Chapter 13: Natural Selection And Adaptation Flashcards
(18 cards)
What does MRSA stand for?
Methicillin-Resistant Staphylococcus aureus
MRSA is an infectious bacterium that is difficult to treat with antibiotics.
What percentage of the U.S. population carries Staphylococcus aureus?
Approximately 33%
This includes both harmless and pathogenic strains.
What is the estimated percentage of the U.S. population that has MRSA strains of Staphylococcus aureus?
Approximately 2%
Most individuals with MRSA are disease-free.
How is MRSA transmitted?
By direct or indirect contact
Athletes are at increased risk due to skin contact.
What is the primary function of antibiotics?
Interfere with essential bacterial cell structures
Beta-lactams specifically prevent bacteria from synthesizing cell walls.
What is binary fission?
A process where one parental cell divides into two daughter cells
This process occurs quickly and can lead to DNA changes.
What can cause some bacteria to be resistant to antibiotics?
Random mutations and gene transfer
These processes can create new alleles for antibiotic resistance.
What is a population in an evolutionary context?
A group of organisms of the same species living together in the same geographic area
Populations can evolve when certain traits are favored.
Define fitness in an evolutionary sense.
The ability of organisms to survive and reproduce in a particular environment
Higher fitness increases the likelihood of alleles being passed to the next generation.
What does natural selection refer to?
Differential survival and reproduction of individuals within a population in response to the environment
Advantageous traits become more common over time.
What is directional selection?
When the predominant phenotype shifts in a particular direction
This occurs when one extreme phenotype is favored by the environment.
What is stabilizing selection?
When the phenotype of a population settles near the middle of the range
Intermediate phenotypes are favored over extremes.
What is diversifying selection?
When the phenotype of a population is at both extremes of the range
Extreme phenotypes are better suited than intermediate phenotypes.
How do antibiotics influence bacterial evolution?
They create an environment where bacteria with resistance genes have greater fitness
This results in strong directional selection for antibiotic resistance.
True or False: Evolution affects individuals rather than populations.
False
Evolution occurs at the population level, not the individual level.
Fill in the blank: Evolution is a change in _______ frequency over time.
allele
This change is often driven by natural selection.
What are the risks of taking antibiotics for a viral infection?
Potential development of antibiotic resistance and ineffective treatment
Misuse of antibiotics can lead to future complications.
What might happen if your friend, a wrestler, takes antibiotics unnecessarily?
Increased risk of spreading antibiotic-resistant bacteria to teammates
This could lead to infections that are harder to treat.
