đề thi học sinh giỏi sinh lớp 9

so crAo ngc vA DAo

r4o

DE'tlrr

BEN TRE

HQC SINrJ ClOr r,Op 9 TRUNG UqC CCr So

NAM rrQC 2013-2074
M6n: SINIT IIQC
Thd'i gian:150 phrit (kh6ng kO phrit d0)

CAu 1. (3 diem)
oA Fr c6 100% ki6u gen di hgp giSng nhau vd 2 c4p gen tuo'ng rmg thi o'P c6 kiiiu gen nhu
th6 ndo v6 Z c6p gen nAy ?
CAu 2. (3 di6m)
C6 3 t6 bdo cilng

loii

nhi6m sdc thO (NST) doii. 56

NSi

bing nhau, cin mdi truong

nQi bdo cung c6p 900
chiia trong cilc t6 Uao con sinh ra vdo dqt nguyOn phdn cu6i citng

nguyOn phdn s6 dqt

b6ng 960.
a) X6c dinh bQ NST lu6'ng bQi (2n) cria lodi.
b) Hey tinh s6 lAn nguy€n phAn cria mdl t6 Uaot

c) C6c t6 bao con duo. c sinh ra chia thinh hai nh6m bing nhau vi titip tpc nguydn phdn. M6i
tii bao thuQc nh6m thir nh6t cO sO l6n nguyEn phAn g6p cl6i so vdi m5i t6 bao thuQc nh6m thrl hai, dd
tpo ra t6t ca 480 te bao con. HEy cho bi€t sO tAn nguyOn phdn cria m5i tii bdo thuQc mdi nh6m?

Ciu 3. (3 tli6m)
a) Trinh bdy kh6i

r-riQm

ciic bitin di khdng ldrn thay OOi cAu trric vd s6 luo. ng NST. Cho thi

dq.

b) O ngud'i, gen l{n a qlry dinh bgnh bpch tpng, gen A quy dinh tinh tr4ng miu da binh
thudng, c6c gen niy ndm tr€n NST thud'ng. Gen l{n m quy dinh bQnh mi miru, gen M quy tiinhtinh
tr4ng rnit binh thudng, c6c gen ndy nEm tr0n NST X. Hiy vi6t ti6u gen ngudi con g6i, con trai binh
thudng cd2loqi t(nh trgng niy.

Ciu

4. (3 tliGm)

d gi, l6ng trdng li tinh

toin

tr4ng trQi hoin

so

vfi

l6ng n6u l& l6n. Gen qui dinh mdu l0ng

nirn tr€n NST gi6'i tinh X.
85 me O p
ki€u gen, ki6u hinh nhu thti ndo d6 F1 c6 xudt hiQn gd tr6ng l6ng tiing, gd m6i
lOng ndu ? Vitit so"O
dO lai. Biiit rang trong qu6 trinh gi&m phin hinh thi.nh giao trl khOng xiy ra tlQt
bi€n.

Ciu 5. (3 tli0m)
Gen cria mQt

loii vi

khuAn cO kh0i luqng 516.000 dvC, tdng hqp ph6n trl mARN. PhSn t0'

mARN tlugc t4o ra c6 hiQu s0 gifta nucl€Otit iopi Ad6nin v6'i Xit6zin ia XW vd hiQu sd gita
nucl06tit lopi Uraxin v6i Guanin la SW s0 nucl€0tit cfia todn m4ch. H6y x6c dinh ti IQ phAn trim vd.
st5 luo,rrg til'ng loqi nucl66tit cta gen trOn.
Cflu 6. (3 tli0m)
Thgc hiQn phdp lai giil'a hai lopi cdy cd chua c6 ki€u gen nhu sau:
P: AaBB (2n) x Aabb (2n).

Hey
vi6t
c6c ki6u gen c6 th6 c6 cria con lai F1 trong trudng hgp con lai Fr duqc da bQi h6a
.
b6ng dung dlch cOnsixin t4o thdnh 4n.
Biet ring rnSi gen nim tr€n mQt NST

cflu

vi

kh6ng

xiy

ra dQt bi6n trong qud hinh gi&m phdn.

7. (2 tli6m)
MQt t€ bdo sinh du6'ng Zn ctta hia nguy0n ph6n li6n ti6p 6 lAn.

Tim

sO

lugng

ti5

bio con hinh

thinh.
Bi0t ring khi ki5t thric l6n ph6n bio 3, c6 1 ti5 bao bi dQt bi6n kh6ng hlnh thdnh thoi ph6n
bdo.

