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Questions and Answers

The most abundant molecule in the human body is
A) phylogenetic B) negative C) H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

During chemical evolution, small organic molecules condense to form more complex molecules called A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

Evolutionary relationships can be visualized using a tree. A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

The organisms most likely to be found in high temperature environments would be A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

L Signup and view all the answers

The organisms most likely to be found in a brine environment would be A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

F Signup and view all the answers

The term used to indicate the degree of randomness within a system is A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

H Signup and view all the answers

Spontaneous processes are characterized by a change in Gibbs free energy that is
A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

B Signup and view all the answers

Gibbs free energy is defined as G = A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

E Signup and view all the answers

The symbol for free energy under standard biochemical conditions is A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

K Signup and view all the answers

Living creatures can be described thermodynamically as systems. A) phylogenetic B)negative C)H2O D)H° E)H – TS F)halobacteria G)open H)entropy I)flux J)polymers K)G°' L)thermophiles M)nitrogen N)positive

G Signup and view all the answers

What are the four most abundant elements in a human body?

C, N, O, H Signup and view all the answers

The atmosphere of prebiotic earth probably contained the following molecules:

H O, CO , N2 , CH4, and NH3. Signup and view all the answers

In 1953, Urey and Miller carried out an experiment in which they subjected a mixture of H2O, CH4, NH3, and H2 to electrical discharges. Which of the following were among the products?

amino acids Signup and view all the answers

Which of the following statements about hydrothermal vents is true?

The vents have temperatures as high as 400°C and emit H S and metal sulfides. Signup and view all the answers

Which of the following developed during the evolution of eukaryotic cells from prokaryotic cells?

nuclear membranes Signup and view all the answers

Using phylogeny all living organisms can be divided into the following domains:

bacteria, eukarya, and archaea Signup and view all the answers

The theory of evolution includes which of the following principles?

A, B, and C Signup and view all the answers

Which three cellular components are present in both prokaryotes and eukaryotes?

Which three cellular components are present in both prokaryotes and eukaryotes? Signup and view all the answers

The bulk of aerobic metabolism in eukaryotic cells takes place in

the mitochondria. Signup and view all the answers

Which cellular compartment or organelle is involved in the synthesis of proteins and lipids?

endoplasmic reticulum Signup and view all the answers

Which of the following is a similarity between all prokaryotes and all eukaryotes?

None of the above is a similarity between prokaryotes and eukaryotes. Signup and view all the answers

Which of the following statements concerning prokaryotes is false?

Prokaryotes are one branch of the newer, more accurate phylogenic tree made up of prokarya, archaea and eukarya. Signup and view all the answers

Which of the following statements about eukaryotes is not true?

They are also called archaea. Signup and view all the answers

Which of the following statements about the theories of (bio)chemical evolution is not true?

Oparin and Haldane demonstrated that by passing an electrical discharge through a vessel containing H O, CO , N , CH and NH3 some basic biological building blocks (like simple amino acids) could have formed abiotically in the earth‘s early atmosphere. Signup and view all the answers

Which of the following statement(s) is (are) not true?

All of the above are true. Signup and view all the answers

Halophiles and thermophiles are

highly evolved organisms that thrive in their specific environments. Signup and view all the answers

Which of the statements about viruses is not true?

Viruses are the simplest living organisms. Signup and view all the answers

Lynn Margulis‘ Theory of Endosymbiosis is an explanation for the origin of

the mitochondria. Signup and view all the answers

Phylogeny is

the science of biological classification based on the evolutionary relationships between organisms. Signup and view all the answers

Taxonomy is

the science of biological classification based on gross morphology. Signup and view all the answers

Which group of organisms is not prokaryotic?

Fungi Signup and view all the answers

The term molecular weight is a term used by biochemists that refers to

a dimensionless quantity that is defined as the ratio of the mass of the particle to 1/12 the mass of a 12C atom. Signup and view all the answers

The second law of thermodynamics states:

that spontaneous processes are characterized by the overall conversion of order to disorder. Signup and view all the answers

Change in enthalpy (H) is best defined as

the heat transferred at constant pressure. Signup and view all the answers

An endergonic reaction with a H and a S can be changed into an exergonic reaction by decreasing the temperature.

negative, negative Signup and view all the answers

The G° for the conversion of glucose 6-phosphate (G6P) to fructose 6-phosphate (F6P) is +1.7 kJ/mole. In a particular human cell the concentration G6P is 8.0 µM and the concentration F6P is 1.0 µM. Calculate the G of the reaction as it occurs in this cell at 37°C?

−3.7 kJ/mol Signup and view all the answers

For a reaction with H = 23 kJ/mol and S =22 J/K•mol, at 2°C, the reaction is:

nonspontaneous Signup and view all the answers

Calculate the G for a reaction with H = 20. kJ/mol and S =20. J/K•mol, that is carried out at 27°C.

14,000 J/mol Signup and view all the answers

A spontaneous process

is all of the above Signup and view all the answers

An increase in disorder in the system

results in the factor TS being positive . Signup and view all the answers

Living organisms

maintain a steady state. Signup and view all the answers

Enzymes accelerate biochemical reactions by

providing a more favorable pathway for the reactions. Signup and view all the answers

A van‘t Hoff plot

is a good method to determine H° and S°. Signup and view all the answers

Keq can be determined from the change in standard free energy using the equation

Keq = e−G°/RT Signup and view all the answers

Living organisms are classified thermodynamically as:

open systems. Signup and view all the answers

Study Notes

Abundant Molecules and Organisms

Water (H2O) is the most abundant molecule in the human body.
Organisms that thrive in high-temperature environments are called thermophiles.
Halobacteria are organisms that live in salty or brine environments.
Entropy is the measure of randomness or disorder within a system.
Spontaneous processes are characterized by a negative change in Gibbs free energy (ΔG).

Thermodynamics in Biology

Gibbs free energy is represented by the equation: G = H - TS, where:
- H is enthalpy (heat content)
- T is temperature in Kelvin
- S is entropy
The symbol for free energy under standard biochemical conditions is ΔG°.
Living creatures are thermodynamically considered open systems, meaning they exchange energy and matter with their surroundings.

Prebiotic Earth and Evolution

The four most abundant elements in the human body are oxygen, carbon, hydrogen, and nitrogen.
The early atmosphere of Earth likely contained molecules like water (H2O), methane (CH4), ammonia (NH3), and hydrogen gas (H2).
In 1953, Urey and Miller conducted an experiment simulating early Earth conditions, resulting in the formation of organic molecules like amino acids, sugars, and nucleic acid bases.
Hydrothermal vents, underwater openings releasing hot, chemically-rich fluids, are believed to have played a role in the origin of life.

Eukaryotic and Prokaryotic Cells

The evolution of eukaryotic cells from prokaryotic cells involved the development of a nucleus, membrane-bound organelles, and a more complex cytoskeleton.
All living organisms can be classified into three domains: Bacteria, Archaea, and Eukarya.
The theory of evolution explains the diversity of life through descent with modification, natural selection, and adaptation.
Both prokaryotes and eukaryotes contain ribosomes, DNA, and a cell membrane.
The majority of aerobic metabolism occurs in the mitochondria of eukaryotic cells.
The endoplasmic reticulum is involved in the synthesis of proteins and lipids.
All prokaryotes and eukaryotes possess ribosomes for protein synthesis.
Prokaryotes lack a nucleus and membrane-bound organelles.
One false statement about eukaryotes is that they are always multicellular.
A false statement about the theories of chemical evolution is that it can fully explain the origin of life – it primarily addresses the formation of biomolecules.

Viruses and Symbiosis

Viruses are not considered living organisms because they lack a cellular structure and cannot reproduce independently.
Lynn Margulis proposed the theory of endosymbiosis, which explains the origin of mitochondria and chloroplasts in eukaryotic cells as a result of ancient symbiotic relationships between prokaryotes.

Classifying Organisms and Thermodynamics

Taxonomy is the science of classifying organisms into hierarchical groups based on shared characteristics.
Phylogeny is the study of evolutionary relationships among organisms.
Fungi are not prokaryotic; they belong to the eukaryotic domain.
Molecular weight refers to the mass of a molecule, expressed in atomic mass units (Da).
The second law of thermodynamics states that the total entropy of an isolated system always increases over time.
Enthalpy (ΔH) represents the change in heat content of a system during a reaction.
A reaction with a positive enthalpy change (ΔH) and a negative entropy change (ΔS) can become exergonic (favorable) by decreasing the temperature.
The standard free energy change (ΔG°) for a reaction can be used to calculate the equilibrium constant (Keq) using the equation: ΔG° = -RTlnKeq.

Gibbs Free Energy and Applications

The Gibbs free energy (ΔG) for a reaction reflects the spontaneity and maximum work capacity of a system.
ΔG is calculated using the equation: ΔG = ΔH - TΔS, where:
- ΔH is the enthalpy change
- T is the temperature in Kelvin
- ΔS is the entropy change
Living organisms are classified thermodynamically as open systems due to their constant exchange of energy and matter with their environment.

Specific Examples

The ΔG for the conversion of glucose 6-phosphate (G6P) to fructose 6-phosphate (F6P) is +1.7 kJ/mol.
With a G6P concentration of 8.0 µM and a F6P concentration of 1.0 µM, the ΔG of this reaction, under these specific conditions, at 37°C is calculated as follows:
- ΔG = ΔG° + RTln([F6P]/[G6P])
- ΔG = 1,700 J + (8.314 J/mol•K)(310K)ln(1.0 µM/8.0 µM)
- ΔG ≈ -2,900 J/mol
For a reaction with ΔH = 23 kJ/mol and ΔS = 22 J/K•mol, at 2 °C, the reaction is:
- ΔG = 23,000 J/mol - (275 K) * 22 J/K•mol = 17,640 J/mol (endergonic)
A ΔG for a reaction with ΔH = 20 kJ/mol and ΔS = 20 J/K•mol at 27°C is:
- ΔG = ΔH - TΔS
- ΔG = 20,000 J/mol - (300 K)(20 J/K•mol)
- ΔG = 14,000 J/mol
A spontaneous process has a negative change in Gibbs free energy (ΔG).
An increase in disorder or randomness in the system corresponds to a positive entropy change (ΔS).
Living organisms maintain a high level of order and complexity, which requires a continuous input of energy to counteract entropy.
Enzymes lower the activation energy of reactions, accelerating their rates.
A van't Hoff plot shows the relationship between the equilibrium constant of a reaction and temperature.

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Test your knowledge on the most abundant molecule in the human body. This quiz will challenge you to identify the correct answer from a list of options related to biological molecules and processes. Improve your understanding of human physiology and molecular biology.