Given the age of the meteorite is 4.5 billion years old with 78 atoms of lead-206 the answer should be B. 156. The half-life of uranium-238 in order to decay into lead-206 is 4.46 billion years, which means that the original number of atoms is 156.
<u>Answer</u>: Natural selection.
<u>Explanation</u>:
- The concept of <em>natural selection</em> was given by <em>Charles Darwin.</em>
- According to this concept, in a given environment the organisms that possess <em>better adaptations</em> have<em> higher chances of survival</em> and, leave behind a <em>greater number of progenies</em>.
- When malaria outbreak occurs, the allele frequencies change and only the organisms that possess the alleles which help them to <em>survive</em> this outbreak due to resistance against malarial infection will be selected by nature and<em> hence, this is an example of natural selection.</em>
When a specimen is to be observed under the light microscope, scientists usually stain the specimens using different type of chemical stains depending on the type of specimen to be observed. Staining of specimen make the structures that are to be observed in the specimen very visible under the microscope, this make it easy for scientists to observe their structures.
Answer:
A) To make sure that the effect is not occuring through actions in the nervous system
Explanation:
In the above scenario, researchers actually studies the effect of hormone to the organ but they are in a situation to study the effect on organ are either hormone base or nervous system base (neurons). For this reason they will cut the neurons to study the effect of hormone on the organ.
So, to check the effect of hormone they should cut the neurons to make sure these effect are not due to actions of nervous system.
Answer:
This is because it is a selective antibiotic that, when entering the body, binds to the 50s subunit of bacterial ribosomes, thus causing the disruption of protein transcription of bacteria.
This drug does not stop the transcription of human proteins since bacteria and humans do not have the same ribosomes, therefore, humans or sick cells do not have the active site to which the drug binds.
Explanation:
This is because it is a selective antibiotic that, when entering the body, binds to the 50s subunit of bacterial ribosomes, thus causing the disruption of protein transcription of bacteria.
This drug does not stop the transcription of human proteins since bacteria and humans do not have the same ribosomes, therefore humans or host cells do not have the active site to which the drug binds.
Erythromycin falls into the macrolide family and is considered a drug that is bacteriostatic at low concentrations and bactericidal at very high concentrations.
The difference between these named terms is that one ends the life of the bacterium (bactericidal) and the other stops the bacterial metabolism preventing its possibility of increasing in number.
