BIOL108 Lecture Notes - Lecture 14: Sporangium, Megaspore, Microsporangia
21 Jun 2018
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BIO 108 Lecture 14 – Gymnosperms
Vascular Seed Plants: gymnosperms
Seeds changed the course of plant evolution
Seed-bearing plants are the dominant producers in most terrestrial ecosystems
Seed = embryo + nutrients + protective coat
Non-vascular bryophytes: gametophyte dominant
Seedless vascular plants: Gametophyte independent
Seed plants have sporophyte dominant and gametophyte independent
The evolution of Pollen and seeds
1) Gametophyte dependant on sporophyte – no longer free-living
Gains – protection of game Toyota
Losses – more str
2) Pollen – male gametophyte, protected by a pollen grain
Giants – protection
Loss- need some mechanism to carry pollen (ex: air, insects)
3) Ovule – female gametophyte protected by sporophyte (non-motile)
Gain – protection
Loss – requires extra care for sporophyte
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Loss – requires extra care for sporophyte
4) Seeds – (fertilized ovule) contains the next generation sporophyte
Gain- protection, dispersal, food storage, dormancy
Loss- reat energy cost to plant
Female Gametophytes:
Integuments + megasporangium + megaspore = ovule (egg)
Megaspore (1n) produced within the megasporangium (2n)
Male Gametophytes:
Within the pollen grain
oMicrospore (1n) produced within microsporangium (2n)
MISSED SOME SLIDES ^^^^
Pollen:
Pollen rains coated with sporopollenin, making them tough
Can withstand drying, UV and physical damage
Important since male gametophytes have to disperse to pollinate and then fertilized ovule
Seed: (embryo + nutrient + protective coat)
find more resources at oneclass.com
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BIO 108 Lecture 14 – Gymnosperms
Embryo in gametophytes in parent sporophyte wrapping = seed
Range in size from minute orchid seed to giant “coco-do-mer”
Gymnosperm Life Cycle:
Mature tree is 2n sporophyte
Sporangia are located on scale-like leaves (sporophylls) in clusters (cones)
Heterospory = two types of sporangia (mega and micro – may be on same tree or different trees)
Pollination by wind
Seed dispersal also by wind
EXAM = 45 MULTIPLE CHOICE QUESTIONS
COVERS LECTURES: 1 – 18 (UP TO AND INCLUDING FUNGI)
NATURAL SELECTION AND DARWIN
80% of the questions will be knowledge based
20% will be synthesis and application (higher level thinking)
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BIOL108 Full Course Notes
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Document Summary
Seed-bearing plants are the dominant producers in most terrestrial ecosystems. Seed = embryo + nutrients + protective coat. Seed plants have sporophyte dominant and gametophyte independent. The evolution of pollen and seeds: gametophyte dependant on sporophyte no longer free-living. Losses more str: pollen male gametophyte, protected by a pollen grain. Loss- need some mechanism to carry pollen (ex: air, insects: ovule female gametophyte protected by sporophyte (non-motile) Loss requires extra care for sporophyte: seeds (fertilized ovule) contains the next generation sporophyte. Integuments + megasporangium + megaspore = ovule (egg) Megaspore (1n) produced within the megasporangium (2n) Within the pollen grain: microspore (1n) produced within microsporangium (2n) Pollen rains coated with sporopollenin, making them tough. Important since male gametophytes have to disperse to pollinate and then fertilized ovule. Embryo in gametophytes in parent sporophyte wrapping = seed. Range in size from minute orchid seed to giant coco-do-mer . Sporangia are located on scale-like leaves (sporophylls) in clusters (cones)
