Sexual Reproduction in Flowering Plants Flashcards
Further development of the floral primordium forms _______ which bear the floral buds and then the flowers.
Inflorescences
To a biologist, flowers are morphological and embryological marvels and the sites of _______________
Sexual reproduction
In the flower the male and female reproductive structures, the ___________ and the ___________ respectively differentiate and develop.
androecium; gynoecium
The female reproductive organ is represented by?
Gynoecium
The androecium consists of a whorl of:-
Stamen
The long and slender stalk of a stamen is called
Filament
The terminal structure at the top of the stamen is called
Anther
The proximal end of the filament is attached to the __________
Thalamus or petal
A typical angiosperm anther is ______ with each lobe having two theca.
bilobed
A stamen with two anther lobes is called
bilobed
The anther is a four-sided (tetragonal) structure consisting of four _________ located at the corners, two in each lobe.
Microsporangia
The microsporangia develop further and become:-
pollen sacs
A typical microsporangium appears near __________ in outline
circular
Name the four wall layers of microsporangium.
Epidermis, endothecium, middle layers and tapetum
Cells of_______ possess dense cytoplasm & generally have more than one nucleus.
Tapetum
The innermost wall layer of microsporangium is
Tapetum
When the anther is young, a group of compactly arranged homogenous cells called the _________________ occupies the centre of each microsporangium
Sporogenous tissue
As the anther develops, the cells of the sporogenous tissue undergo meiotic divisions to form?
Microspore tetrads
The process of formation of microspores from a pollen mother cell (PMC) through meiosis is called?
microsporogenesis
The ____________ represent the male gametophytes
Pollen grains
The hard outer layer of pollen grains is called the
Exine
No enzyme that degrades _____________ is so far known
Sporopollenin
Pollen grain exine has prominent apertures called
Germ pores
The inner wall of the pollen grain is called the ___________
Intine
When the pollen grain is mature it contains two cells, the ______________ and ________________
Vegetative cell and generative cell
In some cereals such as rice and wheat, pollen grains lose viability within _____ minutes of their release
30
Name the plant families which can maintain pollen viability for several months
Rosaceae, Leguminoseae and Solanaceae
Each pistil has three parts, namely-
The stigma, style and ovary
The _________ serves as a landing platform for pollen grains
Stigma
When the gynoecium consists of a single pistil, it is known as
Monocarpellary
When the gynoecium consists of more than one pistil, it is known as
Multicarpellary
when pistils are fused together, it is called?
Syncarpous
When the pistils are free, it is called:-
Apocarpous
Each pistil has three parts, the part which comes first is known as
Stigma
The _____ is located inside the ovarian cavity.
Placenta
Arising from the placenta are the __________, commonly called ovules.
Megasporangia
The ovule is a small structure attached to the placenta by means of a stalk called?
Funicle
The body of the ovule fuses with funicle in the region called?
Hilum
Each ovule has one or two protective envelopes called?
Integuments
Integuments encircle the nucellus except at the tip where a small opening called the ____________ is organised.
Micropyle
_____ represents the basal part of the ovule.
Chalaza
Enclosed within the integuments is a mass of cells called the _________
Nucellus
Name the structure located in the nucellus.
Embryo sac or Female gametophyte
The process of formation of megaspores from the megaspore mother cell is called?
Megasporogenesis
Only the functional megaspore develops into the __________________
Female gametophyte
In a majority of flowering plants, one of the megaspores is functional while the other ______ degenerate
three
The method of embryo sac formation from a single megaspore is termed _____________ development
Monosporic
A typical angiosperm embryo sac, at maturity, though 8-nucleate is ____-celled
7
Three cells are grouped together at the micropylar end and constitute?
Egg apparatus
The egg apparatus consists of how many cells?
Two synergids and one egg cell
The synergids have special cellular thickenings at the micropylar tip called?
Filiform apparatus
Name three types of pollination.
Autogamy, Geitonogamy and Xenogamy.
The transfer of pollen grains from the anther to the stigma of the same flower is called
Autogamy
The flowers which are similar to flowers of other species with exposed anther and stigma are called?
Chasmogamous
Bisexual flowers which do not open at all are called
Cleistogamous
Transfer of pollen grains from the anther to the stigma of another flower of the same plant is called
Geitonogamy
The transfer of pollen grains from the anther to the stigma of a different plant is called
Xenogamy
Name two agents of pollination
Biotic agents and abiotic agents.
Plants use _____ abiotic agents and _____ biotic agent to achieve pollination.
Two (wind and water) and one (animals)
Pollination by ______ is more common amongst abiotic pollinations
wind
What are the biotic agents for pollination?
Animals
Some examples of water pollinated plants which grow in fresh water are-
Vallisneria and hydrilla
Give an example of marine plant in which pollination occurs by water?
Zostera
In _____________, the female flower reach the surface of water by the long stalk
Vallisneria
Name some common biotic pollinating agents.
Bees, butterflies, flies, beetles, wasps, ants, moths, birds and bats
Among the animals, insects, particularly _______ are the dominant biotic pollinating agents
bees
What are the usual floral rewards for insect pollinators?
nectar and pollen grains
The devices which discourage self-pollination and encourage cross-pollination are called?
Outbreeding devices
If the female parent bears bisexual flowers, removal of anthers from the flower bud before the anther dehisces using a pair of forceps is necessary. This step is referred to as:-
Emasculation
Emasculated flowers have to be covered with a bag of suitable size, generally made up of butter paper, to prevent contamination of its stigma with unwanted pollen. This process is called?
Bagging
The other male gamete moves towards the two polar nuclei located in the central cell and fuses with them to produce a triploid:-
Primary endosperm nucleus (PEN).
After double fertilization, events of endosperm and embryo development, maturation of ovules into seeds and ovary into fruits, are collectively termed as
Post fertilization events.
A typical dicotyledonous embryo, consists of an __________________ and _______________________
Embryonal axis and two cotyledons.
The portion of embryonal axis above the level of cotyledons is called?
Epicotyl
The portion of embryonal axis below the level of cotyledons is called?
Hypocotyl
In the grass family, the cotyledon is called?
Scutellum
In monocotyledon embryos, at its lower end, the embryonal axis has the radical and root cap enclosed in an undifferentiated sheath called ________.
Coleorrhiza
Epicotyl has a shoot apex and a few leaf primordia enclosed in a hollow foliar structure, the ______.
Coleoptile
What is the final product of sexual reproduction in angiosperms?
Seed
