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The gametophytes are ______ and develop within ______ flowers
haploid\nsporophyte
gameophytes compared to sporophytes are
very small and cannot live on thoer own
Pollen develops within
the pollen sacs of anthers
Microspore mother cell (a.k.a. microsporocyte) develops inside
the pollen sacs
Diploid microspore mother cells divide by
to form 4 haploid microspores from each microspore mother cell.
Each microspore divides by mitosis to make an immature pollen grain\n
containing: a. tube cell. \nb. generative cell (inside the tube cell)
The generative cell goes through
two sperm cells \n This is now the mature pollen grain (see fig
Pollen develops within the pollen sacs of anthers the process
1) Microspore mother cell (a.k.a. microsporocyte) develops inside the\n pollen sacs\n\n 2) Diploid microspore mother cells divide by meiosis to form 4 haploid\n microspores from each microspore mother cell.\n\n 3) Each microspore divides by mitosis to make an immature pollen grain\n containing:\n\n a. tube cell. \n b. generative cell (inside the tube cell)\n\n 4) The generative cell goes through mitosis to form two sperm cells \n This is now the mature pollen grain (see fig 44–5)
The outer layer of the ovule is the
integument
The tissue of the ovule is
diploid.
The series of events leading to the female gametophyte are
1) The megaspore mother cell (a.k.a. megasporocyte) develops within the\n ovule that is within the ovary of the carpel.\n\n 2) The megaspore mother cell divides by meiosis to form four haploid\n megaspores \n\n 3) Three of the four megaspores degrade.\n\n 4) The remaining one of the four goes through 3 rounds of mitosis BUT NOT\n CYTOKINESIS which results in 8 nuclei in one cell.\n\n 5) The nuclei are distributed 3 on each end of the megaspore and 2 in the center.
The megaspore mother cell (a.k.a. megasporocyte) develops within
the\n ovule that is within the ovary of the carpel.
The megaspore mother cell divides by
meiosis to form four haploid\n megaspores
Three of the four megaspores
degrade
The remaining one of the four megaspores goes through
3 rounds of mitosis BUT NOT\n CYTOKINESIS which results in 8 nuclei in one cell.
The nuclei of a megaspore are distributed
3 on each end of the megaspore and 2 in the center.
cytokinesis occurs forming
7 (NOT 8) cells.
cytokinesis occurs forming 7 (NOT 8) cells. describe the cells.
–3 cells on each end of the embryo sac (one is the egg)\n –one larger central cell with 2 polar nuclei \n\nThe larger center cell becomes the primary endosperm cell.
Pollination and Fertilization process
1) Pollination starts when pollen from an anther lands on a stigma\n\n2) The pollen grain grow a tube down through the style towards the ovary\n\n3) The 2 sperm cells from the generative cell move down the tube to the ovary where a\n double fertilization occurs
Pollination starts when
pollen from an anther lands on a stigma
The pollen grain grow a tube down through the
style towards the ovary
The 2 sperm cells from the generative cell move down the tube to the
ovary where a double fertilization occurs
Double Fertilization
One sperm fuses with the egg cell to form the zygote \n\nThe other sperm fuses with the polar nuclei in the primary endosperm cell\n making this triploid endosperm (3 sets of chromosomes) tissue
The seed develops from the
ovule
Development of Seeds and Fruits
The seed develops from the ovule\n\n The integuments become the seed coat\n The zygote becomes the embryo.\n The primary endosperm becomes the endosperm that acts as food for the new \n plant.\n\nThe walls of the ovary turn into the flesh of the fruit.
The plant embryo contains the
cotyledons (seed leaves)
In dicots there are
2 cotyledons in the embryo and monocots have only 1 cotyledon
In the monocots the cotyledon is protected by a tough sheath called
the coleoptile
Animal pollinated flowers have several modifications in order to
Attract animal pollinators.\nFrustrate undesirable visitors.\nEnsure cross–fertilization.
