The theory of evolution explains how different species have evolved from ancient organisms to become better suited to its new environment. This theory was proposed by Charles Darwin.

A. Charles Darwin

In biology, the term fitness represents an individual’s ability to adapt and survive life. If an individual is able to live longer and reproduce more offspring in a given environment or condition, it has a high fitness.

D. Fitness

Lamarck explained that due to the involvement of natural selection in the way animals use their organs or body parts, organisms have altered, acquired and lost particular traits in their entire lifetime. Those traits that are well-adapted to the environment are passed down to the next generation. As a result, evolution in the species occurs.

D. II and III only

Darwin came across the comparison between the processes of natural and artificial selection. He concluded that there are three key concepts which are all supporting his theory about evolution. These concepts include the struggle for existence, survival of the fittest, and the descent with modification.

E. I, II and III

Natural variation simply refers to the differences among cells, organisms, or groups of species. This does not provide evidence about evolution. Fossil records, geographical distribution of living things, homologous structures of living organisms, and similarities in embryological development were all evidences used to prove the theory of evolution.

B. natural variation within a species

Artificial selection is the process by which the breeding of animals and plants are done to produce an offspring with a desirable trait.

B. artificial selection

Lyell helped Darwin to grasp the idea behind geology by letting the scientists know the importance of observation. He stressed that processes that shaped the Earth continue until the present time and observing these events may be the key to understanding our world even better.

C. The surface of the Earth changes over time.

Homologous structures usually have the same embryonic tissues during its development stage. However, when these tissues mature, their structures appear differently. An example of two animal structures that are homologous include the limbs of a mammal and the wings of a bird.

D. dog’s front legs

Darwin discovered that the traits of the birds, particularly their beaks varied among the different islands in Galapágos. Variation among these birds helped them to adapt to certain conditions in their habitat. Those who are able to survive the process of natural selection are the ones that are able to reproduce a certain type of trait. As a result, there were differences among the species inhabiting the different islands.

B. natural selection

When Darwin studied the Galapágos finches, he saw some remarkable differences among the beaks of the birds living in the different islands. Birds which pick seeds out of fruits have longer beaks, whereas birds who eat seeds from the ground have shorter beaks. This is an example of adaptation. These birds have a beak which is better suited for their habitat and niche.

D. adaptation