Chapter 25, Evolution of Life

Question 1

What are the four groups of eukaryotes we will study?

Answer 1

Protists, Fungi, plants, and animals

Question 2

When was the earth formed?

Answer 2

4.6 BYO

Question 3

Describe the bias in the fossil record

Answer 3

Not all species are represented equally, there is bias toward those that existed for a long time, were abundant and widespread, and had hard parts such as shells or skeletons

Question 4

Describe radiometric dating

Answer 4

A method used to date fossils using the characteristic rate of decay (half-life) of a parent isotope to its daughter

Question 5

How do we date fossils younger than 75,000 years?

Answer 5

The half-life of C-14

Question 6

How do we date fossils older than 75,000 years?

Answer 6

Isotopes like U-238 are used to date the volcanic rock layers above and below the fossil

Question 7

What are the three most recent eras?

Answer 7

Paleozoic, Mesozoic, Cenozoic

Question 8

What marks the start of the 1st era?

Answer 8

Cambrian explosion-> Paleozoic

Question 9

What was the name of the first prokaryotes? Describe them. When did they appear?

Answer 9

Stromatolites, bacterial mats that lived during the Archaean

Question 10

What was the first eukaryotic organism? When was it?

Answer 10

Red algae, Proterozoic

Question 11

When did the first multicellular eukaryotes appear? What were they?

Answer 11

Proterozoic, sponges and cnidarians

Question 12

When was the age of the dinosaurs?

Answer 12

Mesozoic

Question 13

When was the age of the mammals?

Answer 13

Cenozoic

Question 14

When did atmospheric oxygen first start to rise? Who produced it? What was its effect on the life already present?

Answer 14

Archaean, cyanobacteria, killed many of the prokaryotes but some others used it for cellular respiration

Question 15

When was land colonized? Who colonized it?

Answer 15

Start of Phanerozoic, arthropods (insects)

Question 16

When did humans appear?

Answer 16

Cenozoic

Question 17

What is an endosymbiont?

Answer 17

A cell that lives within a host cell

Question 18

How did eukaryotes get their mitochondia?

Answer 18

A archaean engulfed an aerobic bacterium

Question 19

Describe the theory of serial endosymbiosis. What are some pieces of key evidence to support this theory?

Answer 19

Mitochondria evolved before plastids through a sequence of endosymbiotic events

Inner membranes are similar to plasma membranes, DNA and cell division is similar to bacteria, both transcribe and translate their own DNA, ribosomes are more similar to bacteria

Question 20

How did eukaryotes get their nucleus?

Answer 20

Infolding of the plasma membrane

Question 21

How did eukaryotes get a plastid?

Answer 21

A heterotrophic ancestral eukaryote engulfed a photosynthetic bacterium

Question 22

What is the Edicaran biota?

Answer 22

An assemblage of larger and more diverse soft-bodied organisms that lived from 635 to 541 MYA

Question 23

When were the first real predator-prey interactions?

Answer 23

Cambrian explosion

Question 24

Why did fungi and plants colonize land together?

Answer 24

Plants work with fungi for increased surface area and nitrogen/carbon fixing

Question 25

Describe the first plants. What was their major limitation?

Answer 25

Mosses, lichens and liverworts were the first plants, but they had to rely on diffusion to transport water due to their lack of vascular tissue and were very small

Question 26

Describe the second group of plants. What improvements did they have?

Answer 26

Ferns were the first vascular plants, so they could grow larger but still needed water to reproduce

Question 27

Define mycorrrhizae

Answer 27

Mutually beneficial relationships between plants and fungi

Question 28

How many mass extinctions occurred before humans formed?

Answer 28

5

Question 29

How do foraminifera found in rock layers above the K-T boundary compare to those in rock layers above?

Answer 29

Those above the boundary are smaller and less diverse than those below

Question 30

Why were scientists slow to accept the asteroid impact hypothesis?

Answer 30

At the time, most geologists thought that the Earth changed slowly and gradually, and not by major catastrophes

Question 31

What are the four major eons?

Answer 31

Hadean, Archaean, Proterozoic, Phanerozoic