Question 1

The fact that choanoflagellates and collar cells of sponges resemble each other supports the inference that ________.

Accepted Answer

The fact that choanoflagellates and collar cells of sponges resemble each other suggests that they share a common ancestor and are thus sister groups. This is supported by molecular and morphological evidence, which places choanoflagellates and sponges in the same clade, the Porifera.

Question 2

Cadherin proteins help animal cells stick (adhere) to each other. Choose which statement about cadherin in cancer cells that are metastasising (spreading) throughout a patient's body is most likely correct.

Accepted Answer

Metastasising cancer cells need to detach from their original tumour and move to new locations in the body. Cadherin proteins normally help cells stick together, so it is likely that cancer cells undergoing metastasis would have mutations that make them less "sticky" and more able to detach and move around.

Question 3

Trichoplax adhaerens is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 µm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. Individual animals move using cilia, and any "edge" can lead. T. adhaerens feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. T. adhaerens sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
Which of the following T. adhaerens traits is different from all other known animals?

Accepted Answer

While there are other multicellular animals that lack cell walls and have cilia (such as some sponges), T. adhaerens is unique in that it lacks both muscle and nerve cells.

Question 4

The last common ancestor of all animals was probably a ________.

Accepted Answer

The last common ancestor of all animals was most likely a flagellated protist, as this group of organisms shares many similarities with animals in terms of cell structure and genetic makeup. This ancestor lived over 600 million years ago and gave rise to all animal species alive today. While fungi, algae, and chytrids are also eukaryotic organisms, they are not as closely related to animals as flagellated protists are.

Question 5

The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following is most directly involved in the evolution of these variations in metamorphosis?

Accepted Answer

Changes in the homeobox genes controlling early development are most directly involved in the evolution of variations in metamorphosis. Homeobox genes are responsible for controlling the developmental pathways during embryonic development, including the formation of body segments and appendages. Changes in these genes can lead to variations in the developmental process, resulting in different types of metamorphosis.

Question 6

Arthropods invaded land about 100 million years before vertebrates. This fact most clearly implies that ________.

Accepted Answer

The answer of Arthropods invaded land about 100 million years...

Question 7

As you are on the way to Tahiti for a vacation, your aeroplane crash lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms, and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select four organisms and observe them in detail, making the notations found in the figure.
-In which of the organisms listed would you search for photosynthetic genes?

Accepted Answer

The answer of 
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Question 8

One hypothesis suggests that the Cambrian explosion was caused by the rise of predator-prey relationships. This hypothesis is best supported by an increased incidence of which of the following fossil traces?

Accepted Answer

The rise of predator-prey relationships likely led to an increase in the evolution of hard parts, such as shells and exoskeletons, as a defense mechanism. Therefore, an increased incidence of fossil traces of hard parts is the best support for this hypothesis.

Question 9

Which of the following is (are) unique to animals?

Accepted Answer

While chitin is found in certain fungi and insects, heterotrophy is also exhibited by many fungi and some plants. Flagellated gametes are found in some protists such as certain algae. Therefore, nervous system signal conduction and muscular movement are unique to animals.

Question 10

Which of the following would you classify as something other than an animal?

Accepted Answer

Choanoflagellates are protists, not animals. Sponges, coral, and jellyfish are all classified as animals.

Question 11

As you are on the way to Tahiti for a vacation, your aeroplane crash lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms, and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select four organisms and observe them in detail, making the notations found in the figure.
-In which of the organisms listed would you search for collagen?

Accepted Answer

The answer of 
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Question 12

The evolution of animal species has been prolific (current estimates of species numbers reach into the tens of millions). Much of this diversity is a result of the evolution of novel ways to ________.

