Natural selection Elaborate

Which of the following is the best explanation of natural selection?

• Organisms with favorable traits survive and reproduce more than those with alternate traits.

• The biggest and strongest organisms survive and the small ones do not.

• Species change over time.

• Some animals have better genes than other ones.

Answer explanation

The correct choice explains that natural selection favors organisms with advantageous traits, allowing them to survive and reproduce more effectively than those without such traits, which is the essence of the process.

The caterpillar has two large spots that look like large eyes as shown. How are these large false (fake) eyes an adaptation for the caterpillar?

• They allow the caterpillar to see farther than other insects.

• They allow the caterpillar to scare away predators.

• They allow the caterpillar to move around at night.

• They allow the caterpillar to find more food.

Answer explanation

The large false eyes on the caterpillar serve as a defense mechanism, making it appear larger and more intimidating to potential predators, thus helping to scare them away.

The arctic fox, polar bear, and snow rabbit live in snow-covered environments. What is the best explanation for why this trait evolved?

• It is a coincidence that these animals are all white now.

• People selectively bred white members of these populations and over time, the darker members of the population died out.

• Darker members of these populations moved to regions where they would be camouflaged better.

• White members of these populations that lived in cold regions were able to survive better than darker ones because they were harder for prey and predators to see.

Answer explanation

White members of these populations evolved to be better camouflaged in snow-covered environments, allowing them to evade predators and hunt prey more effectively, thus enhancing their survival.

Which statement best describes a current understanding of natural selection?

• Organisms that are better adapted to an environment tend to survive and reproduce.

• Natural selection has been discarded as an important concept in evolution.

• New mutations of genetic material are due to natural selection.

• The biggest and strongest organisms survive and the small ones do not.

Answer explanation

The correct statement highlights that natural selection favors organisms that are well-adapted to their environment, leading to their survival and reproduction, which is a fundamental principle of evolution.

When the antibiotic penicillin was first introduced, it was immediately effective in combating staphylococcus bacterial infections. After a number of years, there were outbreaks of staphylococcal infections that did not respond to treatment with penicillin. The best explanation for this situation is that -

• the bacteria that survived exposure to penicillin learned to avoid it

• The bacteria that caused the new outbreaks were different from populations that had never been exposed to penicillin

• members of the original population of bacteria that were penicillin resistant survived and reproduced, creating a more resistant population

• during each generation, the bacteria modified their own DNA to increase the ability to resist penicillin and passed this ability on to their descendants

Answer explanation

The correct choice explains that members of the original penicillin-resistant bacteria survived treatment and reproduced, leading to a population that was more resistant to penicillin over time.

The females of certain species of turtles will sneak into a nest of alligator eggs to lay their own eggs and then leave, never to return. When the baby turtles hatch, they automatically hide from the mother alligator guarding the nest and go to the nearest body of water when it is safe to do so. Which statement best explains the behavior of these baby turtles?

• The baby turtles are genetically identical, so they behave the same way.

• Turtles are not capable of evolving, so they repeat the same behaviors generation after generation.

• The baby turtles' ancestors who learned to behave this way taught the behaviors to their offspring.

• More of the turtles' ancestors who acted in this way survived to reproduce, passing this behavioral trait to their offspring.

Answer explanation

The baby turtles' survival is linked to their ancestors who successfully hid from predators. This behavior was favored by natural selection, allowing those traits to be passed down, explaining their instinctive actions.

Which characteristic is necessary for natural selection to occur in a species?

• stability

• complex cellular organization

• variation

• a very low mutation rate

Answer explanation

Variation is essential for natural selection because it provides the diversity needed for certain traits to be favored in a changing environment. Without variation, there would be no differences for natural selection to act upon.

Which of the following is an example of an adaptation that helps an organism survive in its environment?

• A bird's beak shape that allows it to eat specific types of food.

• A fish swimming in water.

• A tree growing taller over time.

• A human learning to read.

Answer explanation

A bird's beak shape is a specific adaptation that enables it to access certain food sources, enhancing its survival. The other options do not illustrate adaptations that directly aid in survival.

Why do some insects develop resistance to pesticides over time?

• They learn to avoid the pesticides.

• They mutate their DNA to resist the pesticides.

• Insects with natural resistance survive and reproduce, passing on the resistant traits.

• They become stronger and bigger over generations.

Answer explanation

Insects with natural resistance survive pesticide exposure and reproduce, passing on their resistant traits to the next generation. This process, known as natural selection, leads to increased resistance over time.

What is the primary reason for the diversity of life forms on Earth?

• All organisms are genetically identical.

• Natural selection and genetic variation.

• Organisms do not change over time.

• Environmental stability.

Answer explanation

The primary reason for the diversity of life forms on Earth is natural selection and genetic variation. These processes allow species to adapt and evolve over time, leading to a wide range of organisms.