Question 1

It is thought by scientists that the earliest living organisms

Accepted Answer

The earliest living organisms are believed to have been chemosynthetic, using sulfur and hydrogen gas as energy sources, rather than relying on photosynthesis or aerobic respiration.

Question 2

The Cambrian Explosion provided a wealth of fossil remains for scientists to uncover. Many of the animals from this time period had tough skins or shells. This would

Accepted Answer

Tough skins or shells would protect the animals from predators, which was an advantage during the Cambrian Explosion when predation was becoming more prevalent.

Question 3

Oxygen built up in the atmosphere approximately 2 billion years ago and

Accepted Answer

Oxygen helped to form the ozone layer that is so important to life today. The highly reactive oxygen molecules combined to form ozone, which absorbs potentially dangerous ultraviolet radiation from the sun.

Question 4

Many biologists feel that the first self-replicating organic systems were

Accepted Answer

RNA is believed to be the first self-replicating organic system because it can store genetic information and also catalyze chemical reactions, which are the two key functions of life. Moreover, RNA is simpler and more versatile than DNA, which implies that it could have arisen earlier in the history of life.

Question 5

Which of the following is not associated with mass extinctions?

Accepted Answer

Mass extinctions are defined as rapid and widespread extinctions that occur over a relatively short period of geological time, usually taking place within a few million years. Therefore, option D stating that mass extinctions take place over a very long geologic period of time is incorrect.

Question 6

What term is used to indicate a characteristic that is shared and inherited from a common ancestor?

Accepted Answer

An ancestral trait is a characteristic that is inherited from a common ancestor and is shared by all members of a group. This trait may change or evolve over time, but is considered the original or basic trait from which other traits may develop.

Question 7

Eukaryotic cells are thought to have

Accepted Answer

Eukaryotic cells are believed to have first appeared about 2.1 billion years ago, which is much later than the appearance of prokaryotic cells. This is based on fossil evidence and molecular clocks, which suggest that eukaryotic cells evolved from simpler prokaryotic ancestors. Eukaryotic cells are generally larger and more complex than prokaryotic cells, and they contain many organelles that perform specific functions, such as mitochondria and chloroplasts.

Question 8

According to the endosymbiont hypothesis, what cellular components originated from free-living bacterial cells?

Accepted Answer

The endosymbiont hypothesis proposes that mitochondria and chloroplasts originated from free-living bacterial cells that were engulfed by a host cell. Therefore, the choices that include either mitochondria or chloroplasts as originating from free-living bacteria are the correct answers. Only option D includes both mitochondria and chloroplasts, making it the best choice.

Question 9

Around 580 million years ago, the first simple animals are seen in the fossil record. These first fossilized animals

Accepted Answer

The passage indicates that these early animals were "probably not related to the modern jellyfish and worms they resembled." This rules out choices A, B, and C. The passage does not mention anything about the animals being land animals, so D can also be ruled out. Therefore, the best answer is E.

Question 10

Atmospheric chemists think that Earth's first atmosphere

Accepted Answer

Earth's first atmosphere likely contained nitrogen in the form of ammonia and nitrogen gas, but it did not contain significant amounts of molecular oxygen, which appeared later due to photosynthetic organisms.

Question 11

When taxonomists classify organisms using a phylogenetic approach, they are most concerned with

Accepted Answer

Taxonomists using a phylogenetic approach are most concerned with derived traits, as they are used to determine evolutionary relationships between organisms. Ancestral traits may be present in multiple lineages and do not provide as much information about relationships between organisms. Cladists, outgroups, and ingroups are all related concepts within phylogenetics but are not the main concern of taxonomists classifying organisms.

Question 12

Scientists have determined that the silversword alliance is most closely related to the tarweed based on

Accepted Answer

Molecular comparisons provide more accurate and specific information about the genetic relatedness between species compared to other methods. Therefore, it is the best choice out of the options given.

Question 13

Stanley Miller conducted a famous experiment in the 1950s. This experiment

Accepted Answer

Stanley Miller's experiment used a mixture of gases (methane, ammonia, hydrogen, and water vapor) that were thought to represent the early Earth's atmosphere. He then subjected this mixture to electric sparks to simulate lightning, and after a week, he found that some organic molecules, including amino acids, had formed. This experiment provided evidence that organic molecules could be formed from non-organic starting materials, and possibly contributed to the origin of life on Earth.

Question 14

During which geological era did Pangea break apart?

Accepted Answer

Pangea broke apart during the Mesozoic era, specifically during the Late Triassic and Early Jurassic periods.

Question 15

What level of biological classification is less inclusive than class?

Accepted Answer

Order is less inclusive than class, meaning that it contains fewer organisms that have more similarities to each other. The correct hierarchical order, from most inclusive to least inclusive, is: domain, kingdom, phylum, class, order, family, genus, species.

Question 16

What type of organisms can generate organic molecules and obtain energy from inorganic molecules like iron, sulfur, and hydrogen?

Accepted Answer

Chemoautotrophs are capable of converting inorganic compounds such as iron, sulfur, and hydrogen into organic molecules for their own energy source. This is in contrast to photoautotrophs, which use light energy from the sun to convert inorganic compounds into organic molecules for energy, and heterotrophs, which obtain their organic molecules by consuming other organisms. Homotrophs are not a recognized classification of organisms, and organotrophs obtain energy from organic molecules.

Question 17

What term is used to indicate a relatively new characteristic, in an evolutionary sense?

Accepted Answer

A derived trait refers to a characteristic that has recently evolved and is not present in the ancestor or predecessors of the group. This trait is unique to a specific group or species and distinguishes it from its ancestors. Therefore, this is the best choice for the given question.

Question 18

Paleontologists have found fossils dating back 3.6 billion years. These closely resemble

Accepted Answer

The fossils found by paleontologists dating back 3.6 billion years closely resemble blue-green algae that are still present today.

Question 19

What is the proper way to write a species name?

Accepted Answer

The proper way to write a species name is to capitalize the genus (Pantera) and use lowercase for the species (leo) with both in italics or underlined.

Question 20

Biologists think that the first photosynthetic cells

Accepted Answer

Biologists believe that the first photosynthetic cells lived more than 2.8 billion years ago. This is based on the age of the oldest-known fossilized cyanobacteria, which were photosynthetic organisms. Choices A, B, D, and E are all incorrect.

Quiz 10: Lifes Origins and Biodiversity