Phan tich bai 28

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  1. 1. Phntchbi28: LOI CU TRC LOGICI. KHI NIM LOI SINH HC1. KhinimLoi l 1 hay 1 nhm qun th gm cc c th c kh nng giao phi vinhau trong t nhin, cho ra i con c sc sng v kh nng sinh sn nhng licch li sinh sn vi cc nhm qun th khc.2. Tiu chun phn nh loiTiu chun phn bit loi: cch li sinh sn, hnh thi, tiu chun sinh l, hasinh, tiu chun di truyn. phn bit hai loi th s dng tiu chun cch li sinh sn l chnh xcnht, c bit i vi trng hp cc loi thn thuc c cc c im hnh thirt ging nhau. phn bit loi ny vi loi kia, nhiu khi chng ta phi s dng cng lcnhiu c im v hnh thi, ha sinh, phn t...II. CC C CH CCH LI SINH SN GIA CC LOI1.Cch li trc hp tKhi nim cch li sinh sn: l cc tr ngi trn c th sinh vt ngn cn ccc th giao phi vi nhau hoc ngn cn vic to ra con lai hu th ngay c khicc sinh vt ny sng cng mt ch.a. Cch li ni cc c th sng trong cng khu vc a l nhng trong sinh cnh khc nhaunn khng th giao phi.b. Cch li tp tnhCc c th ca cc loi khc nhau c nhng tp tnh giao phi ring cchli sinh sn. c. Cch li thi gian (cch li ma v):Cc c th thuc cc loi khc nhau c ma sinh sn khc nhau, khng thgiao phi vi nhau c.
  2. 2. d. Cch li c hc Do cu to ca c quan sinh sn khc nhau cc c th thuc cc loi khcnhau khng giao phi c vi nhau 2. Cch li sauhpt Khi nim: l c ch ngn cn vic to ra con lai hoc ngn cn vic to racon lai hu th C ch: c th ca hai loi thn thuc c th giao phi vi nhau to ra conlai nhng con lai khng c sc sng hoc con lai c sc sng nhng bt th VD: Lai gia la c v nga ci cho ra con la nhng con la khng th sinhsn c. 3. Vai tr ca cc c ch cch li. Cc c ch cch li ng vai tr rt quan trng trong qu trnh tin ho : + Ngn cn cc qun th ca loi trao i vn gen cho nhau cng c, tngcng s phn ho thnh phn kiu gen trong qun th b chia ct hnhthnh loi mi. + Duy tr s ton vn ca loi : v chng ngn cn cc loi trao i vn gencho nhau, do vy mi loi duy tr c nhng c trng ring. TRNG TM BILm rkhi nimloisinhhcvkhinimcch lisinhsngiphcsinhhiucthnolloisinhhcvtiuchunphnbitccloitrongcchcch li sinhsnlquantrngnht. PHNG PHP GING DY: trc quan SGK hi p.t vn : Ngan, g, vt cng sng trong trang tri c giao phi vi nhaukhng? Ht phn ca cy la c th phn c cho cy ng khng?V sao chng li khng giao phi vi nhau?Cu tr li cho cu hi trn nm trong ni dung ca bi hm nay, chng ta scng tm hiu.I. KHI NIM LOI SINH HC
  3. 3. 1. Khi nimNgan, g, vt cng sng trong trang tri c giao phi vi nhau khng? Htphn ca cy la c th phn c cho cy ng khng?V sao chng li khng giao phi vi nhau?Nm 1942, Nh Tin ha hc nxt May a ra khi nim loi sinh hc.(?) Nghin cu SGK v cho bit th no l loi sinh hc?(?) u im ca khi nim ny khi dng phn bit cc loi?Khch quan khng ph thuc vo ngi phn loiC th phn bit c cc loi ng hnh vi nhau(?) Nhc im ca khi nim loi sinh hc l g?Khng th dng tiu chun cch ly sinh sn phn bit loi sinh sn v tnh.Khng th phn bit nhm loi tuyt chng vi nhm loi hin ti hoc ccnhm xut hin khng cng thi im.Kh xc nh c hai qun th c mc cch li sinh sn nh th no vinhau.(?) Voi Chu phi v voi n c cng thuc mt loi khng? V sao?Voi chu Phi v voi n khng thuc cng 1 loi v gia chng khng ckh nng giao phi vi nhau trong t nhin (c cch li sinh sn), c hnh thikhc nhau, c khu vc sng khc nhau.Con lai (con la) gia nga ci v la c c c coi l loi mi khng? Vsao?Khng, v chng khng tn ti nh mt nhm qun th, khng c kh nnggiao phi vi nhau v sinh ra i con c sc sng.(?) Ngi chu v ngi chu M c hnh thi khc nhau, sng khu phnb khc nhau c c xem l hai loi khng? Ti sao?Khng, v khng c cch li sinh sn vi nhau.(?) Ngoi du hiu cch li sinh sn c nhng hn ch trong vic phn nhloi chng ta cn dng tiu chun no khc phn nh loi hay khng?Tiu chun hnh thi
