Deck 21: Defining Life and Its Origins

Question 1

Which property of RNA makes some RNA molecules able to act as catalysts?

A) They are single-stranded molecules that can fold into very specific shapes.
B) They are single-stranded molecules that cannot fold into very specific shapes.
C) They are double-stranded molecules.
D) They are double-stranded molecules that can fold into very specific shapes.

Answer 1

A

Question 2

Which statement best describes the importance of banded iron formations?

A) The rust layers in them serve as evidence for the presence of rocks on early Earth.
B) The rust layers in them serve as evidence for the presence of iron on early Earth.
C) The rust layers in them serve as evidence for the fall of atmospheric oxygen on early Earth.
D) The rust layers in them serve as evidence for the rise of atmospheric oxygen on early Earth.

Answer 2

D

Question 3

How old is Earth?

A) about 4.6 million years old
B) about 1 billion years old
C) about 3.6 billion years old
D) about 4.6 billion years old

Answer 3

D

Question 4

What is the flow of information that the central dogma refers to?

A) DNA
B) DNA
C) RNA
D) RNA

Question 5

Which of these statements does NOT describe eukaryotic cells?

A) Their cytoplasm consists of the cytosol and organelles.
B) They possess a selectively permeable membrane.
C) Their genetic material is localized in the cytoplasm.
D) Their DNA is organized into chromosomes.

Question 6

In the 1920s, Aleksandr Oparin and John Haldane each made independent proposals about the formation of life on Earth. What did they say about essential organic molecules?

A) that these could not have been made in the absence of life in the conditions on primordial Earth
B) that these could have been made in the presence of life in the conditions on primordial Earth
C) that these could have been made in the absence of life in the conditions on primordial Earth
D) that these could have been made in the absence of life in the conditions on modern Earth

Question 7

Why was ATP a primary molecule in connecting energy-releasing and energy-requiring reactions in early cells?

A) because it was the only molecule available to transfer energy
B) because of its versatility and efficiency in transferring energy
C) because of its structure
D) because of its attraction to energy

Question 8

What is the importance of the ALH84001 meteorite finding?

A) It carried fossilized microorganisms.
B) It fell from Mars.
C) Its composition is similar to rocks on Earth.
D) It was found in the Antarctic.

Question 9

Which of the following is in the correct sequence?

A) the origin of self-replicating molecules
B) packaging of molecules into protobionts
C) the abiotic synthesis of polymers
D) the abiotic synthesis of small molecules

Question 10

What is the name of the process by which mitochondria and chloroplasts probably evolved?

A) endocytosis
B) endosymbiosis
C) exocytosis
D) exosymbiosis

Question 11

Which of the following contribute to evolutionary change over time?

A) changes in RNA
B) changes in DNA
C) changes in proteins
D) changes in cells

Question 12

From which of the following processes did the first oxygen molecules come from?

A) aerobic respiration
B) anaerobic respiration
C) the oxidization of water
D) the reduction of water

Question 13

If an electrode is analogous to the Miller-Urey experiment, which of the following is analogous to primordial Earth?

A) water vapour
B) a strongly reducing atmosphere
C) lightning
D) a primeval sea

Question 14

Which of the following describes the order of emergence of various organisms on Earth?

A) land plants, first prokaryotes, animals, first eukaryotes, humans
B) first prokaryotes, first eukaryotes, land plants, animals, humans
C) animals, first prokaryotes, first eukaryotes, land plants, humans
D) humans, animals, land plants, first eukaryotes, first prokaryotes

Question 15

What are protobionts?

A) a group of abiotically produced organic molecules surrounded by a membranelike structure
B) a group of biotically produced inorganic molecules surrounded by a membranelike structure
C) a group of biotically produced organic molecules surrounded by a membranelike structure
D) a group of abiotically produced inorganic molecules surrounded by a membranelike structure

Question 16

Which of the following factors is the most important requirement in order for life to emerge?

A) the presence of liquid water
B) the presence of air
C) the presence of soil
D) the presence of sunlight

Question 17

If a condenser is analogous to the Miller-Urey experiment, which of the following is analogous to primordial Earth?

A) a primeval sea
B) water vapour
C) cold temperature
D) lightning

Question 18

Which of the following would you take into account if you wanted to define viruses?

A) Viruses are between the biotic and abiotic worlds.
B) Viruses are able to live outside a host organism.
C) Viruses are able to synthesize their own proteins.
D) Viruses are able to remain unchanged.

Question 19

Where did the oxygen that has accumulated in the atmosphere come from?

A) hydrothermal vents
B) as a by-product of oxygenic photosynthesis
C) a farther atmosphere
D) oceans

Question 20

If a warmed flask of water is analogous to the Miller-Urey experiment, which of the following is analogous to primordial Earth?

