Question 1

Which of the following organelles is believed to have originated through endosymbiosis, and what is a key piece of evidence supporting this theory?

Accepted Answer

Mitochondrion; it contains prokaryotic-sized ribosomes and its own circular DNA

Question 2

A patient presents with a fungal infection that began as a respiratory illness after visiting a cave with many bats. Which category of mycoses does this infection most likely belong to, and what is a likely causative agent?

Accepted Answer

Systemic mycoses; caused by Histoplasma capsulatum

Question 3

Which of the following best describes the function of the eukaryotic glycocalyx?

Accepted Answer

It is involved in adherence, environmental protection, and signal reception

Question 4

A scientist observes a unicellular organism with cilia, a flexible pellicle, and a macronucleus. Which group does this organism most likely belong to, and what is its primary mode of locomotion?

Accepted Answer

Ciliophora; cilia

Question 5

Which of the following statements about viral genomes is correct?

Accepted Answer

Viral genomes can be either DNA or RNA, but never both

Question 6

During DNA replication, which enzyme is responsible for synthesizing short RNA primers required for DNA polymerase to begin synthesis?

Accepted Answer

Primase

Question 7

A mutation changes a codon from UAU (tyrosine) to UAA. What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; results in premature termination of translation

Question 8

Which of the following best explains why most pathogenic fungi are dimorphic?

Accepted Answer

They exist as molds in the environment and as yeasts in human tissues, adapting to different conditions

Question 9

A bacterium acquires antibiotic resistance by taking up a plasmid from its environment. Which genetic process is responsible for this event?

Accepted Answer

Transformation

Question 10

A viral infection results in the formation of multinucleated giant cells (syncytia) in host tissue. What is the most likely explanation for this cytopathic effect?

Accepted Answer

The virus induces cell fusion by altering host cell membranes

Question 11

Which of the following equations correctly calculates the final number of bacterial cells ($$N_f) $$after a given number of generations ($$n$$), starting from an initial population ($$N_i$$)?

Accepted Answer

$$N_f = N_i 	imes 2^n$$

Question 12

Which of the following statements about the lac operon in E. coli is correct?

Accepted Answer

It is an inducible operon that is normally OFF and turned ON by the presence of lactose

Question 13

A patient is diagnosed with a disease caused by a prion. Which of the following best describes the infectious agent?

Accepted Answer

A misfolded protein with no nucleic acid

Question 14

Which of the following best describes the difference between the lytic and lysogenic cycles of a bacteriophage?

Accepted Answer

The lytic cycle results in host cell lysis and release of new phages, while the lysogenic cycle involves incorporation of viral DNA as a prophage without immediate lysis

Question 15

Which of the following is a correct pairing of a fungal phylum and its sexual spore type?

Accepted Answer

Ascomycota – Ascospores

Question 16

A protozoan parasite is transmitted via contaminated water and forms highly resistant cysts. Which stage is responsible for transmission, and what is a key property of this stage?

Accepted Answer

Cyst; highly resistant to heat, drying, and chemicals

Question 17

Which of the following statements about DNA replication is correct?

Accepted Answer

The leading strand is synthesized continuously, while the lagging strand is synthesized in Okazaki fragments

Question 18

A patient is infected with a roundworm that has separate sexes and a complete digestive tract. Which group does this organism belong to?

Accepted Answer

Nematodes (roundworms)

Question 19

Which of the following best describes the function of tRNA during translation?

Accepted Answer

It carries specific amino acids to the ribosome and contains an anticodon complementary to an mRNA codon

Question 20

A virus with a single-stranded RNA genome that can be immediately translated by host ribosomes is classified as which of the following?

Accepted Answer

Positive-sense RNA virus ($$+ssRNA)$$

BIO-55 Exam 2 Study Guide: Eukaryotes, Fungi, Protists, Helminths, Viruses, Microbial Genetics, and Bacterial Growth

Study Guide - Practice Questions

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