Biology 1407 Lesson 1 Review
It is thought that life originated approximately
3.8 billion years ago. Life originated approximately 3.8 billion years ago.
The move towards a three-domain system reflects
A means of classifying prokaryotes that more accurately reflects evolutionary history. Based on information gathered by molecular techniques, it has been determined that one group of prokaryotes is as different from the second group of prokaryotes as it is from eukaryotes. The first group is placed under the domain Bacteria, and the second under the domain Archaea.
Evidence suggests that 4.5 billion years ago the atmosphere most likely consisted of
CH4, H2O, CO2, N2, and NH3. Evidence suggests that 4.5 billion years ago, the Earth's atmosphere is thought to have largely been a reducing atmosphere consisting of H2O, CO2, N2, CH4, and NH3.
Match the following kingdoms with their descriptions. 1. Protista 2. Plantae 3. Fungi 4. Animalia A. multicellular, heterotrophic consumer B. multicellular, heterotrophic absorber C. multicellular, photosynthesizer D. single-celled, eukaryote
D, C, B, A Protista are all single celled (D) and the other kingdoms are multicellular. Animalia are consumers (A), Fungi are absorbers (B), and Plantae are photo-synthetic(C).
Which of the following may not have been required at the beginnings of life on earth?
DNA The first information molecule may have been RNA instead of DNA. RNA-containing protobionts may have been able to reproduce, and RNA molecules called ribozymes are capable of catalyzing reactions.
Which of the following is not a part of the five-kingdom system of classification?
Eubacteria The five kingdom system of classification groups all prokaryotes into the kingdom Monera. More recent phylogenetic analysis, which have employed molecular sequencing, show that grouping all prokaryotes into one kingdom is not appropriate. The six-kingdom system splits prokaryotes into two separate kingdoms, Eubacteria and Archaebacteria.
Which of the following does not support the hypothesis that RNA served as the first genetic material?
In experiments that re-create the atmosphere of primitive Earth, RNA acts as a template for DNA synthesis. In experiments that attempt to recreate primitive Earth's atmosphere (such as the Miller/Urey experiment), organic molecules such as lipids, nucleotide bases, sugars, and amino acids have been produced. Such experiments have not shown RNA acting as a template for DNA synthesis.
The first person to obtain indirect evidence that organic molecules could have formed on early Earth was
Miller Stanley Miller, and colleague Harold Urey, tested the hypothesis that primitive Earth had a reducing atmosphere by creating conditions comparable to those of early Earth.
In the five-kingdom system, bacteria are assigned to kingdom
Monera. In the five-kingdom system, the kingdom Monera consists of bacteria and archaea.
According to most ideas about the earliest atmosphere on Earth, all of the following gases were present except
O2 Molecular oxygen is not thought to have been present in the Earth's early atmosphere. The early atmosphere is thought to have been highly reducing, and oxygen is an oxidizing molecule.
Who were the scientists responsible for proposing that primitive Earth's atmosphere was reducing?
Oparin and Haldane Oparin and Haldane proposed that primitive Earth was devoid of oxygen and contained multiple molecules that could act as electron sources.
One reason RNA is thought to have been the first genetic material is because
RNA can act as a catalyst. One reason why RNA is thought to have been the first genetic material is because RNA can act as a catalyst. Ribozymes are RNA catalysts that can remove introns from RNA and catalyze the synthesis of new RNA. The first genes could have been abiotically produced RNA sequences that served as templates for both polypeptide synthesis and RNA synthesis.
Which statement concerning stromatolites is true?
Stromatolites provide evidence that the earliest organisms on earth were prokaryotes. Stromatolites are sedimentary rocks that contain some of the oldest fossils known. Prokaryotic fossils as old as 3.5 billion years have been found within stromatolites. This supports the idea that the earliest organisms were prokaryotes.
Regarding the cyanobacteria that form stromatolites, which of the following statements is false?
They are the first eukaryotic organisms. Cyanobacteria are not eukaryotic, they are prokaryotic.
Which of the following is not true about prokaryotes?
They have a nuclear membrane. Prokaryotes are defined primarily by the fact that they lack a nuclear membrane and thus lack a nucleus.
In Manfred Eigen's experiments, what was the role of zinc?
Zinc acts as a catalyst in RNA replication. When Eigen added zinc to his experiments, RNA's ability to self-replicate was greatly enhanced.
Liposomes are
a collection of molecules surrounded by a lipid shell. Liposomes have a lipid shell that surrounds water and other molecules. A liposome can actually grow, and when it gets to a certain size, it will divide.
Closely related genera are placed into
a family. Closely related genera are placed into the same family. In the Linnaean system, the designation of family is broader than the designation of genus.
Which of the following molecules is not formed by the process of polymerization?
a nucleotide A nucleotide is the basic subunit from which the polymers DNA and RNA are made.
A hypothesis is
a tentative explanation of observations. A hypothesis is a tentative explanation of observations. In hypothetico-deductive thinking, a hypothesis is tested by predicting results of an experiment that is designed to attempt to disprove the hypothesis.
A ribozyme is
an RNA molecule that can catalyze chemical reactions. A ribozyme is an RNA molecule that can serve as a catalyst in chemical reactions of the cell, such as the removal of introns and the synthesis of new RNA.
