ANDROECIUM Flashcards
The long and slender stalk of stamen is _________
Filament
How many lobes does anther generally have ?
2
Proximal end of filament attached to __________ or __________
Thalamus , petal
What 4 characteristics of stamen are variable in flowers of diff. species?
Number , length
shape,attachment of anther
Anther has 2 theca. True or false
False
each lobe has 2 theca (dithecous)
Often a horizontal groove runs lengthwise separating the theca. True or false
False
Longitudinal
Anther is a four sided str. What is such a structure called?
Tetragonal
How many microsporangia does anther have ?
4
Microsporangia develop into __________
Pollen sacs
Pollen sacs extend ________ in anther
horizonatally/longi.
longitudinally
What do pollen sacs contain ?
Pollen grains
In transverse section, outline of microsporangium resembles which shape?
Circle
What are the walls that surround microsporangium?
Epidermis , endothecium, middle layers, tapetum
outer to inner
What are the functions of outer three layers of microsporangium?
2
1) protection
2) help in dehiscence to release pollen
What is the function of tapetum ?
Nourishes the developing pollen grains
List 2 characters of tapetum cells?
1) Dense cytoplasm
2) More than one nucleus
What occupies the centre of microsporangium of young anther?
Sporogenous tissue
sporogenous tissue is a group of loosely arranged heterogenous cells. True or false
False
compactly , homogenous
Cells of sporogenous tissues go under meiosis to form ___________
microspore tetrad
All cells of sporogenous tissues are capable of giving rise to microspore tetrad. True or false
True
Cells capable of giving rise to microspore tetrad are called _________
Microspore mother cell/ Pollen mother cell
The process of formation of microspores
Microsporogenesis
What 2 conditions are required for microspores to dissociate from each other and develop into pollen grains ?
Mature , dehydrated
Describe the pollen grains released from opened anthers of Hibiscus
2 characters
Yellowish , powdery
Pollen grains of different species are completely similar.
True or false
False
variety in sizes,shapes,colours,designs
Pollen grains are generally spherical. What is their diameter?
25-50 micrometers.
What is the hard outer layer of pollen grain wall called?
Exine
Which layer of pollen grain shows array of designs and patterns?
Exine
Which substance is Exine made of?
Sporopollenin
What are the characters of sporopollenin
- temp. resistant
- strong acids, alkali resistant
- Cannot be degraded by enzymes
Pollen grains are well preserved as fossils due to the presence of __________
Sporopollenin
Prominent apertures in Exine are called __________
Germ pore
Function of germ pore
Emergence of pollen tube
Do germ pores lack sporopollenin?
yes/no
Yes
Inner wall of pollen grain is called______
Intine
Is intine thick or thin?
Thin
Intine is a discontinuous layer.
True or false
False
Continuous
Intine is made up of
Cellulose and pectin
How many cells does a mature pollen grain contain?
2
Vegetative, generative
Describe 3 characters of vegetative cell
- bigger
- abundant food reserve
- large irregularly shaped nucleus
List 4 characters of generative cell
- Small
- Floats in cytoplasm of vegetative cell
- spindle shaped
- dense cytoplasm
In over ________ percent of angiosperms , pollen grains are shed at the 2-celled stage
60
In rest of angiosperms , the generative cell divides meiotically to give rise to 2 male gametes before pollen grains are shed ( 3-celled stage)
True/false
False
mitotically
Chronic respiratory disorders caused by pollen grains
2 examples
Asthma, bronchitis
Example of plant which causes pollen allergy
Parthenium or carrot grass
How did Parthenium enter India ?
As a contaminant with imported wheat , then became ubiquitous
Are pollen grains lacking nutrients?
Yes/No
No
rich in nutrients
Pollen products like syrups and tablets were used as food supplements in eastern countries in ancient times.
True/False
False
Western, are being used in recent times.
What does pollen consumption help in?
Increases performance of athletes and race horses.
Pollen grains have to land on stigma after they lose their viability to bring about fertilisation.
True/False
False
before
What two factors does the viability of pollen grain depend on?
Prevailing temp. , humidity
In how much time do the pollen grains of rice and wheat lose their viability?
30 mins
What is the viable time period of Rosaceae, leguminoseae, solanaceae?
few months
Pollen grains can be stored for years using ____________ at __________(temp.)
Liq. nitrogen at -196 degree celsius
Stored pollen can be used as________ in crop breeding programmes.
Pollen banks
