U4 L1 - KINGDOM PLANTAE

What are key characteristics of Kingdom Plantae?

• Multicellular eukaryotes

• Autotrophs (photosynthesis)

• Mainly terrestrial, with adaptations to prevent drying out

What are the two main criteria for classifying plants?

1. Presence or absence of vascular tissues

2. Produce seeds or are seedless

What is the difference between vascular and non-vascular plants?

• Vascular: Have roots, stems, and leaves with vascular tissues (transport tissues)

• Non-Vascular: Lack or have poorly developed roots, stems, and leaves (e.g., mosses)

What are characteristics of seedless non-vascular plants?

• Include mosses, hornworts, liverworts

• No vascular tissues (rely on diffusion/osmosis)

• No roots; have rhizoids (root-like structures that hold water)

What are examples and traits of seedless vascular plants?

• Include whisk ferns, club mosses, horsetails, and ferns

• Have vascular tissues

• Range in structure: whisk ferns (no leaves/stems) → ferns (developed leaves and thick rhizomes)

What challenge do seedless plants face in sexual reproduction and how is it solved?

• Problem: Gametes need water to move without drying out

• Solution: Rely on dew or rain for fertilization

What is the difference between haploid (n) and diploid (2n) cells?

• Haploid (n): 1 set of chromosomes

• Diploid (2n): 2 sets of chromosomes

What is "alternation of generations"?

A life cycle alternating between a haploid (gametophyte) and a diploid (sporophyte) stage

What happens in the diploid (2n) stage of alternation of generations?

The sporophyte (2n) produces haploid spores (n) by meiosis. These spores grow into gametophytes (n) through mitosis

What happens in the haploid (n) stage of alternation of generations?

The gametophyte (n) produces male and female gametes (n) by fertilization to form a zygote (2n), which grows into a sporophyte (2n) via mitosis.

What are the steps in alternation of generations?

1. Gametophyte (n) produces gametes (n) by mitosis

2. Gametes fuse → zygote (2n)

3. Zygote grows → sporophyte (2n)

4. Sporophyte (2n) produces spores (n) by meiosis

5. Spores (n) grow into mature gametophytes (n)

Which generation is dominant in different plant types?

• Non-Vascular Plants → Gametophyte dominates

• Vascular Plants → Sporophyte dominates

What are the two groups of seed-producing vascular plants?

Gymnosperm and Angiosperm

What are key characteristics of gymnosperms?

• Cone-bearing plants (e.g. conifers)

• “Naked seeds” (not covered by fruit)

• Seeds exposed on cone scales

• Pollen from male cones is carried to female cones by the wind

How do gametophytes exist in gymnosperms?

• Gametophytes reduce in size (microscopic, inside cones)

• Male gametophyte = pollen grain

• Female gametophyte = small group of haploid cells

What are characteristics of angiosperms?

• Flowering plants (e.g. trees, grasses)

• Seeds covered by fruit

• ¾ of plants today

What are the two angiosperm subgroups?

Monocots and Dicots

How does pollination and fertilization occur in angiosperms?

• Pollinators (insects, birds, etc.) transfer pollen

• Pollen lands on stigma, grows pollen tube to reach the ovule

What happens after fertilization in angiosperms?

Seeds develop and ovary matures to form a fruit/pod

What is the function of fruit in plant reproduction?

Seed dispersal, aided by wind, animal digestion, or attachment to animals