PL SCI 221 EXAM QUESTIONS AND ANSWERS
LATEST UPDATE
Why do we need plants and plant science ?
- provide oxygen, food and more
- slow down erosion, desertification and dust storms
- trees provide habitat for animals, shelter and wood
Improve mental health (place for recreation, people love forest, parks and gardening)
Seed: definition and significance
Seed is a mature fertilized ovule consisting of embryo, seed coat (testa) (protects
embryo) and food source (nourishes embryo)
Alternation of generations define
Subsequent generations of individuals alternate between haploid and diploid organisms.
In these organisms, most or all tissue can be haploid
Gametophyte
Haploid gamete- producing phase in the life cycle
Gametes are formed in sexual organs: antheridia (-> sperm) and archegonia (-> egg)
gametophyte dominant
bryophytes
Sporophyte
Is the diploid spore-producing phase in the life cycle
sporophyte dominant
Ferns
Sporophyte dominant and gametophyte greatly reduced
Gymnosperms and angiosperms
Homospory vs. Heterospory
homospory is the production of a single type of spores with the same size whereas the
heterospory is the production of two types of spores, megaspores and microspores, with
different sizes.
Disadvantage of homospory
The new sporophyte, while developing from the zygote is temporarily dependent on a
tiny gametophyte for its start in life
Why is megagametophyte inside maternal sporophyte (ovule)
LATEST UPDATE
Why do we need plants and plant science ?
- provide oxygen, food and more
- slow down erosion, desertification and dust storms
- trees provide habitat for animals, shelter and wood
Improve mental health (place for recreation, people love forest, parks and gardening)
Seed: definition and significance
Seed is a mature fertilized ovule consisting of embryo, seed coat (testa) (protects
embryo) and food source (nourishes embryo)
Alternation of generations define
Subsequent generations of individuals alternate between haploid and diploid organisms.
In these organisms, most or all tissue can be haploid
Gametophyte
Haploid gamete- producing phase in the life cycle
Gametes are formed in sexual organs: antheridia (-> sperm) and archegonia (-> egg)
gametophyte dominant
bryophytes
Sporophyte
Is the diploid spore-producing phase in the life cycle
sporophyte dominant
Ferns
Sporophyte dominant and gametophyte greatly reduced
Gymnosperms and angiosperms
Homospory vs. Heterospory
homospory is the production of a single type of spores with the same size whereas the
heterospory is the production of two types of spores, megaspores and microspores, with
different sizes.
Disadvantage of homospory
The new sporophyte, while developing from the zygote is temporarily dependent on a
tiny gametophyte for its start in life
Why is megagametophyte inside maternal sporophyte (ovule)