Bee pollinated flowers
Brightly colored (white, yellow, or blue) with ultraviolet patterns (see fig 44–13)\n\nThese flower are tubular and produce their nectar (the food enticement) at the bottom of a short tube (see fig 44–14)
Butterfly pollinated flowers
Also brightly colored with have long tubular flowers.
Moth pollinated flowers
Light colored and sweet smelling so they’re easier to find in the dark. \n\nTypically night flowering plants.
Fly pollinated flowers
Smell like rotting flesh or dung
Hummingbird pollinated flowers
Very deep tubular flowers of red or orange colors that produce large amounts of nectar.\n\nThese flowers usually lack fragrance (birds attracted by color not scent) and don’t have a landing zone.
Copulatory pollinated flowers
Sex is the enticement.\n\nSome orchids mimic female wasps in scent and shape, attracting males that attempt to copulate with the flower picking up pollen in the process.
The main function of the fruit is to aid in
seed dispersal\n\n –wind dispersal (see fig 44–18)\n –mechanical dispersal (see fig 44–20)\n –water dispersal (see fig 44–19)\n –animal dispersal (see fig 44–21)
Plants perceive and respond to environmental stimuli by regulating growth and development through the action of
chemicals called plant hormones or growth regulators.
What are the stimuli that plants receive from their environment?
Direction of gravity.\nDirection, intensity, and duration of sunlight.\nStrength of the wind.
Phototropism
(the bending of plants towards sunlight) was the first plant response discovered and studied by Charles and Francis Darwin
The Darwins experiments (see Scientific Inquiry pages 890–891) found that:
1) The region below the tip of a grass coleoptile bends towards light\n\n2) Covering the tip with an (dark) opaque cap stops the bending.\n\n3) Covering the bending region does not stop the bending.
The region below the tip of a grass
coleoptile bends towards light
Covering the tip with an
(dark) opaque cap stops the bending.
How does the plant bend?
One side gets longer than the other.
discovered the mechanism of the bending
Peter Boysen–Jensen
Peter Boysen–Jensen discovered the mechanism of the bending.
He found that a chemical is produced in the tip and moves down the shoot causing cell elongation\n\nIf the tip of the plant was cut off, then the elongation and bending is stopped.\n\nIf the tip of the coleoptile was replaced, then the elongation and bending is restored.\n\nIf the replaced tip of the coleoptiles had a porous gelatin slab between the severed tip and shoot, then the elongation and bending is restored.\n\nIf the replaced the tip of the coleoptiles had a thin layer of non–porous mica between the severed tip and shoot, then the response to light remained blocked.\n\n\nConclusion: something was being made in the tip that caused the cells to elongate.
auxin
n the tip that caused the cells to elongate.
Frits Wents experiment showed that agar cubes could
absorb the chemical from the severed tips of oat coleoptiles\nThese agar cubes could then cause the elongation of cells in plants that had their tips removed.If the agar cube was placed directly in the center then all of the cells would elongate.\n\nIf the agar cube was placed off–center then the shoot would bend.
Plant Hormones and Their Action
chemicals produced in one location and transported to other regions where they Hormones are exert specific effects.\n\nThis definition can be applied to all organisms plants and animals.
There are 5 major types of plant hormones
–Auxins\n –Gibberelins\n –Cytokinins\n –Ethylene\n –Abscisic acid
Abscisic acid
is an inhibitory hormone\n\n –Causes stomata to close when water is scarce.\n–Maintains dormancy in buds and seeds in bad weather by inhibiting the action of other hormones especially gibberellin.
Auxins characteristics
–Regulate plant responses to light (phototropism) and gravity (geotropism)\n The bending in response to gravity is mediated by \n statoliths (see fig 45–4)\n –Promote cell elongation in shoots\n –Prevent growth of lateral buds (see fig 45–7)\n –In roots \n low concentrations stimulate elongation (see fig 45–2)\n higher concentrations inhibit elongation.\n stimulate root branching.\n –Stimulate fruit development
Gibberellins
–Promote cell elongation in stems.\n –Stimulate flowering, fruit development (see fig 45–10), seed germination, and \n bud growth
Cytokinins
–Promote cell division including lateral meristems (see fig 45–7)\n –Stimulate overall metabolism, delaying the aging of leaves.
