Question 1

-Fossils of ancient organisms are found in deep layers of rock, while the fossils of more recent organisms are found in shallower layers. Which two groups' common ancestor would be found in relatively shallow fossils?

Accepted Answer

Animals and plants are more recent groups in the evolutionary timeline compared to the other groups listed, so their common ancestor would be found in relatively shallower fossils.

Question 2

In what way is a member of domain Archaea similar to a member of domain Bacteria?

Accepted Answer

Both Archaea and Bacteria are prokaryotic cells, which means they lack a membrane-bound nucleus and other membrane-bound organelles.

Question 3

Which kingdom would include an organism that is multicellular and makes its own food?

Accepted Answer

Organisms that are multicellular and make their own food are typically classified under kingdom Plantae.

Question 4

In what period did all modern animal groups first appear in the oceans?

Accepted Answer

The Cambrian period is known as the "Cambrian explosion" because it is during this period that all modern animal groups first appeared in the oceans. This event was marked by a significant diversification and rapid evolution of life forms.

Question 5

Dr. Smith has discovered a bird that he believes is a new species. Dr. Wilson says he will only be convinced if Dr. Smith finds several more birds of the same type. Why might Dr. Wilson feel this way?

Accepted Answer

Dr. Wilson wants to ensure that the bird Dr. Smith found is not just an unusual example of an already-described species. Finding multiple birds of the same type would provide more evidence for it being a new species, rather than just an abnormal individual of an existing species.

Question 6

Which kingdom would include an organism that is multicellular, relies on other organisms for food, and reproduces by spores?

Accepted Answer

The characteristics listed are all typical of organisms in the kingdom Fungi. Many fungi are multicellular, they obtain nutrition from other organisms (such as by decomposing dead matter), and they reproduce through the production and dispersal of spores. Kingdom Animalia includes multicellular organisms that obtain nutrition through ingestion, while kingdom Plantae includes multicellular organisms that are photosynthetic. Kingdom Protista includes a diverse group of unicellular or multicellular organisms that lack defining characteristics of other kingdoms.

Question 7

What does the main trunk at the far left of the "tree of life" represent?

Accepted Answer

The main trunk at the far left of the "tree of life" represents the earliest common ancestor of all the organisms in the tree, also known as the root of the tree.

Question 8

Scientists can compare the relationships between all modern species by examining a gene that performs a similar function in species from all kingdoms. What does this one gene encode?

Accepted Answer

Ribosomal RNA is a highly conserved gene and is found in all living organisms. Comparing this gene between different species allows scientists to determine how closely related they are.

Question 9

How does the DNA of related organisms show similarity?

Accepted Answer

The sequence of bases (adenine, guanine, cytosine, and thymine) in DNA determines the genetic information of an organism. If two organisms have a similar DNA sequence, it suggests that they are closely related in terms of their evolutionary history. Therefore, the similarity in the DNA sequence provides evidence of their relationship.

Question 10

For what reason might scientists change the most current classification system?

Accepted Answer

As new information about the evolutionary history of existing species becomes available, scientists may need to revise the current classification system to better reflect the relationships between different organisms. This could result in changes to the taxonomy of certain groups of organisms or even the creation of new taxonomic groups. Changes to the classification system based on the discovery of new species or the extinction of existing ones would likely be more limited in scope.

Question 11

Of the four kingdoms in the domain Eukarya, which one is most likely to be split into two or more new kingdoms as scientists perform more genetic analyses on evolutionary relationships?

Accepted Answer

Kingdom Protista is the most diverse and least understood kingdom. It includes a wide range of eukaryotic organisms that don't fit in any other kingdom, including protozoans, algae, and slime molds. As more genetic analyses are performed, it's likely that scientists will discover significant differences within the kingdom that warrant dividing it into multiple new kingdoms.

Question 12

How have classification systems for living things changed over the years?

Accepted Answer

Classification systems for living things have evolved over time. Initially, organisms were classified into two: animal or plant kingdom. Later on, a five-kingdom system was developed, which became the preferred classification system for many years. However, with advancements in science, the three-domain system was introduced within the last 30 years to supplement the five-kingdom system. This new system is based on molecular evidence and recognizes three domains: Bacteria, Archaea, and Eukarya.

Question 13

In which era did primitive bacteria first appear?

Accepted Answer

The era in which primitive bacteria first appeared is the Precambrian, which preceded the Paleozoic, Mesozoic, and Cenozoic eras.

Question 14

DNA is found in every cell of an organism. What subset of DNA changes would be most useful to molecular biologists to determine evolutionary relationships?

Accepted Answer

DNA changes in genes that are shared by a common ancestor would be the most useful subset for determining evolutionary relationships. This is because these changes would provide information about the similarities and differences in genetic sequences between organisms that are descended from a common ancestor, which can be used to construct phylogenetic trees and determine the degree of relatedness between different groups of organisms. Changes in genes specific to organisms in one kingdom (A) would provide less information and may not be useful for comparing evolutionary relationships between different kingdoms. Changes in genes that occur in body cells and cannot be passed to offspring (C) or in genes that do not generally code for any function (D) would not provide useful information for determining evolutionary relationships.

Question 15

True or false: Organisms on Earth are currently classified first as either plant or animal.

Accepted Answer

Organisms on Earth are no longer classified exclusively as plant or animal. The current system of classification is based on three domains: Archaea, Bacteria, and Eukarya. The Eukarya domain includes all organisms with eukaryotic cells, which can be further classified into kingdoms such as Protista, Fungi, Plantae, and Animalia.

Question 16

What trait distinguishes different phyla of fungi from each other?

Accepted Answer

The way fungi form spores is a key characteristic used to distinguish between different phyla. This includes differences in the structure of the spore-producing bodies and the processes by which spores are formed and released.

Question 17

What free-living organisms developed into both mitochondria and chloroplasts?

Accepted Answer

Mitochondria and chloroplasts are believed to have evolved through endosymbiosis, where an organism lives inside another organism and eventually evolves to become an organelle. In this case, the ancestral organism that gave rise to mitochondria and chloroplasts was likely a free-living prokaryotic bacterium.

Question 18

According to the most current classifications, which group is the most different from all the others?

Accepted Answer

The answer of According to the most current classifications, which...

Question 19

True or false: It's possible for the same species to be categorized under two different names in different natural history museums around the world.

Accepted Answer

This is true. Different natural history museums may use different taxonomic systems or have different naming conventions, which can result in the same species being categorized under different names. Additionally, as new information and research becomes available, species may be reclassified or renamed, leading to further discrepancies between museums.

Question 20

Why is it so difficult for scientists to know how many species have already been described?

Accepted Answer

There isn't one location for cataloguing all species. Researchers are spread out around the world, working independently or in small groups, and there's no central database of all the species descriptions that have been published. As a result, different estimates of the total number of species exist.

Quiz 13: The Greatest Species on Earth Biodiversity and Classification