Thiết kế bài giảng sinh học 11 nâng cao (tập 1) phần 1

Dac didm cua con dudng van chuyen nudc d than - Nudc va cac ch^t khoang hoa tan trong nudc dugc van chuydn theo 1 chidu tii rd -^ than -> la... Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

TRAN KHANH PHUONG

IRAN KHANH PHaONG

THIET KE BAI GIANG

f

NANG CAO - TAP MOT

NHAXUA'TBANHANQI

Jlcfl not ddu

? ~

D^ lid tra cho vi$c day - hoc mon Sinh hoc 11 theo chifdng trinh sach giao Idioa (SGK) mdi ban hanh nam hpc 2007- 2008, ch ung toi vHi cudh Thii't ki'Mi giang Sinh hoc 11 nang cao (hai tip) Sach gidi thiiu each ihii't M'bai giang Sinh hoc 11 theo tinh thin dSi mdi phucfng phap day hoc nhkm phat huy tinh tich cttcnhSn thifc cua hoc sinh (HS)

vi noi dung: Sach bam sat noi dung sach giao khoa Sinh hpc 11 theo chiTcfng trinh mdi gom 48 bat Ngoai ra sach co md rdng, bd sung them mdt s6'ndi dung liin quan din bai hpc bang nhiSu boat dong nham cung dp them titliiu dS cac thiy, cd giao tham khao vSn dung tuy theo ddi tttdng HS timg dia phucfng

Ni phirong phap day - h9c: Sach dixcfc triin khai theo hirdng tich cue hda hoat ddng cua HS, lay ccf s6 cua moi hoat ddng la nhOng viec lam cua }iS dttdi stthttdng din, gcfi m(^ cua thiy, cd giao Sach cung dwa ra nhiSu hinh thifc hoat ddng hap din, phu hpp vdi dac diem mdn hpc, dam bao tinh chSn thitc va khoa hoc giup cac em lihh hdiki^h thuv Sinh hpc mdt each cd chit litcfng tot nhit, nhd bai va hiSu bai ngay tr€n Idp Sach cdn chi ro hoat ddng cu the cua giao vi^n (GV) va HS trong mdt tiih trinh day- hpc, coi day ia hai hoat ddng cung nhau, trong do ca GV

va HS diu la ch u thd

Gil ling tdi hi vpng cudh sach nay se la tai lieu tham khao him ich giiip cac thiy, cd giao day mdn Sinh hpc 11 trong viSc ning cao hi$u qua bai giang cua minh Bong thdi rit mong nh$n duac nhOngy kiih ddng gdp cua cac thiy, cd giao va ban dpc gin xa di cudh sach ngay cang hoan thien han

TAC GIA

Phan bon SINH HOC Cd THE

Chiioing I

•

V A N A N G LUONG

vA NANG LUCJNG a THIJC VAT

Bai 1 IRAQ eOl Nl/6C 6 THlJC VAT

I MUC TIEU

1 Kien thurc

- Mo ta ducfc qua trinh hap thU nirdrc d rt va qua trinh vSn chuydn nu6c cf than

- Trinh bay ducfc moi lien quan gifla ca'u true cua long hiit trong m^i lien quan vdi qua trinh hap thu nu6c

- Giai thich ducfc cac con duomg vfin chuyen nu6c tii I6ng hut vao mach g6 ciia rS, tijf mach g6 cua r6 len mach g6 ciia than, la

- Tha'y ro tinh thong nha't giiJa ca'u true va chiic nang trong cac co quan cua thuc vat

2 KTnang

Ren m6t so ki nang:

- Thu nhan kien thiic tii kenh chO, kenh hinh

- Khai quat kien thu"c

- Suy doan logic

- van dung ki6'n thiic giai thich thuc te

II THIET Bj DAY ~ HOC

- Tranh hinh SGK phong to

- Sach: Sinh Ii hoc thuc vat cua tac gia Vu Van Vu

- Thi nghifem hien tuong ri nhua va hien tuong u: giot 6 la.,

- Tranh cam hinh 1.2 trang 8 SGK

- Thong tin b6 sung: Cac trang thai t6n tai ciia nu6c trong dSit Nude trong da't

CO 2 dang chinh la nude lien k6t va nudrc tu do

* Nude lien ket gom:

- Nude lien ket chat: la nude bam tr6n b^ mat cac hat keo cua dat va nude ngam trong long cac hat keo Dang nude nay cay hoan toan kh6ng sir dung duoc

- Nude mang: bao quanh cac hat keo bi gifl bang nhiJng luc tuofng doi yeu hcfn n6n cay cd the hut ducrc nhung kho khan

* Dang nude tu do gom:

- Nude trong luc: La dang nude nam trong cac khe tuong doi rong giGa cac hat da't Dang nude nay di chuyin nhanh chdng theo chieu tiJf tren xuong,

thudng cd nhi^u trong da't luc mua hay tudi ^m, duac cay hiit dt dang

nhung d l rut khoi tdng da't canh tac xudng sau ,

- Nude mao dan chira trong cac mao quan kha hep giita cac hat dSt cd vai tro

chii yeu va duoc cay hap thu di dang Dang nude nay cd thi di chuyen theo nhieu hudng, ki ca theo chilu tur dudi len tren

III HOAT DONG DAY - HOC

Hoqt dong I: Tim hieu vai tro cua nude va nhu c^u cua nude ddi vdi thUc vAt

Muc tieu:

- HS chi ra duoc cac dang nude trong cay va vai tro cua no ddi vdi cay

- HS neu dugc vai tro cua nude ddi vdi cay

- Litn he v^ viec cung c^p nude cho cay

Hoqt dong cua GV

-GVneu y^u chi

+ Hay n6u vai tro chung

cua nude ddi vdi thuc vat?

