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Airida [17]
3 years ago
11

What is the function of the valves in veins in the legs?

Biology
2 answers:
emmasim [6.3K]3 years ago
4 0

Answer:

D

Explanation:

qwelly [4]3 years ago
3 0

Answer:

D.

Explanation:

You might be interested in
You dilute an unknown sample of bacteria to 1 x 10-6 and plate out 10 onto a Petri dish. The next day you count 64 colonies. The
Sveta_85 [38]

Answer:

b

Explanation:

The correct answer would be 6.4 x 10^6 cells/ul.

For 1 x 10-6 dilution, the plating factor is 10^6. To find the number of bacteria in the original sample, the plating factor is multiplied by the colony count per ul.

<em>Number of viable bacteria = plating factor x colony count/ul</em>

Since 10 ul gives 64 colonies.  1 ul will give:

         64/10 = 6.4 colonies.

Therefore, the viable bacteria in the original sample = 6.4 x 10^6 cells/ul

The correct option is b.

3 0
2 years ago
Name two things that increase the amount of nitrogen in the nitrogen cycle
Allushta [10]

The majority of Earth's atmosphere contain 78% is nitrogen, The Nitrogen cycle is the geochemical cycle in which nitrogen is converted into multiple chemical forms. Nitrogen cycle occurs in terrestrial and marine ecosystem. Nitrogen can be converted through both biological and physical process. The processes that are involved in nitrogen cycle are fixation, ammonification, nitrification, and denitrification.

There is limited amount of nitrogen that is useful but <u>increase of fossil fuel combustion, use of artificial nitrogen fertilizer</u> have dramatically increased the amount of nitrogen in nitrogen cycle.

8 0
3 years ago
Please give a small paragraph quickly summarizing the what, when and how of each of the following techniques: PCR, DNA gel elect
Anuta_ua [19.1K]

Answer:

All are used to resolve questions in molecular and biochemistry/biotechnology

Explanation:

PCR: resolution of an amplicong on agarose gel to chech size after thermocycling

DNA gel electrophoresis,

Recombinant DNA, A DNA fragment that it attached to another such as a reporter, commonly used is GFP attached to protein of interest to track movement

Cloning, Duplicate an amplicon, insert into a vector, transform this vector into a bacteria that is designed to make multiple copies of itself

Northern blots, Method used to detect different sizes RNA from a mixture of other products

Southern blots, method used to detect different sizes of DNA similar to the idea of a Northern Blot

Western blots, Resolution of protein sizes by running the protein through an acrylamide gel in an ionic buffer

Antibody production (polyclonal and monoclonal),  Generating an antigen against a protein using different parts of the same protein (polyclonal) or only a specific sequence of the protein not a variety of antigens from the full length (monoclonal)

ELISA, enzyme-linked immunosorbent assay is used to check the presence of a protein

FRET, Transmission energy of one molecule to another, it is usually included in the detection of colors in fluorescence microscopy

FRAP, this method will is called Fluorescence recovery after photobleaching, a microscospy measurement

FACS, this is a type of cell sorting Fluorescence-activated cell sorting

Fractionation by centrifugation, Lysis of agents such as cells that can be lysed by spinning in a centrifuge

Chromatography, separation of chemical thru a media by colors

Fluorescence microscopy,  use of fluorophore to detect specimen under a microscope a specific wavelength

Coomassie staining,  procedure used to stain an acrylamide gel or membrane to show protein presence

Silver staining, use of a silver colloid to change the way proteins are seen on a Western blot or under a microscope

His tag, a string of histidine residues attached to a protein for easy manipulation/detection

GST tag, Glutathione S-transferases is a group of proteins used in protein purification an option other than His tag

Confocal microscopy,

FISH, The generation of a nucleotide probe used in DNA sequence detection in histology

PCR, Polymerized chain reaction used to amplify selected region of DNA

DNA library, the collection of gDNA of a specific specie or tissue

cDNA library, collection of the coding sequence of a organism/tissue

Microarrays, the platform used to detect thousands of gene sequences at once

Sanger sequencing, Method used to derrive DNA sequence developed by Frederick Sanger by incorporating a single nucleotide at a time

GFP, Green fluorescent protein, a reporter protein used in recombination protein creation

Bright field microscopy, microscopy that uses light or natural light to detect samples

DIC microscopy, Differential interference contrast is used to detect and enhance the different levels of contrast of a specimen

Phase contrast microscopy, Microscopy technique used to detect the different states of matter of a specimen

Fluorescence microscopy, use of fluorophore attached to sample for investigation

Transmission electron microscopy, uses beams of electrons to pass through a sample to then create an image

Scanning electron microscopy,  the surface of a sample is scanned with a beam of electrons to generate an image

X ray crystallography, determining a structure of a protein my using an x-ray technique

2D PAGE electrophoresis,  separation of proteins by two phases sizes and charges

NMR,  Nuclear magnetic resonance, spinning of all the nuclei and measurement of the energy that it gives off.

Mass spectrometry Protein sequencing technique based on weight

4 0
3 years ago
In photosynthesis, carbon dioxide is reduced and h2o is oxidized. What type of chemical reaction is this?.
Vilka [71]

In photosynthesis, carbon dioxide is reduced and H₂O is oxidized. The type of chemical reaction is an oxidation-reduction reaction.

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Explanation

Oxidation-reduction reaction are reactions that take place in electrochemical processes. Reduction is the reaction of decreasing oxidation number and increasing electrons and it can be said that reduction is the reaction of a substance losing oxygen. Oxidation is the reaction of increasing the oxidation number and decreasing electrons and can be said that oxidation is a reaction where the reaction of a substance binds oxygen.

Photosynthesis is one type of oxidation-reduction reaction that occurs naturally in everyday life. Photosynthesis has a complex process and involves green plants and certain bacteria. In the event of photosynthesis, carbon dioxide is reduced to carbohydrates and water is oxidized to oxygen.

The oxidation-reduction reaction in photosynthesis is:

6CO₂(g) + 6H₂O(l) + energy --> C₆H₁₂O₆(aq) + 6O₂(g)

Learn more about oxidation-reduction reaction on

  • brainly.com/question/13559667
  • brainly.com/question/16867778

#SPJ4

6 0
1 year ago
During which phase does the cell actually separate into two individual daughter cells?
Neko [114]
The cell actually divides in Cytokinesis.
6 0
3 years ago
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