Answer:
The hypothesis that eukaryotic cells evolved from a symbiotic association of prokaryotes—endosymbiosis—is particularly well supported by studies of mitochondria and chloroplasts, which are thought to have evolved from bacteria living in large cells.
Explanation: Both mitochondria and chloroplasts are similar to bacteria in size, and like bacteria, they reproduce by dividing in two. Most important, both mitochondria and chloroplasts contain their own DNA, which encodes some of their components. The mitochondrial and chloroplast DNAs are replicated each time the organelle divides, and the genes they encode are transcribed within the organelle and translated on organelle ribosomes. Mitochondria and chloroplasts thus contain their own genetic systems, which are distinct from the nuclear genome of the cell. Furthermore, the ribosomes and ribosomal RNAs of these organelles are more closely related to those of bacteria than to those encoded by the nuclear genomes of eukaryotes.
Nucleus. Ribosomes. Endoplasmic reticulusGolgi apparatusChloroplastsMitochondria
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Answer:
Examples: Si, B, Ge, Sb, Ga
Explanation:
The majority of elements in the periodic table are classified as either a metal (a species that can lose electrons to become a cation) or a non-metal (a species that can gain electrons to become an anion).
However, there are several atoms which are considered to be metalloids. Metalloids are elements which possess properties that resemble both metals and non-metals. Examples of metalloids would be: silicon (Si), boron (B), germanium (Ge), antimony (Sb), gallium (Ga).
Since metalloids have properties of both metals and non-metals, they are widely used in semiconductors, as they might both donate and accept electrons in their shells.
The fourth most abundant element in terms of mass is Carbon.
The first, second, and third most abundant element in terms of mass are Hydrogen, Helium, and Oxygen, respectively.
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Answer:
1) high pH is required
2) other ions are precipitated along with the strontium ions
Explanation:
According to the solubility rules all phosphates are insoluble except those of sodium, potassium, and ammonium. This implies that strontium phosphate is insoluble in water. This explains why strontium ions can be precipitated from drinking water supply using phosphate. The main problem with the precipitation of strontium using phosphate is that it usually requires a high pH as the precipitation occurs under very alkaline conditions.
The main reason why the results may not be accurate is that other ions are precipitated along with the strontium such as calcium ions and magnesium ions. This may lead to inaccurate determination of the amount of strontium ions present.