+ Hoan thanh bang - kie'n

thiJc ve cac dang nude

trong cay

- GV nhan xet danh gia va

thdng bao dap an

Hoqt dong cua HS

- HS van dung ki^n thiJc

sinh hoc Idp 10

- Nghien cuu thfing tin trang 6, 7 SGK

~ Lua chon kid'n thiic de

hoan thanh bang kie'n thiic

-> Dai dien mdt vai HS trinh bky

-> Ldp nhan xet va bd sung

" HS theo doi va bd sung kie'n thirc

Ndi dung

1 Cac dang nude

tro cua nude

- Nude trong cay dang chinh la:

- La dang nU6c chCra trong cac

th^nh phan cCia te bao, trong

khoang gian bao, mach dlin

- Khong bj hut bdi cac phan tCr tich

dien hay dang li§n ket hoa hpc

- GiCr duac tinh chat vat ly, hoa

hoc, sinh hoc binh thudng

Nu6c lien ket

- La dang nudc bj cac phSn t^ tich di§n hut bdi m6t lUc nhat ^nh hoac trong cac lien ket hoa hoc 6 cac thanh phan t§' bao

- Khdng giCr duoc cac dSc tfnh vat

ly, hoa hpc, sinh hoc cCia nude

Vai tro - Lam dung moi

- Lam giam nhiet do cOa cd the khi

thoat hoi nude, tham gia vao mot sd

qua trinh trao ddi chat, dam bao do

nhdt cOa chgt nguyen sinh

- Giup qua trinh trao dpi chat djen

ra binh thudng

- Dam bao do ben vijfng cCia he thdng keo trong chat nuyen sinh cfla te bao

Hoqt ddng cua GV

- GV neu vi du:

+ 1 cay ngd cdn 200 kg

nudc trong ddi sd'ng

+ 1 hecta ngO cin 8000 t^n

nudc

+ cay can tft 200 - 800

gam nudc de tdng hcfp 1

gam chait khd

- GV hoi: Em cd nhan xet

gi \i nhu cdu nudc ciia

cay?

- GV nhan xet, danh gia va

bd sung kien thiJc

Hoqt dong cua HS

- HS theo doi vi du va dua

ra nhan xet + cay cdn nhi^u nudc

+ Nhung tuy thuoc vao nhi^u yeu td

- HS khai quat kieh thlic

- Nhu ciu nudc phu thuOc

vao cac dac di^m sinh thai cua thuc vat

- Nhu cdu nudc con phu thuPc vao cdc loai cay khac nhau, nhom cay khac nhau

Hoqt dong 2: Tim hi^u qua trinh hap thu nudc d vk

Muc tieu:

- HS chi ra dugc C3LU tao ciia rl phu hop vdi chiic nang hut nudc

- HS hieu va trinh bay dugc ca che' van ehuydn nudc mot chieu tijr d^t vao rl len than

Hoqt dong cua GV

- GV cung ca'p thPng tin ve

cac dang nudc trong da't va

neu cau hoi:

+ Nudc trong ddt cd nhijng

dang nao?

+ Dang nudc nao cay cd thd

ha'p thu dugc?

+ Thuc vat hdp thu nudc

nhu the' nao?

- GV nhan xet, danh gia va

torn tat kien thdc

- GV dan dat: Bo re cd dac

didm gi phii hop vdi chiic

nang hSp thu nudc?

Hoat ddng cua HS

- HS thu nhan va ghi nhd

kie'n thfe tir cac th6ng tin

dd tra Idi cau hoi, yeu cau neu:

+ Nudc trong ddt co 2 dang

+ Dang nudc tu do cay hap thu de dang

+ Thuc vat thuy sinh va thuc vat can hSp thu nudc khac nhau (nhd te^ bao bidu

bi hay Idng hlit)

- cay hSip thu nudc tu do

dh dang

- Tu^ loai cay ma kha nang hut nudc bang Idng hut hay bd mat t^ bao bidu bi

1 Dac didm ciia bo rl lien quan dfe'n qua trinh hap thu nudc

Hoqt dong cua GV Hoat dong cua HS Npi dung

- GV nhan xet, danh gia va

giup HS khai quat kien thiic

- GV thong bao dac didm

- HS tiinh bay -> ldp bd sung

- HS khai quat kie'n thiic

- GV treo tranh cam v^ con

dudhg hap thu nudc tir d^t

vao mach gO

- GV dan dat: Dd tim hidu

re hap thu nudc, cac em hay

quan sat tranh tren bang va

tra idi cau hoi

- HS CO thd lien he tdi bd

re cua nhung cay to, cay sdng d viing dat khP can thieu nudc

- Bd re do nhidu loai r§ tao thanh

- B6 r^ phat tridn manh v^

so lugng, kich thudc va dien tich

- Be mat rl cd t^ bao bieu

bi va long hiit (do te' bao bidu bi bien ddi thanh)

- ca'u tao te' bao long hut + Thanh t^ bao mong khdng thaim cutin

+ Chi CO 1 khdng bao trong tam

+ Ap suat tham ra't cao

- L6ng hlit hap thu nudc nhd su chenh lech vd ap sudt th^m than

2 Con dudng hap thu nudc d re

Hoqt ddng cua GV

+ Nudc dugc htfp thu tir da't

vao mach g6 bang con

dudng nao?

- GV treo tranh "Con dudng

di cua nudc tir long din tdi

mach dan ciia re" va yeu

cduHS:

+ Quan sat dpc chii thich

tren hinh ve

+ Viet so d6 tom tat 2 con

dudng di cua nudc vao mach

dan cua rd

- GV yeu cdu ldp nhan xet

bd sung

- GV danh gia, chiJa bai va

yeu cin HS khai quat kie'n

thiic

* Md rpng: Nudc dugc hip

thu vao ri nhd 2 con dudng,

song ddng nudc dugc hut

theo 1 chieu

+ Em hay giai thich vi sao

nudc dugc hiit theo 1 chieu?

- GV ggi y:

+ So sanh lugng nudc cua 2

te' bko gdn nhau

+ Co su chenh lech vd siic

hut

Hoqt ddng cua HS

- HS quan sat tranh, trao

ddi nhanh trong nhom, yeu

- Thao luan va neu dugc:

Ndi dung

'

- Con dudng hdp thu nudc

d rd bao gdm

* Con dudng qua te" bao: •

Nudc tir dat -^ mang te

bao long hiit -» te' bao nhu

md vo -> t^ bao ndi bi -> machgd

* Con dudng qua gian bao: Nudc tir dat -> mang td bao Idng hiit -» gian bao, thanh te bao nhu mC vo, td bao n6i bi -> mach gd

11

Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

+ Nudc van chuyen tii ncri

the nudc cao d^n noi th^

nudc thap

- GV dat vail di: Chung ta

biet nudc dugc hut 1 chieu

tir dat vao long hiit cua rd,

vay nudc dugc chuyen tir ri

vao than nhu the nao? De

tim hidu vin de nay chiing

ta Cling nghien ciiu thi

+ Nhua ri ra tir ch6 than cay

bi cat chiing to dieu gi?

