CH 30

Which is the most numerous and diverse group of gymnosperms today? What are some examples? Why are they unique among all organisms on earth?

Conifers-- Coniferophyta Spruce, fir, pine, redwood, Sequoia -tallest organism record breaker -oldest organism -most massive organism -cone bearers

How and where does pollination and fertilization occur in conifers and angiosperms?

Conifers: Pollination: Pollination occurs when a pollen grain reaches the ovule. The pollen grain then germinates, forming a pollen tube that slowly digests its way through the megasporangium. Fertilization: By the time the eggs are mature, two sperm cells have developed in the pollen tube, which extends to the female gametophyte. Fertilization occurs when sperm and egg nuclei unite. Angiosperms: Pollination: A microspore develops into a pollen grain. The gen- erative cell of the gameto- phyte will divide, forming two sperm. The tube cell will produce the pollen tube. In the megasporan- gium of each ovule, the megasporocyte divides by meiosis, producing four megaspores. One survives and forms a female gametophyte. Fertilization: In nucleus of developing endosperm-- Double fertilization occurs. One sperm fertilizes the egg, forming a zygote. The other sperm fertilizes the central cell, forming the endosperm (a food supply, 3n in this example).

Where are female gametophytes and male gametophytes found in conifers and angiosperms?

Conifers: megaspores in ovules; microspores in pollen grain Angiosperms: Stamens produce microspores that develop into pollen grains containing male gametophytes. Carpels make megaspores and their products, female gametophytes

How does the relative size and independence of the gametophyte an the sporophyte compare in the bryophytes, seedless vascular plants, and the seed plants?

Tiny gametophytes can develop from spores retained within the sporangia of the parental sporophyte. This arrangement protects the gametophytes from environmental stresses. Most Relationship also enables the dependent gametophytes to obtain nutrients from the sporophyte. In contrast, free living gametophytes of seedless plants must fend for themselves

Why would having an animal pollinator increase reproductive success?

The movement of the animals enhance seed dispersal.

What are the parts of a flower and what are their functions?

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What is the biological relationship between an ovule and a seed?

Seeds develop from fertilized ovule.

How does pollination improve reproductive success in drier environments, as compared to life cycles of mosses and ferns?

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What are the three extant angiosperm clades that are called the "basal angiosperms" because they represent the most ancient lineages of the angiosperms? Identify a fourth clade, closer in relationship to eudicots and monocots.

"Basal Angiosperm" Clades: 1. Amborella 2. Water Lillies 3. Star Anise and Relatives 4th clade closer to monocots- Magnoliids Clade

What reproductive adaptations distinguish the angiosperms from the gymnosperms?

-Flower protects ovule within ovary; makes pollen transfer efficient by attracting animal pollinators -Fruit enhances seed dispersal; protects dormant seeds

Which group of animals is completely dependent upon flowering plants?

Butterflies and moths

What are the states of the life cycle of the pine tree as shown in Fig 30.6?

1. (2n) In most conifer sp, each tree has both ovulate and pollen cones. 2. (2n) Microsporocytes divide by meiosis, producing haploid microspores. A microspore develops into a pollen grain (a male gametophyte enclosed within the pollen wall). 3. (2n) Ovulate cone scale ha 2 ovules, each containing a megasporangium. 4. (2n) Pollination occurs when a pollen grain reaches the ovule. The pollen grain then germinates, forming a pollen tube that slowly digests its way through the megasporangium. 5. (n) While the pollen tube develops, the megasporocyte undergoes meiosis, producing four haploid cells. One survives as a megaspore. 6. (n) The megaspore develops into a female gametophyte that contains two or three archegonia, each of which will form an egg. 7. (n) By the time the eggs are mature, two sperm cells have developed in the pollen tube, which extends to the female gametophyte. Fertilization occurs when sperm and egg nuclei unite. 8. (2n) Fertilization usually occurs more than a year after pollination. All eggs may be fertilized, but usually only one zygote develops into an embryo. The ovule becomes a seed, consisting of an embryo, food supply, and seed coat.

What are the stages of the life cycle of a flowering plant?

1. Pollen lands on stigma 2. Pollen tube grows through style and ovary (grows until reaches the ovule). 3. In the megasporangium of each ovule, the megasporocyte divides by meiosis, producing four megaspores. One survives and forms a female gametophyte. (haploid- n) 4. Discharged sperm nuclei (n) Embryo (2n) Endosperm (3n) Seed coat (2n) Seed 5. In the megasporan- gium of each ovule, the megasporocyte divides by meiosis, producing four megaspores. One survives and forms a female gametophyte. 6. After pollination, eventually two sperm cells are discharged in each ovule. (haploid- n) 7. Double Fertilization with 2 sperm nuclei. a. One fuses with egg forming zygote (2n) b. One fuses with two* central nuclei forming endosperm (3n) (food supply) 8. The zygote develops into an embryo that is packaged along with food into a seed. (diploid- 2n) 9. When a seed germinates, the embryo develops into a mature sporophyte. (diploid- 2n)

What are some of the ways flower structure can vary?

A. Flowers can be incomplete- missing; unisex- only carpel parts or only stamens B. No petals if wind pollinated C. flowers may be clustered in an inflorescence (composite; sunflower)

In what ways are seed plants important to humanity?

Almost all food and beverages and spices come from seed plants. Wood products, fuel, fiber for clothing; rope. Secondary compounds incl: drugs & medicines, perfumes, latex rubber, outdoor recreation.

