Plant Morph Exam 2

botanical terms, major topics, and info on study guides and quizzes

Alternations of Generations

describes a life cycle in which an organism has both haploid and diploid multicellular stages (BOTH MULTICELLULAR LIFE STAGES!)

Diploid cells

cells that contain 2 sets of each chromosome (2N)

Haploid cells

cells which contain 1 set of each chromosome (N)

Sporophyte

• multicellular diploid (2N) phase of a plant’s life cycle, the stage where spores are produced

• -phyte suffix = plant

Spores

• haploid cells (N) that will undergo mitosis to produce a gametophyte structure

Sporangium (plural = sporangia)

• structure (enclosure) that houses diploid sporocytes, which undergo meiosis to produce haploid spores.

• for example, the megasporangium is within the ovule. the microsporangium is in the anther sac

Sporocytes

• diploid cells that undergo meiosis to produce haploid spores

• also called mother cells

• -cyte = cell

Meiosis

• process of a diploid cell dividing, producing haploid cells

Mitosis

• process of cell division ( chromosome #, or ploidy level stays the same)

Gametophyte

• multicellular haploid (N) phase of a plant’s life cycle; stage where gametes are produced

Gametes

• single-celled haploid sex cells (eggs and sperm)

Pollen

• a microgametophyte structure (male gametetophyte that includes sperm)

Pollination

• process of pollen from stamen anther sacs transferring to stigma of a pistil

• self-pollinators or regular pollinators, who rely on many types of pollination (insect, wind, bird, bees, etc.)

Fertilization

• process of the fusion of egg and sperm cells

Zygote

• single-celled diploid cell that results from the fusion of egg and sperm gametes

Embryo

• multicellular diploid organism in early stages of development

Endosperm

• nutrient-rich tissue in angiosperm seeds that is a triploid (3N) product of double fertilization

• Feeds the embryo

Double Fertilization

• a process mostly unique to angiosperms where two haploid (N) sperm cells from pollen tube fertilize haploid (N) cells inside of the female gametophyte, resulting in s (2N) zygote (fusion of sperm with egg), and the triploid (3N) endosperm

Why do plants have a sporic life cycle?

• product of meiosis in plant reproduction is spores, not gametes directly, extra step

Where does fertilization occur in a flower?

• in the ovules (ovule sac) in the ovaries

What is a megaspore

• female spore found in ovule sac, haploid (N).

• went through meiosis

• produces the megagametophyte

Pollen tube

• emerges from pollen grain (goes thru mitosis and creates the pollen tube)

• sperm contained and not free swimming in pollen tube before reaching ovule

• generative nucleus produces sperm, tube cell nucleus produces pollen tube

When might self-pollination be advantageous for a plant?

• When pollinators are limited

• sparse or isolated plant populations (island plants)

• guarantee fertilization

What is cleistogamy

• plants produce flowers that are used for out-crossing (pollinators) and also produce small flowers that do not emerge or open for self pollination

• not lots of energy put into the self fertilization flowers

What is a flower (biologically)

• a whorl of modified leaves with distinct functions

• can be clustered with multiple flowers as an inflorescence

• is a determinate structure (ends branch growth)

• an important adaptation to changed of life on land (dispersal of male gametes, specifically with pollinators)

Flower parts and functions (13)

1. pedicel - floral stalk- stem supporting single flower

2. receptacle - modified floral stem, axis where floral organs attach

3. sepal - outer whorl of leaves, can be green or colored and protects inner whorls

4. petal - 2nd whorl of leaves, often brightly colored to attract pollinators

5. perianth - sepals+petals; when indistinguishable called tepals

6. filament - slender stalk of stamen supporting anther

7. anther - made of anther sacs, open to release pollen grains

8. stamen - male structure of flower; filament + anther

9. ovary - basal part of pistil that contains ovules, becomes fruit with seeds at maturity

