Question 1

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

Accepted Answer

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

Question 2

A chain consisting of a number of amino acids is a

Accepted Answer

A)  quaternary structure.
B)  dipeptide.
C)  polypeptide.
D)  None of the choices is correct.E) A) and D)
F) A) and C)

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

A)  1.5
B)  2.8
C)  3.8
D)  4.8E) A) and D)
F) All of the above

Question 5

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

Accepted Answer

Scientists have gathered evidence to support the idea that Earth's primeval atmosphere was a reducing atmosphere, meaning it had little to no free oxygen and was rich in hydrogen, methane, ammonia, and other reducing gases. This evidence comes from several lines of inquiry:

1. Geological Evidence: The oldest rocks on Earth, which are about 3.8 billion years old, show signs of having formed in an environment lacking in oxygen. These rocks contain minerals that are easily oxidized and would not have survived in an oxygen-rich atmosphere. Additionally, the presence of banded iron formations (BIFs) in ancient rock layers suggests that iron was once present in its reduced form in the oceans, which would have been possible only in the absence of oxygen.

2. Chemical Evidence: The Earth's early atmosphere is thought to have been produced by outgassing from volcanic activity, which would have released large amounts of water vapor, carbon dioxide, nitrogen, and smaller amounts of reducing gases like hydrogen and methane. The absence of significant amounts of oxygen in volcanic gases supports the idea of a reducing atmosphere.

3. Biological Evidence: The earliest known life forms were anaerobic, meaning they did not require oxygen to live. This suggests that life originated in an oxygen-free environment. Furthermore, the evolution of photosynthesis, which produces oxygen as a byproduct, is believed to have occurred later, leading to the gradual accumulation of oxygen in the atmosphere (the Great Oxygenation Event).

4. Experimental Evidence: The famous Miller-Urey experiment in 1953 simulated the conditions of the early Earth by passing an electric current (simulating lightning) through a mixture of water, methane, ammonia, and hydrogen. This experiment produced a variety of organic compounds, including amino acids, which are the building blocks of life. This supported the idea that a reducing atmosphere could have been conducive to the formation of complex organic molecules.

5. Isotopic Evidence: The ratios of certain isotopes, such as carbon and sulfur isotopes, in ancient rocks can provide clues about the composition of the atmosphere at the time the rocks formed. Isotopic ratios that differ from those expected in an oxygen-rich environment support the hypothesis of a reducing early atmosphere.

6. Comparative Planetology: By studying the atmospheres of other planets and moons in our solar system, scientists have gained insights into how atmospheres can evolve. For example, Venus and Mars have atmospheres with very little free oxygen, which may resemble the early Earth's atmosphere before the rise of oxygen-producing life forms.

Taken together, these pieces of evidence paint a picture of an early Earth with a reducing atmosphere that was very different from the oxygen-rich atmosphere we breathe today. This atmosphere set the stage for the chemical processes that eventually led to the origin of life.

Question 6

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

Accepted Answer

The answer of When hemoglobin takes up or releases oxygen,it...

Question 7

Carbohydrates are categorized into

Accepted Answer

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.F) D) and E)
G) C) and D)

Question 8

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

Accepted Answer

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

Question 9

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

Accepted Answer

A)  1.5
B)  2.5
C)  3.5
D)  4.5E) None of the above
F) A) and C)

Question 10

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

Accepted Answer

The answer of Amino acids are linked together to form...

Question 11

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

Accepted Answer

A)  Starch
B)  Chitin
C)  Cellulose
D)  GlycogenE) C) and D)
F) A) and D) B

Question 12

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

Accepted Answer

proteinoid...

Question 13

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?

Accepted Answer

A)  Fructose and glucose in the form of honey
B)  High-calorie fat molecules
C)  Starch
D)  Glycogen with extensive side branches of glucoseE) A) and D)
F) None of the above

Question 14

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

Accepted Answer

A)  Steroids
B)  Neutral fats
C)  Triglycerides
D)  PhospholipidsE) B) and C)
F) A) and D)

Question 15

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

Accepted Answer

A)  were copies of a cell nucleus that failed to be separated by cytokinesis.
B)  were prokaryotes that were taken into a cell and now live there symbiotically.
C)  were variations of the plasma membrane.
D)  were new forms of life that arose inside other cells.E) B) and C)
F) None of the above

Question 16

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

Accepted Answer

A)  Steroids
B)  Waxes
C)  Phospholipids
D)  LipoproteinsE) A) and B)
F) B) and D)

Question 17

Which pairing of occurrence and date is correct?

Accepted Answer

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 of the choices are correctE) C) and D)
F) A) and D)

Question 18

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

Accepted Answer

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.F) None of the above
G) A) and C)

Question 19

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

Accepted Answer

The answer of The alpha-helix is an example of the...

Question 20

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

Accepted Answer

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

Exam 2: The Origin and Chemistry of Life

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

Correct Answer
verified

A chain consisting of a number of amino acids is a

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

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

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

Correct Answer
verified

Carbohydrates are categorized into

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified
B

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

Correct Answer
verified
proteinoid...
View Answer

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?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

Which pairing of occurrence and date is correct?

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified

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

Correct Answer
verified
B

Exam 2: The Origin and Chemistry of Life

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

Correct AnswerverifiedShow Answer

A chain consisting of a number of amino acids is a

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

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

Correct AnswerverifiedShow Answer

Carbohydrates are categorized into

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedB

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

Correct Answerverifiedproteinoid...View AnswerShow Answer

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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Which pairing of occurrence and date is correct?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedB

Correct Answer
verified

Correct Answer
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Correct Answer
verified
B

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

Correct Answer
verified
proteinoid...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

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verified

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verified

Correct Answer
verified
B