Question

question 1-7
a disease which causes a plant disease that usually kills the plant before it reproduces. what will most likely happen to the frequency of this allele in the population? the frequency of the allele would -

• decrease extremely since plant survival is not influenced by genetic traits.
• decrease because affected plants would not survive to pass it on to offspring.
• increase as it is more likely to be passed on due to dominant expression.
• stay the same because dominant alleles are always expressed in the population.

Explanation:

The problem is about a plant disease killing plants before reproduction. We analyze each option:

• Option 1: If the allele is lethal before reproduction, plants with it can't pass it on, so its survival (and thus frequency) isn't just genetic traits; this is incorrect.
• Option 2: Since the disease kills the plant before reproduction, the allele - carrying plants won't survive to pass the allele to offspring. Over time, the frequency of this allele in the population will decrease as it's not being transmitted to the next generation. This makes sense.
• Option 3: A lethal allele (killing before reproduction) isn't more likely to be passed on due to dominant expression. In fact, it's less likely to be passed on as carriers die early, so this is wrong.
• Option 4: Lethal alleles that kill before reproduction won't be expressed in the population over time as carriers die, so they aren't always expressed. This is incorrect.

Answer:

The correct option is the second one (the option stating "decrease because affected plants would not survive to pass it on to offspring").