Accepted Answer

Sensing, feeding, and moving are key functions necessary for survival in most animal species. As such, evolution has led to the development of diverse structures and strategies to accomplish these tasks, resulting in the vast diversity of animal species we see today. While reproduction and embryonic development are also important aspects of animal evolution, they are not the primary drivers of diversity in the same way as functional adaptations for sensing, feeding, and movement. Arranging cells into tissues is also important, but it is just one aspect of the larger functional adaptations necessary for successful animal life.

Question 13

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of ________.

Accepted Answer

The Cambrian explosion refers to a rapid diversification of animal life during the Cambrian period, with the appearance of many new body plans and structures over a relatively short period of time. This is considered an example of adaptive radiation, whereby a single ancestral lineage rapidly diversifies into a variety of species that occupy different ecological niches.

Question 14

Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?

Accepted Answer

Gene duplication is the most likely genetic process that could have contributed to the Cambrian explosion. This is because the rapid appearance of diverse new body plans during the Cambrian period could have been facilitated by the duplication of existing genes and subsequent modification of the duplicated copies, allowing for the evolution of novel structures and anatomical innovations. The other processes listed (binary fission, random segregation, and chromosomal condensation) do not seem as directly relevant to explaining the Cambrian explosion.

Question 15

In individual insects of some species, whole chromosomes that carry larval genes are eliminated from the genomes of somatic cells at the time of metamorphosis. A consequence of this occurrence is that ________.

Accepted Answer

The answer of In individual insects of some species, whole...

Question 16

As you are on the way to Tahiti for a vacation, your aeroplane crash lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms, and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select four organisms and observe them in detail, making the notations found in the figure.
-Which organism would you classify as an animal?

Accepted Answer

The answer of 
As you are on the way to...

Question 17

A researcher is trying to construct a molecular-based phylogeny of the entire animal kingdom. Assuming that none of the following genes are absolutely conserved, which of the following would be the best choice on which to base the phylogeny?

Accepted Answer

Collagen genes are present in all animals and have a relatively slow evolutionary rate, making them a good choice for constructing a phylogeny of the animal kingdom. Genes involved in chitin synthesis, directing segmentation development, and eye-lens synthesis may not be present in all animals or may evolve too quickly, making them less suitable for constructing a comprehensive phylogeny.

Question 18

What do animals ranging from corals to monkeys have in common?

Accepted Answer

The answer of What do animals ranging from corals to...

Question 19

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________.

Accepted Answer

Most animals derive their nutrition by ingesting materials, while fungi absorb nutrients from their surroundings.

Question 20

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

Accepted Answer

The Ediacaran fauna is known for lacking hard parts, so the discovery of fossils with hard structures would be surprising. The other options (A, C, and D) are characteristic of later organisms and not unexpected in the Ediacaran fauna.

Quiz 32: An Overview of Animal Diversity

The fact that choanoflagellates and collar cells of sponges resemble each other supports the inference that ________.

Cadherin proteins help animal cells stick (adhere) to each other. Choose which statement about cadherin in cancer cells that are metastasising (spreading) throughout a patient's body is most likely correct.

The last common ancestor of all animals was probably a ________.

Arthropods invaded land about 100 million years before vertebrates. This fact most clearly implies that ________.

One hypothesis suggests that the Cambrian explosion was caused by the rise of predator-prey relationships. This hypothesis is best supported by an increased incidence of which of the following fossil traces?

Which of the following is (are) unique to animals?

Which of the following would you classify as something other than an animal?

The evolution of animal species has been prolific (current estimates of species numbers reach into the tens of millions) . Much of this diversity is a result of the evolution of novel ways to ________.

Whatever its ultimate cause(s) , the Cambrian explosion is a prime example of ________.

Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?

In individual insects of some species, whole chromosomes that carry larval genes are eliminated from the genomes of somatic cells at the time of metamorphosis. A consequence of this occurrence is that ________.

A researcher is trying to construct a molecular-based phylogeny of the entire animal kingdom. Assuming that none of the following genes are absolutely conserved, which of the following would be the best choice on which to base the phylogeny?

What do animals ranging from corals to monkeys have in common?

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________.

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?