Deck 2: The Origin and Chemistry of Life

Question 1

A dissolved substance that has the ability to either remove or add H⁺ and OH^- ions to resist pH changes is

A) a solution.
B) pure water.
C) a buffer.
D) a solvent.

Answer 1

C

Question 2

Perhaps a better description of an organic compound is that an organic compound is any substance

A) derived from living matter.
B) containing carbon.
C) found within a cell.
D) consumed by animals.

Answer 2

B

Question 3

Which of the following is the most abundant carbohydrate in the world?

A) Cellulose
B) Glycogen
C) Fructose
D) Glucose

Answer 3

A

Question 4

Polysaccharide are polymers made up of which kind of monomers?

A) Simple sugars
B) Amino acids
C) Nucleotides
D) Alternating sugar and phosphate groups
E) Fatty acids and glycerol

Question 5

Which of the carbohydrates given below is a major component of the cuticle of arthropods (e.g.,insects,crayfish,etc.)?

A) Starch
B) Chitin
C) Cellulose
D) Glycogen

Question 6

Which of the following is NOT a steroid?

A) Vitamin D
B) Adrenocortical hormones
C) Sex hormones
D) Cholesterol
E) All of the choices are steroids

Question 7

The three principal groups of lipids are neutral fats,phospholipids,and

A) glycogen.
B) steroids.
C) amino acids.
D) fatty acids.

Question 8

Spontaneous generation was first proposed as

A) a concept to explain the formation of the first living cells on earth.
B) a concept to explain the evolution of simple chemicals into complex macromolecules.
C) an explanation for the appearance of maggots and mice from rotting material, fish from leaves that fall into water, etc.
D) an explanation by Pasteur accounting for the germination of spores in broth.

Question 9

Which of the lipid groups below is structurally unlike the others?

A) Steroids
B) Neutral fats
C) Triglycerides
D) Phospholipids

Question 10

A solution that has a pH of 5 has

A) a concentration of H⁺ 20 times higher than water.
B) a concentration of H⁺ 100 times higher than water.
C) a concentration of H⁺ the same as water.
D) a concentration of H⁺ 20 times lower than water.
E) a concentration of H⁺ 100 times lower than water.

Question 11

Carbohydrates are categorized into

A) organic and inorganic carbohydrates.
B) saturated and unsaturated carbohydrates.
C) monosaccharides, disaccharides and polysaccharides.
D) primary, secondary, tertiary and quaternary carbohydrates.
E) monomer and polymer carbohydrates.

Question 12

Which of the following is a "structural" carbohydrate molecule?

A) Sucrose
B) Glycogen
C) Cellulose
D) Glucose

Question 13

Pasteur's work with spontaneous generation showed that

A) life could not have evolved from non-living chemistry on the early earth.
B) mice came from mother mice and maggots from mother flies.
C) simple chemicals could become complex organic macromolecules without any living cell involved.
D) broth did not ferment spontaneously but required contamination with organisms.

Question 14

Which of the following lipids forms a bilayer between two fluid regions,such as in the plasma membrane of a cell?

A) Steroids
B) Waxes
C) Phospholipids
D) Lipoproteins

Question 15

Most organic molecules are associated with living organisms.Which of the following statements is NOT related to the general distinctions between these types of molecules?

A) Carbon dioxide (CO₂) lacks hydrogen atoms found in most organic molecules and therefore is usually not considered to be "organic."
B) Formaldehyde (CH₂O) is a small molecule compared to most organic molecules but does have carbon and hydrogen covalently bonded together and therefore is considered to be "organic."
C) Salt (Na⁺Cl ) is not an organic molecule but is important to the life of many organisms.
D) Organic carbon atoms are more diverse than inorganic carbon molecules that form the molecular structure of soot or a diamond from pure carbon.
E) All of the choices are correct.

Question 16

Which of the following carbohydrates is used in animal muscle and liver cells for energy storage?

A) Starch
B) Chitin
C) Cellulose
D) Glycogen

Question 17

Neutral fats are

A) stored as glycogen.
B) not stored.
C) made of fatty acids and glycerol.
D) made of chains of fatty acids linked together by water molecules.