* Thi nghiem 2: Hien tugng

ligipt

GV cho HS quan sat hien

tugng thi nghiem va hoi:

- Em thay hien tugng nay

vao miia nao trong nam?

Mua do khi hau co dac didm

gi?

+ Lugng nudc chenh lech

gitia 2 t6 bao g^n nhau theo

hudng tiJf re vao mach gd

+ Stic hlit nudc theo hudng tang dan tir ngoai vao mach

gd

+ The nudc giam d&n tir rd

vao mach gd

- HS theo doi thi nghiem

- Thao luan nhanh, neu dugc:

+ Miic thuy ngan tang do

cd 1 luc day tir phia rd cay

+ Nhua ri ra tiJr chd than cay

bi cat chiing to nudc bi day tir rd len than?

- HS trao ddi nhanh trong nhdm va neu dugc:

+ Hien tugng nudc dong d mep la hay gap vao mua xuan

+ Khi hau mua nay cd dp

am rat cao

3 Ca chfe' de dong nudc 1 chieu tiir da't vao re len than

Hoqt ddng cua GV

- GV: Danh gia y kie'n ciia

HS va bd sung kie^n thiic

- GV dan dat: Tir nhung

hidu bidt d thi nghiem 1 va

2 em hay riit ra ket luan vd

CO che de dong nudc chuydn

tir re len than

- GV nhan xet -> giiip HS

hoan thien kidn thiic

* Lien he: Tai sao hien

tugng li gipt chi xay ra d

nhOng cay bui thap va

nhiing cay than thao?

- GV bd sung kidn thiic nhu

sach GV

Hoqt ddng cua HS

- HS van dung kien thiic va

khai quat thanh k^t luan: co chd chu ydu la luc d^y tCr

- HS van dung kie'n thiic vd giai phau thuc vat dd tra Idi

Ndi dung

Ket luan:

Nude bi d^y tir rd len than

do 1 luc d^y tir rd, gpi la ap sua't rd

Hoqt dong 3: Tim hieu qua trinh van chuydn niidc d than

Muc tieu:

- HS hidu va trinh bay dugc dac didm cua qua trinh van ehuydn nudc d than

- HS nam dugc ecf che va trinh bay eon dudng van chuydn nudc trong than

Hoqt ddng cua GV

- GV hoi: Con dudng van

chuydn nudc d than c6 dac

didm gi?

Hoat ddng cua HS

- HS sir dung kie'n thiic d

hoat ddng 1,2 va thong tin SGK muc 1 trang 9 dd tra Idi

Ndi dung

1 Dac didm cua con dudng van chuyen nudc d than

- Nudc va cac ch^t khoang hoa tan trong nudc dugc van chuydn theo 1 chidu tii

rd -^ than -> la

13

Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

- GV yeu cau HS quan sat

hinh 1.5 va mP ta con

dudng van chuydn nudc,

cha't khoang hoa tan va chat

hOu ccf trong cay

~ GV treo tranh hinh 1.5

phong to va yeu cau HS len

trinh bay con dudng van

chuyen nudc d than

- GV hoi them:

Trong thuc te chiing ta ddu

bie't cay CO nhieu canh, vay

nudc dugc van chuyen nhu

the' nao?

- GV neu van de:

+ Trong thuc td chiing ta

tha'y cay cao iOOm nhung

nudc van dua dugc len ddn

ngon

+ Co che nao dam bao sir

van chuydn nudc d than?

- HS theo doi hinh chii y chidu mui ten chi dudng di cua nudc

- Dai dien HS Uinh bay trudc ldp vd con dudng van chuydn nudc d than

- Ldp nhan xet bd sung

- HS van dung kien thiic d hinh 1.5 tra Idi: nudc dugc chuyen ngang ra canh, trong canh

- HS khai quat kie'n thiic

- HS quan sat hinh

- van dung kien thirc vd ap sua't rd, hen ket hoa hoc cua phan tir nudc

2 Con dudng van chuyen nudc d than

Kdt luan:

- Nude dugc van chuydn 6 than chii ydu bang 1 con dudng qua mach gO

- Nudc cd thd van chuydn

theo chidu ttr tren xudng b

mach ray, hoac van chuydn ngang

3 Co chd dam bao su van chuyen nudc d than

- GV bd sung kidn thiic va

nha'n manh, co chd van

chuydn nudc la su phdi hgp

cua 3 yeu td

- GV hudng suy nghT ciia

HS vd va'n dd neu ra liic dau

de HS tra Idi

* Md r5ng: Trong cac dong

luc dd van chuydn nudc

trong than thi dong luc nao

la chu ye'u?

- GV ghi lua chgn cua HS

len bang rdi dua mot sd

thdng tin dd khang dinh

ddng luc nao la co ban

+ Theo tinh toan ciia cSc

nha khoa hpc thi luc day

cua rd dat 3atm, c6n lire hut

do thoat hoi nudc d la thi

dat tdi lOOatm

- HS khai quat kien thirc

HS tra Idi dugc:

- Nudc dugc dua len ngon cay mac dii cay cao tdi 100m la do su kdt hgp ciia

3 luc

- HS CO thd lira chpn khac nhau

+ Luc d^y ciia rd (ap suat

rd do qua trinh hap thu nudc)

+ Luc hlit cua la (Do qua trinh thoat hoi nudc)

+ Luc trung gian (Ddng nudc lien tuc do luc lien ket giQa cac phan tii nudc

va luc bam giQa cac phan tir nude vdi thanh mach din)

15

Hoat ddng cua GV

- GV giang giai: Nudc va

mudi khoang dugc rd cay

hap thu va van chuyen 1

chidu lien tuc Uong than

cay nhd cac dPng luc cua

rd, la Didu nay khac vdi

cac CO chd van chuydn vat

- HS CO thd hoi:

Ddng nudc van chuydn hen tuc trong than cay cd bao gid bi tut trd lai xudng rd

do khOng du luc d^y, luc hut hay khdng?

