Wednesday, March 13, 2013

Science: Chapter 6 Review questions

Chapter 6: Review Questions page 198 and 199

2. DNA replication is required for cells to divide. The genetic material, is need to regulate cell activity, so it has to be found in each and every cell.

3. a) The process shown in figure 1 is DNA replication. The Strands of DNA have split and joined with new nitrogen bases to form a copy of the original.
b) The duplication of genetic material is needed for cell division, because both daughter cells have to have a copy of the DNA.

4. DNA molecules are shaped like twisted ladders. They are made up of three components – Sugar, phosphate, and amino acid

5. DNA replicates by unzipping and each strand bonding with free nitrogen bases to create two copies of the original ladder.

6. DNA Fingerprinting:
a)Remove DNA from the nucleus
b) Use special chemicals to cut the DNA apart. (kind of like scissors)
c) small segments of the DNA are placed on a gel and a small electrical current applied to them to get them to line up in bands.
d)These bands of DNA are matched up to known samples. If they match the samples, identity is confirmed.

7. Two methods of cloning plants:
Stem cuttings, Leaf cuttings, Leaf section cuttings, root division, runners, plant tissue culture (explain each of these)

8. Nuclear Transplanting in animals:
Scientists extract the nucleus from an unfertilized egg cell (making it an enucleated cell) by inserting a thin glass tube into the cytoplasm. Next, a nucleus from another animal's (donor) embryo (fertilized egg) in early stage of growth is extracted and placed into the enucleated egg cell. The cell will begin to grow with the new nucleus. This "diploid" cell is usually implanted into a "volunteer mother animal". It will develop as an embryo and be born as a copy of the donor.

9. In plants it can be observed that cells near the root tip grow at a faster rate than elongated cells elsewhere in the root.

10. Salamander cells are not as specialized as those of more complex animals. Cells that aren't as specialized are able to regenerate more easily than more complex cells.

11. Stem cells are immature (embryonic) cells that have not yet specialized. They have a much greater ability to divide than mature specialized cells.

12. Cancer cells divide much more rapidly than regular cells. Normal cells require cell to cell communication, but cancer cells can divide in isolation.

13. Three factors that cause or contribute to cancer development are:
Viruses, Radiation, and carcinogenic chemicals. All of these cause damage to the DNA changing the genetic message that controls cell division.

14. To reduce the incidence of cancer, you should stop smoking, eat a proper diet (reduce process foods and meat), reduce exposure to sunlight.

15. Prior to Dolly, scientists believed that cells that had specialized had lost their ability to be cloned. In the case of Dolly, a mature cell from one sheep was used to create a clone of the sheep.

16. The new Grafted tree might produce different types of fruit. The grafted tree may also be less susceptible to diseases that kill young trees, because the graft is made to a healthy mature tree.

17. The extract from the pine needles (and other plants) kill cells divide rapidly, but do not kill cells that are moderately active. Cancer cells are rapidly growing, so these kinds of chemicals would kill them.

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