Question 1

Which of the following best describes the main structural difference between the cell walls of Gram-positive and Gram-negative bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

Question 2

During the Gram stain procedure, what color will a Gram-negative bacterium appear under the microscope after the final step, and why?

Accepted Answer

Pink, because the thin peptidoglycan layer does not retain the crystal violet stain after alcohol wash.

Question 3

Which of the following cell surface structures allows prokaryotes to attach to surfaces and to each other, playing a key role in the formation of biofilms?

Accepted Answer

Fimbriae

Question 4

Which process involves the uptake of naked DNA fragments from the environment by a prokaryotic cell, leading to genetic variation?

Accepted Answer

Transformation

Question 5

A researcher isolates a prokaryote that thrives in extremely salty environments. Which group does this organism most likely belong to?

Accepted Answer

Halophilic archaea

Question 6

Which of the following statements about plasmids is correct?

Accepted Answer

Plasmids are small, circular DNA molecules that replicate independently of the nucleoid.

Question 7

Which of the following best describes the mutualistic relationship between nitrogen-fixing cyanobacteria and heterocysts?

Accepted Answer

Heterocysts are specialized cells that fix atmospheric nitrogen, providing it to neighboring photosynthetic cells.

Question 8

Which of the following is NOT a way that prokaryotes increase genetic diversity?

Accepted Answer

Binary fission

Question 9

Which of the following statements about endotoxins and exotoxins is correct?

Accepted Answer

Endotoxins are components of the outer membrane of Gram-negative bacteria, while exotoxins are secreted proteins.

Question 10

Which of the following best explains the endosymbiotic theory for the origin of mitochondria in eukaryotic cells?

Accepted Answer

Mitochondria originated from free-living prokaryotes that were engulfed by ancestral eukaryotic cells.

Question 11

Which group of protists is most closely related to fungi, based on molecular and morphological evidence?

Accepted Answer

Nucleariids

Question 12

Which of the following statements about fungal hyphae is correct?

Accepted Answer

Septate hyphae have cross-walls called septa, while coenocytic hyphae lack septa.

Question 13

Which of the following best describes the process of plasmogamy in the fungal life cycle?

Accepted Answer

Fusion of cytoplasm from two parent mycelia without fusion of nuclei, resulting in a heterokaryotic stage.

Question 14

Which type of mycorrhizal fungi penetrates the cell walls of root cells, forming arbuscules?

Accepted Answer

Arbuscular mycorrhizal fungi (Glomeromycota)

Question 15

Which of the following is a key ecological role of fungi in the environment?

Accepted Answer

Decomposition of organic matter, recycling nutrients in ecosystems.

Question 16

Which of the following correctly matches a fungal group with a characteristic reproductive structure?

Accepted Answer

Basidiomycota – basidium

Question 17

Lichens are best described as a symbiotic association between which two types of organisms?

Accepted Answer

A fungus and a photosynthetic partner (alga or cyanobacterium)

Question 18

Which of the following scenarios best illustrates commensalism?

Accepted Answer

Bacteria living on human skin, benefiting from nutrients without affecting the host.

Question 19

A patient is infected with a bacterium that can survive without oxygen but grows better in its presence. Which term best describes this organism's metabolism?

Accepted Answer

Facultative anaerobe

Question 20

Which step in the fungal life cycle immediately follows karyogamy?

Accepted Answer

Meiosis, producing haploid spores

Prokaryotes, Protists, and Fungi: Key Concepts and Structures

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