Answer:
In order to propose a hypothesis, there is a need to first see the function of gills in fishes. The gills of fishes comprise blood vessels that exhibit inherited tendencies of getting oxygen out of the water, which was consumed by fishes from their mouths. These gills also comprise thin walls, and when water moves over these walls of blood vessels, the oxygen from water moves into the blood, and then this oxygen-enriched blood goes to various organs.
Thus, one of the hypotheses in the given case, can be the number of blood vessels, which are found in the gills of the mentioned freshwater fish to be higher in comparison to the blood vessels found in the normal fishes, and apart from this, the surface area of the thin walls, which are found in the gills is also more in the new species of freshwater fish.
Answer:
Killer whales are found in all oceans. While they are most abundant in colder waters like Antarctica, Norway, and Alaska, they are also found in tropical and subtropical waters. The most well-studied killer whale populations occur in the eastern North Pacific Ocean.
Explanation:
Answer:
It's the leaf, or it is called chloroplasts.
Explanation:
<h3>Slowly</h3>
Wegener proposed the hypothesis of continental drift, which suggested that continents are in constant motion on the surface of Earth. Over time Pangaea began breaking apart, and the continents slowly moved to their present positions.
<h3>What is Continental Drift ?</h3>
The theory of continental drift is most associated with the scientist Alfred Wegener.
- Wegener's continental drift theory introduced the idea of moving continents to geoscience. He proposed that Earth (opens in new tab) must have once been a single supercontinent before breaking up to form several different continents.
- The four pieces of evidence for the continental drift include continents fitting together like a puzzle, scattering ancient fossils, rocks, mountain ranges, and the old climatic zones' locations.
Learn more about Continental Drift here:
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Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
