Question 1

Which of the following is a defining characteristic that all protocells had in common?

Accepted Answer

A surrounding membrane or membrane-like structure is a defining characteristic shared by all protocells. While protocells may have had the ability to synthesise enzymes or RNA replication, these traits are not universally shared by all protocells. RNA genes are also not a defining characteristic, as it is believed that some protocells likely relied on other genetic material, such as DNA or even proteins, for their genetic information.

Question 2

Which listing of geological periods is in the correct order, from oldest to most recent?

Accepted Answer

The correct order of geological periods from oldest to most recent is Cambrian, Devonian, Permian, Cretaceous.

Question 3

Which of the following showed their greatest diversity during the Mesozoic era but were a small, less diverse group during the Paleozoic era?

Accepted Answer

A

Question 4

If a fossil is encased in a stratum of sedimentary rock without any strata of volcanic rock (for example, lava or ash) nearby, then it should be ________.

Accepted Answer

Radiometric dating of sedimentary rock is less accurate than that of igneous rock, as sediments can contain materials that have been eroded from a variety of sources and may have different ages. Without nearby igneous rocks to provide a more precise age range, determining the absolute age of the fossil will be difficult.

Question 5

Why are fossils considered to be an incomplete record of evolution?

Accepted Answer

The fossil record is biased towards organisms that had hard shells and skeletons because the soft tissues of many organisms decay rapidly after death and are not preserved. Additionally, the fossil record only represents organisms that were preserved in specific environments, such as sedimentary rock, which is not found in all locations. This means that there are many organisms that existed in the past that are not represented by fossils, making the fossil record an incomplete record of evolution.

Question 6

How was early Earth from more than three billion years ago different from today's Earth? Unlike Earth today, early Earth ________.

Accepted Answer

The early Earth had an atmosphere rich in gases released from volcanic eruptions, which included methane, ammonia, and carbon dioxide.

Answer: B 
 Early Earth had a reducing atmosphere, which means that it lacked oxygen and was instead composed mostly of nitrogen, carbon dioxide, and water vapor.

Answer: C 
 Early Earth received more high-energy radiation from the sun due to a weaker magnetic field and a thinner ozone layer.

Answer: D 
 Early Earth did not have significant quantities of ozone in its atmosphere yet, as the process of ozone formation requires the presence of oxygen and UV light, which came later in Earth's history.

Question 7

Which of the following organisms would be most likely to form a fossil?

Accepted Answer

Fossilization is more likely for organisms with hard parts, like bones or shells, and those that are more common, increasing the chances of preservation. A common possum has bones and is more likely to be preserved than a worm.

Question 8

If the half-life of carbon-14 is about 5,730 years, then a fossil that has 1/16 of the normal proportion of carbon-14 to carbon-12 should be about how many years old?

Accepted Answer

The answer of If the half-life of carbon-14 is about...

Question 9

Fossils of Lystrosaurus, a dicynodont therapsid, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. The animal apparently lived in arid regions and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous period. Some dicynodonts had two large tusks, extending down from their upper jaws. The tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record in sedimentary rocks, these pig-sized organisms were the most common mammal-like reptiles of the Permian.
What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth?
1) origin of mitochondria
2) origin of multicellular eukaryotes
3) origin of chloroplasts
4) origin of cyanobacteria
5) origin of fungal-plant symbioses

Accepted Answer

The answer of Fossils of Lystrosaurus, a dicynodont therapsid, are...

Question 10

Which of the following is the correct sequence of events in the origin of life?
I. Formation of protocells
II. Synthesis of organic monomers
III. Synthesis of organic polymers
IV. Formation of DNA-based genetic systems

Accepted Answer

The most widely accepted sequence of events in the origin of life is believed to be the synthesis of organic monomers (II) followed by the formation of organic polymers (III) that eventually led to the formation of protocells (I). The last step is the synthesis of DNA-based genetic systems (IV).

Question 11

You are the lucky student of a wacky professor who develops a time machine. He asks if you will test it with him. You get in, and there is an immediate glitch-the date readout fails so that when you land, you are not sure what era you are in. Your professor begins to panic, but you see something that tells you are in the Cenozoic era. Which of the following could it be?

Accepted Answer

The answer of You are the lucky student of a...

Question 12

In 2013, researchers constructed a vesicle with replicated RNA. Why was this significant evidence for abiotic origin of life?

