Question

1. practice: evolution through natural selection

how does the reproduction of organisms impact the diversity of genes?
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question 8
if a proportion of individuals in a species dies because of extreme heat, is this an example of genetic drift? why or why not?
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question 9
the bell curve in polygenic traits is becoming narrower over time. what type of selection is occurring?

Explanation:

For the first question, sexual reproduction combines genes from two parents, increasing genetic diversity through processes like crossing - over and independent assortment. Asexual reproduction usually results in genetically identical offspring, limiting diversity unless mutations occur.
For the second question, genetic drift is a random change in allele frequencies. If extreme heat causes a non - random die - off (e.g., if only those with certain heat - sensitive traits die), it's not genetic drift. If it's a random subset of the population that dies due to chance factors related to the heat event, it could be genetic drift.
For the third question, when the bell curve of polygenic traits narrows over time, it indicates stabilizing selection, which favors the intermediate phenotypes and reduces the frequency of extreme phenotypes.

Answer:

Question 1: Sexual reproduction increases genetic diversity through processes like crossing - over and independent assortment; asexual reproduction limits it unless mutations occur.
Question 2: It depends. If the die - off is non - random (related to heat - sensitive traits), it's not genetic drift; if it's a random subset of the population that dies due to chance factors in the heat event, it could be genetic drift.
Question 3: Stabilizing selection.