The organ that living things such as fish use to extract dissolved oxygen from water are the gills. As land animals and humans don't have gills, we can't breath underwater and take in the oxygen from that source.
The last one is the correct answer because biodiversity means the diversity in an ecosystem
Nitrogen-14 has a mass number of 14 which means that it has a total of 14 protons and neutrons. When you subtract the atomic number of nitrogen from the mass number of 14 you get the number of neutrons (14-7), which gives you 7 neutrons. Now for nitrogen-15, you have a different mass number which means there is a different amount of neutrons (15-7), 8 neutrons. So the difference is the mass numbers and the number of neutrons (the number of protons remains the same however). When there are two versions of the same element, and they have the same number of protons, but different number of neutrons and different mass numbers, they are called isotopes. Hope this helped :)
Answer:
D.) Helpful variations allow individuals to survive and reproduce better than members who lack these variations.
Explanation:
Variation is one of among the principles of natural selection.
Variations occur naturally thereby favouring some individual groups over the other.
In the above example, the helpful variations naturally select the parents of the offsprings while the other members of the group are disadvantaged.
