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Sperm cells and egg cells are needed for human sexual reproduction - Edexcel - GCSE Biology - Question 6 - 2012 - Paper 1
Question 6
Sperm cells and egg cells are needed for human sexual reproduction. Describe in detail the type of cell division that produces sperm cells. * (b) The diagram shows... show full transcript
Worked Solution & Example Answer:Sperm cells and egg cells are needed for human sexual reproduction - Edexcel - GCSE Biology - Question 6 - 2012 - Paper 1
Step 1
Describe in detail the type of cell division that produces sperm cells.
Answer
The type of cell division that produces sperm cells is known as meiosis. During meiosis, one diploid parent cell undergoes two rounds of division, resulting in the production of four haploid cells. Each of these cells contains half the number of chromosomes, specifically 23 chromosomes in humans. In this process, genetic variation is introduced as homologous chromosomes are separated and recombined, leading to genetically diverse gametes.
Step 2
Using the diagram and your own knowledge, describe the processes that take place in the formation of the fetus from a sperm cell and an egg cell.
Answer
The formation of a fetus begins with the fertilization of the egg cell by the sperm cell, creating a zygote. This zygote is a diploid cell that results from the fusion of the two haploid gametes, containing a full set of chromosomes (23 pairs). The zygote then undergoes a series of mitotic divisions, first forming a 2 cell embryo, which subsequently divides to form a 4 cell embryo, and continues to grow through several more divisions, ultimately developing into an 8 cell embryo. As the embryo grows, differentiation occurs, allowing for the specialization of stem cells into various cell types necessary for the development of the fetus, which includes organs and various systems of the body.
Step 3
State two differences between sexual reproduction and asexual reproduction.
Answer
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Sexual reproduction involves the fusion of gametes from two parents, leading to offspring that are genetically diverse, while asexual reproduction involves a single parent and produces genetically identical offspring.
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Sexual reproduction typically takes more time and energy, as it requires finding a mate and the process of mating, while asexual reproduction is generally quicker and requires less energy since it can occur through methods like budding or binary fission.