Question 18

The hypothesis that simple chemicals may have naturally become complex macromolecules by natural physical forces was first proposed by

A) Stanley Miller.
B) Graham CairnsSmith.
C) Alexander Oparin and J.B.S. Haldane.
D) Sidney Fox.

Question 19

A dehydration synthesis reaction is also

A) a condensation reaction.
B) a hydrolysis reaction.
C) an isomeric reaction.
D) a reaction that does not require enzymes.

Question 20

Lipids are polymers made of which monomers?

A) Glucose or modified glucose molecules
B) Amino acids
C) Alternating sugar and phosphate groups
D) Fatty acids and glycerol

Question 21

The alpha helix is found at which level of protein organization?

A) Primary structure
B) Secondary structure
C) Tertiary structure
D) Quaternary structure

Question 22

A chain consisting of a number of amino acids is a

A) quaternary structure.
B) dipeptide.
C) polypeptide.
D) None of the choices are correct.

Question 23

A peptide bond is found in which type of biological molecule?

A) Carbohydrate
B) Lipid
C) Protein
D) Simple sugar

Question 24

At the molecular level,a cell's ability to vary in its operational tolerance to temperature,etc.,is most closely related to

A) enzyme activity and protein denaturation.
B) ATP efficiency.
C) replication of nucleic acids.
D) extent of saturation of fatty acids.

Question 25

The splitting of one compound into two by the addition of water is called

A) covalent.
B) ionic formation.
C) hydrolysis.
D) condensation.

Question 26

The term "reducing atmosphere" for the early earth means that the atmosphere

A) was much thinner around the surface of the earth than now.
B) contained only two or three kinds of gases.
C) contained little or no free oxygen.
D) contained little or no free nitrogen.

Question 27

Which of the following forms of energy is NOT one of those thought to have been involved in the production of large organic molecules in the primitive reducing atmosphere?

A) Radioactivity
B) Electrical energy
C) Radiation from the sun
D) Sound

Question 28

If an animal needs to store high-energy compounds for long-term use with the least amount of extra body weight,which would be the best molecule for storage?

A) Fructose and glucose in the form of honey
B) High-calorie fat molecules
C) Starch
D) Glycogen with extensive side branches of glucose

Question 29

A protein is a polymer made up of which kind of monomers?

A) Glucose or modified glucose molecules
B) Amino acids
C) Nucleotides
D) Fatty acids and glycerol

Question 30

Cholesterol belongs to which of the following groups?

A) Steroids
B) Neutral fats
C) Carbohydrates
D) Phospholipids

Question 31

You eat eggs for breakfast and return in the evening to dirty dishes with "dried on" yellow streaks.After soaking awhile,the egg yolk protein molecules easily "wash off." What happened?

A) Heating denatured the egg protein molecules, hydrolysis reactions then formed bonds in the dried egg yolk, and soaking in water eventually resulted in condensation reactions where water broke these bonds
B) Heating denatured the egg protein molecules, unorganized condensation reactions formed bonds in the drying egg, and soaking in water resulted in hydrolysis reactions where water broke these bonds
C) Egg monomers were fused to become one polymer, which was easily dissolved by water back into monomers
D) Addition of water converted organic molecules into inorganic molecules

Question 32

Prions are infectious

A) carbohydrates.
B) proteins.
C) lipids.
D) Prions are not actually infectious.

Question 33

Fish sperm is mostly made of male DNA.A chemical test would find high amounts of

A) nitrogenous bases, sugar, and phosphate groups.
B) phospholipids and steroids.
C) amino acids and unsaturated fats.
D) triglycerides and ATP.
E) globular proteins and stored fats.

Question 34

Which of the following is a correct statement about oxidation reduction reactions?

