Answer: Layer a is 500 million years old.
Explanation:
Trilobite is a member of the group of extinct arthropods found as fossils and they can be identified by the three-lobed as well as three segmented forms. These were the marine animals. These were appeared initially in the Cambrian Period. They used to live 542 million years ago so the fossils can be estimated to be aged of 500 above years old. These animals used to dominate in the sea area.
• Genes can contain more than one polyadenylation site, which alters the 3' of the mRNA transcript and the inclusion/exclusion of exons.
• mRNA transcripts from the same gene can be differentially spliced to include/exclude exons.
Answer:
Water (H2O) can be called a molecule or a compound because it is made of hydrogen (H) and oxygen (O) atoms. There are two main types of chemical bonds that hold atoms together: covalent and ionic/electrovalent bonds. Atoms that share electrons in a chemical bond have covalent bonds.
Answer:
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Mitosis and meiosis are the ways of cell division which result daughter cells for growth, development and reproduction.
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Explanation:
Mitosis and meiosis result daughter cells for growth, development and reproduction in the living world.
Mitosis results two similar daughter cells which are generally for growth and development. In asexual mode of reproduction, mitosis helps in increasing the number of cells.
Meiosis occurs in germ cells, and in meiosis, one diploid cell produce four haploid cells.
Meiosis results variations by independent assortment and by crossing over and it helps the sexual mode of reproduction. During fertilization, the resultant daughter haploid cells unite and retains the diploid number of chromosomes.