The question above is incomplete, the complete version of the question is given below:
In the early days of germ theory, contagious diseases were thought to be caused by fungi or bacteria. In the 1890s, Dmitri Ivanovski filtered extracts from diseased tobacco plants and discovered that the disease could be transmitted to new plants through the filtrate. He concluded that the disease was caused by particles smaller than bacteria: the tobacco mosaic virus.
Which best explains how Ivanovski’s work led to a change in the germ theory?
A. He tried to promote his hypothesis as a law.
B. He used a new experimental method to test his hypothesis.
C. He used a more powerful bacterial strain than other scientists had.
D. He obtained results that confirmed what other scientists were thinking.
ANSWER
The correct option is B.
The germ theory of diseases states that diseases are caused by microbes. Prior to 1890s, scientists believed that communicable diseases are caused by microorganisms such as bacteria and fungi; viruses were not known during that time. The work of Dmitri Ivanovski on tobacco plant was the one responsible for the discovery of the existence of viruses. Dmitri Ivanovski was able to arrive at the results he obtained because he used a new experimental method to test his hypothesis.
D) Active transport. In this process, dissolved molecules move across plasma membrane from a lower to higher concentration. Because they move against the concentration gradient, an energy from the cell is required.
<h2>Answer is option "B"</h2>
Explanation:
- Our brain requires an enormous measure of vitality and so as to meet this needs the progression of blood must be accurately arranged to guarantee that oxygen is being conveyed where it is required and when it is required.
- Vitality in the mind is created solely from a type of digestion that requires oxygen. However, neurons just keep up a little save of vitality and these cells require a constant inventory of oxygen, particularly when the cells are terminating and speaking with their neighbors.
- Blood dashing through a brain district's trap of vessels is an indication that nerve cells in that region have kicked vigorously. The blood races to dynamic territories to supply terminating neurons with the oxygen and glucose they require for vitality.
- Hence, the correct answer is option B "Active areas of the brain take up more oxygenated blood than they need for their energy requirements"
Explanation:
Vascular plants have two distinct organ systems: a shoot system, and a root system. The shoot system consists stems, leaves, and the reproductive parts of the plant (flowers and fruits). The shoot system generally grows above ground, where it absorbs the light needed for photosynthesis.
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