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marshall27 [118]
4 years ago
15

Radioactive isotopes are often introduced into the body through the bloodstream. their spread through the body can then be monit

ored by detecting the appearance of radiation in different organs. one such tracer is 131i, a β− emitter with a half-life of 8.0
d. suppose a scientist introduces a sample with an activity of 345 bq and watches it spread to the organs.
Biology
1 answer:
german4 years ago
4 0

Answer:

We are asked for the decay rate (which means the same as activity) after 24 days. The half life is 8 days. After 8 days the activity is halved: A = 425/2 = 212.5Bq ;)

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Please answer as many as possible! Thanks♡​
4vir4ik [10]

Answer: number 8:

they form right angles just do a google search

number 9:

Crayfish turn blood into neurons. ... Olfactory nerves are continuously exposed to damage and so naturally regenerate

number 10: molting is the process of shedding and replacing the rigid exoskeleton and spiders are an animal that molts

Explanation:

7 0
3 years ago
Read 2 more answers
A student set up an experiment to show that carbon dioxide is consumed by Elodea plants during photosynthesis. She filled two te
bixtya [17]

Answer: The NEGATIVE CONTROl is the test tube that is filled with ONLY distilled water.

Explanation:

A negative control of an experiment is carried out alongside the main primary experiment except that the treatment is changed to something that is predicted to have no result. In the negative control, the student does not expect any response. This would help the student compare the result of a new experiment against an already known existing results.

Analysing the experiment carried out by the student, She filled two test tubes with distilled water and placed a piece of Elodea in one of the tubes, leaving the other without a plant. The other test tube that contains only distilled water is the negative control because she wasn't expecting any result from it. It's also served as a control sample to the primary experiment. This is observed as she blew in each tube to add carbon dioxide, which caused the distilled water to become more acidic. This would help the student know that the that experimental results are valid and to ensure that time is saved.

8 0
3 years ago
True or false? most antigens are large, complex molecules that are not normally present in the body.
MAVERICK [17]
The answer is true.
<span>Antigens are molecules capable to induce an immune response, "targeted" by antibodies. Antigens are usually proteins, peptides, or polysaccharides but they can combine with lipids and nucleic acids and form more complex antigens (lipopolysaccharide). Usually, antigens are exogenous (foreign substances), but sometimes are part of the host itself (in an autoimmune disease). All of them contain an epitope which is a part of an antigen that can be recognized and bound by an antibody.</span>
4 0
4 years ago
How much fertilizer is applied each year on lawns throughout the united states?
Stells [14]

Answer:

1.8 pounds  of Nitrogen per year; (based on 1000 square feet per application) for cool season grasses.

Explanation:

The above application shows  an average of 0.9 pounds of inorganic and organic  nitrogen per 1000 square feet per application . Therefore not more than 0.9 pounds of nitrogen will be needed  per application.And for a whole year 1.8 pounds of Nitrogen per year will be needed.

This calculation was based on 1000 per square.But most lawn are not 1000 per square, therefore calculation can be done using the 1000 per squares as the  reference point .

AMMONIA and its solutions, AMMONIUM NITRATE AND UREA  (which is organic source)<u>are the sources of this Nitrogen</u>.

Urea is non -explosive in nature and solid. However, ammonia and ammonium Nitrate are both explosive.

5 0
4 years ago
Explain the functions of the muscular system to a child
Talja [164]

The main function of muscular system is movement, but also stabilization

8 0
3 years ago
Read 2 more answers
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