natural selection and adaption

Which of the following statements describes an example of natural selection?

An aloe vera plant possessing a trait for extra thick leaves survives a long drought in a desert, while an aloe vera plant that has thinner leaves does not.

Which of the following are main tenets of Darwin's theory of natural selection?

Individuals most adapted to their environments have a better chance of surviving to reproduce. Individuals compete for resources. The traits within a population vary and are heritable. Individuals can produce more offspring than can survive.

Allele frequency refers to the fraction of individuals with a particular version of a given gene. What effect does natural selection have on the allele frequency of a population?

It increases the frequency of alleles that improve a species' survival in a particular environment.

Several species of finch live on the Galapagos Islands. They are very similar in appearance, but have adapted beaks of different sizes and shapes based on their major food source. Finches with large beaks eat mainly large seeds and cacti. Finches with small beaks eat mainly small seeds and insects. Which of the following best explains the variety of beaks found in finches on the

Natural selection can cause speciation, which increases the biodiversity of an ecosystem.

An individual hydra is swept by an ocean current to an area of the ocean where no other hydras reside. The hydra asexually reproduces, as does its offspring, until there is a population of genetically identical hydra. Is it possible for this population to undergo natural selection?

No, there is no genetic variation upon which natural selection can operate.

All organisms that sexually reproduce exhibit behavior that prompts reproductive activities with the opposite sex. Why would this form of behavior most likely be naturally selected?

Organisms that have behaviors that encourage reproduction would be more likely to reproduce.

Which of the following is the most likely side effect of the overusage of pesticides?

Pesticide-resistant pests will survive, reproduce and flourish.

The graphs above show the difference between an initial population of colored lizards and the same population after 100 generations. Which of the following is the most likely explanation for the difference?

Some change in the environment selected for red and blue lizards, but against green ones.

An industrial accident five years ago spilled thousands of gallons of toxic chemicals into a freshwater lake inhabited by several species of fish. After the spill, a biologist began studying three of these species of fish over a five-year period. Species A Lost 80% of its population; the remaining population migrated upriver to another lake. Species B Lost 95% of its population; the remaining population survived and eventually became larger than the pre-spill population. Species C Showed no change in population size over the five-year period. Which fish species most likely underwent a genetic adaptation as a result of the chemical spill?

Species B only

The figure above shows plates made from a culture growing bacteria during specified generations. The culture has white and dark bacteria. After generation 1, scientists applied an experimental drug intended to kill the bacteria and kept the experimental drug in the culture during successive generations. Which statement best explains the results of the experiment?

The dark bacteria showed resistance to the drug.

A particular environment has enough food to support 50 rats through the winter. At the end of winter one year, there are 25 female rats and 25 male rats. Each of the 25 females gives birth to several litters of 3-6 pups each. In the fall, there are 300 rats. Ignoring the effects of predators and disease, what will happen to this population of rats between fall and the next spring?

The fifty rats best able to get and keep food will survive to reproduce next spring.

Which of the following best explains how genetic recombination influences how species change over time?

The genetic variation introduced during recombination provides new allelic combinations for natural selection to act upon.

A scientist is studying the structural adaptations that occurred in a particular horse species over time. For several generations, the horses tended to have smaller teeth and longer toes. Then, there was a shift in the fossil record, and the horses tended to have larger teeth and shorter toes. What is the most likely cause for this shift in the horses' anatomy?

The horse species traveled to a new ecosystem in a different geographical location.

7. Peppered moths use the adaptation of camouflage as protection from predators. They may have a variety of colors or shades, but before the Industrial Revolution, they were typically white with black speckles. The Industrial Revolution in the 1880s introduced large-scale pollution into the environment. The pollution resulted in widespread, dark-colored staining of buildings and trees. Which of the following was the most likely effect of the Industrial Revolution on peppered moths in cities?

The population of light-colored moths decreased and the population of dark-colored moths increased.

Over the years, bacteria have become less sensitive to antibiotics used for medicinal and sanitation purposes. This lack of sensitivity is termed antibiotic resistance. How is antibiotic resistance an adaptation?

The trait giving bacteria antibiotic resistance has become common, giving bacteria with the trait a selective advantage.

Rabbits use camouflage as a way to hide from predators. A population of rabbits ranging in color from brown to white lives in a forest ecosystem where much of the soil and vegetation is brown. However, a recent climate change has resulted in most of the forest floor being covered in snow. Which of the following will most likely occur?

The white rabbits will gain an advantage over brown rabbits.

All species have a certain amount of genetic diversity within their populations. How is genetic diversity important to the concept of natural selection?

Without genetic diversity, natural selection cannot occur.

Natural selection causes gradual changes in _______.

a population

After collecting data on tail lengths in a population of ground squirrels, a scientist compared her results with data from fifty years earlier. The following graph shows a comparison of both data sets. What type of selection could explain the differences in tail length over the past 50 years

directional selection

In some cases, members of a population can become reproductively isolated from the rest of the population without being geographically isolated. In other words, speciation can still occur when members of a population are able to intermingle in the same area. What type of selection is most likely responsible for splitting a population into separate species within the same habitat?

disruptive selection

There is a large amount of biodiversity throughout the world. According to the theory of natural selection, which of the following factors is primarily responsible for biodiversity?

environmental diversity

Several bacterial colonies are placed on a petri dish that contains agar with antibiotics. After 24 hours, ninety percent of the original bacterial colonies die, but the remaining ten percent survive and later reproduce. Which of the following theories is demonstrated by this experiment?

natural selection

1. Some organisms have favorable traits that are well-suited to the environment in which they live. Organisms with this advantage are more likely to thrive, reproduce, and pass their traits to future generations than organisms without favorable traits. This process is known as

natural selection.

10. Some behaviors, such as nest building in birds, are determined by the genes of an organism. These innate behaviors are inherited from parent to offspring and exhibited even if the offspring does not observe its parent performing the behavior. Nest building behaviors most likely developed because birds that built nests were more likely to raise their young to maturity and thus increase their reproductive success. That is, birds that laid their eggs in nests had more offspring survive to adulthood than those that did not. Behaviors that are determined by genes and that give an organism increased reproductive success usually become common in a species due to

natural selection.

Over time, color variation in a population of butterflies declined. The number of color variations within the population was twelve in 1985. In 2005, the number of color variations reduced to three.

stabilizing selection

Which of the following is a behavior shaped through natural selection?

wolves hunting in packs