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Question Video: Recalling the Defining Features of Asexual Reproduction Science

Complete the following sentence: Asexual reproduction produces offspring that are _ identical to the parents, so it reduces genetic _. [A] not, expression [B] genetically, variation [C] almost, mutations [D] partially, similarities

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Video Transcript

Complete the following sentence. Asexual reproduction produces offspring that are blank identical to the parents, so it reduces genetic blank. (A) Not, expression; (B) genetically, variation; (C) almost, mutations; or (D) partially, similarities.

The two words in each answer choice will be used to fill in each of the two blanks. For example, if we choose the answer choice almost, mutations, then we would be saying that the correct sentence should read “Asexual reproduction produces offspring that are almost identical to the parents, so it reduces genetic mutations.” To fill in the first blank of the sentence, we need to know the relationship between offspring produced by asexual reproduction and their parents.

You may recall that asexual reproduction requires only one parent. So let’s take a look at a single bacterium as it undergoes the common form of asexual reproduction called binary fission. Bacteria are prokaryotes, so their DNA floats freely in the cytoplasm, often in the form of a circular chromosome. As the bacterium enlarges to prepare for division, it makes a copy of its chromosome. The bacterium then splits into two daughter bacteria, each containing a copy of the chromosome. Because there is no second parent to mix genes with, the two daughter bacteria are genetically identical. Or to put it another way, they are clones of each other. So we have determined that the correct term to fill in the first blank is genetically.

Unlike asexual reproduction, sexual reproduction requires two parents, with the biological father typically providing the sperm cell and the biological mother providing an egg cell. After the sperm and egg unite in a process called fertilization, they form a structure called a zygote. And the nucleus of the zygote will have genetic material from both of the biological parents, represented here by green and pink squiggly lines. The zygote will divide and grow, eventually becoming a fully functioning offspring.

Because of how genes are rearranged and inherited during sexual reproduction, this new offspring will be genetically unique from its biological parents and from any additional offspring those same parents have together. Each instance of sexual reproduction produces genetically unique offspring. And over time, this increases the genetic variation within a population, which refers to the differences in the genetic material between individuals in the same population.

In contrast, if we look at asexual reproduction over time, we can see that the same chromosome is copied and passed down to each generation of offspring, leading to a population of clones with reduced genetic variation. This example shows that the correct term to fill in the second blank is variation. So the correct complete sentence is “Asexual reproduction produces offspring that are genetically identical to the parents, so it reduces genetic variation.”

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