There are four mechanisms that can cause changes in the frequencies of genes in populations: mutation, migration, genetic drift, and natural selection. All four are mechanisms of evolutionary change. What is genetic drift? A) In a population, it is the changes in allelic frequencies of a gene that are due to chance.
B) A random error/change in the DNA sequence. These may be inherited or occur in cells during the lifetime of the organism
C) Also known as gene flow. It is any movement of individuals and/or the genetic material they carry, from one population to another.
D) There is variation in any population differential reproduction occurs and over time a more advantageous trait exists in the population.

Sally and sue were investigating the topic of friction in science. they used a small car and a ramp as seen in the picture to test what they were learning. they knew that they slipped easily on waxed floors but not on carpet, so they decided to change the material on the surface of the ramp to see what happened. they planned to use glass, carpet, aluminum foil, and sandpaper and run the car down the ramp over each surface. what would be the best research question to guide the girls' experiment? a) does the amount of surface area affect the friction on the moving car? b) will the car travel fastest on the glass surface? c) how does the angle of the ramp affect the speed of the car? d)do rougher surfaces tend to create more friction than smooth surfaces?