Week 1 Flashcards
(31 cards)
What is the closest relative to land plants?
Charophytes (stoneworts)
Charophytes and land plants share which 4 features?
- Cell wall composition
- Cytokinesis
- Biochemistry
- Sperm Ultrastructure
What are ancestral traits?
Traits that stayed in the species from its ancestor.
What are derived traits?
Traits that evolved, that are innovative. These are due to adaptations and are not found in ancestors.
What are the adaptations to grow in dry conditions?
- Waxy cuticle
- Stomata
- Vascular tissue
What was the adaptation to defy gravity?
Lignified vascular tissue
What is lignin?
A complex polymer built from six-carbon rings. It is extraordinarily strong for its weight and is particularly effective in resisting compressing forces such as gravity.
What adaptations to provide protection from UV radiation?
Flavonoids acts as plants sunscreens (in all but hornworts)
What was the reproducing adaptation used to resist desiccation?
Desiccation-resistant walled spores (with sporopollenin) produced in multi cellular sporangia.
Are spores haploid of diploid?
Haploid (n)
What is the adaptation used to protect reproductive cells?
Multicellular gametangia that produce gametes. The benefit of this is to protects gamers from drying and from physical damage in gametophyte.
What is archegonia and antheridia?
The sperm producing structure is antheridium.
The egg producing structure is archegonium.
What are the adaptations to protect the embryo?
Multicellular embryo that develops within the mother plants. This is beneficial because the embryo is protected and nourished by the mother through the initial stages of life.
What is a sporophyte? What is a gametophyte?
A sporophyte is a diploid multicellular adult which produces spores by meiosis.
A gametophyte is a haploid multicellular adult which produces gametes by mitosis.
Explain/draw the alternation of generations.
- Sporophyte is a diploid multicellular adult that produces haploid spores by meiosis.
- Spores don’t fertilize but grow by mitosis into multicellular gametophytes.
- Gametophyte is a haploid multicellular adult that produces gametes by mitosis.
- Gametes must fertilize to create diploid zygote, which grows by mitosis into multicellular sporophyte.
- Cycle continues.
What is the benefit of alternation of generations?
- Diploid, multicellular sporophytes can make many more spores via meiosis than a single diploid zygote would.
- Spores produced on land are easily dispersed through wind and can travel long distances.
- In early lineages (mosses and ferns) sperm still requires water in order to swim to the egg. Later lineages, however (most seed plants) transfer their sperm in pollen grains.
What is the adaptation to successful reproduction on land? What is the benefit of this?
The transition from gametophyte-dominant to sporophyte-dominant life cycles (within land plants).
This is beneficial because diploid sporophyte cells can respond more effectively to changes in the environment than gametophyte haploid cells can (hence the advantage of sporophyte-dominant life cycles).
What is heterospory? What is homospory? What is the befit of heterospory?
Heterospory: The production of two different spores by different structures. This made possible 2 of the most important adaptation for life in dry environments: pollen and seeds.
Homospory: The production of a singly type of spore.
What are microspores and megaspores?
Microspores: male gametophyte; sperm by mitosis
Megaspores: female gametophyte; eggs by mitosis
How are pollen grains formed?
In heterosporous seed plants, the microspore germinates to form a tiny male gametophyte that is surrounded by a tough coat of sporopollenin.
What are the benefits to pollen?
- Pollen grain can be exposed to air for long periods of time without drying out.
- They are tiny enough to be easily carried away by wind or animals.
- Once it evolved, heterosporous plants lost their dependence on water to accomplish fertilization.
What is the downside of retaining embryo’s? What is the function of a seed plant?
In ferns and horsetails, sporophytes have to live in the same place as the parent gametophyte. Seed plants overcome this limitation via well-packed embryos that can be dispersed to new locations.
What are the benefits of the seed?
- Seeds encase the embryo to protect in from drying out.
- Seeds contain food supply for the early embryo survival.
- They can be dispersed.
What are The 3 misconceptions?
1) Misconception 1: Algae are embryophytes.
CORRECTION: Algae are not embryophytes, and this feature distinguishes plants from algal protists.
2) Misconception 2: Charophyceans are plants.
CORRECTION: Charophyceans are larger algae resembling plants but are not plants.
3) Misconception 3: Charophyceans are ancestral to plants.
CORRECTION: Charophyceans are not ancestral to plants nor identical to the last common ancestor shared with the plants.