The best and most correct answer among the choices provided by your question is the first choice or letter A. <span>A biological agent that cannot reproduce on its own is a VIRUS.
</span>A virus<span> is a small infectious agent that replicates only inside the living cells of other organisms.
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Chromatography is a simple technique in principle, it remains the most important method for the separation of mixtures into its components. It is quite versatile for it can be used to separate mixtures of solids.
Explanation:
- The two elements of chromatography are the stationary phase and the mobile phase. There are many choices of stationary phases, some being alumina, silica, and even paper. The mobile phase, in liquid chromatography, can also vary. It is often either a solvent or a mixture of solvents and is often referred to as the eluant.
- A careful choice of eluting solvent helps to make the separation more successful. The mixture is placed on the stationary phase. The eluant passes over the mixture and continues to pass through the stationary phase carrying along the components of the mixture.
- Chromatography is used in industrial processes to purify chemicals, test for trace amounts of substances, separate chiral compounds and test products for quality control. Chromatography is the physical process by which complex mixtures are separated or analyzed.
- Chromatography is based on the principle where molecules in mixture applied onto the surface or into the solid, and fluid stationary phase (stable phase) is separating from each other while moving with the aid of a mobile phase

The ability of organisms to regulate and thus maintain a relatively stable internal environment, despite external pressures, is called HOMEOSTASIS. This word comes from two Latin/Greek root words: "homeo" and "stasis".
"Homeo" means constant or unchanging. And "stasis" or "static" refers to stillness, non-movement. So, together, we can translate Homeostasis into a constant stillness inside, which makes sense for "maintaining normal internal states."
They both deal with diseases just that pathogens cause disease while antibodies fight against disease
Answer:
A nucleus is the membrane-bound organelle, and it has the chromosomes, and genes are made up from DNA.
Explanation:
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