Answer:
4
Explanation:
Carbon has four valence electrons, so it can achieve a full outer energy level by forming four covalent bonds. When it bonds only with hydrogen, it forms compounds called hydrocarbons. Carbon can form single, double, or triple covalent bonds with other carbon atoms.
Answer:
Sickle cell anemia is an inherited condition in which there aren't enough healthy red blood cells to carry oxygen through an individual's body. The red blood cells of a healthy individual are flexible and round, and they move through blood vessels with no problem, transporting oxygen successfully. However, a person with sickle cell anemia has rigid, sticky red blood shaped like sickles or crescent moons. These cells often get stuck in small blood vessels, which can slow or block blood flow and oxygen delivery to different parts of the body.
The sickle cell anemia trait is found on a recessive allele of the hemoglobin gene, while the regular red blood cell trait is found on the dominant allele. This means that a person must have two copies of the recessive allele (one from their mother and the other from their father) to be born with this condition. People who have one dominant and one recessive allele or both dominant alleles will have healthy red blood cells.
<h2>
Reproductive Method </h2>
Explanation:
<em>The rank in order from the most specific which is following .</em>
<em>(1) Reproductive isolating mechanism</em>
<em>(2) Sperm-egg incompatibility in sea urchins</em>
<em>(3) Gametic isolation </em>
<em>(4)Prezygotic isolating mechanism</em>
<em>(1) Reproductive isolating mechanism-</em> The components of regenerative confinement are an assortment of transformative instruments, practices and <em>physiological procedures basic for speciation.</em> They keep individuals from various species from delivering posterity, or guarantee that any posterity are sterile.
(<em>2) Sperm-egg contradiction in ocean urchins-</em> Bindin is a gamete acknowledgment protein known to control species-explicit <em>sperm-egg grip</em> and layer combination in ocean urchins.
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(3)Gametic isolation - Prezygotic hindrances </em>keep preparation from occurring. Gametic disengagement is a sort of prezygotic hindrance where the<em> gametes (egg and sperm) </em>come into contact, yet no preparation happens. Gametes might be not able to remember each other in various species
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(4) Prezygotic isolating mechanism- </em>while postzygotic segregation forestalls the arrangement of rich posterity. Prezygotic systems incorporate environment segregation, mating seasons, "mechanical" disconnection, gamete detachment and conduct seclusion.
The correct answer choice is answer B.) The fossil record provides evidence of a common ancestor to many species. Hope this helped!
Answer:
In a pinhole camera, light passes through the pinhole to project an upside-down image onto the back of the box, and in the human eye, light passes through the lens to project an upside-down image on the back of the retina
