Sexual rep in flowering plant Flashcards
Are we not lucky that plants reproduce sexually? The —- that we enjoy gazing at, the —- that we swoon over, the — that attract us, are all there as an aid to sexual reproduction.
myriads of flowers
scents and the perfumes
rich colours
Flowers do not exist only for us to be used for —.
our own selfishness
All flowering plants (—-) show sexual reproduction. T/F
Angiosperms
True
A look at the diversity of structures of the — , —- and — shows an amazing range of —- to ensure formation of the end products of
sexual reproduction, the — and —-.
inflorescences, flowers , floral parts,
adaptations
fruits and seeds
Human beings have had an intimate relationship with —- since time immemorial.
flowers
Flowers are objects of —- (5) value
– they have always been used as —-for conveying important human feelings such as love, affection,
happiness, grief, mourning, etc.
aesthetic, ornamental, social, religious and cultural
symbols
To a biologist, flowers are — and —marvels and the —-.
morphological and embryological
sites of sexual reproduction
Much before the actual flower is seen on a plant, the — has taken place.
decision that the plant is going to flower
Several — and —- changes are initiated which lead to the differentiation and further development of the —-.
hormonal and structural
floral primordium
Inflorescences are formed which bear the —- and then the —-.
floral buds
flowers
In the flower the male and female reproductive structures, the — and — differentiate and develop.
androecium and the gynoecium
Androecium consists of a whorl of —- representing the male reproductive organ and the — represents the female reproductive organ.
stamens
gynoecium
Two parts of a typical stamen – the —- called the filament, and the —
called the anther.
long and slender stalk
terminal generally bilobed structure
The proximal end of the filament
is attached to the —- of the flower.
thalamus or the petal
The — and —- of stamens are variable in flowers of different species.
number and length
A typical angiosperm anther is — with each lobe having —-, i.e. they are —–
bilobed
two theca, i.e., they are dithecous
Often a —– runs —- separating the theca.
longitudinal groove
lengthwise
The —- of an anther is very distinct in the transverse section of the anther.
bilobed nature
The anther is a —-sided (—) structure consisting of — located at the corners, two in each lobe.
four
tetragonal
four microsporangia
The microsporangia develop further and become —-
pollen sacs.
Pollen sac extend — all through the —- and are packed with —-
longitudinally
length of an anther
pollen grains.
Structure of microsporangium:
In a transverse section, a typical microsporangium appears — in outline.
near circular
Microsporangium generally surrounded by — wall layers – the —, —, — and —–.
four
epidermis, endothecium, middle layers and the tapetum
The — three wall layers perform the function of —- and help in
—- .
outer
protection
dehiscence of anther to release the pollen
The innermost wall layer is
the —. It nourishes the —-.
tapetum
developing pollen grains
Cells of the tapetum possess —-cytoplasm and generally have—-
nucleus.
Can you think of how tapetal cells could become BI-NUCLEATE?
dense
more than one
When the anther is —, a group of —, —– cells called the —- tissue occupies the centre of each
microsporangium.
young
compactly arranged homogenous cells
sporogenous
Microsporogenesis :
As the anther develops, the cells of the —– undergo meiotic divisions to form —-.
What would be the ploidy of the cells of the tetrad?
sporogenous tissue
MICROSPORE TETRADS
As each cell of the sporogenous tissue is capable of giving rise to a
—-. Each one is a —-.
microspore tetrad
potential pollen or microspore mother cell
The process of formation of —- from a —- through meiosis is called microsporogenesis.
microspores
pollen mother cell (PMC)
The microspores, as they
are formed, are arranged in a —-–the —-
cluster of four cells
microspore tetrad
As the anthers — and —-, the microspores dissociate from each other and develop into —
mature and dehydrate
pollen grains
Inside each microsporangium —- of microspores or pollen grains are formed that are released with the —-
several thousands
dehiscence of anther
The —– represent the male gametophytes.
pollen grains
If you touch the —- of Hibiscus or any other flower you would find
deposition of —– on your fingers.
opened anthers
yellowish powdery pollen grains
Sprinkle pollen grains on a drop of — taken on a —- and observe under a microscope. You will really be amazed at the variety of —-– sizes, shapes, colours, designs – seen on the pollen grains from different species
water, glass slide
architecture
Pollen grains are generally —measuring about —- in —-.
spherical
25-50 micrometers
diameters
Pollen has a prominent —-
wall.
two-layered
The —- outer layer called the —- is made up of —-
hard, exine
sporopollenin
Sporopollenin is one of the —-
known.
most resistant organic material
Sporopollenin can withstand —- and —-.
—- that degrades sporopollenin is so far known.
high temperatures
strong acids and alkali
No enzyme
Pollen grain exine has — called —- where sporopollenin is absent.
prominent apertures
germ pores
