<span>Human skin color is a polygenic trait, which means that multiple gene loci (with different alleles) are involved in its expression. It has been shown that there more than 350 genetic loci involved in determining skin color. Because of that, there is the enormous number of possible genotypes for the skin color and as a result, the phenotypes vary from the darkest brown to the lightest hues.</span> <span> Different populations have different allele frequencies of genes for human skin color, and the combination of these allele variations brings about complex and continuous variation in skin coloration. Natural skin color can change due to exposure to sunlight (becomes darker) and that is the way it adapts to intense sunlight irradiation (protection against the UV exposure).</span>
I believe it's sexual reproduction in sea stars if that's the question.
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Answer:
plicae circulares and intestinal villi
Explanation:
The inner wall of the intestine is full of wrinkles, called villi. An enlargement of them under the microscope reveals that they are formed by cells whose surface has innumerable small "wrinkled" structures. The small intestine is the largest viscera of the body (about six meters). Intestinal villi and microvilli increase the area of contact with the intestine as well as the speed of absorption of food. Blood capillaries and lymph are in these villi to absorb nutrients.
The intestinal villi, have the function of increasing the absorption of nutrients after digestion. They are the folds of the intestines. The surface of the villi has an area of 12 cm² and the microvilli 240 cm².
Villi and microvilli increase the area of intestinal absorption by approximately 30 times and 600 times, respectively, providing exceptionally efficient absorption of nutrients in the lumen.
The entire small intestine has circular folds of mucosa, also called Kerckring valves and circular plicae. Most extend transversely around the small intestine cylinder for about half or two-thirds of its circumference, but some form complete circles, and some have a spiraling direction; The latter usually extend a little more than once around the bowel, but occasionally two or three times. Circular folds slow the passage of partially digested food along the intestines and provide an increased surface for absorption.
I think they are different in that they have jaws. Rays are predominantly marine and are found in all the oceans. Many are slow-moving bottom dwellers. They include, Manta ray which is one of the most known type of rays, Spotted eagle ray (pacific ocean), sting ray among others. They are about 15 types of rays in the oceans. Sharks, Lampreys and rays, like all fishes they are aquatic, water-breathing vertebrates with a brain and spinal cord, fins, plate-like pairs of internal gills, and paired sense organs.
Answer: There should be concern because zoonotic diseases passes from an animal or insect to a human very easily, and although they do not always represent a danger, they can cause serious symptoms and even death.
Explanation:
Zoonotic diseases are caused by microorganisms such as bacteria, virus, parasites and fungi, and they can be transmitted between animals and humans. Some examples of zoonotic diseases are Brucellosis, Anthrax and Rocky Mountain Fever (rickettsiosis)
Sometimes, people with zoonotic infections can get very sick and have symptoms such as fever, diarrhea, muscle pain and others. While in other cases, people may have no symptoms and never get sick, without representing a risk
. <u>Besides being important because they can make many people sick, we have to take into account that the way of transmission or propagation can be very simple.</u> Food can be a source of zoonotic infections, for example when farm animals re infected with parasites and these animals are consumed as food. Another example is when people get trichinosis by eating undercooked meat, or consuming fruit without washing it properly, or raw meat from animals infected with the Trichinella parasite. Also, people can get the parasites swimming in a lake if they accidentally swallow water contaminated with the feces of infected animals. Besides, pets can have parasites and pass them on to people, and wild animals can also have infection from parasites that can infect people.
Therefore, we must be concerned about zoonotic diseases, since they can be transmitted very easily from animals to humans, and although they do not always represent a danger, they can cause serious symptoms and even death.