What is a heterotroph?
an organism that obtains energy by taking in food and processing it Heterotrophs obtain energy by taking in food and processing it. "Hetero" means "other," and "troph" means "eating," and heterotrophs obtain energy by taking in food and processing it.
Coacervate drops are important to understanding life's origins because coacervates
are able to absorb substrates from the environment and release products of chemical reactions. Coacervate drops are important for understanding life's origins because they can exhibit some properties that are associated with life. Enzymes can be among the ingredients incorporated into a coacervate. Coacervates with enzymes are able to take in substrate molecules and convert them into products and release them to the surroundings.
Protobionts
are aggregates of abiotically produced organic molecules. Protobionts are aggregates of abiotically produced organic molecules. Three types of protobionts are microspheres, coacervates, and liposomes.
True or false? Archaeans share a more recent common ancestor with Bacteria than Eukaryotes, since both Archaeans and Bacteria both lack a nucleus.
false Archaeans and Eukaryotes are thought to share a more recent common ancestor than Archaeans and Bacteria.
True or false? It's been proposed to split the kingdom Monera into three separate kingdoms: Archaezoa, Protista, and Chromista.
false It's been proposed that the kingdom Protista be split into three separate kingdoms: Archaezoa, Protista, and Chromista.
True or false? Stromatolites are dome-shaped fossils of protists that are between 3.5 and 4 billion years old.
false Stromatolites are dome-shaped fossils of bacteria (prokaryotes) that are between 3.5 and 4 billion years old.
Which of the following forms of energy was not available for chemical reactions on primitive earth?
fossil fuel Fossil fuel results from phytoplankton that has been buried for millions of years. Because primitive Earth was abiotic, no fossil fuel existed.
An abundance of __________ was absent from the Earth's atmosphere four billion years ago.
free oxygen The Earth's early atmosphere is thought to have largely been a reducing atmosphere lacking in free oxygen. Any free oxygen that might have existed could react with other atoms and molecules to produce water, iron oxides, carbon dioxides, and other molecules.
To simulate the atmosphere that was thought to have been present in early Earth, Stanley Miller and Harold Urey used an apparatus with an atmosphere containing
hydrogen, ammonia, methane, and water vapor. The atmosphere that Miller and Urey used was made up of water vapor, hydrogen, methane, and ammonia. These are the gases that scientists believed prevailed in primitive Earth.
Sidney Fox's experiment showed that
if the "thin soup" was subjected to drying conditions, dipeptides and polypeptides could form. Fox's experiment showed that when the "thin soup" was dried, dipeptides and even longer polypeptides could form.
When proteinoids are mixed with cool water they form _________________.
microspheres When proteinoids are mixed with cool water they self-assemble to form what are called microspheres. Microspheres have a protein membrane that is selectively permeable to water and can swell and shrink depending on the solute concentration in the surrounding environment.
If humans and cats belong to the same class, then they must also belong to the same
phylum. Humans and cats are in the same class, and thus they are in the same kingdom and the same phylum.
The earliest classification schemes recognized two kingdoms of organisms
plants and animals The earliest classification schemes recognized two groups of organisms, plants and animals.
The Earth's early atmosphere is thought to have primarily been a (an) ______________ atmosphere, which is conducive to the synthesis of the molecules that make up the building blocks of life.
reducing Earth's early atmosphere is thought to have largely been a reducing atmosphere containing hydrogen-rich molecules, such as methane, ammonia, and water vapor.
Which one of the following was not a characteristic of Earth approximately four billion years ago?
shallow seas At this time, the surface of the Earth's crust was too hot to allow the water condensation to form shallow seas.
Which of the following lists the levels of classification in increasingly broad categories?
species, genus, family, order, class, phylum, kingdom This sequence is correct because the categories are listed from the most specific to the most broad as requested in the original problem.
The Miller / Urey experiment showed that
the hypothesized conditions on early Earth could generate organic molecules. The Miller / Urey experiment showed that the conditions on early Earth could generate organic molecules. Miller and Urey created a reducing atmosphere made up of water vapor, hydrogen, methane, and ammonia.
Many scientists believe that the formation of life from abiotic substances could not occur on modern Earth. The best explanation is that
the oxidizing atmosphere present today is not conducive to the synthesis of complex organic molecules. The synthesis of organic molecules is not likely to take place in the oxidizing atmosphere of present-day Earth. A reducing atmosphere enhances the joining of simple molecules to form more complex molecules, but an oxidizing atmosphere is much more conducive to the breakdown of molecules. Oxygen is able to attack chemical bonds and extract electrons.
An explanation with overwhelming evidence supporting it is known as a scientific
theory A theory is a comprehensive explanation based on a broad set of observations. It is an explanation with overwhelming evidence supporting it.
True or false? The chemicals in a reducing atmosphere act as reducing agents by donating electrons.
true Chemicals in a reducing atmosphere can act as reducing agents by donating electrons to other molecules.
True or false? DNA is an unlikely choice for the original unit of heredity because it is a large, stable molecule, unlikely to form spontaneously in the "thin primordial soup."
true DNA is an unlikely candidate for the original unit of heredity. It is thought that RNA acted as the original replicator.
