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Tju [1.3M]
2 years ago
4

Which method developed at the end of 1980 lead to a major change in how scientists categorized organisms

Biology
1 answer:
notsponge [240]2 years ago
7 0

Answer:

Polymerase Chain Reaction (PCR) technique

Explanation:

The Polymerase Chain Reaction (PCR) technique was developed by Kary Mullis in 1984.  This technique exploits the ability of the DNA polymerase to amplify a specific DNA sequence (template), which is then observed as a band by traditional electrophoresis. Since PCR is highly specific and sensitive, it has enabled the detection of genetic variation among different DNA samples, and thereby this technique can be used to identify new species. One of the molecular markers most widely used to identify new species is the Citochormoe Oxidase I (COI) gene, which is amplified by PCR in order to detect genetic variation useful to classify species.

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A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the
xz_007 [3.2K]

Answer:

100 units

Explanation:

The interphase of the cell cycle includes three stages: G1, S, and G2. During the S phase of interphase, the cell enters the process of DNA replication. DNA replication duplicates the existing DNA molecule and doubles the DNA content of the cell. The cell accommodates the newly formed DNA in two sister chromatids of chromosomes. If a cell of grasshopper contained 200 units of DNA in the G2 phase, the cell would have 100 units of DNA in the G1 phase. The S phase would have doubled the DNA content and the G2 phase had 200 units.  

7 0
2 years ago
Which process of soil erosion is being prevented by the activity shown below?
diamong [38]
A- Gravity. I believe it is gravity since that is the only one that makes sense in this situation. I hope i helped! :)

7 0
2 years ago
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To help explain surface tension, use a single water molecule in the template, and draw arrows representing the possible location
kramer

Answer:

The correct representation is attached with the explanation.

Explanation:

In this representation of the surface tension, blue arrows between green water molecules are the possible molecules that can be used as the location for forming hydrogen bonds by a single molecule. Surface tension is the tendency of a liquid surface strectch to neighbouring molecules or ability to shrink in minimum surface area possible. Hydrogen bonds is an intermolecular force or interaction responsible for the surface are of liquide molecules. This bonds is towards every direction where the similar molecule present.

3 0
2 years ago
During presentation of APC-bound antigen, macrophages and dendritic cells secrete the cytokine, _____, that activates T helper c
Rom4ik [11]

Answer:

During presentation of APC-bound antigen, macrophages and dendritic cells secrete the cytokine, interleukin-1, that activates T helper cells

Explanation:

Macrophages interact with T cells in order to generate T cell activation in target organs, and are themselves activated by inflammatory messenger molecules (cytokines) produced by the T cells.

Macrophages produce toxic chemicals, such as nitric oxide, that can kill surrounding cells.

During presentation of APC-bound antigen, macrophages and dendritic cells secrete the cytokine, interleukin-1, that activates T helper cells

4 0
2 years ago
A team of biologists develop a new drug, and one team member hypothesizes that the drug is incapable of freely passing across th
matrenka [14]

Answer:

<em>B: The drug is a small charged molecule</em>

Explanation:

Substances can passively diffuse in and out of the cell via the cell membrane in two ways;

  • Simple diffusion
  • Facilitated diffusion

The cell membrane allows small molecules or ions to freely diffuse across it in response to concentration difference between the inner and outer parts of the cell membrane. This is known as simple diffusion.

In facilitated diffusion, special proteins in the cell membrane, known as channel/carrier proteins binds with molecules and facilitates their diffusion across the cell membrane by carrying them through special channels in the membrane.

Hence, to support the alternative hypothesis that the new drug will exhibit simple diffusion across the plasma membrane, the drug should be a small charged molecule.

<em>Correct option: B</em>

5 0
2 years ago
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