After incubation, you observe that your streak-plate has heavy, uniform growth but no isolated colonies. Which of the following could explain this result? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. A streak plate achieves isolated colonies by physically diluting the culture as it is spread over the plate. After incubation, you observe that your streak-plate has heavy, uniform growth but no isolated colonies. Which of the following could explain this result? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer.1. The specimen was a mixed culture.2. The plate is contaminated.3. Area three of the streak plate crossed into area one of the streak plate.4. The loop was not properly sterilized between plate sections.

Option 3 and 4 are most likely correct

Explanation:

Option 3: We know that area 1 would contain heavy streaking and not single colonies. Therefore, if the loop crosses area 3 and enters area 1, it will definitely result in heavy streaking again.

Option 4: We always need to sterilize properly the loop when streaking in different areas. If we don't do it, it is possible that the loop contains a lot of bacteria that would be streaked again.

Options 1 and 2 are incorrect because, according to question, there is a uniform growth but no isolated colonies. So, contamination or mixed culture would not produce uniform growth streaking rather mixed with other bacterial types.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!