All AP Biology Resources
Example Questions
Example Question #881 : Ap Biology
Gram staining is a helpful technique for differentiating between different types of bacteria. What part of the bacterial envelope is exploited by the gram staining process?
The periplasmic space
The plasma membrane
The peptidoglycan layer
The capsule
The peptidoglycan layer
The difference between gram-positive and gram-negative bacteria is the thickness of the peptidoglycan protein layer. Gram-positive bacteria have a thick peptidoglycan layer that retains the gram stain well, making it purple under a microscope. Gram-negative bacteria have a thinner peptidoglycan layer, and do not retain the stain as well as gram positive bacteria. This makes it pink when viewed under a microscope.
Example Question #2 : Microorganisms And Viruses
Leukocytes are classified as either granulocytes or agranulocytes. Which of the following are granulocytes?
T-cells and B-cells
Macrophages and lymphocytes
Basophils
Eosinophils and basophils
Basophils, eosinophils, and neutrophils
Basophils, eosinophils, and neutrophils
Leukocytes can be broken down into the following categories and cells types.
Example Question #883 : Ap Biology
A cell placed in an environment in which there are more solutes outside the cell than inside the cell will __________ and is said to be in a __________ environment.
swell . . . hypotonic
lyse . . . isotonic
shrivel . . . hypotonic
swell . . . hypertonic
shrivel . . . hypertonic
shrivel . . . hypertonic
We need to know the different between hypertonic, hypotonic, and isotonic. An environment is said to be hypertonic is there are more solute outside of the cell than inside. Since these solutes do not cross the cellular membrane very easily, but water can cross, water will travel out of the cell to balance the concentrations. This would cause the cell to shrink and shrivel.
The opposite is true for a hypotonic scenario, in which the cell will swell and maybe burst as water flows from the environment into the solute-filled cell. An isotonic environment is one in which solute concentrations are even, so there is no net movement of water into or out of the cell.
Example Question #1 : Microorganisms And Viruses
If a colony of round or oval-shaped bacteria are arranged in a random grape-like cluster, they must be:
Spirochetes
There is no way to predict based on the information provided.
Staphylococci
Streptococci
Streptobacilli
Staphylococci
The two most common bacterial arrangements are Staph- and Strep-. Staph- is a non-symmetrical arrangement like a cluster of grapes. Strep- indicates a chain of bacteria.
The three most common bacterial shapes are listed below.
Coccus—round or oval
Bacillus—rectangular or rod-shaped
Spirilla (spirochete)—spiral
By breaking down names into arrangement and shape, students can predict or identify the appearance of an organism by its name. In the example Staph indicates arrangement in a chain. Coccus indicates round or oval in shape. Therefore, Staphylococci are round or oval-shaped organisms arranged in a cluster.
Example Question #1 : Understanding Bacteria
The aldehyde chemical family contains powerful microbial killing agents. Which bacterial structures do they effect?
Cytoplasm
Ribosomes
Nucleic acids
Cell walls
Cell membranes
Nucleic acids
Aldehydes are powerful, toxic chemicals which work by denaturing DNA and RNA (nucleic acids).
Modern antibiotics are less toxic and work by disrupting cells' production of ribosomes. Common household cleaners, containing chlorine, work by oxidizing cell membranes. Older antibiotics, such as penicillin, work by dissolving cell walls. These modes of destruction are also known as mechanisms of cell death.
Example Question #4 : Understanding Bacteria
Which of the following would be considered a lethal means of controlling bacterial endospores?
Pasteurization
Boiling
None of these answers
All of these answers
Freezing
None of these answers
Spores can survive most methods of control and are resistant to cold and heat. Pasteurization is a heating process that destroys some pathogenic microorganisms in foods and beverages, but does not kill spores. Boiling is not considered a reliable lethal control because the destruction of bacterial spores cannot be guaranteed. Cold temperature is a non-lethal means of microbial control that can slow multiplication or induce stasis, but cold is only effective while conditions are maintained.
Incineration is the use of extreme temperature to reduce matter to ash and is an effective means of sterilization.
Example Question #3 : Microorganisms And Viruses
Which of the following does not describe a detergent action against bacteria?
Mechanical mode of action
Static control
Removes lipids
Emulsification
Lethal control
Lethal control
Detergents, or soaps, are non-lethal microbial controls. They emulsify lipids and oils, making it easier to wash them away. The action of washing away substances is strictly a mechanical mode of action. Detergents provide only static control, and have no killing power.
Example Question #4 : Microorganisms And Viruses
Which of the following can be found in prokaryotes, but never in viruses?
Attachment proteins
DNA
Ribosomes
RNA
Ribosomes
Prokaryotes create their own proteins, which means that ribosomes are present in the cell. Viruses, however, rely on the ribosomes of the host cell in order to create proteins. This means that ribosomes are not present in viruses, but are present in prokaryotes.
DNA and RNA will both be found in prokaryotes. Some viruses will contain DNA, while others will contain RNA. Attachment proteins allow viruses to bind to cell membranes, but also can allow one cell to bind to another.
Example Question #4 : Microorganisms And Viruses
Bacterial ribosomes contain a __________ and __________ subunit. This forms a __________ ribosome.
30S . . . 50S . . . 70S
40S . . . 60S . . . 80S
30S . . . 50S . . . 80S
40S . . . 60S . . . 100S
30S . . . 50S . . . 70S
Recall that bacterial ribosomes contain a 30S and a 50S subunit. The ribosome itself is a 70S ribosome, as the combination of the two subunits results in a smaller mass than the two separate units. Eukaryotic ribosomes contain a 40S and 60S subunit and form an 80S ribosome.
Example Question #5 : Microorganisms And Viruses
Which of the following statements is true regarding flagella?
Only bacterial flagella are made up of flagellin
Both bacterial and human flagella are made up of flagellin
Bacterial flagella are not used for mobility
Only human flagella are made up of flagellin
Only bacterial flagella are made up of flagellin
Flagella are used for mobility by both prokaryotes (bacteria) and eukaryotes. In humans, you can find these structures in sperm cells, which are propelled by the motion of flagella. Similarly, bacterial cells move through the environment with the aid of flagella. The key difference between a bacterial and eukaryotic flagellum is its composition. Bacterial flagella are made up of a protein called flagellin, whereas eukaryotic flagella are made up of microtubules, formed from the protein tubulin.
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