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Multiple Choice
Select the correct statement about reproduction and eukaryotic life cycles.
A
All eukaryotes have a dominant haploid stage in their life cycle.
B
Fertilization in eukaryotes always results in haploid offspring.
C
Mitosis is the process that reduces chromosome number by half in sexual reproduction.
D
In most eukaryotic life cycles, meiosis produces haploid gametes that fuse during fertilization to form a diploid zygote.
Verified step by step guidance
1
Understand the key terms in the problem: 'haploid', 'diploid', 'meiosis', 'fertilization', and 'zygote'. Haploid cells have one set of chromosomes (n), while diploid cells have two sets (2n). Meiosis is a type of cell division that reduces the chromosome number by half, producing haploid cells. Fertilization is the fusion of haploid gametes to form a diploid zygote.
Analyze the incorrect statements: The first statement ('All eukaryotes have a dominant haploid stage') is incorrect because not all eukaryotes have a dominant haploid stage; some, like humans, have a dominant diploid stage. The second statement ('Fertilization always results in haploid offspring') is incorrect because fertilization produces a diploid zygote, not haploid offspring. The third statement ('Mitosis reduces chromosome number by half') is incorrect because mitosis maintains the chromosome number; meiosis is the process that reduces it.
Focus on the correct statement: The correct statement is that 'In most eukaryotic life cycles, meiosis produces haploid gametes that fuse during fertilization to form a diploid zygote.' This accurately describes the process of sexual reproduction in eukaryotes.
Relate the correct statement to biological processes: Meiosis occurs in specialized cells to produce haploid gametes (e.g., sperm and egg cells in animals). These gametes fuse during fertilization, combining their genetic material to form a diploid zygote, which then undergoes mitosis to develop into a multicellular organism.
Summarize the concept: In eukaryotic life cycles, meiosis and fertilization are key processes that alternate between haploid and diploid stages. Meiosis ensures genetic diversity by producing haploid gametes, while fertilization restores the diploid chromosome number, enabling the continuation of the species.