Exam 3 Flashcards
Plant spores are
single-celled haploid
structures that
develop into
gametophytes
Seeds are
multicellular
structures that
develop into mature
sporophytes
Most seedless vascular plants
are homosporous
– Produce ONE type of spore
hermaphroditic gametophyte
Heterospory
sporophyte is dominant
Independent
Longer lived
Larger
* Branching
More reproductive structures
* More spores
Survival following herbivory
Vascular plant
What are the vascular seedless plants
Seedless plants are lycophyta (club mosses), Psiotophyata( whisk ferns) , pteridophyta( ferns)
Equisetophyta (horsetails)
Structures that produce spores
– Meiosis
* Cluster of sporangia called sori
Sporangia
Arise from a spore
– Mitosis
* Independent
– Photosynthetic
– Rootlets
* Often contain both:
– Antheridia (produce sperm)
– Archegonia (produce eggs)
Gametophytes
Vascular naked seeds
Gymnosperms
Seed plant characteristics
Continued reduction in size of gametophytes
Heterospory
Pollen
Ovules
Produce seed
No antheridia in seed plants
* Microspores develop into pollen grains
* Pollen grain contains the male gametophyte
– Sperm produced from the male gametophyte
* Sperm do not swim (use water) to the egg
pollen
Pollen travels long distances
* Wind
– All Gymnosperms
– Some Angiosperms
* Pollinator
– Many angiosperms
Objective: 28-14
Dispersal of pollen
Contains 2 nuclei
* Pollen tube nucleus creates
tube
* Generative nucleus divides by
mitosis to create 2 sperm
- First sperm fertilizes egg
- Second sperm
- Dies in Gymnosperms
- Fertilizes the polar bodies in Angiosperms
Pollen structure
Female structures before fertilization
* Contains
– Integuments (diploid)
– Megasporangium (diploid)
– Archegonium (haploid) – gymnosperms only
– Megaspore (haploid)
* Develops into the seed after fertilization
Objective: 28-14
Ovules
What important role does lignin play in vascular plants?
A.It is the major component of the cuticle, which prevents plants from drying out.
B.It forms the outer layer of pollen grains.
C.It forms the tough, rigid cell walls of water-conducting cells.
D.It nourishes the embryo in seed plants.
C
t/f: pollination is fertilization
false (it is not)