Rocky mountain juniper (juniperus scopulorum) and one-seeded juniper (j. monosperma) have overlapping ranges. pollen grains (whi
ch contain sperm nuclei) from one species are unable to germinate and make pollen tubes to bring the sperm nuclei to the female ovules (which contain egg cells) of the other species. these two juniper species are kept separate by ________.
mechanical isolation is a form of prezygotic reproductive barrier, whereby similar species organisms become isolated and unable to successfully interbreed with each other to form zygote, as a result of incompatibility of their reproductive organ or structure, which prevents them from copulating. As a result of this, both species become separated as there is no gene flow between both.
The two species of juniper can be said to be kept separate by <em>mechanical isolation</em>, due to the differences and incompatibility of their reproductive structure.
Mechanical isolation occurs when
two organisms of the same species are unable to copulate because of the
differences in their reproductive organs. In flowering plants, differences in
the structure of the reproductive parts may also hinder pollination. From the question
given above, even though the two plants have overlapping ranges, the pollen
grains from one species are unable to grow thus disallowing the pollen tubes to
connect or transport the sperm nuclei to the female ovules of the other species
where the fertilization of the eggs will occur. These two species are said to be
isolated mechanically.
Kettlewell thought that if natural selection caused the change in the moth population, the following must be true: Heavily polluted forests will have mostly dark peppered moths. Clean forests will have mostly light peppered moths. Dark moths resting on light trees are more likely than light moths to be eaten by birds.
RNA is single-stranded while DNA is double-stranded. RNA contains uracil while DNA contains thymine. RNA has the sugar ribose while DNA has the sugar deoxyribose.
<span>A person who eats and sleeps too much is experiencing a depressive episode with psychotic features. Psychotic features can impact a person's mood negatively and cause them have hallucinations or delusional feelings of depressive themes such as worthlessness or lacking a sense of self-worth.</span>
