Answer:
Porifera or Sponges
Explanation:
Porifera is the phylum of the simplest multicellular marine animals. Their body is composed of two cell layers (something like tissues) and mesophyl between them. The body is in direct contact with surrounding water through the large number of pores and channels. What makes Sponges so simple is that their cells are unspecialized and that they don't have nervous, digestive or circulatory systems.
DNA themselves discovered DNA
JK
The molecule now known as DNA was first identified in the 1860s by a Swiss chemist called <span>Johann Friedrich Miescher</span>
Answer:
Spermatozoa: 23 chromatids
Ootid: 23 chromatids
Anaphase of mitosis: 92 chromatids
Oogonium prior to S phase: 46 chromatids
Explanation:
1) Spermatozoa, also known as sperm cell is a haploid gamete (n) that results from the meiotic division of a dipoid reproductive cell. Since there are 23 pairs of chromosomes or 46 chromosomes in human somatic cells, there will be 23 chromosomes in the spermatozoa. Also, meiotic division occurs twice and separates sister chromatids in meiosis II. Hence, spermatozoa will contain 23 chromosomes (n) with 1 chromosome each i.e. 23 chromatids
2) Ootid is a haploid cell that arises from the second meiotic division of a secondary oocyte. A primary oocyte, with 46 chromosomes/92 chromatids, undergoes meiosis I to produce secondary oocyte with 23 chromosome/46 chromatids, which in turn undergoes meiosis II to produce ootid with 23 chromosomes/23 chromatids (each chromatid is an individual chromosome).
3) Mitosis is the cell division that produces two identical diploid (2n) daughter cells. Note that, 46 chromosomes get replicated to form 92 chromatids. In the anaphase stage of mitosis, sister chromatids get pulled apart to opposite poles but still remain in the cell as cytokinesis is yet to occur.
4) Oogonium is the diploid (2n) cell that gives rise to primary oocyte via mitosis. Prior to the S phase where chromosomes replication occurs, Oogonium cell will contain 46 chromosomes and 46 chromatids.
B. Mesozoic
The Mesozoic Era is commonly referred to as the Age of Reptiles or the Age of Dinosaurs.
