A horseshoe crab has been around for almost 500 million years. They are classified as arthropods and not actual crabs. However, There are many reasons that have helped them survive this long including, they can eat almost any organic matter. There blood is different from normal, in fact it’s blue. This blood helps them heal any wounds right away. They can also live in areas with very low levels of oxygen, meaning habitat is not a big issue for them. Evolution has also helped them grow and adapt seeing as they’ve survived this long.
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Answer:
Because natural selection selects for it. Thus it persists.
Explanation:
You have to understand heterozygote advantage. Basically, it's where heterozygotes have an advantage over homozygotes. In the case of sickle cell disease, heterozygotes have an advantage, and natural selection favors whatever is advantageous. Thus, because heterozygotes each have one recessive sickle-cell allele, as natural selection favors the heterozygotes, the recessive sickle-cell allele persists and remains in the gene pool.
Answer:
The correct answer is C. be more likely to have cancer at some point in his/her life.
Explanation:
Cell cycle checkpoints are controlled by different proteins which are coded by different genes. They are important in cell cycle regulation and stops cell cycle immediately if they find any problem in the cell like mutation.
The cell cycle will not be continued if the problem does not solve and cell death will occur which prevents cancer by preventing the mutation to spread into new cells.
Therefore if a mutation occurs in certain genes that enforce a checkpoint on the cell cycle then the mutated gene will pass in new cells and the mutated cells will grow uncontrollably due to no checkpoints so the person will probably have cancer at some point in his or her life.
Nitrogenous bases, double stranded, made of nucleotides, adenine, thymine, cytosine, guanine, A pairs with T, G pairs with C
Oogenesis and spermatogenesis both involve the chromosomal-reduction divisions of meiosis,which takes the gametes from the full complement of chromosomes to the Haploid number of chromosomes. Meiosis is the type of cell division that take place in the gamete cells, where diploid cells of the germ lines undergo cell division to yield haploid cells, normally the gametes are made through this process, that is, the ovum through Oogenesis, and the sperm through spermatogenesis. During fertilization the two combines to produce a diploid cell once again that undergoes continuous mitosis to form a zygote.
