III. HOAT DONG DAY HOC 1 Kiem tra
3. Phirong phap tao uu the la
the lai
* Phuang phdp tao uu thd lai.
- Lai khac ddng.
+ Tao cac ddng thudn chung khac nhau.
+ Lai cac ddng thudn chung vdi nhau dd tim cdc td hgp lai cho uu thd cao.
Hogt ddng cda GV Hogt ddng cda HS Ndi dung
- GV thdng bdo:
+ Phuong phap lai khdc dong su dung thanh cdng vdi ngd tfl thd ki XX. + Sfl dung hat lai dd nhan cay Fl, nang sudt vugt cac dang bd me tdt nhdt tfl 30-50% dugc
trdng b nhidu qudc gia.
- GV hdi: Uu thd lai cd nhflng uu, nhuac didm gi?
- GV nhan xet, danh gia va giup HS hoan Ihien kidn thflc.
- HS nghien cuu SGK trang 77.
- van dung hidu bidt thuc td.
- Thao luan nhdm thdng nhdt y kidn tra ldi.
A x B - > C l C x G
D X E - > G J H
- Lai thuan nghich gifla cac dong tu thu phdn dd dd tim td hgp lai cd gia tri kinh td nhdt.
* Uu diem:
- Con lai cho nang sudt cao, vay cd thd dung Fl vao muc dfch kinh te (lam thuong phdm). * Nhugc didm:
- Viec tim kidm td hop gen cho uu thd lai tdn nhidu cdng sflc.
- Vi6c tao ddng thudn va duy tri gap khd khan va tdn kem.
Hogt ddng cda GV
- GV yeu cdu HS khdi quat kidn thflc vd quy trinh chung dd chgn dugc gidng mdi.
- GV yeu cdu HS
+ Nghien cflu thdng tin va tranh anh suu tdm. + Lua chgn thdng tin tfl sdch bdo do GV cung cdp.
+ Trinh bay thanh tuu flng dung uu thd lai trong san xudt ndng nghiep.
Hogt dpng cda HS
- HS van dung kidn
thflc, kdt hgp so dd hinh 18.1; 18.2.
- Trao ddi nhanh trong nhdm.
- Y6u cdu neu dugc quy trinh chung.
+ Tao ngudn bidn dj lam nguyen lieu cho chgn lgc.
+ Danh gid kieu hinh dd chgn ra kidu gen mong mud'n.
+ Tao va duy tri ddng thudn cd td hgp gen mong mudn.
Npi dung
- Khd tien doan trudc td
hgp lai nao cho uu the lai.
- Khd duy tri uu thd lai vi chung giam ddn qua cac thd he.