35 overview, 38.2, 35.1
A. Discuss the pollination
and double fertilization
B. Describe the development of a seed from the ovule.
Diagram a typical eudicot and a typical monocot
seed, labeling seed coat
, and coleoptile
C. What is the strict definition and functions of the
Describe and diagram the development of a
simple, aggregate and multiple
fruit and give examples.
D. What factors are required to maintain and to break seed dormancy?
Diagram and label the germination of a monocot and a dicot seed.
F. Identify the various tissues of a young stem and discuss their functions.
Distinguish between the
arrangements in eudicot stems and monocot stems.
Polination and Double Fertiliazation
-After landing on a stigma, pollen gains moisture and germinates.
-produces a pollen tube that extends down between cells of style toward the ovary.
-Nucleus of generative cell divides by mitosis and forms 2 sperm cells.
-They are directed to the end of the pollen tube to enter the ovary through the microphyle and
discharge 2 sperm near/within embryo sac.
-1 sperm goes to zygote.
-Other combines with 2 polar nuclei to form a triploid 3n nucleus in the center of
embryonic sac giving rise to the endosperm which stores food and nutrients. [holds sugar of the plant]
-prevents union of 2 sperms with 1 ova.
-Endosperm develops only in ovules where egg was fertilized, preventing
angiosperms from squandering nutrients for nothing.
Structure of a Mature Seed
-last stages of maturation, seed dehydrates until its water content is only 5-15% of its weight.
-Embryo, surrounded by a food supply [cotyledons, endosperm, or both] becomes dormant.
-Stops growing, and its metabolism nearly ceases.
-Embryo and food supply are enclosed by a hard protective
formed from integuments
of the ovule.
Eudicot Garden Bean
-Embryo = elongate structure
= below point that cotyledons are attached at.
-Terminates in the
= embryonic root.