Because viruses have the ability to infect cells. E.G a dendritic cell. So the only thing that can kill then are natural killer cells but then viruses reproduct in these cells
Answer: Layer a is 500 million years old.
Explanation:
Trilobite is a member of the group of extinct arthropods found as fossils and they can be identified by the three-lobed as well as three segmented forms. These were the marine animals. These were appeared initially in the Cambrian Period. They used to live 542 million years ago so the fossils can be estimated to be aged of 500 above years old. These animals used to dominate in the sea area.
Answer:
Insufficient information to generate conclusion
Explanation:
It is really difficult to answer this question based on provided data. Rather speculations can be made. This is because of several reasons. The height of plant varies for different plant species. Likewise, it is really difficult for any plant species to the height of 5 inches (the lowest given option) within period of 8 hours only. It needs 8 hours light for several days to reach this much of height even for studied model plants such as arabidopsis. Thereon, each plant species would need different number of days.
On the other hand, it is important to consider that sunlight is a vital parameter for plant cells to elongate and multiply. This is because of the fact that plant use sunlight to fix carbon dioxide into the carbohydrates which is used in many cellular processes including cell division and growth. However, metabolic machinery in different plants works at different rates. Based on these reasons, it is super difficult to pick one option out of the given information to answer this question. Hope this helps.
C. The Bering Land Bridge once connected what would be Russia and North America but the the movement of these continents separated the land bridge
Answer:
Dust bowl resulted from extreme drying and loosening of the soil that resulted in soil erosion by wind. Thus, it can be related that poor agricultural practices like over plowing , over grazing and leaving the land barren are human activities that must have contributed to the dust bowl.
Explanation:
- Dust bowl is referred to a period in early twentieth century when the the American and Canadian prairies faced severe dust storms.
- These dust storms resulted from severe drought and failure of practices to prevent soil erosion.
- Several people and livestock died as a result of choking.
- Over plowing, removal of top soil and small grasses exposed the soil to eroding winds and caused the dust storms.