A) Reduction is the loss of electrons
B) Reduction is the loss of hydrogen atoms
C) Oxidation is the loss of electrons or hydrogen atoms
D) Reduction and oxidation sometimes occur together, but not always

Question 35

Nucleic acids are important because they

A) act as buffers.
B) are the basic units of neutral fats.
C) direct the synthesis of proteins.
D) None of the choices are correct.

Question 36

Which of these statements is true about DNA?

A) It is the genetic material of the cell
B) It forms a protein
C) It is pure amino acid
D) It contains no sugar

Question 37

Who first performed an experiment that proved that amino acids could be produced in the laboratory from a reducing atmosphere and electrical sparks?

A) Stanley Miller and Harold Urey
B) Graham CairnsSmith
C) Thomas Cech
D) Alexander Oparin and J.B.S. Haldane

Question 38

A nucleic acid is a polymer made up of which kind of monomers?

A) Amino acids
B) Nucleotides
C) Glucose or modified glucose molecules
D) Alternating sugar and phosphate groups

Question 39

In a protein,the folding of a polypeptide into a three-dimensional structure,usually stabilized by covalent bonds between the side groups of the amino acids,is the

A) primary structure.
B) secondary structure.
C) tertiary structure.
D) quaternary structure.

Question 40

DNA and RNA are polymers composed of repeated units called

A) nucleotides.
B) bases.
C) sugars.
D) None of the choices are correct.

Question 41

A(n)_______________ fatty acid has two or more carbon atoms joined by double bonds.

Question 42

The term ____________ refers broadly to compounds that contain carbon.

Question 43

The fact that nucleic acids are very complicated molecules suggests that

A) the RNA-first hypothesis is impossible.
B) the protein-first hypothesis is therefore the only plausible hypothesis.
C) no natural system could ever generate them.
D) None of the choices are correct.

Question 44

Prokaryotic cells are represented by fossils that are dated back as far as _____ billion years ago.

A) 1.5.
B) 2.8.
C) 3.8.
D) 4.8.

Question 45

The most important of the energy-storing carbohydrate monomers is the molecule _______________.

Question 46

Water has which of the following important characteristics that explain its key role in living systems?

A) High specific heat capacity
B) High surface tension
C) Is an excellent solvent
D) All of the choices are correct

Question 47

A molecule of RNA that has enzymatic or catalytic properties is called a _______________.

A) deoxyribose
B) nucleotide
C) ribonucleic acid
D) ribozyme

Question 48

The Precambrian-Cambrian boundary is

A) A point that separates reduction environments from oxidation environments
B) The separation point between prokaryotes and eukaryotes
C) A point of dramatically increased fossilization, although it is likely that many animal groups existed before this time
D) The shift-over from plants to animal life

Question 49

The ancestral protocells

A) may have contained RNA or DNA as their genetic material.
B) may have evolved before the development of a true cell.
C) may have had a lipid and protein membrane surrounding them, forming a proteinoid microsphere.
D) may have contained a biochemical pathway for energy metabolism.
E) All of the choices are correct.

Question 50

Heating dry mixtures of amino acids and then mixing them with water forms small

A) strands of DNA.
B) living cells.
C) proteinoid microspheres.
D) plasma membranes.

Question 51

The first eukaryotic cells probably arose about _____ billion years ago.

A) 1.5
B) 2.5
C) 3.5
D) 4.5

Question 52

An alternative environment to the "hot dilute soup" and clay hypothesis that offers a possible source of energy and molecules for the origin of life is/are the

A) frozen Antarctic ice sheets.
B) surface of Mars.
C) hydrothermal vents in ocean bottoms.
D) Earth mantle and core.

Question 53

Amino acids are linked together to form proteins by __________ bonds.

Question 54

If the hypothesis that protocells were based on an "RNA world" is correct,what would be necessary to shift to a "DNA world"?

A) An enzyme or reaction capable of removing one oxygen from ribose in nucleotides
B) Enzymes for reverse transcription of RNA into DNA
C) New enzymes to replicate the DNA
D) New enzymes for transcribing DNA back to RNA
E) All are necessary to switch to a "DNA world."

