Which of These Is an Example of Natural Selection Acting

question 25

Multiple Choice

Which of these is an example of natural selection acting on genetic variation resulting in evolutionary adaptation?

• A)As global warming has continued, many species that were found near the tropics have migrated either northward or southward toward the poles.
• B)During years of drought, tree rings are narrower.
• C)As the African environment became drier and the grasslands more prevalent, arched feet and non-opposable toes, both more effective for walking upright, became more common in hominins.
• D)Insect diversity in temperate broadleaf forests varies from year to year based on the amount of precipitation.

---

Definitions:

Ventricles

Hollow organs or cavities in the brain filled with cerebrospinal fluid that act as a cushion for the brain, help to circulate nutrients and remove waste, and provide the brain with the appropriate chemical environment.

Motor Neurons

Cells in the nervous system primarily responsible for sending signals to muscles to induce contraction and produce movement.

Cerebellum

A region of the brain that plays a vital role in motor control, and is also involved in some cognitive functions such as attention and language.

Dendritic Networks

Complex branching structures of dendrites in neurons that are involved in receiving and integrating synaptic signals.