Answer:
The <u>biological species concept</u> is not very useful in defining plant species.
Explanation:
The biological species concept says that <em>species are population groups that, in a real or potential way, can reproduce and that </em><em>are reproductively isolated from other groups.</em>
<em>Individuals belonging to a species cannot reproduce with members of other species. </em>
This biological concept has limitations. Its application might present difficulties in concern with asexual reproduction species, such as bacteria, rotifer, cnidarians, plants, and etcetera.
Besides, this concept cannot be applied to the past because it is difficult to deduce reproductive capability between extinct species.
Finally, this concept is not adequate in concern to hybridization zones, something to be expected considering evolutionary processes. This is why this concept has been less accepted by botanists, as some plant species hybridize with other species. For example, species Quercus grisea and Quercus gambelii have overlapping ranges in the southwestern United States. Hybrids showing variation in leaf shape and other traits have been found in many places in this area.
Many rickettsia are PATHOGENS.
Pathogens are micro organism that cause diseases and rickettsia are majorly disease causing organisms. They are rod shaped bacteria and most species are gram negative. They are natural parasite of some arthropods and they cause diseases in both humans and animals.
Climate change
Greenhouse effect
Some heat energy from the Earth’s surface escapes into space. If too much heat energy escaped, the planet would be very cold. However some gases in the atmosphere can trap escaping heat energy, causing some of it to pass back to the surface.
These are called greenhouse gases, and they keep our planet warm, which is a good thing. Carbon dioxide is an important greenhouse gas.
Increasing carbon dioxide levels
Humans burn fossil fuels such as oil, coal and natural gas. The energy released is used to power cars and other machines, to generate electricity, and to keep buildings warm. The burning fuel releases waste gases, including carbon dioxide. As the human population increases, more fuel is used, and more carbon dioxide is released.
Global warming
The extra carbon dioxide increases the greenhouse effect. More heat is trapped by the atmosphere, causing the planet to become warmer than it would be naturally. The increase in global temperature this causes is called global warming.