Ethylene
the only known gaseous hormone:\n\n –Causes fruit to ripen.\n –Causes breakdown of cell walls in abscission layers (see fig. 45–12), allowing\n leaves fruit, and flowers to drop off at appropriate times.
Auxin produce at the shoot tip apical meristem give that part of the plant an
apical dominance as you move away from the shoot tip that dominance lessens
The Kingdom Fungi consists of organisms that are
eukaryotic and mainly multicellular. They are all heterotrophic decomposers that obtain their food by absorption.
Most members of the Kingdom Fungi have several structural elements in common:
Mycelium\n Hyphae (singular hypha)\n Septa (singular septum)\n Chitin\n Spores
Mycelium
is the feeding network of a fungus. (See fig 22–1 a) \n\nThis network may be very large but is usually underground or within the surface of a decaying organism.
The mycelium is composed of a woven mesh of
hyphae
Hyphae
the threadlike filaments of a fungus. (See fig 22–1 b)\n\nThese filaments are the building structure of the mycelium. They consist of a tubular cell wall containing chitin surrounding a plasma membrane and cytoplasm.
Chitin
a structural polysaccharide of modified sugars.\n\nIn some fungi (coenocytic fungi) there are no separate cells and many nuclei are in a common cytoplasm. In other types of fungi (dikaryotic) the nuclei are partitioned into twos by septa.
Septa
structures that partially separate the cytoplasm inside the hyphae (see 22–1c).\n\n\nThis separation is incomplete so that the cytoplasm is contiguous but the nuclei are kept apart.
The general life cycle of fungi involves the production of
spores\n\n We’ve used this term before as a structure which is primarily a “resting state”
For fungi the spore is a
haploid cell, which can grow directly into a hyphae\nThere have been over 100,000 fungal species identified and more are added each year
We will consider five of the major Divisions of the Kingdom Fungi.(
Chytrids – Division Chytridiomycota\n\n Zygote fungi – Division Zygomycota\n\n Mycorrhizae fungi – Division Glomeromycota\n\n Club fungi – Division Basidiomycota\n\n Sac fungi – Division Ascomycota
Two of the main classification criteria for these divisions are the presence (or absence) of
septa in the fungi and differences in the sexual life cycle.
The Chytrids
characterized by swimming flagellated spores (similar to water molds) and \n flagellated gametes.\n –some species of chytrids are linked to parasitic infection of amphibians.
The Zygote fungi
–named for the zygospore, which has a thick cell wall. The zygospore is\n produced from the fusion of two different haploid \n mating types (See fig 22–6).\n –usually only goes through asexual reproduction, involving haploid spores which\n grow directly into sporangia (spore producers). \n –no septa present\n –include Black bread mold and dung fungus
some species of chytrids are linked to
parasitic infection of amphibians.
