Most scientists believe that for half of Earth's 4.6-billion-year history, the atmosphere<span>contained almost no </span>oxygen. Cyanobacteria or blue-green algae became the first microbes to produce oxygen<span> by photosynthesis, perhaps as long ago as 3.5 billion years ago and certainly by 2.7 billion years ago.
this answer came from this website </span>The Rise of Oxygen - Astrobiology Magazine<span>www.astrobio.net/news-exclusive/the-rise-of-oxygen/
it should help</span>
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hope this helps you out good luck
Answer:
Every human has a couple of genes that will be separated when they make gametes. A baby will get one gene from each parent (one sperm and one egg).
Sickle cell gene is inherited by an autosomal recessive pattern, which means you need both defect genes to get the disease. The person with 1 defect gene can survive and live like normal. This person called a carrier because they carry one defect gene.
Someone that carries one defect gene can come as a result if you cross normal or carrier genotype (AA/Aa) with a carrier(Aa), or with homozygote recessive that carries 2 defect genes (aa). The person will get one healthy gene from the first parent with normal genes, and one defect gene from the second parent.
Answers:
Menorrhagia
Explanation:
Menorrhagia is a heavy or prolonged vaginal bleeding that happens in conjunction with menstrual cycle. It is the medical keyword for menstrual bleeding that takes a longer period of more than 7 days. This heavy bleeding causes frequent change of tampon or pad and pass larger clots.
It is mostly seen in women and its due to hormone malfunction, problems with the uterus, or other health situations. it is more often diagnosed with a pelvic exam, ultrasound, pap test, and sometimes a biopsy.
