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Science 09 Biology Unit Review Answers:


1.       Genes2.       Nitrogen bases 3.       Sugar 4.       Mutagens 5.       Ribonucleic acid (RNA)6.       Cell cycle 7.       Chromatids 8.       Stem cells 9.       Clone 10.   Half 11.   Pistil 12.   Stamen 13.   Meiosis 14.   Genetic diversity 15.   Embryo

Short answers are in textbook.


1.      F2.      F3.      F4.      Chromatin5.      Genes6.      Protein7.      Nitrogen bases 8.      Sugar9.      Nucleus 10.  Mutagens 11.  Cell membrane12.  Ribonucleic acid (RNA)13.  Chromatin 14.  Therapeutic cloning 15.  Cell cycle 16.  Stem cells17.  Centromere18.  Cancer 19.  Clone 20.  Mitosis 21.  Cytokinesis22.  Two 23.  Half 24.  Zygote 25.  Embryo 26.  Meiosis 27.  Sexual reproduction 28.  Genetic diversity 29.  Zygote 30.  Embryo 31.  F32.  B33.  A34.  H35.  D36.  C37.  B38.  H39.  A40.  G41.  D42.  C43.  ANSWERS WILL VARY44.  ANSWER IN TEXT45.  ANSWER IN TEXT


Pg 239 #3-27 Textbook

Chapter 4

3. The sides of the DNA ladder consist of sugarsand phosphates. The steps of the ladder aremade of paired A-T, G-C bases.4. Chromatin is the substance that containsDNA and associated proteins.5. A chromosome is a very compact X-shapedstrand of chromatin and contains one DNAmolecule.6. The function of the nuclear membrane is toprotect the contents of the nucleus.7. Genes are important to the functioning of acell because they contain the information tocode for proteins that carry out the activitiesof the cell necessary for the cell’s survival.8. Answers will vary. Accept answers that reflectthe following main ideas.(a) The DNA message for a specific protein iscopied into a small molecule called ribonucleicacid or RNA.(b) The RNA message is copied from theDNA and delivered to the ribosome.(c) The Golgi body repackages the protein fortransport out of the cell.(d) A vesicle forms off the end of the Golgibody to carry the protein to the cell membrane.Or: A vesicle forms off the end ofthe endoplasmic reticulum and carries theprotein to the Golgi body.(e) RNA leaves the nucleus through thenuclear pore.(f) The ribosome is the location where proteinsare made in the cell.(g) Proteins that are made for export out ofthe cell enter the channels of the endoplasmicreticulum.(h) Proteins that are being transported out ofthe cell leave through the cell membrane.9. Three factors that could change the cell’sgenetic information are radiation (X rays,ultraviolet rays), chemicals, and viruses.10. Three different effects of mutations are thatthe mutation could have a positive, negative, orneutral effect on the survival of the individual.Chapter 511. Body cells must be able to reproduce forgrowth and to replace worn-out cells.12. (a) Interphase is important for cell reproductionbecause it prepares the cell for divisionby duplicating all the organelles aswell as the DNA.(b) Mitosis is important for cell reproductionbecause the nuclear material gets equallydivided between the two forming cells.(c) Cytokinesis is important for cell reproductionto separate the two nuclei and cellcontents into two separate cells.13. Cell reproduction is controlled by checkpointproteins that ensure that the cell is ready tomove forward into the next stage of the cellcycle.14. The nucleolus is always visible in interphase asthis is when the cell is busy performing itsfunctions and requires proteins to be made.15. The sister chromatids move to opposite polesin anaphase.16. (a) There are no centrioles for the spindlefibres to attach to in plants.(b) In plant cells, a cell plate forms betweenthe two cells. The cell wall and cell membraneare made from there. In animal cells,there is no cell plate and the cell membranepinches apart.17. Humans assist plant reproduction throughcutting and grafting.18. The benefits of plant grafting are that growerscan reproduce plants that cannot grow rootsfrom cuttings; the stem can be attached to aplant with a strong root system so that it cangrow flowers or fruit much quicker than fromseeds; and you can also control the size of theplant by grafting stems onto dwarf trees whichmakes it easier to obtain the fruit.19. Current uses of reproductive cloning includeproducing a genetic duplicate of a previouslyexisting organism with desirable qualities. Forexample, cows that produce a lot of milk arecloned. Reproductive cloning is also used fortissue matches.Chapter 620. The purpose of meiosis is to create variationamong the individuals of a species and to halvethe number of chromosomes so that when fertilizationoccurs, the diploid number for thespecies will be maintained.21. (a) While mitosis and meiosis are both methodsof reproduction, mitosis is asexualreproduction and meiosis is sexual reproduction.Mitosis produces very littlegenetic variation, whereas meiosis doescreate variation. In the process of mitosis,there is one cell division and diploid cellsare produced. In meiosis, there are two celldivisions and haploid cells are produced.(b) In meiosis I, homologous pairs of chromosomesmove together to the equator andchromosomes separate. In meiosis II, singlechromosomes line up at the equatorand chromatids separate.22. Two chromosomes can be identified as a pairof homologous chromosomes by their size andshape. They will have genes in the same locationthat cannot be identified by a karyotype.23. Homologous chromosomes separate inanaphase I of meiosis I.24. (a) The formation of an egg cell is differentthan the formation of a sperm cell becausein a sperm cell there is an equal division ofcytoplasm distributed among the four cells.In an egg cell, there is an unequal divisionof cytoplasm.(b) All four sperm cells that result are thesame size and available for fertilization.One egg will be larger than the othereggs, and only the large egg is available forfertilization.25. A gene mutation is a change in the basesequence of a single gene. This could includean insertion, deletion, or substitution. A chromosomalmutation occurs when large pieces ofchromosomes (which include many genes) aremoved, deleted, or added to other chromosomes.Entire chromosomes can be duplicatedin a chromosomal mutation.26. Down syndrome and Edwards syndrome arecaused by chromosomal mutations.27. (a) Animals aid plant reproduction throughpollen transport by carrying the pollento another plant of the same species sothat the egg and sperm can unite forfertilization.(b) Animals aid plant reproduction throughseed transport by carrying the seeds ontheir fur or by eating fruit and depositingundigested seeds to a new location. 



Attention all Science 09 and Family Studies 12 students: 

If you have missed a class please email me at virinder_braich@sd34.bc.ca to find out what you missed in the class for the day of your absence.  Daily homework is no longer listed on the webpage but if you need to know what was covered in class today please email me.

Mr Braich



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Email: virinder_braich@sd34.bc.ca

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