The correct answer I think is D. The nucleus
Answer:
oxygen
Explanation:
cells use to produce energy during cellular respiration
<em>For example,</em>
<em> consider a mountain whose summit is 5,000 feet (1,500 m) in elevation, but somewhere on the way up, the trail goes back down 250 feet (76 m). ... </em>
<em>If one hikes over five hills of 100 vertical feet each, the cumulative elevation gain is 5 × (100 feet (30 m)) = 500 feet (150 m).</em>
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<h2>Down Syndrome</h2>
Explanation:
Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
- Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21
- Down syndrome is usually caused by an error in cell division called nondisjunction which results in an embryo with three copies of chromosome 21 instead of the usual two
- Prior to or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separates
- With development in embryo the extra chromosome is replicated in every cell of the body;this type of Down syndrome which accounts for 95% of cases is called trisomy 21
- Maternal age is the only factor that has been linked to an increased chance of having a baby with Down syndrome resulting from nondisjunction;here environmental agents such as drugs, chemicals, and radiation act as mutagens which induce mutation in the fetus
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.
