Answer:
Homeostasis refer to as the maintainence of equillibrium within the body. Endocrine systems play a major role in maintainence of equillibrium. The hormones released are continuously inactivated by negative feeback system to maintain homeostsis.
Explanation:
Homeostasis in a body is refered as a dynamic equillibrium which constantly changes. Feedback regulation systems maintain homeosatsis.
The release of hormones into the blood is controlled by a stimulus. A stimulus can increase or decrease the release of hormones.The response to a stimulus changes the internal conditions and may itself become a new stimulus. This self-adjusting mechanism is called feedback regulation.
There are two types of feedback systems.
Negative feedback occurs when the response to a stimulus reduces the original stimulus. Positive feedback occurs when the response to a stimulus increases the original stimulus.
If the hormones released are not controlled by these feedback systems, enormous amount of hormones will change the whole internal enviornment of the body ,hence, equillibrium will be disturbed and result in death of cells and death of an indivisual.
Regeneration reproduction It grow back regrowth
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:
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Answer:
Genes called "molecular switch" or master genes have the purpose of control when other genes are expressed (option A).
Explanation:
Master gene is so named because it has the function of controlling the behavior of other genes, organizing their functions and regulating when they can be expressed.
The name of molecular switch is synonymous with the master gene, since its activation determines the genetic regulation necessary to establish cell differentiation and even the determination of the sex of some species.
The other options are not correct because:
<em> B. Master genes do not </em><u><em>determine the organization of the genome</em></u><em>
.</em>
<em> C. </em><u><em>Regulation of cell metabolism</em></u><em> depends of substances as hormones and enzymes.
</em>
<em> D. </em><u><em>The rate of translation</em></u><em> does not depend on the activity of master genes.</em>
