Question 1

The feeding and reproducing stage of many protozoa is known as a:

Accepted Answer

The trophozoite stage of many protozoa is when they are actively feeding and reproducing, while the cyst stage is a dormant state for surviving unfavorable conditions. Vector refers to an organism that transmits diseases, while Protista and Mastigophora are broader taxa that include various types of protozoa.

Question 2

What are mycorrhizial relationships? Provide an example.

Accepted Answer

Mycorrhizal associations are relationships between plant roots and associated fungi that grow on the roots. Because both the plant and the fungus benefits from the relationship, this is an example of a mutualistic relationship. In the Zygomycota, the fungus supplies the plant with phosphorus, while the fungus obtains necessary sugars from the plant. Basidiomycota also frequently form mycorrhizal associations, in which the plant obtains nitrogen from the fungus in return for sugars provided by the plant.

Question 3

How are rRNA genes used to deduce evolutionary relationships?

Accepted Answer

All genes experience mutations (changes in their nucleotide sequences) over time. Ribosomal RNA (rRNA) genes mutate slowly and at a fairly constant and predictable rate. By comparing the nucleotide sequence in rRNA genes of any two species, scientists can deduce how long ago the two species shared a common ancestor. Only after the common ancestor split into separate lineages will rRNA mutations accumulate independently in different lineages. Consequently, many differences in the rRNA genes between two species indicate that they diverged long ago. Fewer differences indicate a more recent common ancestor, meaning that the organisms being compared are more closely related.

Question 4

The bacteria that causes diphtheria is called corynebacterium diphtheria. Which of the following has the name of this bacterial species written in proper scientific form?

Accepted Answer

The scientific name of a bacterial species should be written in italics with the genus capitalized and the species in lowercase. Therefore, the correct name is "Corynebacterium diphtheria."

Question 5

Which of the following statements is true about archaea?

Accepted Answer

Archaea are known to thrive in extreme environments such as hot springs, salty water, and acidic or alkaline environments.

Question 6

Which of the following are the most closely related?

Accepted Answer

Two bacteria that are in the same family are the most closely related because the taxonomic hierarchy goes from domain, kingdom, phylum, class, order, family, genus, to species, with family being closer to species than the other options provided.

Question 7

Which of the following is true about viral penetration?

Accepted Answer

Non-enveloped viruses are generally too large to directly penetrate the plasma membrane, so they enter the host cell by endocytosis. Enveloped viruses can enter the host cell either by endocytosis or by fusion. Some enveloped viruses use their envelope glycoproteins to fuse their envelope with the plasma membrane of the host cell, while others are taken into the host cell via endocytosis and then fuse their envelope with the endosomal membrane to enter the cytoplasm. Therefore, option E is the correct choice as it provides the most accurate description of viral penetration.

Question 8

The classification of living things according to their evolutionary relationships is called:

Accepted Answer

The classification of living things according to their evolutionary relationships is called phylogenetics. Taxonomy refers to the science of describing, identifying, and classifying organisms based on shared characteristics. The taxonomic hierarchy is the system of levels of classification, such as kingdom, phylum, class, order, family, genus, and species. The five-kingdom system and three-domain system are specific taxonomic hierarchies.

Question 9

In which of the following ways are prions believed to differ from all other infectious agents?

Accepted Answer

Prions are unique in that they are able to reproduce without any nucleic acid. They are only composed of protein and do not contain any genetic material such as DNA or RNA, which is unlike all other infectious agents.

Question 10

Viruses go through a series of defined steps in their replicative cycle. In which of the following are these steps listed in proper order?

Accepted Answer

The correct order of steps in a viral replicative cycle is attachment, penetration, uncoating, synthesis (of viral components), assembly, and release. Choice D lists the steps in the correct order.

Question 11

Which of the following is true about photosynthetic bacteria?

Accepted Answer

Photosynthesis appears to have evolved several separate times, which is evident from the presence of different pigments and pathways for photosynthesis in various groups of photosynthetic bacteria.

Question 12

What is different about the synthesis stage in a plus- and a minus-strand RNA virus?

Accepted Answer

The answer of What is different about the synthesis stage...

Question 13

Fungi that grow on dead material are called:

Accepted Answer

Fungi that grow on dead material are called saprophytes.

Quiz 4: A Field Guide to the Microorganisms