Final Exam Flashcards
What are the two ways plants grow?
-Cells can divide
-Individual cells can grow larger
What is plant DEVELOPMENT?
change in phase of life or change in life process
What factors influence plant development?
-genetic
-environmental
-hormones
What are the stages of plant development?
Seed Germination, Vegetative Growth, Reproductive Growth, Senescence
Seed Germination
*Inbibition–a dry seed soaking up water
*increase in biological activity–all sorts of biochemical processes begin, hormones and enzymes become active
*radicle growth–to absorb more water
*cotyledon emerges
*cell division begins and primary shoot as well. as first true leaves are growing
Vegetative Growth
-Shoot Growth
-Root Growth
Reproductive Growth
*flowers and fruit develop
-this may be done during or at the end of vegetative growth, depending on the plant
Senescence
loss of leaves and/or plant death
What are the three possible growth patterns of plants?
Annuals, Biennials, Perennials
Annuals
*complete vegetative and reproductive cycle in one growing season
-usually herbaceous plants
Biennials
*perform vegetative growth the first year and sexual reproductive growth the second year
-many are only grown annually
Perennials
live many years and reproduce several years out of their life cycle
What are the two ways plants can reproduce?
*sexual–seed
*asexual–through vegetative structures
Remember: Many plants can reproduce both sexually and asexually. What are the pros and
cons of each?
Sexually Pros: Genetic Variation
-seeds can survive long periods of dormancy/adverse conditions
-seeds can spread a long way
-adapt to new weather, pests
Asexually Pros: No pollination reliance
-if adapted to current conditions, all offspring will be adapted
-less energy intensive for the plant
Describe the process of pollination.
-pollen (male gamete) landing on the receptive stigma of a flower
-insect, vertebrae and wind pollination
Describe the process of fertilization.
*process of nuclei from the pollen traveling down to the ovary to fertilize the egg
*several nuclei are involved–double fertilization
-2 nuclei are in pollen
-3 nuclei are in egg
*1 nucleus from pollen builds pollen tube down to ovary
*1 nucleus from pollen combines with 1 from egg to form zygote
*other 1 nucleus from pollen combines with 2 remaining nuclei from egg–forms endosperm
*endosperm is food storage tissue for egg–high in carbohydrates for germination
Describe the process of fruit development.
*in many plants, only a small percentage of flowers develop into fruits
-some dont become pollinated
-some dont become fertilized
-some abort after fertilization
*very complex processes, some will not understand
*several plant hormones are involved
*For farmers–sometimes need to find right balance of furit–not too little and not too many
-larger=less fruit
-smaller=more fruit
*undergo a period of rapid division, followed by rapid expansion
*starch accumulates & cells continue to expand
*starch remains or breaks down into sugars as ripening occurs
What do plant hormones do?
act as signaling compounds that tell the plant to begin, increase, decrease or cease any processes
What processes might this include?
-cell division
-entering dormancy
-starting reproduction
-seed germination
-root formation
-cell & tissue death
T/F: can the same group of hormones act on plants in multiple different ways, depending on where and when in the plant they are produced?
True
What are the criteria for plant hormones?
*be endogenous–produce within the plant
*be an organic compound (carbon-containing)
*be present in low concentrations
*able to be translocated through the plant
*not a plant nutrient
*plant growth regulators–mimic of naturally produced plant hormones (we apply them to plants in AG)
What are the 5 main plant hormones?
*Auxin
*Giberrelin (s)
*Cytokinin (s)
*Abscisic Acid
*Ethylene
Auxin
*stimulate cell growth–used as rooting hormones in nurseries
*responsible for apical dominance–plants ability to grow/stand upright
*responsible for phototropism–how plants bend towards light
*responsible for thigmotropism–growth of a plant around an object
*certain synthetic auxins (2, 4-D)–used as a herbicide, causes uncontrolled cell division and eventual plant death
Gibberellin
responsible for:
-stem growth
-transition from juvenile to adult phases of perennials
-floral initiation
-sex determination
-seed germination
*sometimes added with seeds or certain plant species that are hard to germinate
*Gibberellin inhibitors are sometimes sprayed on ornamental plants to keep them compact
*Sprayed on certain fruits to increase size