Biology Genetics & Evolution Flashcards
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Read the first 7 Biology Genetics & Evolution flashcards as text
In X-linked recessive inheritance, why are males more commonly affected than females?
Answer: Males lack a second X chromosome that could carry a dominant allele
Males have only one X chromosome (hemizygous), so a single recessive allele on that X is expressed without a dominant allele on a second X to mask it.
What is genetic drift, and which population is most affected by it?
Answer: Random allele frequency changes; affects small populations most
Genetic drift is random fluctuation in allele frequencies, and its effects are most pronounced in small populations where chance events have a larger proportional impact.
What is the central dogma of molecular biology?
Answer: DNA → RNA → Protein
The central dogma describes the flow of genetic information: DNA is transcribed into RNA, which is then translated into protein.
Which of the following is an example of convergent evolution?
Answer: Dolphins and sharks having similar streamlined body shapes
Dolphins and sharks independently evolved similar streamlined shapes due to similar aquatic environments, not common ancestry.
A scientist observes that a population of beetles has become resistant to an insecticide over 20 generations. This is best explained by:
Answer: Natural selection acting on pre-existing genetic variation
Pre-existing genetic variation for resistance allows individuals carrying resistance alleles to survive and reproduce, shifting allele frequencies via natural selection.
During DNA replication, what is the function of DNA ligase?
Answer: Joins Okazaki fragments on the lagging strand
DNA ligase seals the nicks between Okazaki fragments on the lagging strand, creating a continuous DNA strand.
Which of the following best describes epigenetic inheritance?
Answer: Heritable changes in gene expression not involving DNA sequence changes
Epigenetic inheritance involves heritable changes in gene expression, such as DNA methylation or histone modification, without altering the DNA sequence itself.