Ndi dung

IV KIEM TRA DANH GIA

- GV yeu cau HS tdm tat kien thiic ca ban cua bai hoac dpc kdt luan trang 1L

- GV cho HS lam bai tap trac nghiem: chpn cau tra Idi diing

1 Td' bao Idng hiit ed e^u tao va sinh li phu hgp vdi ehdc nang nhan nudc tir

dat VI:

a) Thanh te bao mong, khdng tham cutin

b) Chi cd mdt khdng bao trung tam Idn

c) Ap suat thdm tha'u rSt cao do hoat dong h6 hap manh ciia rd

d) Ca a, b, c

2 cay hap thu nude qua he thdng rd nhd:

a) Trong dat ed dang nude tu do dd ha'p thu

b) Su chenh leeh ap sua't tham tha'u

c) Ap sua't rd

d) Cd vong dai Caspari

3 Qua trinh van ehuydn nudc tii rd len la dugc thuc hien nhd:

a) Luc hlit ciia la

b) Luc ddy cua rd

c) Luc lien ket giiia cac phan tir nude vdi nhau va vdi thanh mach

d)Caa, b, c

V DAN DO

- Hoe bai, tra Idi cau hoi SGK

- Doc muc "Em cd biet?"

- HS dn lai kien thiic ca'u tao cua Id, dac biet la bd phan Id khi

^

Bai 2 TRAO DOI WMOZ O THlTC VAT (Tiep theo)

I MUC TIEU

1 Kie'n thurc ^

- Minh hoa dugc y nghia ciia qua trinh thoat hcfi nudc

- Trinh bay dugc 2 con dudng thoat hoi nude d la ciing vdi nhiing dac diem

ciia no M6 ta dugc cac phan ling ddng md khi khdng '

- Giai thich dugc mdi lien quan giita cac nhan td mdi trudng vdi qua trinh

trao ddi nudc

- Giai thich dugc co sd khoa hoc cua va'n dd tudi nudc hgp ly cho cay trong

- So dd minh hoa ca chd ddng md khi khdng (Tham khdo sdch Sinh ly

thuc vat trang 58)

2.SINHHpC1,1/1(NC) 4y

Thong tin bo sung: Su didu hoa thoat hoi nudc theo co chd ngoai khi khong:

- Qua trinh thoat hcfi nudc phu thuoc vao su ddng md khi.kh6ng, tuy nhien cung cd nhihig trudng hop khdng tuan theo qui luat dd: d cay hudng duong

khi khdng nyd sudt ngay va ddng khi gan chidu td'i; cdn d cd muc tuc thi khi

khdng ddng ngay tir liic Uh trua, nhung nhip dieu thoat hcfi nudc hang

ngay ciia hai cay nay gin nhu nhau

- cay bong trong nhiing ngay trdi ning thudng tha'y cay ngimg thoa hoi nudc trong khi khi khdng vSn md Ngudi ta gpi su thoat hai nude nay la thoat hai nudc ngoai khi khdng Dd la su didu chinh qua trinh bay hai nudc trong cac gian bao cua la., Khi dd, su thie'u nudc d la hoac do thoat hai nude manh

lam cho cac thanh phin te bao bi m^t nudc da giff phan cdn lai vdi luc Idn, hoac do su cung cap nudc tit da't khdng du se la nguyen nhan lam giam

su bay bed nudc va su thoat hoi nude, khong phu thuoc vao hoat dong ciia khi khdng

Ngudi ta Cling cho rang khi khi hau khd ndng, ed gid manh, thudng xay ra

su bdc hcfi nudc rat nhanh tii mat cac te' bao nhu md la bao quanh khoang thd dudi 16 khi lam cho cac te' bao nhu md la bi khd va su bdc hoi nudc tii

be mat cac td bao nhu md nay bj ngiing Nhu vay thuc vat cd the tu didu chinh su thoat hoi nudc thdng qua hoat dong cua khi khdng hoac theo ca che ngoai khi khdng

III HOAT DONG DAY - HOC

1 Kiem tra

- Neu dac diem cua long hiit lien quan ddn qua trinh hap thu nude ciia rd

- Trinh bay eon dudng van chuydn nudc d than

2 Trong tam

- Qua trinh thoat hoi nude d la

- Anh hudng ciia didu ki6n mdi trudng de'n qua trinh trao ddi nudc

Hoqt dong 1: Tim hieu su thoat hoi nudc d la

Muc tieu;

- HS neu dugc y nghia sir thoat hai nudc

- Chi ra dugc hai eon dudng thoat hoi nudc d la

- Trinh bay ca ehe' didu chinh qua trinh thoat hai nude

Hoqt ddng cua GV

-GVhoi:

+ Thd nao la su thoat hoi

nudc?

- GV bd sung kien thiic dd

giiip HS hinh thanh khai

niem thoat hcfi nudc d la

- GV dan dat: E)d tim hidu

y nghia cua su thoat hcri

nudc em hay tra Idi cau

hoi:

+ Lugng nudc do rd hiit vao

dugc cay sir dung nhu the

- HS theo doi so dd va th6ng tin SGK muc 1 trang

12

- Thao luan nhanh trong nhdm

- Yeu cdu neu dugc:

+ Lugng nudc cay ha'p thu vao dugc su dung rat it, chu yeu la thoat ra ngoai

+ Thoat hcfi nudc la tai hoa vi: lugng nudc thoat ra qua Idn

+ Thoat hoi nudc la ta't yeu vi: Thoat hcfi nudc da tao dugc luc hut manh tir phia tren de keo cot nudc len cac la

Npi dung

* Thoat hai nudc la su ma't nudc tir bd mat la qua he thdng khi khdng la chii yeu,

va 1 phdn tir than, canh

1 Y nghia cua stf thoat

hofi nudc

19

Hoqt dong cua GV

- GV hoi: Su thoat hoi

nudc CO y nghia nhu thd

nao dd'i vdi cay?

Hoqt ddng cua HS

- GV bo sung kie'n thiic:

+ La cay hap thu 75% anh

sang mat trdi, chi co 3%

diing cho quang hgp, cdn

lai bidn thanh nhiet nang

lam la ndng len nhanh

+ 1 g nudc thoat ra lam mat

1 lugng nhiet la 2,3 KJ

+ Thoat hcd nudc lam cho

cac dung dich chSt huu ca

do la quang hgp cd dac

hon

- GV neu cau hoi:

+ Su thoat hoi nudc d la

dugc thuc hien nhd con

dudng nao?

