Lecture 9 History of Life

Question 1

what are the six features required for an entity to be considered alive?

Answer 1

1. Organization: structurally composed of one or more cells
2. Metabolism: system of management of energy and materials via chemical reactions
3. Response to stimuli: via changes in growth, alternation of chemical reactions or movement
4. Homeostasis: maintenance of some internal chemical and or thermal consistency relative to variation outside of the entity
5. Adaptation: ability to change over a period of time in response to the environment
6. Reproduction: ability to produce new individual organisms

Question 2

are viruses alive?

Answer 2

• have n.a. that can mutate and respond to selection

- lack metabolism and homeostasis, and cannot reproduce without using the cellular machinery of a host cell

Question 3

what does the fossil record do?

Answer 3

• provides evidence of how life has changed over time

Question 4

what is a fossil?

Answer 4

• preserved remnant/evidence of organisms that lived int the past

Question 5

what are distinct layers in the ground called?

Answer 5

• strata

Question 6

what are four influences that raise the probability of something becoming fossilized?

Answer 6

• hard rather than soft bodied
• aquatic rather than terrestrial
• inshore marine rather than offshore
• decomposing organisms are absent

Question 7

what is our understanding of the diversity and distribution of past life?

Answer 7

• biased and incomplete

Question 8

what are subfossils?

Answer 8

• fossils that have a higher percent of organic matter

Question 9

what are the 4 types of fossils?

Answer 9

1. casts: form when minerals fill the space in sediment where organism decayed after having been buried
2. replacement/petrified fossils: have had their tissues replaced by minerals
3. trace fossils: record evidence of behaviour (tracks, burrows, feces)
4. preserved fossils: original organic material retained (carbon films, amber, tar, peat, frozen)

Question 10

what is relative dating?

Answer 10

dating which tells us the order of which fossils are created

ex: sedimentary statigraphy

Question 11

what are index/indicator fossils?

Answer 11

• fossils that help to “read” incomplete or scrambled layers of sediment

Question 12

what is absolute dating?

Answer 12

• analyzing radioactive isotopes in fossils or rocks

Question 13

what is a half-life?

Answer 13

• the 50% of atoms in a given amount of radioactive substance have decayed

Question 14

what provided the first evidence for continental drift?

Answer 14

• fossil

Question 15

what are two important mass extinctions?

Answer 15

• end permian: 60% of all families, 90% of marine animal species
• end-cretacious: 20% and dinosaurs

Question 16

what is adaptive radiation?

Answer 16

• evolution of diversely adapted species from a common ancestor

Question 17

what are the four chemical and physical processes on early Earth that may have produced very simple cells through a sequence of stages?

Answer 17

1. Chemical evolution - abiotic synthesis of small organic molecules
2. Abiotic synthesis of macromolecules - joining of these small molecules into macromolecules; small organic molecules polymerize when they are concentrated on a surface
3. Packaging of molecules into protocells
4. Origin of self-replicating molecules - RNA, ribosomes

Question 18

how did protocells occur?

Answer 18

• hollow lipid vesicles spontaneously formed

Question 19

what are protocells?

Answer 19

• fluid filled vesicles that form faster in the presence of volcanic clay