Question 55

Our current understanding of the origin of eukaryotic organelles such as mitochondria is that they

A) were copies of a cell nucleus that failed to be separated by cytokinesis.
B) are prokaryotes that were taken into a cell and now live there symbiotically.
C) are variations of the plasma membrane.
D) are new forms of life that arose inside other cells.

Question 56

Which of the following kinds of molecules is thought to have been absent from the primitive reducing atmosphere?

A) Water vapor (H₂O)
B) Carbon dioxide (CO₂)
C) Oxygen (O₂)
D) Nitrogen (N₂)

Question 57

Biological evolution differs from chemical evolution in that biological evolution would have been possible only after the development of

A) true cells capable of replication.
B) nucleic acids.
C) enzymes.
D) a metabolic pathway.

Question 58

Scientists once assumed that the earliest protocells would have been autotrophs.This concept appears to be

A) correct, since heterotrophs would depend upon eating autotrophs.
B) correct, since glycolysis and fermentation only occur after oxygen is present from photosynthesis.
C) incorrect, since the primordial soup likely contained many preformed food molecules suitable for heterotrophic metabolism.
D) incorrect, since glycolysis and fermentation require complex enzymes for catalytic reactions.

Question 59

Which pairing of occurrence and date is correct?

A) Beginning of Cambrian - 600 million years ago
B) Origin of life - 3.8 billion years ago
C) Origin of eukaryotic cells - 1.5 billion years ago
D) All the choices are correct

Question 60

The molecule ___________ is an important form for storing sugar in animals and is found mainly in the liver and muscle cells of animals.

Question 61

What are the essential properties of a "protocell"?

Question 62

Describe the first evidence for chemical evolution that came from Stanley Miller's experiment.

Question 63

What evidence do scientists have that the earth's primeval atmosphere was a reducing atmosphere?

Question 64

Why can't we set up an experiment that would again duplicate the conditions that were present at the early origin of protocells?

Question 65

Assumptions that the earliest life forms had to make their own food have been replaced with the belief that the earliest microorganisms were definitely primary heterotrophs.How could these earliest cells have lived if they did not make their own food,and why do we feel certain that they were not photosynthetic?

Question 66

The earliest source of reduced compounds for oxidative metabolism was probably ____________ _____________.

Question 67

Describe the symbiotic theory of the origin of eukaryotes.

Question 68

When hemoglobin takes up or releases oxygen,it undergoes a change in its _________ structure.

Question 69

The alpha-helix is an example of the _______ structure of a protein.

Question 70

Most biological polymerizations are ___________ dehydration reactions in which monomers are linked together by removal of water.

Question 71

What may have been the "reason" for the "Cambrian explosion"?

Question 72

Bacteria contain a single,large molecule of DNA in the ____________ region.

Question 73

Sidney Fox studied the synthesis of polypeptides into polymers which in water formed small spherical bodies called ____________ _____________.

Question 74

This chapter began with Pasteur disproving spontaneous generation,the theory that life could arise from non-living material.Then Miller and Urey test the Oparin-Haldane hypothesis and suggest that life once did arise from non-living chemicals.Are these experiments contradictory? Explain how the science community recognize both as valid.

Question 75

Submarine hot springs where seawater seeps through cracks in the bottom and comes close to the hot magma are called __________ ___________.

Question 76

The ______________ theory proposes that pre-eukaryotes are the result of anaerobic bacteria ingesting aerobic bacteria and subsequently a symbiotic relationship was formed.

Question 77

A critical answer to the chicken-or-the-egg problem formed by the nucleic-acid-or-enzyme-first dilemma is perhaps solved by the discovery of catalytic RNA called _______________.

Question 78

What evidence leads researchers to believe that there was a diversity of animal life before the Cambrian if we cannot find extensive fossils of earlier animals?

Question 79

The Miller-Urey experiments demonstrated the formation of larger molecules from simple molecules.Why is there still a need for concentration in order to make formation of a protocell more likely?

Question 80

Describe the chicken-or-the-egg dilemma with enzymes and hereditary molecules,and detail how the "RNA world" proposal offers a solution.