Evolutionary Theory

Which of these BEST describes our current understanding about how species evolve over time?

• As organisms use certain traits more frequently, each organism evolves over time.

• Populations of organisms evolve rapidly due to genetic changes brought about by random mating patterns.

• Traits that result in a greater number of mutations occur more frequently, causing the population to evolve.

• Populations evolve as natural selection results in a change in the frequency of alleles within the population over time.

The process of ____________ increases genetic variability as it produces gametes for sexual reproduction.

• conjugation

• meiosis

• mitosis

• replication

A mountain separates a population of mice into two distinct eastern and western populations. The eastern area is inhabited by owls, which hunt at night. No owls live in the western area. Over time, the eastern population of mice will MOST LIKELY

• become more active at night.

• remain identical with the western population.

• change over time and become less active at night.

• grow stronger claws and teeth to better fight the owls.

In a freshwater lake, a population of bony fish called the stickleback were studied over several decades. The presence of armor plating over the bodies of the males was noted. The data is shown below. What explains the trend shown in the data for the freshwater sticklebacks?

• Armor-plating offered a protection from predation, therefore the presence of armor-plating increased in frequency.

• Partially plated males were the preferred mating partner with female sticklebacks, causing an increase in partial armor frequency.

• Armor-plated males were more efficient at migrating to salt water areas for reproduction, resulting in armor-plating increasing in frequency.

• Armor-plated males were slower at acquiring food compared to the non-armored phenotypes, resulting in non-armored males to increase in frequency.

Maria has a sore throat. Her father takes her to the doctor and she is given an antibiotic. After ten days, Maria is still sick. Use the model seen here and describe what has happened to Maria in terms of natural selection.

• The medicine causes some bacteria to become resistant to antibiotics. They survive and reproduce.

• Some of the bacteria are resistant to the antibiotic. They survive and reproduce, keeping Maria sick.

• After being subjected to the antibiotics, some bacteria change and they can survive the medicine. Maria remains sick.

• In a population of bacteria, variation exists. The bacteria that have increased resistance to medicine outcompete the non-resistant bacteria for food.

Darwin hypothesized that there are definite steps to natural selection. One is populations are large and in the population variation exists. Consider this population of disease-causing bacteria. What is the MOST LIKELY cause for variation in this population?

• over-population

• drug resistance

• genetic mutation

• sexual reproduction

According to Darwin, organisms that are best adapted to their environment are more likely to produce offspring than organisms that are less well adapted to their environment. Which phrase is used to summarize this idea?

• species variability

• survival of the fittest

• use and disuse of organs

• evolution through mutation

Darwin hypothesized that there are definite steps to natural selection. Consider the model here. Use the Roman numerals (I - III) to guide you through the steps. Which is an accurate description of Darwin's hypothesized theory of natural selection?

• Sexual reproduction of bacteria cause variation. Some bacteria survive and some do not. Over time all of the bacteria should become extinct.

• In any population, variation exists. Some bacteria are resistant to antibiotics. Most bacteria die, but the bacteria that are resistant survive and reproduce.

• In a population of bacteria that are exposed to antibiotics, some bacteria change their genetic make-up and survive. The new genetic make-up is passed on to offspring.

• There is a change in the environment: an antibiotic is added. Some of the bacteria are capable of changing to the new environment. They survive and reproduce, passing along their favorable traits.

There are many different types of dog breeds, despite the fact that they are all one species, Canis familiaris and all have a common ancestor, the wolf, Canis lupus. Many breeds, such as the Alaskan malamute and the Siberian husky look remarkably like wolves and even retain some of their habits. Other breeds like the daschund above, do not strongly resemble wolves.

What part of the theory of evolution by natural selection would explain why there are no wild wolves that resemble daschunds?

• Natural selection leads to evolution.

• There is very little genetic variation in all living species.

• There is over-reproduction in all living species to ensure their survival.

• Competition favors the most fit organism

The dots represent a bacterial infection. Sal was very sick with this bacterial infection. The infection was treated with antibiotics. Sal seemed to get well, but in a few weeks, she was sick again. How can this be explained using natural selection?

• The antibiotics were ineffective to this strain of bacteria.

• The stronger, more resistant bacteria survived the antibiotics and reproduced.

• The antibiotics did not kill the bacteria; it only forced them to be dormant

• Antibiotics will only kill a portion of the bacteria, no matter how much medicine Sal takes.