Yini i-xylem ne-phloem?

Ngaphakathi kwezitshalo zemithambo, okungukuthi, ama-angiosperms, ama-gymnosperms nama-pteridophytes (ama-ferns), kunemigudu okuhanjiswa ngayo ubisi. Lokhu kuyabizwa xylem kanye ne-phloem.

Kungacishe kuthiwe zifana nemithambo yezilwane, esizifaka phakathi kwazo, ngoba zifeza umsebenzi ofanayo. Kepha kuyini ngempela?

Yini i-xylem ne-phloem futhi uyini umsebenzi wabo?

Ukuze uqonde ukubaluleka kwazo, kufanele uqale wazi ukuthi ziyini nokuthi ziyini izici zazo. Ngakho-ke ake sifike kuyo:

Xylem

El lezwabantu Kuyisicubu esinezinsimbi (yingakho saziwa nangokuthi izinkuni) esakhiwe yizinhlobo ezahlukahlukene zamaseli anomumo wamashubhu amancane. Lezi zinodonga lweseli lwesibili olubanikeza ukumelana. Izinhlobo ezimbili ze-xylem ziyahlukaniswa:

• Okuyinhloko: siqukethe i-protoxylem ne-metaxylem.
  • I-Protoxylem: kuyisicubu sokuqala esibonakala ngokuba nemikhumbi ene-ringed noma evunguza, ngaphezu kokuqina kokuqina lapho ingaguquguquka khona njengoba izitshalo zikhula.
  • I-Metaxylem: yakhiwa yimikhumbi ene-reticulated and scalariform, futhi inobubanzi obukhulu kunaleyo ye-protoxylem. Izitshalo ezincane kuphela ezinazo. Njengoba zikhula, i-metaxylem iyakhula.
• Okwesibili: yiyo ekhiqiza i-cambium *. Lezi zinto zihlukile:
  • Abaqhubi: zakhiwa yimikhumbi ehlanganisiwe esebenzisa ukubhoboza ezindongeni zazo, nangama-tracheids angamashubhu amakhulu.
  • Okungahambisi kahle: yizintambo ze-xylem.

*I-Cambium itholakala kuphela ezitshalweni ezinokhuninjengezihlahla. Kuhlukaniswa izingqimba ezimbili zamaseli amadala: eyokuqala, etholakala ekujuleni ngaphakathi kwesiqu, iyona eyenza izinkuni, nalapho izindandatho zokukhula zakhiwa khona; okwesibili esikhundleni salokho kuhlotshaniswa ne-phloem futhi kulapho kuthuthwa khona isiphu esichaziwe.

Uyini umsebenzi we-xylem?

Uyanakekela thutha amanzi nosawoti wamaminerali kusuka ezimpandeni kuya emaqabungeni. Le ngxube 'yezithako' yaziwa ngokuthi ubisi oluhlaza. Ngenxa yezici zayo, futhi kunikeza ukuzinza esitshalweni.

Kuyadingeka ukwengeza ukuthi lapho isitshalo sikhula ngokugcwele, i-xylem iyisicubu esiphilayo, kepha lapho ikhula, iba izicubu ezifile.

Phloem

Izitshalo zenza okuthile okungekho kithi okwazi: ukukwenza i-photosynthesis, noma okufana nalokhu: zikhiqizele ukudla kwazo ngenxa yelanga ne-carbon dioxide. Kepha ukuze lokhu kudla kufinyelele kuzo zonke izingxenye zawo, kuyadingeka ukuthi kube nemikhumbi eqhubayo, eyaziwa ngegama le-phloem, noma izingilazi zaseLiberia.

Sithola i-phloem kuso sonke isitshalo, ukuze sikwazi ukuthola ukuthi kubaluleke kangakanani kuso. Yenziwe izinhlobo ezimbili zamaseli:

• Amasilingi amasisi: anesimo esihlanganisiwe, futhi ahlelwe abheka phezulu. Amaseli ahlukaniswe phakathi kwawo, futhi aneziphetho ezinezinto lapho izinto ezithile zidlula khona.
• Amaseli anamathiselwe: mancane ngosayizi, futhi ukwakheka kwawo akujwayelekile. Umsebenzi wawo ukulawula ukusebenza kwamaseli we-sieve.

Uyini umsebenzi we-phloem?

Phloem inesibopho sokuhambisa izakhamzimba ezisuka emaqabungeni ziye kuso sonke isitshalo. Lokhu kwaziwa njenge-sap esetshenzisiwe. Ngakho-ke kuyizicubu eziphilayo, futhi ihlala injalo ize ifike ekugcineni kwempilo yayo.

Uyini umehluko phakathi kwe-xylem ne-phloem?

Ngaphandle kwezici zayo eziyisisekelo, umehluko omkhulu phakathi kokunye yilokho i-xylem inesibopho sokuhambisa isiphu esingavuthiwe sisuka ezimpandeni siye emaqabungeni, kanti isithombo se-phloem sikhiqizwa ohlangothini oluhlukile. Ngabe le nsipho emibili yenziwe ngani?

• Ubisi oluhlaza: lolu hlobo oluqukethe kakhulu ngamanzi, kepha futhi namaminerali nokukhula okujwayelekile, kanye nezinye izinto ezincibilikisiwe.
• Isiphu esetshenzisiwe: iqukethe amanzi, amaminerali, ushukela nama-phytoregulators.

Njengoba ukwazi ukubona, i-xylem ne-phloem izingxenye ezimbili ezihluke kakhulu zezitshalo, kepha zinemisebenzi ebalulekile.