BIO 101 Exam 2 — Worksheet Questions

The most ancient of the energy pathways among organisms is probably

• aerobic respiration.

• the Calvin cycle.

• photosynthesis.

• the Krebs cycle.

• glycolysis.

Answer explanation

Glycolysis is the most ancient energy pathway, as it occurs in nearly all organisms and does not require oxygen, making it a fundamental process for energy production in early life forms.

If a chromosome in one of your bone cells becomes mutated, you will not pass this mutation on to your children because

• somatic cells cannot undergo mitosis.

• germ cells cannot undergo meiosis.

• germ cells cannot undergo mitosis.

• somatic cells cannot undergo meiosis.

• germ cells neither undergo mitosis nor meiosis.

Answer explanation

Somatic cells, like those in bone, are not involved in reproduction. Only germ cells undergo meiosis to produce gametes. Therefore, mutations in somatic cells cannot be passed to offspring.

Which of these groups represents organisms that are heterotrophs?

• microorganisms that consume organic carbon for energy

• photosynthesizing bacteria, algae, ferns, and pine trees

• all organisms that arose after the origin of photosynthesis

• microorganisms that harness solar energy, converting it to chemical energy

• all of the organisms in domain Eukarya

Answer explanation

Heterotrophs are organisms that obtain energy by consuming organic carbon. The correct choice, 'microorganisms that consume organic carbon for energy,' accurately describes this group, while the other options include autotrophs or unrelated organisms.

Amanatin, a toxin from the death cap poisonous mushroom, inhibits RNA polymerase, so it

• prevents the initiator tRNA from beginning translation.

• incorrectly places the release factor protein on mRNA and terminates translation.

• stops initiation, elongation, and termination stages of transcription.

• disables any introns from being produced, to complete the protein structures.

• reverses the direction of RNA polymerase action, tearing apart partially formed proteins.

Answer explanation

Amanatin inhibits RNA polymerase, which is essential for transcription. This means it stops all stages of transcription: initiation, elongation, and termination, making the correct choice the one that states this.

The Krebs cycle runs

• twice, once for each acetyl CoA that was formed from the glucose molecule.

• six times for each glucose, because each carbon pulled from the original molecule will power the Krebs cycle.

• once for each glucose consumed, to rearrange the molecule prior to ADP production.

• three times for each glucose, to power the electron transport proteins in hydrogen transport.

• twelve times for each glucose, because all of these processes are associated with the Krebs cycle.

Answer explanation

The Krebs cycle runs twice for each glucose molecule because one glucose produces two acetyl CoA molecules. Each acetyl CoA enters the cycle, leading to two complete turns of the Krebs cycle.

In a eukaryotic cell, the electron transport chain occurs in the

• lysosome.

• nucleus.

• cytoplasm.

• ribosome.

• mitochondrion.

Answer explanation

In eukaryotic cells, the electron transport chain is located in the mitochondrion, where it plays a crucial role in ATP production through oxidative phosphorylation.

The proteins involved in attaching the chromosomes to the mitotic spindle are

• kinetochores.

• chromatids.

• nucleosomes.

• centromeres.

• histones.

Answer explanation

Kinetochores are protein structures on chromosomes that attach to the mitotic spindle, facilitating chromosome movement during cell division. Other options like chromatids and centromeres do not serve this specific function.

Tiny openings in the leaf epidermis that allow gas exchange in and out of the leaf are

• thylakoids.

• stroma.

• stomata.

• grana.

• thylakoid spaces.

Answer explanation

Stomata are tiny openings in the leaf epidermis that facilitate gas exchange, allowing carbon dioxide in and oxygen out, which is essential for photosynthesis and respiration.

In meiosis, chromosomes containing sister chromatids (not homologous chromosomes) align along the center of the cell during

• prophase I.

• prophase II.

• interphase II.

• metaphase I.

• metaphase II.

Answer explanation

During meiosis, sister chromatids align at the cell's center in metaphase II, preparing for separation. In contrast, homologous chromosomes align in metaphase I, making metaphase II the correct answer for this question.

During DNA replication, the lagging strand is synthesized by forming Okazaki fragments. The enzyme that joins Okazaki fragments together is

• primase.

• DNA polymerase.

• ligase.

• ATP synthase.

• helicase.

Answer explanation

During DNA replication, ligase is the enzyme that joins Okazaki fragments on the lagging strand, sealing the gaps between them to create a continuous DNA strand.