Biology Questions and Answers
(that is more external) but preserving
the xylem (that is more internal).
When a girdle like that is removed
below the branches the plant diesbecause organic food (sugar) is
disallowed to pass to the region below
the girdle and thus rlack of nutrients. Since roots die from theoots die the
plant does not get water and mineral
salts and dies too.
- What are plant hormones?
Plant hphytohormones, are ormones, also calledsubstances that (^)
control the embryonic dthe growth of the adult plaevelopment andnt.
- What are the main natural
plant hormones and what are
their respective effects?
The main ntheir respective fatural plant hunctions arormones ande the
following:
Auxins (the best known natural auxin is
IAA, indoleaceticto promote plant growth, diste acid): their function isnsion and (^)
cellular differentiation. Gibberellins:
have action similar to auxiand distension), stimulate flowering andns (growth (^)
fruit formation and activate seed
germination. Cytokinins: icellular division rate and together withncrease (^)
auxins help growth and tissue
differentiation,Ethylene (ethene): a gas r slow the plant aeleased byging. (^)
plants that participates in the growth
process anripening and in leaf abscission.d has noteworthy role in fruit
- What is the plant
coleoptile? Why does the
removal of the coleoptile
extremity disallow plant
growth?
Coleoptile isaerial structure o the first (one or more)f the sprouting plant (^)
that emerges from the seed. It encloses
the young stem anprotecting them. d the first leaves,
The top of the coleoptile gregion where auxins are made. If thisenerally is th e
region is removed, plant growth stops
since auxins argrowth and tissue differentiation.e necessary to promote
- What is indolacetic acid
(IAA)?
Indolaceticor IAA, is the main acid (indolyl-3-aceticnatural auxin ma acid),de (^)
by plants. It promotes pcellular differentiation. lant growth and
- What are synthetic auxins
and what are their uses?
Synthetic auxins, like indolebutyric acid
(IBA) and naphthalenic acid (NAA) aresubstances similar to IAA (a natural
auxin) but artificially made. Some are
used to accelerate mreproduction (like grafting ethods of asexualor budding) (^)
and others are even used as herbicides
since they selectively(mainly dicots). kill some plants
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