- Dai dien HS tra Idi -> ldp

nhan xet bd sung

- HS van dung kie'n thiic tra Idi, yeu c^u nSu dugc 3

* Ket luan: "^ nghia su

thoat hoi nudc d la

- T a o ra sdc hiit nudc tir re len la mPt each dd dang

- Lam giam nhiet dp b^ mat cua la

- Tao didu kien cho dong khi Cacbonic di tir kh6ng khi vao la de thuc hien qua trinh quang hgp

2 Con dudng thoat hoi

nudc a la

Hoqt ddng cua GV

+ Dac diem cua mdi con

dudng thoat hoi nudc la gi?

- GV yeu cin cac nhom

thao luan dd tra Idi thac

mac cua ban

- GV nhan xet ^ kien ciia

cac nhom va bd sung kidn

thdc

+ Nudc cd the thoat mot

ph^n nho d than va canh

nhd cac ve't s^n (bi khdng)

+ Hai con dudng thoat hai

nudc nay phu _ thu6c vao

loai cay, tudi cay, dac didm

giai phdu

+ Cay con non ldp cutin

mong nen cudng do thoat

hai nudc d hai con dudng

la nhu nhau

Hoqt ddng cua HS

- Yeu cin ntn ro hai con

dudng thoat hoi nudc

- Dai dien HS ua Idi

- HS CO the hoi:

4- Nudc cd dugc thoat ra ngoai d ph&i than va canh khdng?

+ Con dudng thoat hoi nao

Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

+ Cay trudng thanh qua

trinh thoat hoi nudc qua khi

khdng la chu yeu

- GV giang giai: Nudc

thoat ra khoi la chu ydu

qua khi khdng, vi vay co

chd didu chinh qua Uinh

thoat hoi nudc chinh la ca

chd didu chinh ddng md

khi khdng

- GV hoi: Khi khdng cd

ca'u tao phu hgp vdi chiie

nang thoat hoi nudc nhu

thd nao?

- GV danh gia va bd sung

kien thiic

* Md rpng: GV hoi

+ Mep trong td bao ddng

day hon mep ngoai cd tac

dung gi?

+ Em hay lien tudng ddn 1

- HS qUan sdt hinh 2.1 SGK trang iS va neu^ dugc cau tao:

+ Gdm 2 td bao

+ Tao 15 khi

+ Mep trong va mep ngoai ciia td bao cd dd day khac nhau

- Trong td bao dong co hat luc lap, nhan ti thd

- Mep trong ciia td bao ddng sat 16 khi day hon mdp ngoai

Hoqt ddng cua GV

vat gi tuong tu nhu 2 td bao

ddng?

- GV dat va'n de: Tai sao

khi khdng lai dong md

dugc?

- De giai quydt vSh dd GV

dua mPt sd ggi y:

+ GV thong-bao thi nghiem

neu chuydn cay tir trong tdi

ra ngoai sang thi khi khdng

md va ngugc lai

+ GV hoi: Ydu id nao gay

nen viec ddng md khi

khdng? Co chd dong md

khi khdng la gi?

- GV nhan xet danh gia va

yeu cin HS khai quat kidn

- Thao luan nhdm tra Idi

- Yeu cin neu dugc:

+ Anh sang, ABA la nguyen nhan gay ddng md khi khdng

+ Td bao khi khdng truang nudc, khi khdng md

+ Td bao mat nudc, khi khdng ddng

- Dai dien nhom trinh bay

-^ ldp nhan xet bd sung

Not dung

b) Co che ddng mcf khi khong

* Ket luan:

- Khi khdng md khi td bao dong truong nudc, mep ngoai dan nhidu hon mep trong, lam tang dp cong cua

td bao ddng -*• khi khdng

md

23

Hoqt ddng ciia GV Hoqt ddng cua HS Ndi dung

- GV cho HS quan sat

tranh: So dd minh hoa co

chd dong md 16 khi d muc

thOng tin bd sung

- GV hoi: Nguyen nhan

nao lam td bao ddng bi

truong nudc hoac mSt

nudc?

- GV danh gia y kien ciia

nhdm

- GV bd sung kidn thiic:

Khi giam ham lugng kali

trong td bao ddng lam cho

khi khdng ddng lai Khi

cung cap dii kali khi khdng

CO the md ra

- GV yeu cin HS lien he

vdi viec cung ca'p chat

khoang day du cho cay

- GV neu va'n de: Nhiing

cay d sa mac anh sang gay

gat sudt ngay, neu Id khi

md hoi nudc se thoat ra

- HS quan sat tranh ke't hgp vdi thong tin SGK trang 13

- Thao luan nhanh trong

nhdm -^ thdng nhat y kien

- Yeu cau neu dugc:

+ Ngoai anh sang luc lap trong td bao dong tidn hanh quang hgp ->• ham lugng dudng tang -> tang ap su^t tham than -> td bao hiit nudc

+ Khi thie'u nudc ham lugng ABA trong td bao tang, cac kenh ion rad, ion rut ra khoi td bao -> lam

giam ap suat thim tha'u

- Dai dien nhom trinh bay tren tranh ve

-> ldp nhan xet bd sung

- Khi khdng ddng khi td bao ddng ma't nudc, thd tich

td bao gian, mat sire cang, mep trong te bao dudi

thang -^ khi khdng ddng

Hoqt ddng cua GV

ngoai va cay se nhanh chet,

nhung thuc te' thi cay van

sdng binh thudng Vay

didu gi da xay ra?

- GV nhan xet y kidn cua

HS va bd sung kie'n thiic

* Md rdng: GV gid"! thieu

them ve su didu hoa thoat

hoi nudc theo co chd ngoai

khi khdng d muc thdng tin

bd sung

- GV nha'n manh: Su trao

ddi nudc d thuc vat bao

gdm qua trinh hap thu

nudc, van chuyen nudc

thoat hoi nudc khac vdi su

trao ddi nudc d ddng vat

Ndi dung

c) Dieu chinh qud trinh thodt hcd nudc

~ Qua trinh thoat hoi nudc

dugc didu chinh bang cac phan ling

* Phan ung md quang chu ddng: La phan ling md khi khdng, chu ddng liic sang sdm khi mat trdi moc

* Phan ling ddng thuy chu dong: La hien tugng dong khi khdng chu ddng vao gid trua khi cudng dd thoat hoi nudc cao hoac khi kh6ng lay dugc nUdc

