AP Biology : Microorganisms and Viruses

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #1 : Understanding Fungi

Budding is a form of reproduction that occurs most commonly in __________.

Possible Answers:

animals

fungi

plants

bacteria

Correct answer:

fungi

Explanation:

Budding is a form of asexual reproduction in which a new organism grows as a bud on the parent, and separates once it is fully mature. As a result, daughter cells have the same genetic information as their parent cell, but are not the same size.

While certain types of animals and bacteria can reproduce by budding, it is more common in fungi. Bacteria more commonly reproduce by binary fission, while animals usually incorporate sexual reproduction. Protista also commonly reproduce via budding, but are not given as an answer choice.

Example Question #2 : Understanding Fungi

Which of the following best describes fungi?

Possible Answers:

Chemoheterotrophic

Photoautotrophic

Lithoautotrophic

Chemoautotrophic

Mixotrophic

Correct answer:

Chemoheterotrophic

Explanation:

Like animals, fungi are chemoheterotrophs. They must get both their energy and carbon skeletons by absorbing pre-digested nutrients from the environment.

Heterotrophs are unable to create organic compounds without receiving an input of organic material from an outside source. In contrast, autotrophs are capable for generating organic compounds from inorganic compounds.

Chemoheterotrophs gain organic input by consuming other organic material. Fungi break down organic matter from the soil to generate chemical energy.

Lithoautotrophs use inorganic compounds to generate organic compounds, and photoautotrophs use light. Mixotrophs can use either organic or inorganic materials to generate energy.

Example Question #3 : Understanding Fungi

Which of the following is the primary component of fungal cell walls?

Possible Answers:

Cellulose

Peptidoglycan

Chitin

Phospholipids

Correct answer:

Chitin

Explanation:

Fungal cells, as well as plant and bacterial cells, are encased by a cell wall around their cell membrane. In fungi, this wall is composed of the polysaccharide chitin, the same hard substance that forms the exoskeletons of arthropods. Plants, on the other hand, have cell walls made of cellulose, while bacteria have peptidoglycan cell walls.

All of these cell types still have an inner cell membrane, which is composed of phospholipids.

Example Question #1 : Understanding Fungi

Lichens are formed by a symbiosis between a fungus and a __________.

Possible Answers:

zygomycete

slime mold

dinoflagellate

green alga

moss

Correct answer:

green alga

Explanation:

Green algae are the photosynthetic component of the lichen relationship. The fungus aids by gathering nutrients and providing structural protection.

Dinoflagellates are red algae and are not found in lichens. Mosses are free-living plants, while zygomycetes are another phylum of fungi (the fungi in lichens are ascomycetes). Slime molds are single-celled organisms that congregate to reproduce. Zygomycetes and slime molds are not photosynthetic.

Example Question #4 : Understanding Fungi

Which of the following is not true of fungi?

Possible Answers:

Many plants benefit from the presence of beneficial fungal species (mycorrhizal fungi) that help them absorb water and nutrients through their roots

Humans use some fungi species for food, and other species for the production of antibiotics and drugs

Fungal species' absorptive mode of nutrition helps make them excellent decomposers and mutualistic symbionts

Some species of photosynthetic fungi are present in ecosystems that offer relatively few sources of nutrients

Correct answer:

Some species of photosynthetic fungi are present in ecosystems that offer relatively few sources of nutrients

Explanation:

By definition, fungi are chemoheterotrophs. They are unable to produce their own food through photosynthesis; like humans, they must gather their food from their environment. 

The other answers are all true statements and help illustrate the wide variety of roles that fungi have both in the environment and as a natural resource that benefits humans. 

Example Question #5 : Understanding Fungi

Which of the following is found in fungi, but not in animal cells?

Possible Answers:

Secretory vesicles

Mitochondria

Cell walls

Smooth endoplasmic reticulum

Correct answer:

Cell walls

Explanation:

Fungal cells and animal cells share many similarities; in fact, fungi and animals have more in common with each other than either does with plants. Most eukaryotic cells contain smooth endoplasmic reticulum, an organelle that is used in the production of lipids and decomposition of toxins. Most eukaryotic cells also contain mitochondria, which help generate chemical energy in the form of ATP. Secretory vesicles serve a variety of purposes in nature, all of which center on moving materials out of a cell. For example, some secretory vesicles are used to remove wastes from inside of a cell; other secretory vesicles are used for communication between cells, the production of cell walls, or the formation of extracellular matrix. They are specific to neither animals nor fungi. 