  4. 4. Tiu chun a l sinh thi Tiu chun sinh l sinh haTiu chun di truyn (tiu chun cch li sinh sn)(?) Ti sao hai loi khc nhau li c cc c im ging nhau?- Do chng c tha hng cc c im ging nhau t t tin.- Khng cng t tin nhng v chng sng trong mt mi trng sng gingnhau nn chu tc ng ca chn lc t nhin nh nhau.II. CC C CH CCH LI SINH SN GIA CC LOI(?) Th no l cch li sinh sn?(?) C ch cch li sinh sn c chia thnh my loi?(?) Ch ra c ch cch li sinh sn v d sau:Cu x d hp t b chtNga ci x la c la bt th 1. Cch li trc hp t(?) Cch li trc hp t l g?(?) Cch li trc hp t gm nhng hnh thc no?Cch li ni (sinh cnh)Cch li tp tnhCch li thi gian (ma v)Cch li c hcYu cu hc sinh nghin cu SGK v hon thnh phiu hc tp tm hiu vc im ca cc hnh thc cch li trc hp t. Ccci Vd hnh m thc cch li Cch liCy da nc v cy da cn. ni
  5. 5. Cch li Ruivnhnctptnhgiaophikhcnhaukhnggiaophi. tptnh Cch li Chimnsinhsnvomaxun, chimgysinhsnvomah. thigia n Cch li Cutocquansinhsncamovchkhcnhaunnkhnggi chc aophi. 2. Cch li sauhpt (?) Cch li sauhpt l g? (?)Cthcahailoithnthucnugiaophicvinhauthcthcnhngktqunhthno? Cho vd. (?) Tisao con lai khngckhnngsinhsn ? 3. Vaitrcacccchcch li (?) Nukhngccchcch li thschintnggxy ra? (?) Cc c ch cch li ng vai tr nh th no i vi qu trnh tin ho? Cc c ch cch li ng vai tr rt quan trng trong qu trnh tin ho : + Ngn cn cc qun th ca loi trao i vn gen cho nhaucng c, tngcng s phn ho thnh phn kiu gen trong qun th b chia ct hnh thnhloi mi. + Duy tr s ton vn ca loi : v chng ngn cn cc loi trao i vn gencho nhau, do vy mi loi duy tr c nhng c trng ring. K NNG RN CHO HC SINH K nng lm vic vi SGK. K nng s dng ngn ngting vit trnh bi. K nng suy lun phn on CC KHI NIM TRONG BI
  6. 6. Loi: l 1 hay 1 nhm qun th gm cc c th c kh nng giao phi vinhau trong t nhin, cho ra i con c sc sng v kh nng sinh sn nhng licch li sinh sn vi cc nhm qun th khc tng t.Loi thn thuc: l nhng loi c quan h gn gi v ngun gcCch li sinh sn: L tiu chun khch quan phn bit 2 qun th l cngloi hay khc loi Hai qun th cng loi ch tr thnh hai loi khc nhau khichng tr nn cch li sinh sn C ch cch li : L chng ngi vt lm cho cc sinh vt cch li nhauCch li sinh sn : L cc tr ngi trn c th sinh vt ( tr ngi sinh hc )ngn cn cc c th giao phi vi nhau hoc ngn cn vic to ra con lai hu thngay c khi cc sinh vt ny sng cng 1 chCch li trc hp t: l nhng tr ngi ngn cn cc sinh vt giao phi vinhau ( thc cht l ngn cn th tinh to ra hp t ).Cch li ni (cch li sinh cnh): cc c th sng trong cng khu vc a lnhng trong sinh cnh khc nhau nn khng th giao phi.Cch li tp tnh: cc qun th khc nhau c nhng tp tnh giao phi ring cch li sinh sn.Cch li thi gian (cch li ma v): Cc c th thuc cc qun th c ma sinhsn khc nhau, khng th giao phi vi nhau c.Cch li c hc: do cu to ca c quan sinh sn khc nhau cc c th thuccc qun th khc nhau khng giao phi c vi nhau.Cch li sau hp t: l c ch ngn cn vic to ra con lai hoc ngn cn victo ra con lai hu th XY DNG BI TP GIO VIN.Tm cc hnh nh minh ha cho cc ni dung kin thc trong bi.Thit k phiu hc tp dy phn cch li trc hp t.