* Phan ling ddng va md thuy bi ddng: Khi td bao bao hoa nudc (Sau khi mua)

25

Hoqt dong 2: Tim hieu anh hudng cua dieu ki^n moi trudng

den qua trinh trao doi nudc Muc tieu:

- HS hieu va trinh bay dugc mdi lien quan gitra cac nhan td moi trudng vdi qua trinh trao ddi nudc

~ Lien he vd viec trdng cay trong nha kinh

Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

- GV yeu c^u HS:

+ Phan tich anh hudng ciia

cac ydu td mdi trudng ddn

qua trinh Uao ddi nude

+ Lien he vdi che dC cham

soc cay trong cua ndng

dan

- GV nhan xet va bd sung

kidn thiic

- HS nghien ciiu SGK trang 14

- Trao ddi nhanh trong nhdm

- Kdt hgp vdi thdng tin thdi tidt va tin nPng nghiep,

- Yen cin neu dugc: 4 ydU

td CO ban la: nhiet d6, anh

sang, dd am dit va khdng

khi, dinh dudng khoang

a) Anh sdng

- Anh sang lam tang nhiet

dp cua la nen lam tang tdc

dd thoat hoi nudc

- Anh sang la tac nhan gay

md quang chu ddng

- Anh sang tan xa lam cho cudng d6 thoat hoi nudc tang 30%

b) Nhiet dd

- Nhiet dp da't anh hudng

ddn hoat dong hP ha'p cua

rd, rd hiit nhidu nudc

Hoqt ddng cua GV

- GV nhin manh: Cac ydu

td moi trudng anh hudng

tdi qua Uinh trao ddi nudc

cua cay, do cung chinh la

mdi lien quan giua co thd

+ can tudi nudc mPt each hgp li de tang dp dm cho

dat

+ Bon phan ket hgp vdi che

dd nudc phii hgp

Ndi dung

- Nhiet dp khong khi anh

hudng de'n dp am khPng khi -> anh hudng ddn qua trinh thoat hoi nudc cua la

c) Dp dm ddi vd khdng khi:

- Dp im dat cao -> sir hap

thu nudc cang tdt

- D P ^m khdng khi cang tha'p su thoat hoi nudc cang manh

d) Dinh duang khodng

- Ham lugng cha't dinh dudng trong da't anh hudng den su sinh trudng ciia he rd

va ap sua't th&n tha'u cua dung dich da't, nen anh hudng ddn qua trinh h^p thu nudc va chat khoang cua rd

- Sau khi bon phan cay kho ha'p thu nudc

- Sau khi cac chSt khoang vao rd thi cay hiit nude mdt each dd dang

Hoqt dong 3: Ctf sd khoa hoc ciia viec tudi nudc hgp li cho cay trong

Muc tieii:

- HS giai thich dugc eo sd khoa hpc ciia viec tudi nudc hgp ly cho cay trong

- Biet van dung thuc tidn

27

Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

- GV hoi:

+ Thd nao la trang thai can

bang nudc trong cay?

+ Trang thai can bang nudc

cd dugc duy tri hay khdng?

- GV hoi: Khi nao c^n tudi

nude cho cay?

- GV neu va'n dd

+ Vdi mdt che dd nudc phu

hgp thi cd Igi nhu thd nao

cho cay trdng?

+ Tudi nudc cho cay nhu

thd nao la hgp li?

- HS nghien ciiu SGK

trang 14 muc 1 tra Idi ->

ldp nhan xet bd sung

Yeu cau neu dugc:

+ Khai niem can bang nudc trong cay

+ Phan biet trang thai can bang nudc

- HS sir dung kidn thiic vd trang thai can bang nudc trong cay de tra Idi

- Yeu c^u neu dugc: Tudi nudc khi cay d trang thai can bang am

- HS quan sat mdt sd hinh anh vd cay trdng dugc tudi nudc day dii va cay trdng khdng dugc tudi d^y du

- Nghien eiiu SGK trang

15 muc 2

1 Can bang nudc ciia cay trdng

* Khai niem:

- can bang nudc la su

tuong quan giQa qua trinh hap thu nudc va qua trinh thoat nudc

* Trang thai cSn bang nudc:

- can bang nudc duong: La

su mat nudc dugc bii lai bang su nhan nudc ddn mlic cay bao hoa nudc

~ can bang nudc am: La su thie'u hut nudc trong cay, lam cho cay thidu nudc va bihan

2 Tudi nudc hgp ly cho cay trong

Hoqt dong cua GV

- GV nhan xet danh gia va

yeu cin HS khai quat kien

thfic

- GV giang giai vd thdi

gian tudi, lugng nudc tudi

va each tudi nhu sach GV

trang 33

* Lien he: Viec tudi nudc

cho cay trdng dugc thuc

hien nhu thd nao?

* Cung cd: GV nhSn manh

mdi lien quan giOa 3 qua

trinh: Ha'p thu nude, van

chuydn nudc, thoat hoi

Hoqt ddng cua HS

- Trao ddi nhanh trong

nhdm va yeu cin neu dugc

3 va'n dd:

+ Thdi didm cin tudi nudc

+ Lugng nudc c^n tudi

+ Cach tudi

- HS dua vao cac thfing tin tren dai, bao, tivi, cd thd chi neu dugc lugng nudc

cin cho tijmg loai cay va

each tudi phun phP bien d cac trang trai Ngoai ra HS cdn neu van de chdng han cho cay trong

Ndi dung

Ke't luan: Tudi nudc hgp ly

cho cay trdng bao gdm:

- Can cii vao cac chi tieu

sinh \i vd chd dP nudc cua

cay trdng dd xac dinh thdi didm can tudi nudc

- Lugng nude tudi phai can cii vao nhu e^u nudc cua timg loai cay, tinh cha't da't

va didu kien mdi trudng cu thd

- Cach tudi phu thuoc vao cac nhdm cay trdng, cac loai dat

29

Hoqt ddng cua GV

nudc trong co thd thuc vat

va phan biet dugc su khac

nhau giua qua trinh trao ddi

nudc d td bao va d co the

thuc vat

Hoqt ddng cua HS Ndi dung

IV KIEM TRA DANH GIA

- HS tdm tat bai bang each doe kdt luan SGK trang 16

- HS tra Idi cau hoi trac nghiem:

1 Thoat hoi nudc d la dugc thuc hien bang con dudng:

a) Qua khi khdng \

b)Quacutin •• ' , ,' c) Qua bi khdng

d ) C a a b, c

2 Ca che dieu chinh thoat hai nude d la la:

a) Tang ham lugng axit apxixic

b)-Thay ddi ham lugng kali

c) Ca chd didu chinh su ddng md khi khdng

d) Thay ddi ham lugng dudng

3 Y nghia cua qua trinh thoat hai nudc la:

a) Tao ra luc hut nudc '

b) Didu hoa nhiet do bd mat thoat hai nudc

c) Tao dieu kien cho CO2 tir khong khi vao la de thuc hien chiic nSng quang hop

d) Ca a, b, c

V DAN DO

- Hoc bai tra Idi cau hoi SGK

- Dpc muc "Em cd bie't?"

