Chapter 6: Changes Over Time

This statement is true because when species share similar body structures, it suggests that they have inherited these traits from a common ancestor. Genes are passed down from generation to generation, and over time, they can undergo slight modifications or mutations. However, the overall body structure remains similar, indicating a shared ancestry. This concept is known as homology and is a key principle in evolutionary biology. Therefore, the given answer is true.

Variation refers to any difference that exists between individuals of the same species. This can include differences in physical traits, behavior, or genetic makeup. Therefore, the statement that any difference between individuals of the same species is called variation is true.

An adaptation refers to any trait that enables an organism to survive and reproduce successfully. This means that the organism has developed characteristics or behaviors that allow it to better cope with its environment, find food, avoid predators, and successfully reproduce. These adaptations increase the organism's chances of survival and passing on its genes to the next generation, ultimately ensuring the continuation of its species.

The statement is true because the fossil record is composed of the millions of fossils that scientists have collected over time. These fossils provide evidence of past life forms and help scientists understand the history and evolution of different species on Earth. The fossil record is an important tool for studying paleontology and reconstructing the ancient world.

This statement is false because natural selection acts on inherited traits rather than learned traits. Natural selection is the process by which certain traits that increase an organism's fitness are more likely to be passed on to future generations. These traits are determined by genetic variations and are not acquired through learning. Therefore, only inherited traits can be acted upon by natural selection, not learned traits.

Evolution is considered a scientific theory because it is a well-supported explanation for the diversity of life on Earth. It is based on extensive evidence from various scientific disciplines, including genetics, paleontology, and comparative anatomy. The theory of evolution explains how species change over time through the process of natural selection, and it has been extensively tested and confirmed through numerous scientific studies and observations. It is widely accepted by the scientific community and is considered one of the foundational principles of modern biology.

A species is a group of similar organisms that can mate and produce fertile offspring. This is because mating and producing fertile offspring is a fundamental characteristic of a species. It ensures that the genetic information is passed on to the next generation, allowing the species to continue to exist and evolve. Without the ability to mate and produce fertile offspring, the organisms would not be able to contribute to the gene pool of the species and would not be considered part of the same species.

A branching tree is a diagram that represents the relationships between different groups of organisms according to scientists' understanding. It visually shows how different species or groups of organisms have evolved and branched out from a common ancestor over time. This diagram helps scientists analyze and study the evolutionary history and relationships between different organisms. It is a useful tool for understanding the diversity and interconnectedness of life on Earth.

Radioactive dating is the technique used by scientists to determine the actual age of a fossil. This method relies on the principle that certain elements in rocks and minerals decay at a known rate over time. By measuring the amount of decayed isotopes in a fossil, scientists can calculate its age. This technique is crucial in understanding the geological time scale and the evolution of life on Earth. Gradualism refers to the idea that changes in species occur gradually over long periods of time. Natural selection is the process by which organisms with advantageous traits are more likely to survive and reproduce. Relative dating is a method of determining the age of fossils based on their position in rock layers.

The largest span of time in the Geologic Time Scale is not the Mesozoic Era. The correct answer is False. The largest span of time in the Geologic Time Scale is actually the Precambrian Eon, which encompasses about 88% of Earth's history. The Mesozoic Era is a subdivision within the Phanerozoic Eon, which is a smaller portion of the overall geologic time scale.

Competition refers to the struggle between individuals or species for limited resources such as food, water, and territory. In a situation where there is limited food and other resources, individuals or species will compete with each other to obtain these resources in order to survive and reproduce. This competition can lead to various adaptations and changes in the population over time. Therefore, competition is a plausible explanation for the effect caused by limited food and other resources.

On the Beagle, Charles Darwin's main task was to learn about the living things he encountered during the voyage. This is evident from his detailed observations and collections of various species, which later contributed to the development of his theory of evolution. Darwin's studies on the Galapagos Islands and other locations provided him with crucial insights into the diversity and adaptation of organisms, ultimately leading to his groundbreaking work on the origin of species. Therefore, his primary focus on learning about the living things he saw on the voyage is a valid explanation for the correct answer.

A cast is a fossil made of hardened minerals that replicates the shape of the original organism or one of its parts. It is formed when minerals fill the mold left behind by the organism, creating a replica of its external or internal features. This process preserves the original shape and structure of the organism, providing valuable information about its appearance and anatomy. Casts are important in paleontology as they allow scientists to study and understand extinct organisms and their characteristics.

Scientists use the order of amino acids in a protein as evidence to determine evolutionary relationships. This is because the sequence of amino acids in a protein is determined by the DNA sequence of the genes that code for that protein. Over time, changes in the DNA sequence can result in changes in the amino acid sequence of the protein. By comparing the amino acid sequences of proteins in different organisms, scientists can infer how closely related they are and how recently they shared a common ancestor. This method is known as molecular phylogenetics and has become a powerful tool in understanding evolutionary relationships.

Punctuated equilibria is the correct answer because it refers to a theory of evolution where species experience long periods of stability or equilibrium, interrupted by short bursts of rapid change. This theory suggests that evolution occurs in sporadic events rather than through gradual, continuous changes. It contrasts with the idea of gradualism, where evolution happens steadily over time. Punctuated equilibria helps explain why the fossil record often shows long periods of little change followed by sudden bursts of new species.