of common human diseases caused by viruses include the common cold, the flu, chickenpox and cold sores.</h3>
The answer is C. Mice are mammals so they need to feed on their mother's milk to survive for a few months. After a while, there mother teaches them how to hunt for food. The other animals like frogs, turtles, and snakes leave their babies to fend for themselves.
