Answer:
disturbance has destroyed population in a community
Explanation:
The secondary succession occurs after there has been some disturbance that has manged to badly damage or destroy the populations in a community. This basically means that after some catastrophic event that happened to a certain population or populations, other species moved in to colonize the freed space. There are countless examples of secondary succession in nature, and one of the best is when there is a strong volcanic eruption. The volcano manages to destroy the population of plants and animals in its close surroundings, but after the eruption ends, the space starts to be colonized by new plants and animals step by step until they create a new well functioning community.
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:
Answer B. Endosymbiosis
Explanation:
Early protists were first eukaryotic organisms and had several membrane bound organelles. The anaerobic protists evolved by acquiring purple bacteria. The purple bacteria have the ability to carry out aerobic cellular respiration. The endosymbiont transformed into mitochondria in due course of evolution. Similarly, the photosynthesizing protists were evolved by endosymbiosis of cyanobacteria which in turn was transformed into chloroplast during further evolution.