10. ovules - fertile portions of pistil containing eggs, develops into seeds after fertilized

11. style - slender stalk of pistil above ovary that pollen tube passes through to reach eggs in ovules

12. stigma - part of the pistil; top of the style that receives and recognizes pollen

13. pistil - urn shaped, female structure with 3 main parts, contains one or more carpels (chambers)

What is a fruit (biologically)

• mature ovary (+ sometimes accessory tissues) containing seeds

• Fruit can be fleshy or dry

• seeds are contained inside of the Pericarp (endocarp, mesocarp and exocarp)

Connation

• fusion of floral parts from the same whorl

Adnation

• fusion of floral parts from different whorls

Major angiosperm lineages

• amborella - most ancient angiosperm lineage (nonfunctional stamen, separate carpels)

• water liles - early branching angiosperm (often many petals and stamen, spiraled parts)

• star anise - early brancher (leaf like stamen, multiple pistils/carpels, vascular tissue more similar to gymnosperms

• magnoliids - early brancher (most have broad leaves, large flowers, many spirally arranged perianths. cinnamon, avocado, nutmeg, etc)

• all early angiosperm lineages often have carpels that split open as fruits to release seeds

monocot

• one seed leaf (cotyledon), parallel-veined leaves and flower parts in 3s

Eudicot

• two seeded leaves, pinnate venation, and flower parts in 4 or 5s

Pollinator features (flowers)

• wind - oaks, grasses, sedges; typically small, less showy flowers, lack perianth. not colorful, often feathery stigmas

• birds - red and yellow flowers (birds prefer this), most common in tropics, long corolla tubes, lots of nectar

• bees - food attraction is key, so lots of pollen, nectar and oils; many colors though rarely red. landing platforms common, pollen placement precise

• moths - flowers often open at night/dusk, sweet smelling (lots of nectar), white, lighter, not super showy, long corolla tubes

• butterflies - showy, colorful flowers (reds, oranges and pinks = best), filled with nectar, often have corolla tubes, flat perch for landing

What does ‘gymnosperm’ mean

• naked seeds

• no flowers, no fruits

• seeds found in cones

How are the majority of gymnosperms pollinated

• pollen transmit sperm without water, via a pollen cone (micro-sporangia 2N)

• pollen grain = micro-gametophyte (N) which develops a generative cell and a tube cell where pollen will reach the ovules

• pine cones = ovulate cones (mega-sporangia 2N)

• some cones have dispersers (birds and mammals most common)

4 primary modern gymnosperm groups

• cycads - pan-tropical, very endangered, white-haired cycad

• ginkgo - one species, “living fossil”, fleshy seed coats

• conifers - most species in this group, boreal dominance; pines, cypress, junipers etc.

• gnetophytes - more similar to angiosperms than other gymnosperms; welwitschia, gnetum, lack archegonia

Which gymnosperm group is most closely related to angiosperms

• gnetophytes, as they have vascular tissue including vessels, they lack archegonia, and have double fertilization (though no endosperm)

What feature of the cycads and Ginkgo is similar to older plant lineages?

• dioecious (separate male/female plants)

Monilophytes

• ferns, horsetails, whisk ferns

• no flowers, fruits or pollen

• megaphylls (large leaves with many veins)

Defining features (shared traits) of Euphyllophytes

• collectively monilophytes and seed plants

• euphyllophytes = vascular plants with megaphylls

• multiflagellate sperm

• lateral roots

• overtopping growth (unequal branching of apical meristem)

Eusporangiate versus Leptosporangiate ferns

Based on sporangia

EUSPORANGIATE

• sporangium wall several cell layers thick

• sessile (not stalked)

• no specialized opening for dispersal

• large # of spores and simple dehiscence

LEPTOSPORANGIATE

• thin cell walls

• stalked

• contain usually 64 spores

• annulus (thick part of cell walls that aids to eject spores

What is a sporangium and spores?