Unit 5 Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Define taxonomy

A

Taxonomy is the science of naming and classifying organisms. Taxonomy gives scientists a standard way to refer to species and organize the diversity of living things.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe Aristotle’s classification system

A

Aristotle classified things as either plants or animals. He grouped animals into land dwellers, water dwellers, and air dwellers. He grouped plants into 3 groups based on differences in their stems.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Explain why Aristotle’s classification system was replaced

A

Biologists realized that Aristotle’s categories were not adequate. They also found that using a common name, such as robin or fir tree, for an organism presented its own problems; common names varied from one locale to the next, just as they do today.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is the use of common names problematic?

A

Common names may not describe species accurately. For example, a jellyfish is not a fish at all. Some early scientists devised scientific names that consisted of long descriptions in Latin, but these names were difficult to remember and suggested nothing about how organisms were related to other organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain Linnaeus’s system of classification and identify the main criterion he used to classify
organisms.

A

For the most part, Linnaeus used an organism’s morphology, that is, its form and structure, to categorize it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List Linnaeus’s levels of classification from the most general to the most specific. (7)

A

Kingdom
Phyla
Classes
Orders
Families
Genera
Species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a phylogenetic tree?

A

A phylogenetic tree is a family tree that shows the evolutionary relationships thought to exist among groups of organisms. A phylogenetic tree represents a hypothesis, and it is generally based on several lines of evidence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What information does a phylogenetic tree show?

A

A phylogenetic tree shows the evolutionary relationship thought to exist among groups of organisms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List four types of evidence used to organize organisms in systematic taxonomy and briefly explain each type

A

The Fossil Record- The fossil record often provides clues to evolutionary relationships, but it is important to understand that the fossil record cannot be read like a history book. Some organisms, such as some ocean-living invertebrates, have fairly complete fossil records. Other organisms have incomplete fossil records; there may be series of strata in which no fossils of the organism appear. The fossil record may provide the framework of a phylogenetic tree, but a systematic taxonomist would seek to confirm the information it provided with other lines of evidence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The Fossil Record

A

The fossil record often provides clues to evolutionary relationships, but it is important to understand that the fossil record cannot be read like a history book. Some organisms, such as some ocean-living invertebrates, have fairly complete fossil records. Other organisms have incomplete fossil records; there may be series of strata in which no fossils of the organism appear. The fossil record may provide the framework of a phylogenetic tree, but a systematic taxonomist would seek to confirm the information it provided with other lines of evidence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Morphology

A

Taxonomists study an organism’s morphology and compare it with the morphology of other living organisms. Recall from Chapter 15 that homologous features suggest descent from a common ances-tor. Naturally, it is essential to separate those features that are truly homologous from those that seem homologous but are actually analogous.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Embryological Patterns of Development

A

Early patterns in embryological development provide evidence of phylogenetic relationships. They also provide a means of testing hypotheses about relationships that have been developed from other lines of evidence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Chromosomes and Macromolecules

A

Taxonomists use comparisons of macromolecules such as DNA, RNA, and proteins as a kind of “molecular clock.” Scientists compare amino acid sequences for homologous protein molecules of different species. The number of amino acid differences is a clue to how long ago two species diverged from a shared evolutionary ancestor. This molecular-clock model is not a perfect one. It assumes that all changes in amino acid sequence are random and are not affected by natural selection. This is probably not true. Moreover, sequences of amino acids can change at different rates in different organisms. But the molecular-clock model is used, together with other kinds of data, to estimate degrees of relatedness between different species.
In a similar kind of analysis, biologists compare the karyotypes, or patterns of chromosomes, of two related species.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define blastula

A

A ball of cells formed when a zygote undergoes repeated cycles of cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why are echinoderms thought to be more closely related to vertebrates than they are to mollusks?

A

In echinoderms such as starfish and sand dollars, the blastopore becomes the posterior end of the
digestive system, as it does in chordates, which include vertebrates. This pattern of development suggests that echinoderms are more closely related to vertebrates than they are to other invertebrates, such as mollusks,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain why humans and chimpanzees are thought to have a common ancestor as recently as 5 million years ago

A

The chromosomes of humans and chimpanzees show a surprising degree of similarity. One of the chromosomes in humans is homologous to two smaller chimpanzee chromosomes. This fused human chromosome and six inverted chromosome segments are the only observed chromosomal differences between the two species. The comparison of chimpanzee and human chromosomes prompted several biologists to reevaluate the accepted estimate of how long ago chimpanzees and humans last shared an ancestor. Before chromosomal analysis, it was widely thought that the ancestors of humans and chimpanzees diverged from a common ancestor about 25 million years ago. After the comparisons of karyotypes and amino acid sequences in proteins, molecular biologists decreased the estimate from 25 million years to as little as 5 million years.