-u6t-


so crAo DUC vA DAo -t-Ao

Hr.l'oNG nAnq

BEN TRE

LO?

cuAvr

xi rnr crrgN rrec srmr cror
9 TRUNG rrec co soNArvl rlec 2013_2014
M6n: SINII IIQC

M6i cdp gen nim tr€n rn6r cdp NST:

-

+ TI{l:
+ TH2:
- Hai cIp gen
+ TH3:
+ TH4:

P:
P:

AABB x aabb
AAbb x aaBB

ninl
P:
P:

100% AaBb
100% AaBb

tr€n rn6t cdp NST:

AB/AB x ablab
Ab/Ab x aB/aB

100% AB/ab
100% Ab/aB

a) Theo de bdi, ta c6 h0:

3 .2k
3(2u

,'zn:960

- .2n: 900

1)
Giai h€ ta duo-c
b) SO lAn nguy6n phdn:

Thay

- Mqi

2tt:20

(l)
Qi

2n:20

vdo (l)
3.2*.20:960

?u

:960

: (3

.20):

16:2a => k:4

bdo dd nguydn phdn ti6n titSp 4 IAn.

tC
c) Sd l6n nguyOn ph6n cr}a rrr6i t6 bio cria m6i nh6m
- SO t0 bdo con thu6c m6i nh6m:

3 .2a : Z: iq.
- Goi x ld s5 I6n nguy€n ph6n rn6i t6 bao thuQc nh6m thri.hai.
2x h s6 IAn nguy0n ph6n m6i ti5 fao thuQc nh6m thrl nh6t.
- Ta c6:
24 .22* +24 .2* = 4g0

:)

=>2*-22:>x:2,2x=4

-

V{y: Udi ti5 bdo thuQc nh6m thri nh6t nguydn

ph6n 4 lAn.
thri hai reuv6n pi,an z tAn.
a) - Thu'd'ng
aJ
I nu'o'ng bren:
bi6n: Thud.ng
I huong bi€n
bien Id
Ia sg
s1r b
bi6n d6i ki6u hinh cta cirns mOt ki6u serr.
ph6t sinh trong qu6 trinh ph6t trirln cfia c6thii, dudi tric dQng tr,,r"c

ti6p c,na aT6u'
'
kiQn mOi
rn6i ,:udlg,
trud'ng, kh-6ng
kh6ng li€n quan diin bi6n eoi ti6u g"n..'
,"n. ih;
ir,i rrrr
du r,rrino
dring
B.iqn
tO
Id sy t6 hqp lai c6c tinh trpng cria bri nrg. Loai biEn di ndy
.,I
9i lep
khd phd bi0n 6'Iodi sinh vflt sinh sin htiu tfnh. Thi du dring
b)
- Con trai: AAXAY, AaXAy
- con g6i: AAxoxo, AAxAxu, AaxAxA, AaxAxo.
- Quy u6'c gen: A: quy dinh l6ng
a: quy -THl: P: d x'Xo
x
-TH2: P: d XoXu x

U6it6

-TI{3:

Uao thu6c nh6rn

P: d XoXo

x

300: ti2O lnuy
vi s6 lugng ttrng lo4i nucl66tit c0a gen:
Goi: Ar, IJ*, G*, X* : c6c rib6nucl06tit ctia mARN.

SO nuclOOtit c0a gen: 516000 :

Ti

l€ ph6n trdm

. A, T, G, X : c6c nucl€dtit c0a gen.
Theo d6 ta c6: A, - X^: 35Yo (l)
U,,., - G,n = 5oZ (Z)


(1) + (2) ( An,

*

U,,) - ( Xn,

*

G,,)

A - G
A +c
(3) + (4) 2A:700/o
A: T : 35Yo;
G: X : lsYo.

6

(3d)

7

(2d)

:

40%

:20%(3)
:50%(4)
0,75
0,7 5

* S0 nucl06tit rn6i loaicria gen:
A: T :1120 x35o/o :602 (nu)
G : X : 1720 x 15% : 258 (nu)
P: AaBB x Aabb
,.1
F1 : c6 cdc l(2n) AABb ) (an) AAAA BBbb

(2n) AaBb ) (an) AAaa BBbb
(2n) aaBb ) (an) aaaa BBbb
K6t thfic nguy0n ph6n l6n 3 tpo 8 tE bdo. Trong d6,7 G bdo vdn nguy6n phin
binh thub'ng, cdn I tti bao bir6i lo4n.
- Z t6 bdo binh thu6'ng nguyen phdn titip 3 6n t4o ra:7 x23 :56 ti5 bao.
- MOt te bao b! r6i lo4n phin bdo Dn thri 4 tVo ra bO NST 4n t6n tai trong
1 t6 bAo. tC bao ndy ti6p tqc trAi qua IAn phdn bio 5 vi 6 tpo n€n 4 t6 bao tt?
bQi. Vflv tOng s5 tti bao con hinh thinh: 56 + 4: 60 t6 bdo.

IIgc sinh c6 th6 gini bni tflp bing cdc phutrng ph{p khic
thing vdn cho dfr di6m.
-u6t-

so

0,75
0,75

i,0
l,o
1,0

0,5
0,5
1,0

v6t hu0ng d6n ch6m, n6u