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:
bicycle I may be wrong sorry
Answer:
Scientists believe that prokaryotes existed earlier than eukaryotes because certain eukaryote cell structures resemble prokaryotes.
Explanation:
Thank me later.
Answer:
Food 5
Plastic 1
Explanation:
behaviors of people as well as the rapid advances of technology, amounts and the composition of MSW have been also changed. In a study carried out by the European Environmental Agency to study the per capita annual MSW produced by 32 European countries during 2001–2010, they found that this waste increased in 21 countries, and was decreased in 11 countries. The study also studied the amount of wastes of 26 countries between 2001 and 2008; they found that these amounts decreased in 6 countries. Thus, the amounts and characteristics of the wastes varied from country to another country, as well as from region to region even within the same city according the mentioned factors including the usage habits of people
Answer:
Your answer is A.They contain chloroplasts both in the mesophyll and bundle sheath cells.
Explanation:
C4 plants have two types of photosynthetic cells: mesophyll and bundle sheath cells. Mesophyll chloroplasts are randomly distributed along cell walls, whereas bundle sheath chloroplasts are located close to the vascular tissues or mesophyll cells depending on the plant species. The cell-specific C4 chloroplast arrangement is established during cell maturation, and is maintained throughout the life of the cell.
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