5.3

5.3

PART 1: Homologous features

Definition: features with similar structures but different functions.

Basically this is the understanding of how different structures evolved to become what they are today. A whale has forelimbs but they use them differently in the fact that whales swim and humans walk. This feature is also present on humans and horses but we all use them quite differently.

As we know a bird uses her forelimbs to fly while a rabbit will use theirs to hop.

PART 2: Vestigial features

Definition: Rudimentary structures with no useful function

Okay so let's start off with the whale example. It has been proven that whales used to have legs or a similar species to whales that evolved into whales. So now whales and even snakes have hip and leg bones that come to no purpose

You can't really tell very well but the eye sockets here are actualy empty on this blind cave salamander suggesting that they have evolved from a species that have had eyes that were able to see.

PART 3: biochemistry

Biochemistry has alot to do with the genetic make up of cells. This could be the amino acid sequence in your skin cells and biochemistry is determining how the amino acid chain differs from other species over time that once had the same protein make-up. Scientists have started using this method in DNA. Scientists use the four bases in DNA- adenine, thymine, cytosine, and guanine- to compare different genetic make-ups in species to determine their similarities and differences. the pig and peccary have 7 similarities according to their DNA make-up, which can help up to determine their ancestores and different features that they have in common to also help us determine their ancestores and how they have changed according to their environment.

PART 4: Embryology

Definition: the branch of biology and medicine concered with the study of embryos and their development.

-Study of the formation of life.
-Embryologists examine fertalization and track the development of the embryo.
-Study of sperm and eggs and the whole process of a little creature growing from a one celled organism to many.