Natural Selection and Selective Breeding

1. Study the picture to the left. A population of insects is sprayed with a new insecticide. Most of the insects are killed but a few survive. In the next generation, spraying continues, but many more of the insects are unaffected by the insecticide than the first spraying. Which of the following BEST explains these results?

• The insecticide caused a mutation in the species

• A few insects in the first population were immune and passed this trait to their offspring

• The insecticide caused a side effect of immunity that was passed on to the next generation of insects. The insects learned to fight off the insecticide.

1.  A farmer noticed that some of her sunflower plants were healthy but most of the plants were infested with worms that were killing plants. How could the farmer use selective breeding to try to produce a greater number of healthy plants next season? Choose best answer:

• Use plants that require less sunlight
• Use plants that are distasteful to bugs
• Plant only seeds from the healthy plants
• Plant only seeds that require less water from growth.

Which of the following statements best describes what will most likely occur to the moth populations in the image below?

• The light moths will be captured by predators more easily than the dark moths, and the population of dark moths will rise.
• The light moths will be captured by predators more easily than the dark moths, and the population of light moths will rise
• The dark moths will be captured by predators more easily than the light moths, and the dark moths will probably go extinct.
• The light moths will change their wing color to match that of the dark moths.

Suppose a certain species of insect lives in the lush green canopy of the rain forest. Some of the insects are bright green in color, and some are bright yellow. Assume there is a natural predator of the insect in the area. What do you expect to happen to the populations of the green and the yellow insects over time?

• The green insect population will increase and the yellow insect population will decrease.
• The green insect population will decrease and the yellow insect population will increase
• Both insect populations will remain constant over time.
• Both insect populations will increase over time.

The pair of population graphs below display the results of two different five-year hunting cycles, one on light trees and one on dark trees. The population of light-colored moths is shown by the light gray dots, and the population of dark moths is shown by the dark gray dots. How do these results demonstrate natural selection?

• The moth populations shown here demonstrate random fluctuations over time that are not explained by tree color.
• On light trees, individual moths tried to become lighter in color to match the tree background. On dark trees, individual moths tried to become darker in color.
• The moths that were the same color as their background were more likely to survive and reproduce. Over time, the populations of these well-adapted moths increased.
• Small particles of tree bark became embedded in the moth’s wings, causing the moths to become darker on the dark trees and lighter on the light trees. These acquired traits were then passed down to the next generation of moths, causing the populations to change color over time.

Natural selection can operate on predator populations as well as on prey. Suppose that over time trees became covered in lichen and the proportion of light moths increased to nearly 100%. What is the most likely consequence for predator populations?

• Bird populations will decrease, at least for a while.
• Over time, birds with better eyesight will become more common.
• Birds may change hunting strategies or seek other sources of food.
• All of the above.

The variation among domesticated animals is due to

• natural selection.

• artificial selection.

• genetic modification.

• random chance

Evidence shows that the wolf is the ancestor to all of the breeds of dogs shown below. How did this variation arise in a relatively short period of time?

• Genetic manipulation

• Natural selection

• Random chance

• Selective breeding

The process of choosing parent organisms for desired characteristics is called

• natural selection.

• artificial selection.

• genetic manipulation.

• random chance.

Farmers often choose the pollen from one plant and place it on the flower of another plant.  What is this type of plant breeding called?

• Natural selection
• Artificial selection
• Genetic cloning
• Random chance