A) a strongly reducing atmosphere
B) lightning
C) a primeval sea
D) water vapour

Question 21

Important molecules that were present in the reducing atmosphere of primordial Earth were oxygen (O₂), hydrogen (H₂), and methane (CH₃).

Question 22

Ribozymes are biological catalysts that are proteins.

Question 23

Which statement characterizes mitochondria and chloroplasts?

A) Over 60% of the proteins required for mitochondrial or chloroplast function are encoded by genes that are found in the nucleus.
B) Both mitochondria and chloroplasts contain genetic material.
C) Over 80% of the proteins required for mitochondrial or chloroplast function are encoded by genes that are found in the nucleus.
D) Neither mitochondria nor chloroplasts contain genetic material.

Question 24

What is the most surprising feature of the tree of life?

A) It has a single branch.
B) It has many branches.
C) It has many starting points.
D) It has a single starting point.

Question 25

Earth is approximately 4.6 million years old.

Question 26

The Miller-Urey experiment was the first experiment to demonstrate the biotic formation of molecules critical to life.

Question 27

Which of these statements does NOT describe prokaryotic cells?

A) They are 10 times smaller than typical eukaryotic cells.
B) They vastly outnumber all other types of organisms.
C) They have much less internal membrane organization than eukaryotes.
D) They are less versatile biochemically than eukaryotes.

Question 28

What is a key trait of a multicellular organism?

A) A division of labour exists among the organism's cells.
B) All the organism's cells have the same function.
C) The organism has many cells.
D) All the organism's cells are similar in shape.

Question 29

The energy for the synthesis of organic molecules on primordial Earth came from lightning and intense UV radiation.

Question 30

What are the major membrane components in a eukaryotic cell?

A) the nuclear envelope, the endoplasmic reticulum, and chloroplasts
B) the nuclear envelope, the endoplasmic reticulum, and mitochondria
C) the nuclear envelope, the endoplasmic reticulum, and the Golgi complex
D) the nuclear envelope, mitochondria, and chloroplasts

Question 31

What does a cell of prokaryotic type lack that differentiates it from a cell of eukaryotic type?

A) a plasma membrane
B) a nucleus
C) DNA
D) chromosomes

Question 32

Scientists believe that hydrothermal vents could have produced a lot more organic material than generated by the Miller-Urey experiments.

Question 33

Endosymbiosis means that eukaryotic cells evolved from ingested prokaryotic cells.

Question 34

The evolution of multicellularity meant that cells no longer needed to be complex.

Question 35

The first cells were probably aerobic heterotrophs.

Question 36

What is indicated by the fact that NOT all eukaryotic cells contain both mitochondria and chloroplasts?

A) Endosymbiosis did not occur at all.
B) Endosymbiosis occurred only in the evolution of mitochondria.
C) Endosymbiosis did not occur in stages.
D) Endosymbiosis occurred in stages.

Question 37

The early atmosphere, as proposed by Aleksandr Oparin and John Haldane, was an oxidizing atmosphere.

Question 38

Today's atmosphere is an oxidizing atmosphere. The presence of oxygen allows complex molecules to be formed because oxygen is a strong oxidizing molecule.

Question 39

Which of these statements best describes the fossil record?

A) It helps us to understand soft-bodied organisms from the past.
B) It has all been discovered by now.
C) It is an invaluable resource to understand the past.
D) It represents all organisms that once lived on Earth.

Question 40

The energy for the synthesis of organic molecules on primordial Earth came from lightning only.

Question 41

Explain the advantage of proteins acting as catalysts, and compare them with ribozymes.

Question 42

Briefly describe the conditions on primordial Earth and why these were important for the first life to be created.

Question 43

Explain the theory of endosymbiosis.

Question 44

What are stromatolites?

Question 45

Explain how the discovery of ribozymes revolutionized our thinking about the origin of life.

Question 46

Fossils form in sedimentary rocks, where there is lots of oxygen present.

Question 47

Explain how we can be confident that stromatolites were formed by microbial activity.

Question 48

Compare contemporary cells and primitive cells with respect to oxidation-reduction reactions.

Question 49

Describe and explain the Miller-Urey experiment.

Question 50

If you were to prove that the RNA molecule was a component of the first cells, how would you do that?

Question 51

Explain the seven characteristics shared by all life-forms.

Question 52

Explain two points that support the extraterrestrial origin of life on Earth.

Question 53

Explain this statement: "Proteins are much more diverse than ribozymes."

Question 54

What is the difference between a unicellular organism and a multicellular organism (other than the actual number of cells)?

Question 55

Explain why DNA was favoured by selection as a much better way to store information than RNA.