Chapter 8 and 9: Biodiversity and Evolution Flashcards
Evidence of Evolution include:
- fossil records
- comparative anatomy
- comparative embryology
- comparative biochemistry
- geographical distribution
The preserved remains of animals and plants that lived in the past.
Fossils
Examples of animals.
- imprints of plant or animal parts on rocks
- animals trapped and frozen in ice
- insects trapped in a hardened plant resin (amber)
- bones preserved in a peat bog (spongy ground with decaying plants, etc.)
- stone casts of mollusks and animal shells
- wood or giant plant parts replaced by minerals
Where are most fossils formed?
Most fossils were formed at the bottom of shallow bodies of water, where the remains of dead organisms settled to the bottom and were covered by mud or sand that slowly turned into sedimentary rocks.
These are formed in layers stacked on top of another. The oldest fossils were stacked at the bottom, while the most recent ones were stacked on top.
Sedimentary rocks
_ provide most important evidence to compare it with using organisms’ structure and all.
layers of sedimentary rocks
Through this process, scientists reconstruct complete structure of organisms from past.
Fossil Reconstruction
These show that many organisms were very much different from the organisms that exist today. They also show the succession of organisms that is consistent with the stacking of sedimentary rocks from the older to the younger layers.
Fossil records
The rate of decay for each element is steady. Scientists use the unit called _ to measure the rate of decay of an radioactive element. The _ of an element is the time it takes for half of the radioactive element to decay. By determining how much of a particular radioactive element (usually uranium) has changed into a stabilized form (usually lead), scientists can approximate the age or rocks or fossils.
half-life
One way of approximating the age of rocks or fossils. Radioactive elements in rocks or fossils give off radiation at constant known rate, and gradually transform into different elements until they stabilize into an element that no longer emits radiation.
– igneous and metamorphic rocks –
– static-correlation method –
– method of dating rocks and materials using radioactive act.
Radioactive dating
Another method used to date fossils is by _ where most fossils are found. The lowest layers of rocks are the oldest, thus scientists can estimate the age of a fossil by noting its placement in rock layers.
examining sedimentary rocks layers
The sedimentary layers are stacked in order of their ages. This is based on the principle known as the _, which states that in a series of sedimentary rock layers, the younger rocks are normally found on top of older rocks.
law of superposition
Using fossil records, paleontologists are able to trace and reconstruct the transformation of an organism over a span of time. One example is the proposed evolution of the horse. The _, which has been widely known as _ (dawn horses), appeared about 50 million years ago (mya).
Hyracotherium; Eohippus
This provides clues pointing to evolution and common answers. Similar structures evolve.
Comparative Anatomy
Structures that are similar in form and origin, but became modified to adapt to different functions. They have the same basic structure and origin.
homologous structures
In plants, what are the homologous structures?
leaves, petals, sepals, pistils, stamens
Some body parts among different organisms are similar in function, but different in origins. These are?
For examples, the wings of birds, butterflies, and moths are used for flying. Organisms with _ structures may not be closely related.
analogous structures
These are assumed to have lost their primordial functions as species of organisms adapted to changes in their environment. While these organs in some groups of organisms may have lost most or all of their original functions, these organs in other groups of organisms may still be useful and functional.
Vestigial organs
Humans vestigial structures include:
- appendix
- body hairs
- muscles that move ears
- wisdom teeth
This is vestigial, but this organ is a functional structure in herbivores, such as rabbits. It has gradually diminished its function as our ancestors’ diet started to contain less cellulose and food was made more palatable by cooking.
human appendix
According to scientists, embryos appear so similar that it is difficult to tell them apart.
Comparative Embryology
A German biologist noted distinct similarities in the embryological development of fish, reptiles, birds, and mammals. The early stages of growth in all these vertebrates are marked by pharyngeal pouches and tails.
Karl Ernst von Baer (1792-1876)
As the embryos continue to develop, the distinguishing characteristics of each of these species begin to appear. This similarity in the early development of embryos in vertebrates suggests a common ancestry among them.
Comparative Embryology
Perhaps, the most convincing evidence of common descent is the _.
biochemistry of cells