What is the main part of the flower that develops into the fruit?

Derived from ovary tissue after fertilization.

What is the function of endosperm? How is it formed and where is it found?

Endosperm is the food supply. It is formed when a sperm nuclei fuses with two central nuclei (triploid, 3n). Triploid central cell of female gametophyte develops into endosperm, tissue rich in starch and other food reserves that nourish the developing embryo.

Based on the summary given in lecture notes, which kinds of plants (gymnosperms, flowering plants, nonvascular plants, seedless vascular plants) first dominated the earth with forest like growth? What kinds of plants were they largely replaced by? What kinds of plants are now the most dominant and diverse?

First dominated earth forest: Seedless vascular plants (lycophytes, horsetails, and ferns) Replaced by: Gymnosperms Now most dominant: Angiosperms

What is the different between fleshy and dry fruits, esp in terms of their functions in dispersal?

Fleshy fruits are adapted to be eaten by animals. Seeds of fruits are scattered or passed through gut of animal. Dry fruits help dispersal by animals, wind, water. Some dry fruits protect dormant seeds as well. Animal digests fleshy part of fruit, and the tough seeds usually pass through unharmed through animal's digestive tract.

What are the key functions of the flower and the fruit in the life cycle of an angiosperm?

Fruit- enhances seed dispersal; protects dormant seeds Flower- makes pollen transfer efficient by attracting animal pollinators; protects ovule within ovary

What are the gymnosperm phyla? What are their distinguishing features? Examples of each?

Ginkgophyta: -one extant sp: Ginkgo bioloba -herbal medicine -flagellated sperm Cycadophyta: -form like a palm tree ex: Zamia sp in Florida; Sago Palm -central male and female cones -flagellated sperm Gnetophyta: -3 distinct genera (70 spp) -sperm not motile ex: Welwitchia in SW Africa deserts; Gnetum in tropics; Ephedra in US deserts Coniferophyta: -most diverse gymnosperms today -cone bearers -male pollen one (sperm) -female ovulate cone -dominate high altitude and latitudes in N hemisphere -most are evergreen with needle like leaves ex: pine, fir, spruce; redwood, Sequoia; includes record breaker- tallest organism -the oldest organism -most massive organism

What does it mean for a plant to be heterosporous? What happens to microspores and megaspores in seed plants?

Heterosporous: make two types of spores; megaspore and microspores. Female gametophyte is developed from a megaspore into one or more eggs in the ovule. Microspore develops into a tiny male gametophyte, within pollen grain which is transported by wind, etc.

What are the characteristics that distinguish eudicots from monocots? What are some examples of each group?

Monocots: -one cotyledon -parallel veins -flower parts multiples of 3 -vascular tissue in stem scattered -fibrous root system Incl: Grasses, grains, palm trees, coconut, some garden plants like lilies, onions Eudicots: -2 cotyledons -net like vein -flower parts multiples of 4 or 5 -vascular tissue in stem arranged in rings -taproot Incl: Most veggies we eat, most trees; apple, bean, pea, tomato, oak tree

Why would it be impossible to find a gymnosperm that bears fruit?

Naked seed plants. Ovules born exposed on sporophylls, arranged in cones. No flowering fruits; fleshy seeds.

What comprises an ovule? Where are ovules found in conifers and angiosperms?

Ovule: consists of megasporangium, megaspore, and integuments. Conifers: Ovulate cone scale has two ovules. Angiosperms: Ovary is at base of carpel; the ovary contains one or more ovules.

What is a pollen grain biologically (as part of the life cycle)? what is the difference between pollen grain and sperm? Between sperm and spore?

Pollen grain is the male reproduction part. Pollen grain is what is dispersed through air to reach ovule bearing parts, whereas sperm occurs after pollen grain grows pollen tube after pollination. Sperm is released within pollen tube. A spore is the different male and female parts (megaspore and microspore), whereas sperm is what is released after pollination and the pollen grain has grown a pollen tube.

What is pollination and how is it distinct from fertilization? What must happen between pollination and fertilization?

Pollination: When pollen grains reach ovule bearing parts Fertilization: occurs within the ovules when sperm and egg nuclei unite Pollen grain must germinate forming pollen tube that slowly digests its way thru the megasporangium. While pollen tube develops, the megasporocyte undergoes meiosis = 4 haploid cells. One survives as a megaspore. Megaspore develops into a female gametophyte that contains 3 or 3 archegonia, each of which will form an egg. Two sperm cells must develop in pollen tube, which will no extend to female gametophyte.... then fertilization.

What comprises a seed?

Seed coat, food supply, and embryo

What are the adaptive advantages of producing seeds (as compared to seedless plants)?

Seeds enhances survival on land. Efficient adaptive dispersal. Underground germination possible. Stored food allows embryos growth without photosynthesis. May stay dormant until OK conditions.

What kind of climate change toward the end of the Paleozoic era led to the domination of gymnosperms during the Mesozoic era (dinosaur age)?

Swamps replaced with drier conditions

Why does flower color, shape, and scent vary from species to species? What is the function of nectar?

The different flower color, shape and scent attract the specific pollinator needed for the species. Natural selection occurs regarding the color. Nectar is used as a reward for promoting loyalty. Pollinators is not thinking about the plant-- it's thinking about getting the reward (nectar) which is energy for them.