<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.
Answer:
An experiment where an antibiotic is tested against bacteria. The antibiotic can vary in its concentration for example, different amounts are applied to a sample of bacteria to see if it is affected by the action of the antibiotic and if so, in what concentration. So, the independent variable is the concentration of antibiotic while the dependent variable is the survival (or not) of the bacteria.
Explanation:
An independent variable is a variable that represents a quantity that the scientist modifies in an experiment. A dependent variable represents a quantity whose value depends on how the independent variable is modified. This is the variable being studied and measured.
So, an example of this applied to bacteria or viruses could be:
<u>An experiment where an antibiotic is tested against bacteria</u>. The antibiotic can vary in its concentration, different amounts are applied to a sample of bacteria to see if it is affected by the action of the antibiotic and if so, in what concentration. So, the independent variable is the concentration of antibiotic while the dependent variable is the survival (or not) of the bacteria.
To complete the experiment, an antibiotic whose effect is already known can be used as a positive control. That is, it is already known to kill the bacteria. And as a negative control you can simply use water, which has no effect and is known not to kill the bacteria. In this way, we validate the results and make sure that there is not something else that is affecting the bacteria and that only the antibiotic being studied has an influence.
Answer:
1)Genus 2)Family 3)Order 4)Phylum 5) Domain
Explanation:
Species is a large group of living organisms that can breed freely among themselves, exchange genes and produce offspring.
Taxonomic rank is the group of living organisms that are related to each other and most basic rank is species. The lower the rank the smaller it be and contain most similar organisms.
The higher rank comprises by combining of smaller ranks like in your question the family contain many genus and order contain many families and so on. Thatswhy most higher rank would contain maximum number of species.
C no because many species went extinct without leaving fossils behind
