DNA model given by Watson and Creek in the year of 1953 gave a very detailed study regarding the structure of B DNA which is valid till date and is essentially corroborating with Chargaff's data and Xray diffraction pattern.
<h3><u>Explanation:</u></h3>
The DNA is the most common nucleic acid found in the living organisms as a genetic material. As stated by Watson and Creek, this DNA contains a double helical structure with two sugar phosphate backbones and the nitrogen bases getting projected from it inwards. The backbones are formed of ribose sugar and phosphate and joined together with a phosphodiester bond. The ribose sugar is attached to phosphates at its 3' and 5' Carbon atoms. The nitrogen bases found in DNA are Adenine, Guanine, Thymine and Cytosine. The Adenine has two hydrogen bonds with thymine and guanine has 3 hydrogen bonds with cytosine.
Each full turn of a helix is 34A and each base pair is 3.4A apart. The distance between two strands of DNA is 20A.
Chargaff's rule regarding the equal amount of adenine and thymine as well as guanine and cytosine is matching with this structure. All the other rules also do match with this DNA structure.
<h2>Answer is option "b"</h2>
Explanation:
- Non-ionizing radiation is radiation that has a lower frequency, or longer wavelength, in the EMR spectrum. These frequencies range from that of power lines, radios, and cell phones, up to visible light. Non-ionizing radiation is not powerful enough to break the chemical bonds in molecules. In general, it is not harmful to human health as radiation per se, but could be harmful in terms of the transfer of heat energy. An example of an emitter of non-ionizing radiation is a microwave oven.
- Non-ionizing radiation is less harmful because the rays carry much less energy. Radio waves, light, and even heat are examples of non-ionizing radiation. For the most part, these kinds of radiation do not cause any damage. However, ultraviolet light is a kind of non-ionizing radiation that can be harmful - it can cause mutations in DNA
- Non-ionizing radiation is limited to the lower energy range electromagnetic radiation, which is more commonly known as light. However, the light we can see with our eyes, visible light, is only a small section of the electromagnetic radiation spectrum as seen here
- Hence the right answer is option "b"
I believe A is the most correct (i assume it's about antibiotics - they actually DO harm our immune system in some way).
B is partially correct because, the colds indeed should be treated by anti-viral medication (because the virus is a cause of typical cold) but using antibiotics during recovery is needed only when an additional bacterial infection occurs as a complication after the viral infection. and it doesn't happen very often.
C - what works? antibiotics doesn't work for viral infections (colds). anti-viral medication do.
D i won't discuss.
I am sorry for a so long answer. but your question is so linguistically twisted that i am not sure which of the following choices is actually correct because of a big amount of mistakes.
B <span>What is the effect of crop selection for pest resistance on the distribution of leaf size in a population of plants?
</span>
