Answer:
B, extraction through fracking can contaminate groundwater.
Explanation:
Well, it's really the only downside available. Hope this helps :)
Photosynthesis still occurs but the amount of red pigment is greater than the amount of green pigment. The chlorophyll still absorbs light energy. The red leaves does not affect the process of photosynthesis.
Answer:
An effective vaccine was developed
Explanation:
(I actually learnt about this is history!)
Smallpox was around 75-100 years before 1977, and people continued to die from it especially when there were severe outbreaks (thousands of people lost their lives). The main technique for vaccination was to make a small cut in the patients arm or wrist, and then to rub a smallpox scab into the open wound (inoculation). However this was not as effective as it sometimes, brought infections into the wound, but the success rate was still pretty high.
Edward Jenner was convinced that there could be a more effective way of vaccinating people against the smallpox. Jenner discovered (from a milk maid!), that those that have been infected with cowpox won't catch small pox, as they are from the same family. Instead of small pox being the vaccine, Jenner used weakened cowpox pus instead. This was much effective as the side effect of having cowpox mild, and the patient made a full recovery.
Jenner put this cowpox vaccine in injections so that an open wound is not needed.
By the 1850's the vaccine was made compulsory, but many were against it: still believing that miasma (foul air) was the cause of the small pox. It was made compulsory or face a fine in the mid 1950's, hence small pox was eradicated by 1977
Hope this helps!
Answer:
Single-cell organisms
Explanation:
In 1735, Linnaeus introduced a classification system with only two kingdoms: animals and plants. Linnaeus published this system for naming, ranking, and classifying organisms in the book "Systema Naturae". In the epoch that Linnaeus created this system, single-cell organisms such as bacteria and protists were almost unknown. In 1866, E. Haeckel added a category including both bacteria and protozoa, thereby adding a category formed by single-cell organisms (different from animals and plants). During the 1900-1920 period, bacteria were classified as a separated kingdom named 'prokaryotes'. The current three-domain classification system was introduced by C. Woese in 1990. In this system, all forms of life are divided into three different domains: archaea, bacteria, and eukaryote domains (this last composed of protists, fungi, plants and animals).