- On lai kien thiic vd van chuyen chii ddng va thu ddng cac cha't qua mang sinh chat

Bai 3 TRAO f)6l KHOANG VA NITO 6 THl/C VAT

I MUG TIEU

1 Kie'n th Lire

- HS phan biet dugc 2 each hap thu cac chat khoang d rd: chu ddng va bi ddng

- Trinh bay dugc vai trd cua cac nguyen td da lugng, vi lugng

- Chiing minh dugc tinh thdng nhat va mdi lien quan chat che giiia cac qua trinh trao ddi chat trong cac ca quan khac nhau cua cay

2 KT nang

Ren mot sd kT nang:

- Phan tich so sanh, khai quat kien thiic

- Hoat dong doe lap va hoat dong nhdm

- Van dung thuc tidn

II THIET Bj DAY - HOC

- Tranh hinh SGK phdng to

- Thi nghiem muc SGK trang 17

- Phie'u hpc tap: Thi nghiem vd su ha'p thu cac mud'i khoang

d giai doan d^u tien ciia qua trinh hiit khoang: Cac ion di vao rd nhd hiit bam tren cac gdc mang dien trai da'u NH4'' tren thanh xenluloza, mang cha't

nguyen sinh va nhd viec diy ra ngoai m6t lugng tuang duong cac ion cilng

da^u da bam tren dd

31

- So dd trao ddi ion giiia rd va dung dich da't, keo d^t (Tham khdo hinh 62

sdch Sinh li thuc vat trang 116)

- Thuye't chat mang: Giai thich ca che hiit chu dong cac nguyen to khoang cd lien quan true tie'p ddn su trao ddi chit cua td bao hiit Thuye't nay da giai thich CO ehe hiit va van chuydn khdng chi cac cation, anion ma ch^t hiJu eo nira Thuye't cha't mang dua tren quan niem vd su cd mat tren be mat chat nguyen sinh, mot mang khdng tha'm ddi vdi cac ion tu do va khdng cho cac ion tham nhap vao te bao tu khuech tan ra ngoai Tren bd mat ciia mang chat nguyen sinh trong qua trinh trao ddi ch^t hinh thanh nen nhiing chat khdng chi ed kha nang tuong tac vdi cac nguyen td khoang cua m6i trudng ngoai ma cdn van chuydn chiing qua mang nhu phiic he ion Chat mang sau khi xam nhap qua mang phiic he a'y dugc phan giai, ion giai phdng tham gia tuang tac vdi cac phan tir cua cha't nguyen sinh, cdn chat mang lai quay trd lai be mat mang va lai thuc hien tiep tuc van chuyen cac nguyen td khoang Theo quan niem nay, cha't mang la phuang tien vin chuydn, nhd

nd ma ion chui qua dugc mang ngan each giiia mdi trudng trong va ngoai, cdn cac ion tu do thi khong vugt qua dugc

Theo gia thuydt chat mang nang lugng giai phdng trong qua trinh hd hap dugc sit dung d^u tien vao vice tdng hgp phan tii cha't mang, hinh thanh phde he ion - ch^t mang, van ehuydn phiic h6 ion - ch^t mang va cuoi cung giai phdng chat mang

(Scf dS minh hoa thuye't chat mang: sdch Sinh li thUc vat trang 118)

III HOAT DONG DAY - HOC

1 Kiem tra

- Y nghia ciia qua trinh thoat hai nudc qua la?

- Su thoat hoi nudc d la thuc hifn nhd con dudng nao?

- Khi khong cd ca'u tnic lieri quan tdi phan ling ddng md cua nude nhu the nao?

2 Trong tam

- Cac nguyen td khoang dugc rd hap thu tii da't nhu the' nao?

- Vai trd ciia cac nguydn td khoang?

- van dung giai thich hien tugng thuc t6'

- GV neu cau hoi

+ Cac cha't khoang trong

dat tdn tai d dang nao?

+ Su hap thu cac nguyen td

khoang nhd b6 phSn nao la

chu ydu?

- GV neu van dd: Dd tim

hidu vd sir ha'p thu khoang,

yeu cau cac nhom hoan

thanh phidu hpc tap "Thi

nghiem vd su hap thu cac

mudi khoang" d muc: Thidt

bi day ~ hpc

- GV chQa bai bang each

chidu phidu hpc tap cua

+ Chat khoang tdn tai d dang hoa tan hay phan li

+ Hap thu chat khoang chii ydu nhd rd

- HS nghien ciiu SGK trang 17

+ Ca nhan ghi nhd kien thirc

- Ldp nhan xet bd sung

- HS theo doi va tu sira chifa phie'u hoc tap

1 Dac diem su hap thu

cac nguyen td khoang

DAP AN PHIEU HOC TAP

Tien hanh

- Dung 1 cay nho con

nguyen bp r§, rufa sach

- NhOng bo re vao dung

Giai thich

- Dung dich CaCIs tU mau trang chuyen sang mau xanh chufng td dung djch mStilen da khdng ngam v^o trong rd ma chi bam trdn be m5t rd

- Khi nhung rd vao dung djch CaCIs cac ion Ca**,

o r hot bam v^o re day cac phan tli metllen vao dung djch

Ke't luan:

- Rd hut eac ch^t cd tinh chpn Ipe

- Cd su hlit bam trao doi cua rd vdi dung dich

Hoqt ddng cua GV

- GV yeu c^u khai quat

kidn thiic vd su hap thu cac

chat khoang ciia rd

* GV hdi them: Cay co thd

ha'p thu chat khoang bang

bd phan nao? Minh hoa

- Vi du: Bon phan tren la

- HS quan sat hinh

- van dung cac kidn thiic

vd van chuven cac cha't qua

Ndi dung

* Ket luan:

