Multiple Choice
In human sexual reproduction, what does a sperm cell contribute to the embryo at fertilization?
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17. Meiosis and Sexual Reproduction
Basics of Meiotic Genetics
Multiple Choice
In humans, which of the following cell types is diploid (2n) under normal conditions?
A
Ovum (egg cell)
B
Primary spermatocyte (before meiosis I)
C
Sperm cell
D
Secondary spermatocyte (after meiosis I)
Verified step by step guidance1
Understand the concept of ploidy: Diploid (2n) cells contain two sets of chromosomes, one from each parent, while haploid (n) cells contain only one set of chromosomes.
Identify the stage of each cell type in terms of meiosis: Ovum and sperm cells are gametes, which are haploid (n) because they result from the completion of meiosis.
Primary spermatocytes are cells that have not yet undergone the first meiotic division, so they still have the full diploid (2n) chromosome number.
Secondary spermatocytes are the product of meiosis I and are haploid (n), even though their chromosomes are still duplicated (sister chromatids).
Therefore, the cell type that is diploid (2n) under normal conditions is the primary spermatocyte, as it precedes the meiotic divisions that reduce chromosome number.
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