Lecture 20: Seed Plants, Gymnosperms and Angiosperms (Midterm III) Flashcards
1
Q
What are two key adaptations that allowed plants to inhabit terrestrial ecosystems?
A
seeds and pollen grains
2
Q
what is a seed
A
consists of an embryo (entire individual) and nutrients surrounded by a protective coat
3
Q
4 common characteristics among seed plants
A
heterospory, reduced gametophytes, ovules, and pollen
4
Q
- heterospory (seed plants)
A
- ancestors of seed plants were likely homosporous, while seed plants are heterosporous
- sees plants produce two different spore sizes: microspores –> males, megaspores –> female gametophytes
- Megasporangia (2n) –> megaspores (n) & microsporangia (2n) –> microspores (n)
5
Q
- reduced gametophytes (seed plants)
A
- provides protection as the gametophytes of seed plants develop within walls of spores retained within tissues of the parent sporophyte
6
Q
- ovules (seed plants)
A
- integument + megasporangium + megaspore or egg
- gymnosperm megasporangia have one integument
- angiosperm with two integuments
7
Q
- pollen (seed plants)
A
- microspores develop within **pollen grains **
- pollination
- **pollen eliminates the need for a film of water and can be dispersed great distances by air or animals **
- if a pollen grain germinates, it gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovule
8
Q
explain seeds and their development
A
- a seed develops from the whole ovule
- a seed is a sporophyte embryo, along with its food supply, packaged in a protective coat
9
Q
evolutionary advantage of seeds
A
- may remain dormant for days to years, until conditions are favorable for germination
- may be **transported long distances ** by wind or animals
10
Q
Gymnosperms and their 4 phyla
A
- they have “naked” seeds not enclosed by ovaries
1. cycadophyta (cycads)
2. gingkophyta (ginkgo biloba)
3. gnetophyta ( 3 genera: Gnetum, Ephedra, Welwitschia)
4. Coniferophyta (conifers, such as pine, fir, or redwood)
11
Q
Ginkgophyta
A
- ## high tolerance to air pollution & a popular ornamental tree
12
Q
Cycadophyta
A
- 200 species
- palm-like
- seeds produced large cones
- thrived during the Mesozoic, relatively few species exist today
13
Q
Gnetophyta
A
- diverse
- ## species vary in appearance, some tropical others live in deserts
14
Q
Coniferophyta
A
- 550 species, important ecologically and economically
- needle-shaped leaves
- mostly evergreen
- largest forests on Earth are mostly conifers
- largest organism: giant sequoia
- tallest organism: coast redwood
- oldest non-clonal organism: bristlecone pine
15
Q
3 key features of the gymnosperm life cycle
A
a. dominance of sporophyte generation
b. development of seeds from fertilized ovules
c. transfer of sperm to ovules by pollen
16
Q
life cycle of a pine
A
- familar pine tree is the sporophyte and produced sporangia in male & female cones
- small cones produce microspores within pollen grains; microspore will develop into male gametophyte
- familar large cones contain ovules, which produce megaspores that develop into female gametophytes
17
Q
over time, what two adaptations occur in plants (angiosperms)
A
- decreasing reliance on liquid water for fertilization
- increasing dominance of sporophyte generation
18
Q
what are angiosperms
A
- seed plants with reproductive structures called flowers & fruits
- most widespread & diverse of all plants
19
Q
3 characteristics of angiosperms
A
- all classified in a single phylum, Anthophyta
- the flower is a unique structure to Angiosperms specialized for sexual reproduction
- many species are pollinated by animals, while some are wind-pollinated, others are selfing
20
Q
four types of leaves on flowers
A
- sepals (calyx) – cover immature flower bud
- petals: (corolla) - brightly colored & attract animals to serve as **pollinators **
- stamens: microsporophylls; make microspores which make male gametophytes (pollen) within the anthers
- carpels: megasporophylls; make megagaspores, female gametophytes, and seeds
21
Q
fruits and their characteristics
A
- consists of a mature ovary but can also include other flower parts
- fruits protect seeds and aid in their dispersal
- mature fruits can be either fleshy or dry
- fruits help disperse seeds
- seeds can be carried by wind, water or animals
22
Q
Angiosperm Life Cycle
A
- flower of sporophyte is composed of both male and female structures
- male gametophytes are contained within pollen grains produced by microsporangia of **anthers **
- female gametophyte/**embryo sac **develops within an ovule contained within an ovary at the base of a stigma
- flowers have mechanisms for cross-pollination between flowers from diff plants from the same species
23
Q
3 unique reasons for angiosperms success
A
- rapid life cycle
- symbioses
- pollination: efficient targeted delivery
- fruit & suit dispersal: for transport
- mycorrihizae (interactions between soil fungi & roots) - more effective vascular tissues - vessel elements, sieve tube members
24
Q
two main types of angiosperms
A
monocots (one cotyledon) & eudicots (two cotyledons)
25
monocots
a. single cotyledon (embryo starts with **one leaf**
b. **parallel leaf vasculature**
c. **complex arrangement of vascular bundles**
d. fibrous roots
e. flowers in multiples of 3
f. ex ( major grains, lilies, orchids, yuccas, palms, grasses)
26
eudicots
a. **double cotyledon** - starts with two leaves
b. leaf vasculature tends to be a **network **
c. vascular bundles in stem arranged in a ** ring**
d. central large **taproot**
e. flowers in multiples of 4 or 5
f. ex ( legumes(peas), broad-leafed trees (oaks, maples), roses; most human crops
