Answer:
Molecules which move against the concentration gradient across the cell membrane employ the mechanism of active transportation.
Explanation:
Normally, permitted molecules moves across the cell membrane of the cell by the process of diffusion and osmosis. This is used when molecules move from hypertonic region to hypotonic region (if ions) and hypotonic to hypertonic (if water). This is a passive transportation which do not require the expense of energy from the cell.
In contrast, when molecules move in or out of the cell against their concentration gradient, that is ions moving from hypotonic region to hypertonic region, they implore the expense of energy in form of adenosine triphosphate (ATP), and the involvement of the membrane carrier proteins. This is called active transport.
The answer is graded potential<span>. Its made of various action potentials that depolarise the neuron incrementaly, in short interspersed intervals that do not give time for the neurons to return to resting potential. Therefore, the actions potentials, of varying sizes, grade up in sum and when they cumulatively reach the threshold level, they invoke an impulse in the nerve</span>
B, metals, nonmentals all bond to be stable
Answer:
There are two possible answers: Deep-sea vents provided the energy needed for the first organic compounds to form OR self-replicating RNA molecules passed on genetic information.
Explanation:
The reason for the first answer is due to the hypothesis that indicates that life (organic molecules) arose from inorganic molecules synthesized from the amino acids in those energy vents. This is called the metabolism first hypothesis. The Miller-Urey Experiment provided evidence that organisms could rise from inorganic molecules (they simulated under the conditions you would see on early Earth). The second hypothesis is the RNA World hypothesis (second answer) which suggests that the formation of RNA that could replicate (possible due to mutation or evolution), led to life that could preserve its genetic integrity through replication (greater stability to the organism) and create lipid bi-layer membranes/other organelles. Some scientists support the Metabolism First Hypothesis, while others are skeptical (this goes for the RNA World Hypothesis as well). However, the RNA World Hypothesis is for more reasonable in the fact that its main point is the fact that RNA molecules were able to replicate and maintain genetic stability despite early Earth conditions. Although either hypothesis could explain why all organisms share the same genetic code, the RNA World Hypothesis better explains the universality of DNA/RNA of genes that we see today.
Answer:
Water sample showing pink/purple color is an error.
Explanation:
Biuret is a blue color reagent that changes its color to pink/purple whenever it detects protein in a sample. Water don't contain proteins so it should not show pink/purple color instead it should maintain the blue color. Food items generally contain proteins so it show pink/purple color but it showed blue color.
Error might have caused by wrong marking of the samples, test tube marked with Water might contain a mystery food while Mystery food tube might contain water.
