<span>Gametogenesis is the process of forming gametes (by definition haploid, n) from diploid cells of the germ line. Spermatogenesis is the process of forming sperm cells by meiosis (in animals, by mitosis in plants) in specialized organs known as gonads (in males these are termed testes).</span>
False
Sedimetary rocks can be formed from changes in igneous rock, and igneous rock can be from changes in sedimentary rock.
Answer:
PFFT this might help? sorry if not mate
Explanation:
Cell cycle checkpoint controls play a major role in preventing the development of cancer [see Sherr, 1994, for a more detailed discussion]. Major checkpoints occur at the G1 to S phase transition and at the G2 to M phase transitions. Cancer is a genetic disease that arises from defects in growth-promoting oncogenes and growth-suppressing tumor suppressor genes. The p53 tumor suppressor protein plays a role in both the G1/S phase and G2/M phase checkpoints. The mechanism for this activity at the G1/S phase checkpoint is well understood, but its mechanism of action at the G2/M phase checkpoint remains to be elucidated. The p53 protein is thought to prevent chromosomal replication specifically during the cell cycle if DNA damage is present. In addition, p53 can induce a type of programmed cell death, or apoptosis, under certain circumstances. The general goal of p53 appears to be the prevention of cell propagation if mutations are present. The p53 protein acts as a transcription factor by binding to certain specific genes and regulating their expression. One of these, WAF1 or Cip1, is activated by p53 and is an essential downstream mediator of p53-dependent G1/S phase checkpoint control. The function of p53 can be suppressed by another gene, MDM2, which is overexpressed in certain tumorigenic mouse cells and binds to p53 protein, thus inhibiting its transcriptional activation function. Other cellular proteins have been found to bind to p53, but the significance of the associations is not completely understood in all cases. The large number of human cancers in which the p53 gene is altered makes this gene a good candidate for cancer screening approaches.
Answer:
Answer is explained below;
Explanation:
Mercury is a liquid metal that is released into the environment by both natural processes such as volcanic activity, weathering of rocks, etc and human activities such as waste materials from factories. The mercury that reaches the ocean and other water sources is converted into methylmercury by bacteria. Methylmercury is a neurotoxin that interferes with the nervous system and is easily absorbed by the human body.
The methylmercury is taken up by planktons. Small fishes consume large quantities of plankton. Tilapia is a small, short-lived freshwater fish. The methylmercury level in tilapia is lower than that of other fish. When large, long-living predatory fishes such as tuna, shark, king mackerel, swordfish, etc consume many smaller fish with low mercury levels, this causes accumulation of methylmercury at extremely high levels in their tissues over time i.e., the amount of mercury in such bigger fish biomagnifies.
So large, long-lived predators like swordfish and shark often have the highest methyl mercury levels than a small, short-lived tilapia.
