BIOL-1507EL Study Guide - Winter 2018, Comprehensive Midterm Notes - Zygote, Xylem, Xerophyte
12 Oct 2018
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Department
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BIOL-1507EL
MIDTERM EXAM
STUDY GUIDE
Fall 2018
PART A— PLANT BIOLOGY CONTENT
1. Plant diversity and colonization of land
Biodiversity in the plant kingdom
Origin: Algae in the water
When moved to land, started to create pollen
In the green algae:
The haploid dominates the life cycle
The haploid alga spends most of its life producing and releasing gametes into the surrounding water
The single zygote is the only diploid stage
Defining characteristics of land plants—
Land plants are eukaryotes
Not all are capable of photosynthesizing
Almost all plants are photoautotrophs
Photoautotrophs definition- organisms that use light as their energy source and carbon dioxide as their carbon source
Plants differ from animals in that plants:
All plants are multicellular
Plant cells have walls that are made up of cellulose
All plants are sessile or stationary (not able to move around) and no terrestrial animals are sessile
All plants have
Cell wall
Vacuole
Chloroplast
Plants have an alternation of generations life cycle
Two multicellular stages in the life cycle
One diploid
One haploid
Sporophyte—The diploid generation produces spores
— sporophyte generation begins after fertilization
Gametophyte — The haploid generation produces gametes by mitosis
—The function is to nourish and protect the forthcoming sporophyte generation
—The embryo is retained inside of the gametophyte tissue
Plants are nearly all terrestrial, although some plants have returned secondarily to water during their
evolution
Zygote— diploid stage
Zygote divides by meiosis to produce spores that gives rise to the haploid stage again
Spores— haploid stage
LIFE CYCLE of land plants:
1. The haploid phase of the plant life cycle begins in specialized cells of the sporophyte, where haploid spores are
produced by meiosis
— plants meiosis produces spores not gametes
— spores are single haploid cells with fairly thick cell walls
2. When a spore germinates, it divides by mitosis to produce a multicellular haploid gametophyte
1
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3. Each generation gives rise to the other “Alternation of generation”
4. Embryo is known as the new sporophyte generation
*Figure 26.1- Life cycle of land plants*
Plants produce their gametes within the gametangia
Gametangia: Organs having protective jackets of sterile cells, that prevent the delicate gametes from drying out
In the life cycle of all plants there is an alternation of generation occurring in which haploid (n) gametophyte
and diploid sporophyte takes turns producing each other
Sporangia: produce spores by meiosis
The transition to life on land—
Algae
Greening of the earth:
For more than first 3 billion years of the earth’s history, the terrestrial surface was life-less
Geochemical evidence suggests that a thin coating of cyanobacteria (Blue-Green Algae) existed on the land
surfaces approximately 1.2 billion years ago
Only approximately 500 million years ago plants, fungi, animals joined on the land
2
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find more resources at oneclass.com
Document Summary
Fall 2018: plant diversity and colonization of land. When moved to land, started to create pollen. The haploid alga spends most of its life producing and releasing gametes into the surrounding water. The single zygote is the only diploid stage. Photoautotrophs definition- organisms that use light as their energy source and carbon dioxide as their carbon source. Plant cells have walls that are made up of cellulose. All plants are sessile or stationary (not able to move around) and no terrestrial animals are sessile. Plants have an alternation of generations life cycle. Two multicellular stages in the life cycle. Gametophyte the haploid generation produces gametes by mitosis. The function is to nourish and protect the forthcoming sporophyte generation. The embryo is retained inside of the gametophyte tissue. Plants are nearly all terrestrial, although some plants have returned secondarily to water during their evolution. Zygote divides by meiosis to produce spores that gives rise to the haploid stage again.