Comparatively, cell walls are found in fungi but not in animal cells. The cell wall surrounds the cell membrane of fungal cells and confers protection and support. Fungal cell walls are usually made of the polymer chitin (which, interestingly, is also used in the exoskeletons of arthropods such as lobsters).

Example Question #6 : Understanding Fungi

Which of the following are present in both bacteria and fungi?

Possible Answers:

A nucleus, organelles, and unicellularity

A cell wall, mitochondria, and unicelluarity

A plasma membrane, organelles, and multicellularity

A cell wall, DNA, and a plasma membrane

A cell wall, a plasma membrane, and a Golgi apparatus

Correct answer:

A cell wall, DNA, and a plasma membrane

Explanation:

Bacteria and fungi both have DNA, a plasma membrane, and a cell wall. The bacterial cell wall is made of peptidoglycan, whereas the fungal cell wall is made of chitin. Bacteria do not have nuclei and are only unicellular, while some fungi are multicellular, they are eukaryotes, and thus all have nuclei. Furthermore, eukaryotes have membrane-bound organelles. Since bacteria are prokaryotes, they lack membrane-bound organelles, but they still have ribosomes for protein synthesis (ribosomes are not membrane-bound). 

Example Question #935 : Ap Biology

A species of marine bacteria was found to be able to inhibit the shell growth of marine arthropods (crabs and shrimp). The enzyme responsible for this is identified and isolated. Amazingly, this enzyme is also found to inhibit fungal growth and is subsequently sold as an fungicide. Why would this enzyme work on both types of organisms?

Possible Answers:

Most fungi engage in a symbiotic relationship with microscopic arthropods that are essential for the growth of the fungi. Inhibiting the growth of these arthropods inhibits the growth of the fungi.

Fungi and arthropods are extremely closely related with respect to phylogeny.

The fungal DNA polymerase is extremely similar the the arthropod DNA polymerase and the enzyme can bind to both do due this similarity.

Fungi and arthropods use similar protein transporters in their cells that are being affected by this enzyme.

The same molecule that makes up the exoskeleton of arthropods also makes up the cell wall of fungi.

Correct answer:

The same molecule that makes up the exoskeleton of arthropods also makes up the cell wall of fungi.

Explanation:

The exoskeletons of arthropods is made up of the polymer chitin. Fungal cell walls are also made up of this polymer. Since this enzyme can inhibit the shell growth of marine arthropods its likely that it is breaking down the chitin in them. Since the fungal cell wall is also made up of chitin this enzyme would also be able to inhibit fungal growth by cleaving their cell walls.

Example Question #7 : Understanding Fungi

The cell walls of fungi are composed of what substance?

Possible Answers:

Chitin

Cellulose

Peptidoglycan

Keratin

Pectin

Correct answer:

Chitin

Explanation:

The cell walls of fungi are made of chitin, a modified polysaccharide similar to cellulose but with nitrogen-containing groups. Keratin is a structural protein with comparable toughness to chitin, but keratin is found in vertebrate animals. Peptidoglycan is a polymer of sugars and amino acids that makes up the cell walls of bacteria. Cellulose and pectin are both polysaccharides that together, along with hemicellulose, make up the cell walls of plants.

Example Question #1 : Understanding Fungi

Which of the following best describes fungi? 

Possible Answers:

Chemoautotroph

Lithoautotroph

Phototroph

heterotroph

Autotroph

Correct answer:

heterotroph

Explanation:

Fungi are heterotrophs. A heterotroph is an organism that gains its nutrients by feeding on other organisms, or substances produced by them. Fungi obtain nutrients through absorption; some fungi act as decomposers that break down dead organic matter, some can be parasites, and others can exist in a mutually beneficial relationship with a host. 

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