1.1
Meiosis I
The first meiotic division: diploid → haploid
Prophase I: Chromosomes condense, nuclear membrane dissolves, homologous chromosomes join and occurs crossing over.
Metaphase-I: the homologous chromosomes align in the middle of the cell. Spindle fibers from the centrosomes connect to the chromosomes.
Anaphase -I: Spindle fibers contract and split the homologous chromosomes, moving them to opposite poles of the cell.
Telophase -I: Chromosomes decondense; cell divides to form two haploid cells.
1.2 Meiosis II
The second division: separates sister chromatids (these chromatids may not be identical due to crossing over in prophase I)
Prophase II: Chromosomes condense, nuclear membrane dissolves, centrosomes move to opposite poles (perpendicular to before)
Metaphase-II: the chromosomes align in the middle of the cell. Spindle fibers from the centrosomes connect to the chromosomes (at the centromere)
Anaphase-II: Spindle fibers contract and split the sister chromatids, and moves them to opposite poles of the cell.
Telophase-II: Chromosomes decondense,cells divides again to form another 2 haploid daughter cells. Final: 4 new cells.
2. The differences:
Mitosis:
- has 1 division per cycle
- one cell produces 2 new cells
- the genetic information in the mother-cell and the daughter-cells are the same. ( the number of chromosomes is also the same)
- it occurs in somatic cells
Meiosis:
- two divisions per cycle
- one cell when divides produces 4 new cells
- the new cells have different genetic information. mixes the genetic material from the parent cells
- the number of chromosomes of the daughter cells is half of the mother's.
3. Prokaryotic organisms don't divide through mitosis, they use a different process called binary fission. Only eukaryotic organisms, or those whose cells have a defined nuclei, undergo mitosis. Bacteria, for example, are prokaryotic organisms that use binary fission.
4.
It can't occur. Cross over is the exchange of DNA between homologous chromosomes. That will result in recombinant chromosomes during sexual reproduction. It can't occur on different chromosomes because they don't code for the same genes.
5. There are a lot of different theories about that, but it's mostly believed that meiosis must evolve before sexual reproduction. That's because The cell replicates their information first and then divides. Plus the cell does that even though it didn't recombine DNA with another organism (sexual reproduction).
Answer:
D. Meiosis forms four cells all with different genetic material
Explanation:
They are haploid cells and each cell only had one set of chromosomes. Meiosis results in variation.
Answer:
Pioneer species/organisms help modify the environment because they are the first organism to live on that "terrain" or environment and they open up the chance to make more organism, also when they die and decompose they make more soil so that more organisms can grow.
Explanation:
Environments likely to be characterized by the presence of dry scrubs and frequent wildfires are those that lack the presence of rain and suffer high sunlight hours.
When referring to the terrestrial biomes that meet the characteristics described, we can include:
- <u>Temperate grasslands</u>
- <u>Cold deserts</u>
The temperate grassland/cold desert biomes have:
- cold and dry winters
- hot, dry summers
- Extended sunlight hours
This biome is very dry, and the harsh weather makes it difficult for plants to grow, leading to their <em>dry scrub</em> characteristic. This biome also experiences frequent wildfires due to the <u>intense sunlight and lack of rain to which it is exposed.</u>
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Answer:200m
Explanation: If we do the math here we will see that they multiplied 1,000 by 100 to get 100,000 so we will multiply the 2 by 100 and we will get 200.
