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Umnica [9.8K]
3 years ago
12

Before replication can take place.(1) A. DNA polymerases must add complementary nucleotides to DNA. B. the two strands of DNA mu

st separate. C. the covalent bonds in DNA must break. D. helicases must break the bonds in the nucleotides.
Biology
1 answer:
andriy [413]3 years ago
4 0

Answer:

The correct answer is B. the two strands of DNA must separate.

Explanation:

DNA is a double-stranded structure. The two strands are joined together by the formation of hydrogen bonds between complementary nucleotides. So before the replication takes place these two strands must be separated.

The separation of DNA strand is accomplished by the action of a helicase enzyme which breaks the hydrogen bond between complementary nucleotides and separated the two DNA strands.  

After separation, the DNA polymerase binds to separated DNA and replicating the DNA. So the right answer is B.

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Which of the following is TRUE regarding the flow of blood through the heart:__________
Charra [1.4K]

Answer:

a The pulmonary artery carries deoxygenated blood.

Explanation:

This is the the only artery that transports deoxygented blood in mammals. specifically it carry deoxgenated blood from the the atria  to the pulmonary circulation. That is to the lungs  for the exchange of the C02 in the deoxygenated blood with oxygen  in the lungs.

The  blood thus become oxygenated,and therefore return through the pulmonary veins to the left ventricle.

From the left ventricle ,through ventricular systole,blood is empty into the aorta through the aortic valves into the  systemic circulation.

Although,they carry blood away from the heart,but the blood is de oxygenated instead of the usual oxygenated by arteries,They are still regarded as arteries  because of convey of blood away from the heart,a typical role of arteries

7 0
3 years ago
12. Recent developments have resulted in the ability to clone cats. Many people argue that cloning offers pet owners comfort in
ipn [44]

Cloning is a process of producing genetically identical organisms through the techniques of biotechnology. Reproductive cloning of animals involves the somatic cell nuclear transfer in which the nucleus from an adult donor cell is transferred to an egg cell from which the nucleus has been removed. It is then incorporated into the uterus of a surrogate animal.

Pet cloning is not acceptable because of the following reasons-

(1) Its a very expensive procces with a high rate of failure.

(2) The clones produced tend to develop health problems. Large Offspring Syndrome (LOS) with very large organs is observed showing problems with blood flow and breathing with respect to heart and lungs, renal failure and other complicated issues.

(3) The clones are susceptible to skeletal abnormalities, higher rates of infection and tumour development. This results in a high mortality (death) rates.

(4) Since a surrogate mother is involved in the process of cloning, they experience a lot of health problems while carrying the embryos and sometimes it can be even killed.

Thus, cloning of pets is not acceptable as it affects both the cloned animal and the surrogate mother which is not preferred. Instead, adopting a homeless pet will provide shelter to another animal with a better nourishment.

7 0
3 years ago
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The answer is A. An organism living at the bottom of the ocean is used to a high pressure so they cannot study them as the lower pressure kills the organisms as they reach the surface.
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2 years ago
Which consequence of pollution is shown in the photograph?
irga5000 [103]
D is the answer because I had to answer the same question
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3 years ago
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