Ch. 38 Notes

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14 Δεκ 2012 (πριν από 7 χρόνια και 6 μήνες)

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Chapter 38: Angiosperm
Reproduction and Biotechnology


Amy Molina

James Duong

Pollination enables gametes to come
together within a flower


In diploid plant, which is the
sporophyte



Produces haploid spores by meiosis


These spores divide by mitosis giving rise to
gametophytes


Male gametophyte (
pollen grains
), Female
gametophyte (
embryo sac
)


Flower Structure


Are composed of floral organs:
sepals
,
petals
,
stamens
, and
carpels
; attached to the
receptacle
.


Complete flowers
have all four basic floral organs,
Incomplete
flowers
lack one or more.


A stamen consists of stalk called
filament

and
terminal structures called
anther
.


A carpel has an
ovary

at the base and a slender neck
called the
style
, on top of the style is a sticky
structure, the
stigma
.



Gametophyte Development and
Pollination


Pollination

is the transfer of pollen from an anther to
a stigma.


If pollination is successful, a pollen grain produces a structure
called a pollen tube, which grows down into the ovary and
discharges sperm near the embryo sac.


Within the pollen sacs of an anther are many diploid
cells called
microsporocytes
, which undergoes
meiosis forming four haploid
microspores
, which
later becomes a male gametophyte


Similarly in the ovary,
megasporangium

forms which
undergoes meiosis producing four
megaspores


Mechanisms That Prevent Self
-
Fertilization


The most common mechanism is
self
-
incompatibility
, the plant rejecting its own
pollen

After fertilization, ovules
develop into seeds and
ovaries into fruits


Double Fertilization


Double Fertilization
:
the union of two sperm
cells with different
nuclei of the embryo

From Ovule to Seed


After double fertilization


Each
ovule

develops into a seed


The
ovary

develops into a fruit enclosing the seed


Embryo Development


The first division of the
zygote is transverse,
splitting the egg into a
basal and terminal cell


The
terminal cell
gives
rise to most of the
embryo


The
basal cell
continues
to divide forming a
suspensor
, which
anchors the embryo to
the parent


Structure of the Mature Seed


During last stages of maturation the seed
becomes dormant and a protective
seed coat
is formed enclosing the embryo.



Hypocotyl
: embryonic axis


Radicle
: embryonic root


Epicotyl
: consists of the
shoot tip and miniature
leaves


Cotyledon
: absorbs
nutrients during germination


Coleoptile
: covers the shoot


Coleorhiza
: covers the young
roots


From Ovary to Fruit


Fruit protects the enclosed seed and aids in the dispersal of seeds

Many Flowering plants clone
themselves by asexual reproduction

Mechanisms of Asexual Reproduction


Fragmentation
-

the separation of a parent plant
into parts that re
-
form whole plants


Apomixis
-

the production of seeds without
fertilization


Callus
-

undifferentiated cells that allow shoots or
stems to develop roots and regenerate


Grafting


A twig or bud from one plant can be grafted onto a
plat of closely related species


Grafting

makes it possible to combine best qualities
of different species into a single plant


The plant that provides the root system is called the
stock

and the twig grafted is called the
scion

Test
-
Tube Cloning


Biologists have adopted
in vitro
methods to
clone plants


Trangenic
: genetically
modified organisms


Protoplast fusion
: used
to invent new plant
varieties that can be
cloned

Plant biotechnology is
transforming agriculture

innovations in the use of plants

use of genetically modified organisms

Reducing World Hunger and
Malnutrition


Genetically modified plants
have the potential of
increasing the quality and
quantity of food worldwide


Many political, social and
ethical debates >.<


Human Health


genetic engineering may transfer allergens
from a gene source to a plant used for food.


No creditable evidence



Possible Effects on
Nontarget

Organisms


Many ecologists are concerned that the growing
of genetically modified crops might have
unforeseen effects on nontarget organisms.


Must emphasize need for accurate field testing of
all genetically
modified

crops.

Addressing the Problem with
Transgene

Escape


Possibility of the introduced genes escaping from
a transgenic crop into related weeds through
crop
-
to
-
weed hybridization.


Despite all the concerns with genetically modified
crops their benefits should be considered.

Work Cited


Campbell and Reece 7
th

edition


Through the process of meiosis, diploid plants
are able to produce :

a) haploid spores

b) diploid spores

c) both a and b


d) none of the above

Male gametophytes are :

a) embryo sacs



b) pollen grains

c) formed from haploid

d) both b & c



microspores

Which of the following is the mechanism where
a plant rejects its own pollen?

a) double fertilization


b) fragmentation

c) self
-
incompatibility


d) grafting

What are some forms of asexual reproduction?

a)
fragmentation


b) apomixes and



and apomixes



callus

c) both a and b



d) all of the above

Which of the following describes grafting?

a) makes it possible to combine best qualities of
different species into a single plant

b) the separation of a parent plant into parts
that re
-
form whole plants

c) absorbs nutrients during germination

d) The first division of the zygote, splitting the
egg into a basal and terminal cell

Which of the following is not part of the flower
structure?

a) anther



b) ovary

c) receptacle


d) none of the above

Answers


Through the process of meiosis, diploid plants
are able to produce :

a)
haploid spores

b) diploid spores

c) both a and b


d) none of the above

Male gametophytes are :

a) embryo sacs



b) pollen grains

c) formed from haploid

d)
both b & c



microspores


Which of the following is the mechanism where
a plant rejects its own pollen?

a) double fertilization


b) fragmentation

c)
self
-
incompatibility


d) grafting


What are some forms of asexual reproduction?

a)
fragmentation


b) apomixes and



and apomixes



callus

c) both a and b



d)
all of the above


Which of the following describes grafting?

a)
makes it possible to combine best qualities
of different species into a single plant

b) the separation of a parent plant into parts
that re
-
form whole plants

c) absorbs nutrients during germination

d) The first division of the zygote, splitting the
egg into a basal and terminal cell


Which of the following is not part of the flower
structure?

a) anther



b) ovary

c) receptacle


d)
none of the above


Which of the following is not part of the flower
structure?

a) anther



b) ovary

c) receptacle


d)
none of the above