The excerpt is from an article that Roberto read for science class called “Using the Scientific Method to Study Tomatoes.” The student performed an experiment to test his hypothesis about sunlight and plant height using two plants. He kept everything the same between two tomato plants except he exposed them to different amounts of sunlight. He also used a third plant as a control group, or a group in which no variables are manipulated to confirm the results.
Roberto critiqued the work. Which problem did Roberto most likely identify?
The sample size is too small.
Too many variables are manipulated.
It is not possible to keep the conditions the same.
Controls should only be used in studies of animals.

The sample size is too small.

Explanation:

The process of elimination helped me find this answer.

It is possible to keep the conditions the same.

there are only 2 plants and one control, that's obviously not a lot.

and controls can be used on more than studying animals.

When using the scientific method you can use as many test subjects as you can so it can help you confirm. two plants are not a lot.

I've also had a teacher confirm that this is the correct answer.

edge 2020

ans.

dna fingerprinting is defined as a process that determines the dna characteristics of an individual. these dna characteristics are unique among individuals as their fingerprints, so it is known as dna fingerprinting.

steps of dna fingerprinting includes extraction of dna from sample, amplification of dna, restriction digestion of amplified dna, and then analysis of dna by gel electrophoresis, respectively.

thus, the next step performed by the scientist is 'to cut the amplified dna (obtained by polymerase chain reaction) by restriction enzymes that cleave the dna into fragments and their analysis.'

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.