Answer:
The answer is <em><u>D.
</u></em>
Explanation:
Viruses can evade the processing and presentation of antigens, for example by interfering with the expression of MHC class I proteins, although this increases their susceptibility to be detected by natural killer cells (NK). However, some members of the herpesvirus, papillomavirus, retrovirus, poxvirus and flavivirus families have also developed strategies to escape the attack of NK cells and promote their survival, inhibiting cell apoptosis. Finally, some pathogens often change surface antigens frequently, as in the case of influenza viruses (orthomyxovirus).
The human immunodeficiency virus (HIV) affects CD4 + T cells and degrades the host's ability to counterattack with a strong cell-mediated immune response. There are so many tactics of immune evasion used by HIV, which have so far hindered the development of an effective vaccine.
Answer:
Sterol lipids are common in human cell plasma membranes
Explanation:
Human plasma cell membrane contains sterol lipids and proteins which serves as structural maintainers of the cell.
Answer: Farming
Explanation: Plowing the land is the first source of wealth.
Answer:
B
Explanation:
The more the soil absorbs water the less space there is for the soil to absorb more therefore it runs off.
The taiga biome is the largest terrestrial biome and extends across Europe, North America, and Asia. It is located right below the tundra biome. The taiga biome is also known as coniferous forest or boreal forest. This biome typically has short, wet summers and long, cold winters. Precipitation is moderate in the taiga. It gets plenty of snow during the winter and plenty of rainfall during the summer.<span>Interesting Taiga Biome Facts:Fires are very common in the taiga biome. These fires are necessary to help rid the area of old and sick trees.There is not much variety in plants. Majority of the plants are conifer trees which is why the taiga is referred to as the coniferous forest.The conifer trees in the taiga biome are referred to as evergreen. This means they remain green all year round and never drop their leaves.<span>Because evergreen trees do not drop leaves, there is nothing to keep the soil in the taiga full of nutrients. This is the reason why there is not much variety in the vegetation. </span>Softwood timber is used to make paper. Majority of softwood timber comes from the taiga biome.<span>Although two major cities, Toronto and Moscow, are located in the taiga biome, most of this biome is uninhabited by people. </span>The taiga biome is very cold during the winter. Temperatures can reach as low as -60° F.For six months out of the year, the temperature in the taiga biome is below freezing.Plants can only grow during the summer when temperatures are favorable. This growing season only lasts about three months.Many animals of the taiga biome have to migrate to warmer areas or hibernate during the long, cold winters.Animals of the taiga have many specialized adaptions including lots of thick fur or feathers and the ability to change colors during different seasons.Scientists believe that the taiga biome was completely covered by glaciers many years ago.The taiga forests are endangered due to logging and mining by humans. When trees are cut down in the taiga, it takes a very long time to restore itself because of the very short growing season.Although there are not many animals in the taiga biome, it inhabits millions of insects. Birds migrate there to feed off these insects every year.<span>The temperature change in the taiga is extreme. It is either summer (hot) or winter (cold). The spring and fall are too short to notice.</span></span>
