BIO 1510: Lecture Exam 4-1: 41
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- Dominance of Angiosperms
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Most abundant plants on earth - 250,000 species (only 750 species of gymnosperms)
Cross-pollination between individuals lead to more genetic diversity
-Plants became more & more adapted to their environments
Co-evolution with insects, birds, & mammals facilitated pollination & seed dispersal
Fruits for seed protection
Fast seed production - Flowers: Definition
- Modified stems bearing modified leaves
- Flowers: receptacle
- Flower parts are attached in whorls to the receptacle (flower base that sits on the end of the stem)
- Flowers: Sepals
- 3-5; green & leaflike; protect the immature flower; have the ability to preform photosynthesis
- Flowers: petals
- colored to attract pollinators; may be separate, fused, or missing
- Flowers: Androecium
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whorl of stamens (pollen-bearing anthers attached to stalk-like filaments)
Pollen: usually contains male gamete - Flowers: Gynoecium
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one or more carpels (pistil), each containing an:
Ovary
Ovule
Stigma -
What do these 3 structures develope into?
Ovary
Ovule
Stigma -
(develops into a fruit)
(develops into a seed)
(sticky or feathery to adhere to pollen grains) - Flowers: Nectaries
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structures located at base of ovary that secrete nectar
fluid that contains sugars & other molecules to attract insects, birds, & other pollinators - corolla
- whorl of petals
- calyx
- whorl of sepals
- Pollination
- Process by which pollen is placed on the stigma
- What do pollen grains consist of?
- a tube cell & a generative cell
- Cross-pollination
- between individuals (carried by wind or animals)
- Self-pollination
-
male & female gametes from same plant
Ecologically advantageous under certain circumstances - What are the 2 major pollinators and what attracts each?
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Bees usu. attracted by odor
Birds usu. attracted by color - Dichogamous
- male and female parts mature at different times
- Name 2 advantages to dichogamous plants
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prevents self-polination
increases diversity - Double Fertilization
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Pollen grain adheres to stigma
- Tube cell grows down toward ovary
**Generative cell divides to form 2 sperm**
Tube penetrates the embryo sac
- One sperm fertilizes the egg, forming a diploid zygote (which becomes the seed)
- The other sperm fuses with 2 polar nuclei, forming a triploid endosperm (food supply for growing seed) - Through what process does the generative cell divide?
- MITOSIS
- Vegatative Reproduction
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A form of asexual reproduction resulting in genetically identical individuals
Offspring are clones from portions of roots, stems, leaves, or ovules - Types of Vegatative Reproduction
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Runners
Rhizomes
Suckers
Adventitious plantlets - Runners
- modified stems (strawberries)
- Rhizomes
- underground modified stems (weeds, potato “eyesâ€)
- Suckers
- buds on underground modified stems (bananas, dandelions)
- Adventitious plantlets
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arise from meristems on leaves
ex. maternity plant