What is the purpose of the oil on the oil immersion lens? a- oil provides a medium for the bacteria to float on the slide b- oil is a lubricant and allows the objectives to slide easily c- oil prevents any water from seeping into the cover slip d- oil prevents light distortion and makes the images clearer

The eruption of a nearby volcano causes a prairie ecosystem to receive a lot less sunlight. which of these is the most likely effect on the ecosystem? a-an increase in biodiversity. b-an increase in immigration to the area. c-a decrease in available water. d-a decrease in plant growth.

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.

Fredrick griffith made a scientific discovery in 1928