Biological cell membranes are selectively permeable, which means that the ease and rate of small molecules passing through membranes vary widely. The plasma membrane regulates exchange of nutrients, oxygen, inorganic ions, waste products, and water. The cellular membrane’s molecular organization controls permeability.
Tentative means possible
So a possible explanation of any matter on whuch you are working will be called astentative explanation which may be correct or incorrect
Answer:
The answer is b. the theory must be changed or abandoned.
Explanation:
If a scientist finds a contradictory fact to an already existing theory, then after a scientific validation of the new found fact, the existing theory has to be changed or be replaced with a new one.
The rest of the answer options are silly and incorrect!
Answer:
B) As seen from Earth, the Sun is the brightest star on the chart, and Barnard's Star is the dimmest
Explanation:
Among the given choices:
A) Of the stars listed, Proxima Centauri and Barnard's Star appear red because they burn the hottest.
This is not the correct answer because temperature of Barnard's star is 5000° F which is lowest in the data.
C) Small dwarf stars, like Proxima Centauri and Barnard's Star, do not burn as hot as medium dwarfs.
Proxima centauri being a small dwarf has a higher temperature than sun which is a medium dwarf.This shows that small dwarfs can burn hotter than medium dwarfs. So this option is not suitable.
D) Proxima Centauri and Barnard's Star are the closest because they are classified as "small dwarfs."
This is not correct choice because the data clearly states they are at greater distance.
So ,the correct choice is:
B) As seen from Earth, the Sun is the brightest star on the chart, and Barnard's Star is the dimmest.
Because: Sun is closest to the Earth and thus will appear the brightest as maximum light from it Reaches the Earth. Barnard's star is Farthest so less light reaches the Earth from it and it appears the dimmest.