Identify the process that is necessary for sexual reproduction and explain why it is necessary. Identify how this process increases genetic variation.
2. Summarize the differences between mitosis and meiosis.
Please help! I dont really understand the questions.
1. Sexual reproduction was an early evolutionary innovation after the appearance of eukaryotic cells. During sexual reproduction, the genetic material of two individuals is combined to produce genetically-diverse offspring that differ from their parents. The fact that most eukaryotes reproduce sexually is evidence of its evolutionary success. In many animals, it is actually the only mode of reproduction. The genetic diversity of sexually-produced offspring is thought to give species a better chance of surviving in an unpredictable or changing environment.
2. Mitosis involves the division of body cells, while meiosis involves the division of sex cells. The division of a cell occurs once in mitosis but twice in meiosis. Two daughter cells are produced after mitosis and cytoplasmic division, while four daughter cells are produced after meiosis.
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1. The process necessary for sexual reproduction is known as meiosis. Meiosis is a type of cell division that occurs in specialized cells called germ cells, which are involved in the production of gametes (sperm and egg cells). Meiosis is essential for sexual reproduction for several reasons:
- Production of haploid cells: Meiosis reduces the number of chromosomes in the resulting cells to half the original number, creating haploid cells. This is important because during fertilization, two haploid gametes (sperm and egg) fuse to form a new diploid organism with a complete set of chromosomes.
- Genetic variation: Meiosis leads to the creation of genetically diverse offspring. This is because during meiosis, homologous chromosomes pair up and exchange segments of DNA through a process called crossing over. This recombination of genetic material leads to the shuffling and mixing of genes, resulting in new combinations of traits in the offspring.
- Fertilization: Meiosis ensures that each parent contributes an equal number of chromosomes to the offspring. When a haploid sperm cell fuses with a haploid egg cell during fertilization, the resulting zygote will have a full set of chromosomes, half from each parent.
2. Mitosis and meiosis are two different types of cell division processes:
Mitosis:
- Purpose: Mitosis is the process by which somatic cells (non-reproductive cells) divide to produce two daughter cells that are identical to the parent cell.
- Number of divisions: Only one division occurs in mitosis.
- Chromosome number: The resulting daughter cells have the same number of chromosomes as the parent cell, i.e., they are diploid.
- Genetic variation: Mitosis does not involve crossing over or the shuffling of genetic material, so it does not lead to genetic variation. The daughter cells are exact replicas of the parent cell.
Meiosis:
- Purpose: Meiosis is specifically involved in the production of gametes (sperm and egg cells) for sexual reproduction.
- Number of divisions: Meiosis involves two divisions: meiosis I and meiosis II.
- Chromosome number: The resulting daughter cells have half the number of chromosomes as the parent cell, i.e., they are haploid.
- Genetic variation: Meiosis promotes genetic variation through crossing over, where homologous chromosomes exchange genetic material, and independent assortment, where chromosomes align and separate randomly during cell division, resulting in the mixing and shuffling of genes.
In summary, mitosis is the process of cell division for growth and tissue repair, producing identical copies of cells, and maintaining the same chromosome number. On the other hand, meiosis is the process of cell division for sexual reproduction, creating genetically diverse gametes with half the chromosome number.