Hi!
The ancestral finch founded a new population on one of the Hawaiian Islands. Due to the founder effect , allele frequencies of the first small population on one of the islands could have differed from their continental goldfinch-like ancestors. The process of natural selection resulted in adaptation and evolution of the island population into a new species over time. Some of the birds crossed to some of the other islands where they were geographically isolated and evolved into more species occupying different niches.
In terms of population genetics, founder effect is when there is a loss of genetic diversity as a result of the establishment of a new population by a relatively few individuals. Following such an establishment, natural selection is the process which results in the genes of the fittest individuals of the population being selected over generations. This process ultimately results in evolution, and over time may give rise to new species. Geographical isolation is the physical separation of a population from another owing to geographical changes in the terrain or area. If two populations of the same species are geographically isolated, there is a great chance over time they may evolve into two different species.
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Answer: Weathering constantly changes the earth's surface by wearing away exposed surfaces, smoothing rough areas of rocks and causing rock materials to break down in time. Weathering creates soil and happens due to ice, wind, water, salt, acids and changes in temperature Gravity shapes the Earth's surface by moving weathered material from a higher place to a lower one.
Answer:
1. Heme iron is found in animal foods like meat and poultry, whereas the nonheme iron form is found in plant foods like grains and vegetables.
2. The metal and trace mineral copper is part of several enzymes and proteins.
3. Adequate zinc is important for maintaining a healthy immune system and may aid in wound healing.
4. Selenium acts as an antioxidant and aids in thyroid function.
5. Fluoride is not considered essential, but it is very important for maintaining strong, healthy teeth.
6. The deficiency disease goiter was much more common before iodine was added to salt in the United States.
7. Manganese acts as a cofactor for a variety of enzymes and also plays a role in synthesis of bone.
Explanation:
- Iron: The major difference between the iron provided by animals Heme Iron) and plants (Nonheme iron) is that the heme iron is better absorbed by the organism. There are several mechanisms in the intestine that improve the heme iron absorption that is used for producing red globules for the organism. Carnic products such as red meat, fish, and poultry are rich in heme iron. Vegetables contain nonheme iron, which is harder to assimilate by the organism and thus its absorption is lower.
- Copper: Is an essential element for life that intervenes in the electronic transport chain, being part of the IV complex. It is also part of the enzyme that catalyzes the decomposition of the superoxide ion, toxic for living organisms. Copper is an element of the hemocyanin which is a protein present in some invertebrates, with a function similar to hemoglobin.
- Zinc: This metal has many uses in industry. In health, it is used in dietetic supplements, to maintain its correct levels. It is also useful in wound healing, in reducing duration and severity of colds, and has antimicrobial properties that help to relieve gastroenteritis symptoms. It is added in solar protectors, in toothpaste for good breath, and in the shampoo to deal with dandruff problems.
- Selenium: It is an antioxidant component of some enzymes that act in the elimination of substances with reactive oxygen. Besides this element is important in the regulation of the thyroid function.
- Fluoride: Although it lacks if metabolic activity in mammals and superior plants, some plants and marine sponges can synthesize a fluor compound as a poison for protection. Fluoride is used in many kinds of toothpaste because it interacts with calcium to create a harder and more stable fluorapatite matrix that protects the teeth.
- Iodine: Is an essential element that intervenes in numerous functions in the organism. The only entranceway of the element is by ingesting it with a recommended diet. Iodine lack might cause several problems in health such as thyroid problems or goiter.
- Manganese: This metal is an essential element that exists naturally in the ground and water. For animals, the manganese is an essential component of enzymes that are used in carbohydrates, fat, and protein metabolism. Manganese is a cofactor for numerous enzyme activities. It is also important in bony tissue development and reproduction.
The amount of ATP (Adenosine Triphosphate) produces is a characteristic that would best describe or distinguish glycolysis and the Krebs cycle from the electron transport chain.
Answer:
E. All of the above
Explanation:
In cardiac contractile cells there is rapid depolarization, then a plateau phase and repolarization.
when an action potential stimulates the cell, voltage-gated channels open quickly commencing the positive-feedback mechanism of depolarization. This in turn raises the membrane potential to approximately +30 mV, and this closes the sodium channels. Next comes the plateau phase, where membrane potential declines relatively slowly due to the opening of the slow Ca2+ channels, allowing Ca2+ to enter the cell while few K+ channels are open, leading to K+ to exit. Once the membrane potential reaches approximately zero, the Ca2+ channels close and K+ channels open, allowing the exit of K+. The repolarization lasts approximately for a while and here is when the membrane potential drops until it reaches resting levels once more and repeats the cycle.
