Answer: number 1
Explanation: that is when we could first sustain life because that is when we gained atmosphere and when we could hold carbon and oxogen
Answer:
Explanation:
Wind t Water + Season changing
I would say that the fishes exhibited the greatest diversity (though the brachiopods also had considerable diversity) and mostly were of the ostracoderms (with a platey or shell-like skin and no jawbone) which exhibited many varieties and also the placoderm which had gills, a jawbone and fins so was developing characteristics of modern fish.
Answer:
Different brands of nail polishes used by Sarah.
Explanation:
While conducting an experiment two different variables are considered namely dependant variable and independent variable. The variable which is continuously changed to see the effects is called as independent variable and the variable which is being tested is called as dependant variable.
In the given scenario, Sarah want to know best brand of nail polishes which lasts longest without chipping. Thus the different brands of nail polish used by her is considered as independent variable.
Answer:
The correct answer is C) gene flow
Explanation:
The biological species concept defines what is a species. It says that a species is a group of individuals in a population that interbreed with each other. So there should be gene flow between the members of the population to come under species.
Appearance does not define that two individual are of same species because even different species can look same for example Western meadowlarks and eastern meadowlarks looks identical to each other but they do not interbreed so there is no gene flow between them so they are not same species.
Therefore the primary criteria for determining species boundaries is gene flow.
