To perform this test to check if gold is real, make a light, tiny scratch on the item using a small nail file. Choose a spot that is not noticeable if possible. Use a dropper to apply a small drop of nitric acid to the scratch. If there is no reaction, then the piece is probably made from real gold.
<span>Dr. Stott is researching epigenetics. Epigenetics is the study of changes that occur in gene expression with no changes in the actual gene sequences. Environmental factors can influence gene expression without changing the DNA sequence, making this the study of epigenetics.</span>
Answer:
The placenta is a unique vascular organ that receives blood supplies from both the maternal and the fetal systems and thus has two separate circulatory systems for blood: (1) the maternal-placental (uteroplacental) blood circulation, and (2) the fetal-placental (fetoplacental) blood circulation. The uteroplacental circulation starts with the maternal blood flow into the intervillous space through decidual spiral arteries. Exchange of oxygen and nutrients take place as the maternal blood flows around terminal villi in the intervillous space. The in-flowing maternal arterial blood pushes deoxygenated blood into the endometrial and then uterine veins back to the maternal circulation. The fetal-placental circulation allows the umbilical arteries
Explanation:
Answer: C. Chromosomes
When an egg and sperm cell
unite, fertilization follows. The chromosomes carry the genes that will be
transferred to the offspring. They have threadlike bodies that made up of DNA
and protein that carries hereditary information, which is used to help a cell
grow and reproduce.
Furthermore, humans have 46
chromosomes and 23 in each sex cell and they are found in the nucleus of a
cell.
A narrow valley is formed. Hope this helps :)