Cac cha't khoang trong dat tdn tai dudi dang hoa tan va phan h thanh cac ion

- Rd ha'p thu khoang dudi dang ion

- Rd hlit cac chat cd tinh chpn Ipc

- Cd su hlit bam trao ddi giQa re va dung dich

2 Cu che ha'p thu khoang

drd

Hoqt ddng cua GV Hoqt ddng cua HS Ndi dung

bi ddng va chii dPng cac

chat khoang

- GV danh gia hoat dPng

nhom,

- GV yeu c^u nhdm trinh

bay CO chd ha'p thu bi ddng

va hap thu chu ddng chat

khoang d cay

- GV bd sung kidn thiic

* Tdc dp xam nhap cua

chat tan vao te bao dugc

xac dinh theo c6ng thiic:

V = Const KM"'^<C ngoai

- C trong)

+ K: He sd bidu thi tinh tan

cua ion trong lipit

+ M: phan tii lugng cua

chat tan khudeh tan

nhien cham hon ra't nhidu

lan so vdi khuech tan ciia

mang sinh chat d sinh hpc 10

- Trao ddi nhom yeu cau neu dugc:

+ Su chenh lech ndng dP

+ Sh dung ATP

+ Cha't trung gian

- Dai dien nhdm trinh bay

va Idp nhan xet

a) Hap thu bi ddng:

- cac ion khoang hoa tan

trong nudc va vao rd theo ddng nudc

- Cac ion khoang hut bam tren bd mat cac keo dat va tren bd mat rd trao ddi vdi nhau khi co tiep xiic gifla rd

va dung dich d^t

- Cac ion khoang khudeh tan ttr dung dich ngoai vao

rd nhd su chenh lech nong

dd tii cao ddn thap, khdng

cin cung cap ATP

- Tdc dp xSm nhap chat tan

35

Hoqt ddng cua GV

chat tan trong td bao

- Trong td bao tdn tai mdt

CO ehe bd trp dd lam nhanh

tdc dd khuech tan: Dd la

kenh ion, thd xuyen mang

Hoqt ddng cua HS Ndi dung

- GV sir dung th6ng tin bd

sung vd cha't mang d muc

II dd giang giai ki hon vd

chat mang

- GV hdi: Tai sao rd hap

thu mOt each chpn Ipc cac

chat khoang?

- GV hdi: Tai sao noi qua

trinh hap thu nude va cac

chat khoang lien quan chat

ehe vdi qua Uinh h6 h^p

ciia re?

- HS van dung eac kien thiic sinh hpc 10 ve cau true cua mang sinh chat

- HS van dung kien thiic vd qua trinh h6 hap te bao tra Idi dupe:

+ Ho hap td bao tao ra ngudn ATP cho mpi hoat dong sdng

+ Ndu qua trinh h6 hap d rd

vao td bao phu thuPc vao cac didu kien:

+ Tinh hoa tan ciia cac ion trong Upit cang cao thi xam nhap cang manh-

+ Phan tir lugng cua chat tan cang nhd thi cang dd xam nhap

+ Su chenh lech ndng d6 chat khudeh tan cang Idn thi ion xam nhap cang nhanh

b) Hap thu chu ddng:

- Cac chat khoang van

chuyen tii noi cd ndng d6, thap d dat den noi cd ndng

dd cao d rd

- Hap thu mang tinh chon Ipc, ngugc gradien nong

dd

- Cd su tham gia cua ATP

va cha't trung gian (ch^t mang)

* nap thu ehii dOng cac chat khoang la do mang smh cha't la mang sdng ed tinh chon loc

Hoqt ddng cua GV

* Lien he;

- Trong san xuat ndng

nghiep lam thd nao dd rd

cay hap thu dugc chat

khoang nhidu nhat?

* Cung cd:

GV yeu cau HS lam bai tap

6 SGK trang 21

Hoqt ddng cua HS

bi ngimg thi ATP se khPng

duoc tao ra -^ qua trinh

hap thu chu dong se ngimg

va anh hudng tdi su sdng ciia cay

- HS CO thd kdt hgp kidn thiic sinh hoc va cPng nghe

- HS nhan bidt dugc:

+ Ndng dd Ca^* trong cay cao hon trong da't

+ Ngupe gradien ndng do

+ cay nhan Ca^^ bang each hap thu chu dong

Ndi dung

Hoqt dong 2: Vai trd cua cac nguyen td khoang

Muc tieu:

- HS chi ra dugc vai trd ciia nguyen td vi lugng, da lugng

- Bidt lien he thuc te nhain biet va cham soc cay dd khdng bi thieu chat khoang

Hoqt dong cua GV Hoqt ddng cua HS

- GV CO thd tidn hanh nhu

sau:

+ Hay ke ten cac nguyen td

da lugng va vi lugng

+ GV treo bang Vai tro

cua cac nguyen td da lugng

va vi lugng " va yeu cau tra

Idi:

+ Cac nguyen td da lupng

va vi lugng co vai trd nhu

thd nao ddi vdi cay trdng?

+ Cac bidu hien thidu

khoang cua cay la gi?

+ Quan sat hinh 3.3 SGK

trang 21 tra Idi cau hdi:

Dua vao gdc hoac phun

tren la chat nao trong 3

chat dudi day de la cay

xanh lai: Ca^\Fe'\Mg'^?

- GV nhan xet danh gia va

yeu cau HS khai quat kidn

thu'c

Ndi dung

- HS van dung kien thiic

sinh hpc 10 de ke dugc cac nguyen td da lupng va vi lugng CO ban

+ Yeu cin neu dupe:

• Vai tro ca'u triic cua nguyen td da lupng

• Vai u6 hoat hoa enzrni ciia nguyen td vi lugng

• Thieu khoang la cay thay doi mau sac, than coi epe

• Dua Mg^* vao de la xanh lai vi Mg^"" la thanh phan ciia clorophyl

- Dai dien cac nhom trinh bay —> ldp nhan xet bd sung

1 Vai tro cua nguyen td

da lugng

- Ddng vai trd cau tnic

trong te bao: la thanh phin

cua cac dai phan tii trong te bao

- Anh hudng ddn tinh chat cua he keo trong chat nguyen sinh nhu: