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:
Improvement of preservation techniques.
Explanation:
The most significant result of the technology revolution in archaeology is the improvement of preservation techniques used for archaeological sites. Modern technology also allows researchers to go to a site in order to find out the answers of additional questions. Modern archaeologists are fighting climate change, discovering how cultures evolved with the passage of time, and using technology to better understand human evolution.
A trait is a characteristic, such as color or size, that is inherited by an offspring from its parents. The genes that control a trait come in pairs, one gene from each parent. We represent these gene pairs by writing a combination of two letters. For example, if one parent contributes a gene for blue eyes (c), and other parent contributes a gene for brown eyes(C), then we write the offspring’s eye color trait as Cc. This combination, of the two genes that determine the trait, is called a genotype. If gene pair contains a dominant allele, the the offspring will show this dominant trait
Hello friend!!
The biggest difference between the two is that the nervous system uses electrical impulses to send signals through neurons, whereas the hormonal system uses chemical messengers transported into blood plasma to target cells.
Transmission by the nervous system is short-lived but quick, whereas transmission by the hormonal system is long-lasting but takes much longer. Hene, communication is faster when using the nervous system.
In the nervous system, responses are localised - whereas in the hormonal system, they are widespread. Responses are often permanent in the hormonal system, but temporary and reversible in the nervous system.
Hope It Helps!!All The Best!!