Accepted Answer

RNA molecules being able to pass on information to their "daughters" is significant evidence for abiotic origin of life because it shows that self-replication is possible without the need for a biological system or cellular machinery. This supports the idea of RNA being one of the first biomolecules to appear on Earth and potentially serving as a precursor to the development of more complex biological systems.

Question 13

The first genetic material on Earth was probably ________.

Accepted Answer

The hypothesis that self-replicating RNA was the first genetic material on Earth is widely accepted by many scientists. RNA is able to store genetic information and catalyze chemical reactions, suggesting that it could have acted as both the genetic material and enzymes necessary for life to begin. There is also evidence that RNA can self-replicate under certain conditions, making it a likely candidate for the first genetic material.

Question 14

What is true of the fossil record of mammalian origins?

Accepted Answer

The fossil record of mammalian origins does include transitional forms with progressively specialised teeth, indicating the evolution of mammals from earlier reptiles.

Answer: C
 The fossil record of mammalian origins shows that mammals evolved after the extinction of dinosaurs, indicating that they did not overlap in geologic time.

Answer: D
 The fossil record does not show a gradual change of scales into fur, but rather a clear distinction between reptilian scales and mammalian hair. Therefore, choice D is incorrect.

Answer: A
 While some scientists believe that birds evolved from a particular group of dinosaurs (theropods), there is no evidence that mammals and birds evolved from the same kind of dinosaur. Therefore, choice A is incorrect.

Question 15

Which hypothesis for the abiotic formation of organic molecules suggests that early Earth's atmosphere was a neutral atmosphere?

Accepted Answer

The hypothesis that suggests early Earth's atmosphere was a neutral atmosphere is the one that suggests the early atmosphere was made up primarily of nitrogen and carbon dioxide. This is because a neutral atmosphere would not have had an excess of either hydrogen or oxygen, which would have prevented the synthesis of organic molecules.

Question 16

Which of the following statements suggests natural selection as a mechanism in the evolution of ribozymes?

Accepted Answer

The answer of Which of the following statements suggests natural...

Question 17

A sediment core is removed from the floor of an inland sea. The sea has been in existence, off and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilised in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonised by life. 
To assign absolute dates to fossils in this sediment core, it would be most helpful if ________.

Accepted Answer

Volcanic ash layers provide a way to assign absolute dates to the fossils in the sediment core, as these layers can be radiometrically dated. Knowing the order in which the fossils occurred (choice A) may be helpful for interpreting the evolutionary history, but it does not provide absolute dates. The sediments being undisturbed by underwater currents (choice B) may help preserve the integrity of the fossils, but it does not provide a method for absolute dating. Fossils throughout the column being equally spaced apart (choice D) is not necessarily indicative of anything and does not provide a method for absolute dating.

Question 18

Which of the following would be least likely to appear in the fossil record?

Accepted Answer

Desert-dwelling species may be less likely to be preserved as fossils because deserts typically have dry and arid conditions which may cause rapid decomposition and destruction of organic matter. Fossils are more commonly found in environments that facilitate preservation such as aquatic or marshy areas. Burrowing species may also leave behind recognizable fossilized burrows or tracks in sedimentary rocks.

Question 19

You are the lucky student of a wacko professor who develops a time machine. He asks if you will test it with him. You get in, and there is an immediate glitch-the date readout fails so that when you land, you are not sure what era you are in. As your time machine lands, you see an unusual landscape before you. As you open the door, you realise you cannot breathe. You quickly shut the door, realising you are in the ________.

Accepted Answer

The Archaean eon is the earliest eon of the Earth's history (4 to 2.5 billion years ago) when the atmosphere did not contain oxygen and the surface of the Earth was largely inhospitable to life as we know it. Therefore, it is possible that the atmosphere of the Archaean eon could have been toxic to humans, making it impossible to breathe outside the time machine.

Question 20

What is the most accurate method used to measure the age of a fossil?

Accepted Answer

Radiometric dating is the most accurate method used to determine the age of a fossil. This method uses radioactive isotopes to determine the age of rocks or fossils based on the rate of decay of certain isotopes. By comparing the ratio of the radioactive isotope to the stable isotope, scientists can calculate the age of the sample. Other methods, such as sequencing fossils in rock strata or using whole-life decay, may provide some information about the age of a fossil, but they are not as accurate as radiometric dating.

Quiz 25: The History of Life on Earth