This is the excretory system
Answer:
The first thing to look at would be type of symmetry the organism exhibits. If it is asymmetrical then it would be a sponge and the discovery could stop right there. If not, other characteristics need to be investigated.
Knowing the type of body cavity this organism has would be helpful.
It would also be beneficial to know what type of skeleton (endo or exo) this organism has and what its appendages look like.
Finally, the type of digestive tract and the presence or absence of a head would help to determine what this creature is.
Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
I believe your Answer would be:
A: Sister Chromatids.
Explanation:
A sister chromatid refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be 'one-half' of the duplicated chromosome.
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