IV - TUONG QUAN HOOCMON THUC VAT
2. Phdt trid'n qua biein thdi khdng hodn todn
Phat triln qua bien thai khdng hoan todn cd d mdt sd lodi cdn tning nhu chau chau, cao cao, gian,... . Phat triln ciia chau chau la mdt vf du dien hinh vl phdt triln qua biln thai khdng hoan toan.
TruTig da phat trien ''^z^)* thanh phoi
Nhpng'
Sau budnn
Hinh 37.3. SO do phat then qua bien thai hoan toan a budm
149
Qua trinh phdt triln eiia chau chau ed the chia lam 2 giai doan : giai doan phdi va giai doan hau phdi.
a) Giai doqn phoi
Giai doan phdi diln ra trong tning da thu tinh. C) giai doan nay, hgp tir phan chia nhilu ldn hinh thanh phdi. Cdc t l bdo ciia phdi phan hod vd tao thanh eae cO quan cua du triing. Au triing chui ra tir trdng.
b) Giai doqn hdu phoi
Giai doan nay d chau ehdu cd biln thdi. Au truiig (con non) phdt triln chua hoan thien . Vi du, a'u tmng chau cha'u chua ed ednh. Au triing chau chau trai qua nhilu lan lot xae (khoang 4 - 5 ldn) vd sau mdi ldn lot xdc du trung ldn ldn rat nhanh (hinh 37.4). Sir khdc biet vl hinh thai va ca'u tao eiia a'u triing giiia cdc ldn lot xdc k l tie'p nhau la khdng ldn.
Chau chau trudng thanh
TrLrng da ( phat trien
thanh phoi
Au trung
Au trung Lot xae Au trung
Hinh 37.4. Sa do phat then qua bien thai khdng hoan toan d chau chau
Nhilu loai a'u trung cung an Id cay nhu bd me chiing, trong dng tieu hod cua ehiing cd ddy dii cdc enzim tieu hod prdtdin, lipit vd cacbohidrat dl tao ra cac chat dl bdp thu nhu dudng don, axit beo, glixdrin va axit amin.
• - Cho biet su khae nhau gii/a phat then qua bien thai va khdng qua bien thai.
- Cho biet sU khae nhau giira phat trien qua bien thai hoan toan va khdng hoan toan.
150
- Biin thdi Id su thay ddi dot nggt vi hinh thdi, cdu tao vd sinh li ciia ddng vdt sau khi sinh ra hodc nd td tning ra.
- Phdt trien cua dgng vdt kkdng qua biin thdi la kieu pkdt trien md con non co cdc ddc diim kink tkdi, cdu tqo vd sink li tuang tu vdi con trudng thdnh.
-Phdt triin cua dgng vdt qua biin thdi hodn todn la kieu phdt trien md du triing cd kink dqng, cdu tqo vd sinh li rdt khdc vdi con trudng tkdnk, trdi qua giai doqn trung gian (a cdn triing Id nhdng) du triing biin ddi thdnh con trudng tkdnk.
- Phdt tiien ciia dgng vat qua biin tkdi kkdng koan todn Id kiiu phdt trien md du triing phdt triin chua hodn thien, trdi qua nhieu ldn lot xdc du trung biin ddi thank con trudng thank.
Cau hoi vet boi top
1. Phan biet sinh trUdng vdi phat trien.
2. Cho biet ten vai loai dgng vat ed phat then khdng qua bien thai, qua bien thai hoan toan va qua bien thai khdng hoan toan.
3. Tai sao sau budm pha hoai cay cdi, mua mang rat ghe gdm, trong khi dd budm trudng thanh thudng khdng gay hai cho eay trdng ?
4. Phat trien eua ech (hinh 37.5) thugc kieu bien thai hoan toan hay khong hoan toan ? Tai sao ?
Ech Z trudng thanh
Trirng da thu tinh
Nong npc
Hinh 37.5. So do phat then qua bien thai d ech
151
(Bd 38 CAC NHAN TO ANH HI/ONG DEN
SINH TRirOTNG VA PHAT TRIEN 0 DONG VAT
Sinh trudng va phat triln ciia mdi loai, mdi cd the ddng vat trudc tien do nhan td di truyen quylt dinh. Cdc nhan td anh hudng den sinh trudng va phat triln cua ddng vat cd the chia thanh cac nhan td bdn trong va cae nhan to ben ngoai.
I - NHAN TO BEN TRONG
Hoocmdn la nhan td ben trong anh hudng den sinh trudng vd phat triln eiia dgng vat.
1 . Cdc hoocmdn dnh hi/dng den sinh t r a o n g vd p h o t t r i e n c u a dong vdt cd xUOng song
• Quan sat iimh 38.1 va cho bie't:
- Ten cac hoocmdn anh hudng den sinh trudng va phat then cua dgng vat cd xuong song.
- Cac hoocmdn dd do cac tuyen ndi tiet nao tiet ra.
."^y '.J
Hoocmon - sinh trudng
-Tiroxin
Ostrogen (dnii)
Testosteron (d nam)
- Kich thi'ch phan chia te bao va tSng kich thude cua te bao qua tang tdng hop protein.
- Kfeh thfch phat trien xUdng (xUOng dai ra va to len).
Kich thfch chuyen hoa 6 te bao va kich thi'ch qua trinh sinh trudng va phat then binh thudng cua co the.
- Kfeh thi'ch sinh trudng va phat then manh d giai doan day thi nhd :
+ Tang phat then xuong.
+ Kich thich phan hoa te bao de hinh thanh cac dac diem sinh due phu thU cap.
- Rieng testosteron con lam tang manh tong hdp protein, phat then manh co bip.
Hinh 38.1. Cac hoocmdn anh hudng den sinh trudng va phat then
152
Ridng dd'i vdi ludng cu, tirdxin gay biln thdi tir ndng nge thdnh ech. Thieu tirdxin, ndng nge khdng biln thanh ech duge. Idt la thanh phdn ca'u tao nen tirdxin, do dd thilu idt trong thiic an va nudc ddn din thilu tirdxin.
Ngudi l<h6ng l6
L—Ngudi binh thudng
Hinh 38.2. Hau qua tac ddng cua hoocmdn sinh trudng V -Hinh 38.2 minh hoa
3 loai ngudi : ngudi binh thudng, ngUdi be nhd va ngUdi khong Id.
+ Hay chi ra trudng hgp nao la do tuyen yen san xuat ra qua
it hoae qua nhieu hoocmdn sinh trudng vao giai doan tre em.
+ Tai sao tuyen yen san xuat ra qua it hoae qua nhieu hoocmdn sinh trudng lai gay ra hau qua nhu vay ?
- Tai sao trong thUc an va nUdc uong thieu idt thi tre em se cham Idn (hoae ngUng Idn), chiu lanh kem, nao it nep nhan, tn tue thap ?
- Tai sao ga trong con sau khi bi eit bd tinh hoan thi phat then khdng binh thudng: