A nucleotide is made up of one sugar molecule, one phosphate molecule and one of the four bases. Here is the structural formula for the four nucleotides of DNA. Note that the purine bases (adenine and guanine) have a double ring structure while the pyrimidine bases (thymine and cytosine) have only a single ring
That would be C.
Endocrine secretion is when a molecule(usually a hormone) is secreted into the blood. Endo as “in” the blood. Exo as “out” of the blood. You can think of it that way if it helps:)
The first one, ii. Natural selection and the formation of inseticide resistant insects or antibiotic resistant bacteria.
This can be explained in very simple way. As we all know, natural selection works in a way that only that adapted living beings are going to survive through a specific environment, whether it's because they can grab their food without too much work, or even that they can adapt to the weather. When we use inseticide, we are killing lots of non-resistant insects, and what's left are those that are resistant to this inseticide, and they'll reproduce again, and again we'll go through the same process, but remember, this insect is now stronger and more resistant that before.
The second case, iii. speciation and isolation give three examples how it may occur.
Well. the allopatric speciation and isolation will happen when theres a geographic barrier between one species. This one then is divided into two diffent habitats, but what can divide than could be a mountain, a tree, a river, a rock, anything. And this could be too called as a geographic isolation, because in this new environment, species are going to develop in a different way.
Two possible answers, the plant kingdom or the eukaryotic kingdom because the plant is within this category along with animals.
