Chapter 6 Test: The History Of Life Of Earth

Explanation
The correct answer is Seaweeds and Jellyfish. According to the fossil record, the first multicellular organisms were believed to be simple marine algae, such as seaweeds, which appeared around 1.2 billion years ago. Jellyfish, which are also multicellular organisms, are believed to have appeared around 500 million years ago. Bacteria and insects are not considered to be the first multicellular organisms based on the fossil record.

Explanation
Simple plants and fungi were the first land-dwelling organisms because they were able to adapt to the harsh conditions of the terrestrial environment. These organisms were able to obtain nutrients from the soil and perform photosynthesis, allowing them to survive and reproduce on land. Insects, amphibians, reptiles, and trees evolved later as the terrestrial ecosystem became more established and diverse.

Explanation
The earliest living things lived in the ocean. This is because the ocean is believed to be the birthplace of life on Earth. The ocean provides a stable environment with a constant supply of water, nutrients, and sunlight, which are essential for the survival and growth of early organisms. Additionally, the ocean offers protection from extreme temperatures and harmful ultraviolet radiation. Fossil evidence also supports the theory that the first life forms originated in the ocean, further confirming that the ocean was the initial habitat for early living things.

Explanation
Scientists determine the absolute age of a fossil by measuring its radioactivity. This is because certain isotopes in fossils decay at a known rate, and by measuring the amount of decay, scientists can calculate the age of the fossil. Radioactive dating is a reliable method for determining the age of fossils and other geological materials.

Explanation
Mass extinctions refer to periods in Earth's history when a significant number of species abruptly disappeared. These events are characterized by a rapid decline in biodiversity and the extinction of numerous plant and animal species. Mass extinctions have occurred multiple times throughout Earth's history, with the most well-known being the extinction event that wiped out the dinosaurs. These events have had a significant impact on the evolution and diversity of life on our planet.

Explanation
The statement that no two zebras have the exact same pattern of stripes demonstrates the concept of variation. Variation refers to the differences that exist among individuals within a species. In the case of zebras, each zebra has a unique pattern of stripes, which sets them apart from one another. This variation is a result of genetic differences and can be observed in many other species as well.

Explanation
An adaptation refers to an inherited trait that provides an advantage to an organism in its specific environment. This trait allows the organism to better survive, reproduce, and compete for resources, ultimately increasing its chances of survival. Adaptations can be physical, behavioral, or physiological and are essential for the organism's ability to thrive and adapt to changes in its surroundings.

Explanation
Isolation refers to the separation or lack of interaction between different populations of organisms. In the case of the Galapagos Islands, the isolated nature of the islands has allowed for the evolution of new species. The absence of gene flow between populations due to geographical barriers or other factors creates opportunities for genetic divergence and the development of distinct traits. Over time, these isolated populations can accumulate enough genetic differences to be considered separate species. Therefore, isolation plays a crucial role in the evolution of new species in the Galapagos.

Explanation
The production of new cells in the body is determined by genes. Genes carry the instructions for cell division and replication, regulating the growth and development of cells. They control the timing and rate of cell division, ensuring that new cells are produced when needed for tissue repair, growth, and maintenance. Variations, isolation, and overproduction do not directly influence the production of new cells in the body.

Explanation
The correct answer is vestigial organs. Snakes have small leg bones in their bodies, which are remnants of their ancestors' legs. These leg bones no longer serve a functional purpose in snakes, indicating that they are vestigial organs. Vestigial organs are structures that have lost their original purpose through evolution but still remain in the body in a modified or reduced form.