Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

In a hypothetical organism, a mutation in the gene encoding for histone H1 results in defective chromatin structure. Which cellular process would most likely be affected?

A. Protein synthesis. B. DNA replication. C. Glycolysis. D. RNA splicing.

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Explanation

Histone H1 is involved in the packaging of DNA into chromatin. Defective chromatin structure would most directly affect DNA replication, as tightly packed chromatin must be loosened to allow replication machinery access to the DNA.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

Which metabolic pathway directly produces NADPH and ribose-5-phosphate?

A. Glycolysis. B. Citric Acid Cycle. C. Pentose Phosphate Pathway. D. Beta-oxidation.

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Explanation

The pentose phosphate pathway generates NADPH for anabolic reactions and ribose-5-phosphate for nucleotide synthesis, without directly producing ATP.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

What is the primary function of the sodium-potassium pump in animal cells?

A. Generating ATP. B. Maintaining the resting membrane potential. C. Facilitating the passive diffusion of sodium and potassium ions. D. Transporting glucose into cells.

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Explanation

The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, which is crucial for maintaining the resting membrane potential and cell volume.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

Which of the following is a correct statement about the function of ribosomes?

A. Ribosomes are involved in the transcription of DNA to mRNA.. B. Ribosomes are the site of lipid synthesis.. C. Ribosomes facilitate the translation of mRNA into proteins.. D. Ribosomes modify and package proteins for secretion..

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Explanation

Ribosomes are the cellular structures where translation occurs, converting the genetic information in mRNA into a sequence of amino acids to form proteins.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

What is the role of the enzyme DNA ligase in DNA replication?

A. Unwinding the DNA double helix. B. Adding nucleotides to the growing DNA strand. C. Sealing nicks and joining Okazaki fragments on the lagging strand. D. Synthesizing RNA primers.

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Explanation

DNA ligase is responsible for joining Okazaki fragments on the lagging strand by sealing the nicks in the sugar-phosphate backbone, ensuring the DNA is continuous.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

Which organelle is primarily responsible for the production of ATP through oxidative phosphorylation?

A. Nucleus. B. Endoplasmic reticulum. C. Mitochondrion. D. Lysosome.

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Explanation

The mitochondrion is known as the powerhouse of the cell, where ATP is produced through oxidative phosphorylation during cellular respiration.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

In the central dogma of molecular biology, which process involves the synthesis of RNA from a DNA template?

A. Replication. B. Transcription. C. Translation. D. Reverse transcription.

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Explanation

Transcription is the process where an RNA molecule is synthesized from a DNA template, following the base pairing rules.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

Which of the following statements about the fluid mosaic model of cell membranes is correct?

A. Phospholipids form a rigid bilayer.. B. Proteins are embedded within and can move laterally through the lipid bilayer.. C. Carbohydrates are only found on the intracellular side of the membrane.. D. Cholesterol is absent in eukaryotic cell membranes..

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Explanation

The fluid mosaic model describes the cell membrane as a flexible structure where lipids and proteins can move laterally within the layer, contributing to the membrane's fluidity.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

During glycolysis, which molecule is directly converted into pyruvate?

A. Glucose. B. Fructose-1,6-bisphosphate. C. Glyceraldehyde-3-phosphate. D. Acetyl-CoA.

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Explanation

Glycolysis converts glucose into two molecules of pyruvate through a series of steps. Glyceraldehyde-3-phosphate is an intermediate that is directly converted into pyruvate in the later stages of glycolysis.

Mushkovic BIOLOGY - Biological and Biochemical Foundations of Living Systems

Which of the following best describes the role of an enzyme in a biochemical reaction?

A. Enzymes increase the free energy of the reactants.. B. Enzymes decrease the activation energy of the reaction.. C. Enzymes are consumed in the reaction.. D. Enzymes shift the equilibrium position of the reaction..

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Explanation

Enzymes act as catalysts that speed up biochemical reactions by lowering the activation energy required for the reaction to proceed, without being consumed in the process.