Chapter 38 Flashcards
Three basic reproductive structures of plants
Flower
Seed
Fruit
Flower
Produces gametes; develops seeds and fruit
Seed
Consists of embryo and nutrient stores
Fruit
Develops from flower and contains seeds
What is sexual reproduction based on
Meiosis and fertilization
Meiosis
nuclear division that reduces the number of chromosomes in the parent cell by half and produces four gamete cells.
Fertilization
fusion of haploid gametes that produces diploid zygote
Alternation of generations
Land plants have a life cycle with two distinct multicellular forms: one diploid (sporophyte) & one haploid (gametophyte)
Mosses
non-flowering plants which produce spores and have stems and leaves, but don’t have true roots.
Gametophyte
Haploid stage of life cycle
In bryophytes, such as mosses and liverworts, the gametophyte is the dominant life phase and the sporophyte is dependent on it
Sporophyte
Diploid multicellular stage of life cycle
In angiosperms and gymnosperms the sporophyte is dominant.
Asexual reproduction
does not involve fertilization & results in genetically identical copies of parent (clones)
- Advantage- very efficient (based on Mitosis)
- Disadvantage- genetically similar populations more likely to succumb to diseases
Rhizomes
horizontal stems from which shoots & roots emerge (nodes separate from parent plant)
Corms
underground modified stems
Plantlets
from meristematic tissue located along margins of leaves (drop off to form new plant)
Apomixis
when seeds form without fertilization (result in seeds genetically identical to parent)
What is flowering stimulated by
External cues
Internal cues
External cues
length of day/night or arrival of seasonal rains
Internal cues
related to nutritional needs
Basic organs of reproductive structures that are modified leaves
- Sepals
- Petals
- Stamens
- Carpels
All attached to receptable
Sepals
Reproductive structure
leaf-like structures, usually green & photosynthetic
- Arranged in circle (whorl) attached to receptacle & enclose flower bud as it develops/grows
Calyx
entire group of sepals in flower
Petals
arranged in whorl, often brightly colored to advertise flower to pollinators
Nectary
Gland contained in base of petals that produces nectar that is harvested by animals