The movement in phloem is bidirectional, whereas, in xylem cells, it is unidirectional (upward).
Answer:
Natural selection can be described as a phenomenon in which individuals of a population which are better adapted to survive in an environment are favored by nature as compared to the individuals of the population which lack better characteristics to survive in the environment.
Through natural selection, evolution occurs and the allelic frequency changes over a period of time. The process of evolution as well as change in the allelic frequencies does not occur just by a single individual, rather it is a collective effort which takes a lot of time. Hence, we say that natural selection changes the population and not a single individual.
Answer:
The correct answer is- IgA
Explanation:
There are five types or class of antibodies found in the human body these are IgA, IgM, IgD, IgE, and IgG. Out of these five class IgA antibody is found in an abundant amount in the mother's milk or colostrum.
Infant take this antibody from the mother through breastfeeding which protects the infant from may pathogenic microbes. The immunity in which antibodies are taken from outside is called passive immunity.
Therefore the passive immunity source that is given by the mother to baby through breast milk is called IgA.
<span>One observation would be the physical size of Russia compared to other countries, despite a lack of visible borders from space. In addition, part of Russia's outline would likely be obscured by the various clouds and objects in the stratosphere; this would allow the astronaut to view potential cloud and weather patterns on earth. Also, an astronaut could see outlines of Russia's geography such as mountain ranges.</span>
Answer:
it will be the answer B. scientists discover new elenents.
