what are theca? - The typical anther is bilocular, i.e. it consists of two thecae. Each theca contains two microsporangia
What are microsporangia? - Are the pollen sacs. Microsporangia produce the microspores, which for seed plants are known as pollen grains
How many theca and sporangia are p...
BIOL 325 Final Exam Questions and
Answers 2024
what are theca? - The typical anther is bilocular, i.e. it consists of two thecae. Each
theca contains two microsporangia
What are microsporangia? - Are the pollen sacs. Microsporangia produce the
microspores, which for seed plants are known as pollen grains
How many theca and sporangia are part of each anther? - Theca: 2
Microsporangia: 4
What separates the two theca? - A longitudinal groove
What are the pollen sacs lined with? - tapetum cells
What are tapetum cells? - Nutrition
What is microsporogenesis? - After meiosis haploid microspores in the pollen sacs
undergo several changes
-Microspore divides once by meiosis to produce two cells
-small generative cell is formed inside larger cell
-Tetrad of microspores separate from each other
-A two-layered wall develops around each spore
-in 2/3 of flowering plant species pollen grain is released at the 2 cell stage
, -For others, the generative cell divides to produce 2 sperm resulting in a 3-celled
microgametophyte
What is reduced male gametophyte? - Another apomorphy of angiosperms is a
reduced 3-celled male gametophyte- no other plant group has a male gametophyte
so reduced in cell number
What is Mature microgametophyte? - germinated pollen grain, with tube nucleus
and 2 sperm cells
What is pollination? - Transfer of the pollen grains to the stigmas.
-Pollen grains hydrate
-Germinate: forming pollen tube
-Pollen tube grows through stigma to ovules
What happens if the generative cell remains undivided? - Divides to form 2 sperm
cells
What is double fertilization? - -Pollen tube enters ovule through micropyle
-then enters 1 of the synergids
-2 sperm and tube nucleus discharged into synergid
-1 sperm enters the egg cell- fertilization
-Other sperm enters central cell and unites with 2 polar nuclei
-tube nucleus, remaining synergid and antipodals degenerate
Definition of double fertilization - The union of one sperm with the egg and the
other with the polar nuclei is called double fertilization
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