Plants

Question 1

Plants

Answer 1

Domain Eukarya,
Kingdom Plantae

• multicellular eukaryotes
• well-developed tissues
• mostly terrestrial and sessile
• exhibit embryo protection
• Photoautotrophic

Question 2

Plants: Major groups

Answer 2

Non-Vascular Plants (all are seedless)

Vascular Seedless Plants

Gymnosperms

Angiosperms

Question 3

Present number of species of land plants

Answer 3

roughly 290,000 species

Question 4

The earliest plants

Answer 4

Fossil spores from about 475 million years ago.

Tough-skinned spores provide excellent fossil records.

(Fungi fossils show 470 myo),

Question 5

Plants: Life on Land (475 mya)

Answer 5

To adapt to life on land, plants evolved features that allow them to

• resist drying out (absorb and retain water)
• absorb nutrients
• stand upright without outside support
• reproduction not dependent on water

These features appeared over time

Question 6

Key traits of land plants

Answer 6

1. apical meristems
2. tough, resistant spores from sporangia
3. special organs for production of gametes

Question 7

Plant Adaptations:

Embryo Protection

Answer 7

all plants nourish a multicellular embryo in the body of the female plant
- this feature distinguishes plants from green algae

first appeared in the non-vascular plants (the bryophytes)

Question 8

Non-Vascular Plants (Bryophytes)

Answer 8

Simplest, most primitive plants

Lack roots and vascular tissue

• water and nutrients move by diffusion
• small in size
• dependent on water for reproduction

Ex: mosses, liverworts, hornworts

Question 9

Earliest plants

Answer 9

mosses

Question 10

Bryophytes

Answer 10

mosses (15,000 species)
liverworts (100)
hornworts (9,000)

Question 11

Qualities of earliest plants

Answer 11

• have cuticle
• don’t have roots or true leaves (require moisture)
• are small
• today compose 7% of plant species

Question 12

vascularity

Answer 12

93%

Question 13

Plant Adaptations:

Vascular Tissue

Answer 13

Distinguishes vascular plants from non-vascular plants

Xylem transports water and minerals from roots upward

Phloem transports organic nutrients from photosynthesis downward

Question 14

Xylem

Answer 14

transports water and minerals from roots upward.

Made of dead cells with rigid cell walls.

Provides the plant with structural support.

Question 15

Phloem

Answer 15

transports organic nutrients (sugar) from photosynthesis downward from the leaves.

Made up of living cells with thinner cell walls.

Question 16

Seedless Vascular Plants

Answer 16

Includes club mosses, ferns, horsetails, and whisk ferns.

The first to evolve vascular tissue to transport:
- water and inorganic nutrients from roots upwards (xylem)
- dissolved sugar the leaves downward (phloem)
- Are larger than bryophytes as a result
- Use spores for reproduction
wind-dispersed

Question 17

Eariliest vascular plants (extant species numbers)

Answer 17

Lycophytes: (1,200 species)
Pterophytes: ferns 12,000 species (ferns) and horsetails 15 species

Horsetails: all in the genus Equisetum

Question 18

Plant Adaptations:

Seeds

Answer 18

• Distinguishes plants with seeds from the seedless vascular plants
• Seed: an embryo and stored nutrients within a protective coat

Question 19

Vascular Seed Plants (Gymnosperms)

Answer 19

• The first plants to evolve seeds; use seeds for dispersal rather than spores.
• Most are cone-bearing (conifers)
• “naked seeds”
• Do not need water to reproduce
• Do not produce flowers or fruit

Examples: conifers: pine, spruce, cycads, ginkos

160 mya, gymnosperms dominated forests

Very successful

• deserts to tundra
• sea level to tree line
• taller and older than any other plants

Question 20

In the beginning, the seeds were naked…

Answer 20

gymn = naked

Gymnosperm = “naked seeds”

Question 21

Gymnosperms 4 Phyla

Answer 21

Cycadophyta (cycads)
Gnetophyta

Gingkophyta (ginko: only extant species is Gingko biloba)
Coniferophyta (conifers) (about 600 species)

Question 22

Plant Adaptations:

Flowers and Fruits

Answer 22

Flowers: reproductive structures that attract pollinators and develop into fruit

Flowers distinguish the angiosperms from the gymnosperms

Question 23

Angiosperms: 1 Phylum

Answer 23

Anthophyta (a.k.a., Magnoliophyta)
= about 90% of all plant species

the first and only plants to have flowers and produce fruit.

Highly diverse: ~six times as many species of angiosperms as there are of all other plant species combined

Question 24

The flowers of angiosperms

Answer 24

The flower is a modified shoot (stem with leaves) with up to four whorls of modified leaves encircling the stem

2 whorls are “sterile” (i.e., not directly involved in reproduction): sepals & petals

2 whorls are “reproductive”:
stamens (produce pollen) and carpels (contain the ovule(s))

Question 25

Flowers

Answer 25

In angiosperms, the ovule is buried in the tissue of a flower (i.e., not naked) - Pollen lands on the stigma and grows through the style to reach the micropyle of the ovule - Leads to more female control of reproduction and sexual selection (e.g., pollen tube can be rejected)

Question 26

Sepals

Answer 26

outermost, green, leaf-like parts that protect the growing bud

Question 27

Petals

Answer 27

parts just inside the sepals; often colorful to attract pollinators

Question 28

Stamen

Answer 28

male flower parts: - anther (produces pollen) - filament (supporting stalk)

Question 29

Carpel

Answer 29

female flower parts: - stigma (sticky tip) - style (stalk) - ovary (contains the ovules)

Question 30

Pollination begins when

Answer 30

a pollen grain sticks to the stigma

Question 31

Pollination and Fertilization

Answer 31

One sperm fertilizes the egg cell - becomes the diploid zygote - grows via mitosis to become the embryo

Question 32

Preventing self-fertilization

Answer 32

The stamens and carpels of the flowers of some angiosperms mature at different times Many angiosperms display self-incompatibility Biochemical blocks prevent pollen from same plant (or closely related individuals) from reaching an egg cell.

Question 33

Explaining angiosperm success

Answer 33

Many gymnosperms have slow life cycles (take many years to reach maturity) Many angiosperms have short reproductive cycles (think, herbaceous flowers), which can evolve more rapidly because of more generations in shorter time(think, natural selection) AND Angiosperms advertise for sex and advertise for dispersal

Question 34

Plant-Pollinator Coevolution

Answer 34

Plants have become more effective at attracting specific pollinators Pollinators have become more effective at exploiting specific plant resources The features of the flower can often tell us about the type of animal that likely pollinates it

Question 35

Fruits develop from pollinated flowers

Answer 35

The embryo will grow to become a seed: an embryo plus stored food inside a protective seed coat. The wall of the ovary typically grows to form some kind of fruit.

Question 36

The next challenge: Seed Dispersal

Answer 36

Fruit structure can tell you a lot about its dispersal

Question 37

Animal-dispersed seeds/fruits

Answer 37

are colorful and conspicuous, taste good, and are usually good for animals Essentially bribes plants pay animals to disperse their seeds