The zygospore is\n
produced from he fusion of two different haploid \n mating types
The Mycorrhizae fungi
–live in intimate contact with the roots of plants\n –no septa present\n –hyphae surround and penetrate root cells (see fig 22–7 and 22–15)\n –interaction forms a beneficial relationship called a mycorrhiza
The Club fungi
–named for the “club” shaped: reproductive structure called a basidia which\n produces basidiospores. (See fig 22–8)\n –usually reproduce sexually\n –septa present \n –the mycelium of this group may grow very large and occasionally produce a\n fairy ring (see fig 22–10) at the circumference.\n –includes the common mushroom and relatives, also shelf fungi, puffballs, rusts\n and smuts
The Sac fungi
named for the sac or ascus, which contains several haploid spores.\n –both sexual and asexual reproduction are common (see fig 22–11) \n –septa present\n–include penicillin fungus (see fig. 22–19), most yeast (good yeast –bread and beer as well as bad yeast – vaginal infections), athlete’s foot fungus,\n Jock itch, powder mildew of rye (LSD), Dutch Elm disease, Blue \n cheese fungus and truffles (see fig. 22–20)
Saprobes
decomposers of dead material (most fungi fall into this group)
Two types of symbiotes
Parasitic – fungi that live on living organisms\n Dutch elm disease, Corn smut, Athletes foot, \n Jock Itch, Yeast infections \n\n Mutualistic – fungi live interdependently with photosynthetic organisms \n Lichens and mycorrhizae
Lichens are formed of a
ymbiotic relationship between a fungal species and either a cyanobacteria or a unicellular photosynthetic eukaryote This partnership requires very little in the way of external nutrients and can often be found growing on bare rock or dead wood
Lichens are often the first organisms to appear in the
primary succession of a community
Mycorrhizae
are a symbiotic relationship between fungi and the roots of a plant (see fig 22–15). \n\nThe fungi help send the plant water, minerals, and nutrients (especially phosphorus containing compounds). In exchange, the fungus absorbs some of the sugars the plant produces.
The main distinguishing features of the Kingdom Animalia are
–Eukaryotic\n –Multicellular\n –Heterotrophic\n –Ingestive method of digestion\n –Sexual reproduction\n –No cell wall\n –Rapid response to stimuli\n (nerves and muscles)
In addition to these characteristics, as animals evolved from the animal–like protists,
they developed more complex and organized bodies.
Some of these increases in complexity and organization are:
–cellular specialization\n –body plan\n –cephalization \n –body cavity\n –segmentation\n –digestive system
Cephalization
is the concentration of nervous tissue (including a “brain” and sensory organs) into a defined region (head) of the body.
Segmentation
is a body design in which similar repeating units are present.
Cellular specialization leads to the development of
tissues, which then can lead to the combination of tissues into an organ.
Organs may then become arranged into
organ systems.
Tissues
are specialized cells with a common structure and function that are\n grouped together.
Organs
are centers of bodily function, which are usually made up of different\n tissues.
Organ systems
are groups of two or more organs that function together to\n perform a common task (e.g., digestion, gas exchange, reproduction)
Organ systems
are groups of two or more organs that function together to\n perform a common task (e.g., digestion, gas exchange, reproduction)
The presence or absence of tissues in an organism defines the
first separation of a group from the rest of the animals.
Sponges – Phylum Porifera
–Sessile – non–moving\n –Filter feeders\n –May reproduce sexually or asexually by budding \n –Most species have an asymmetric body plan designed for water filtration\n –Lack tissue structure but have specialized cells (see fig 23–5)
Three types of specialized cells are found in the sponge phylum
Epithelial cells –outer covering layer (like a skin)\n Make up and regulate the pores\n\n Collar cells – Inner layer which pumps water through the sponge using\n flagella and filters out the food\n\n Amoeboid cells – mobile cells between the two layers that ingest the\n collected food \n –Responsible for reproduction\n –Secretion of skeletal structure of spicules.
Epithelial cells
outer covering layer (like a skin)\n Make up and regulate the pores
Collar cells
Inner layer which pumps water through the sponge using\n flagella and filters out the food
Amoeboid cells
mobile cells between the two layers that ingest the\n collected food \n –Responsible for reproduction\n –Secretion of skeletal structure of spicules.
The lack of tissues in sponges also result in the
asymmetric body plan.
All other animal phyla have both
defined tissues and body plan or symmetry.
Symmetry
indicates that a geometric plane could be drawn through an organism such that the halves of the organism are “mirror” images of each other.
Two types of symmetry are seen
Radial symmetry – round body plan\n Animals have a top and bottom but no back/front or left/right.\n\n Bilateral symmetry – body plan with a left side and a right side.\n Also means a back (dorsal) and front (ventral) surface can be determined
Radial symmetry
round body plan\n Animals have a top and bottom but no back/front or left/right.
Bilateral symmetry
body plan with a left side and a right side.\n Also means a back (dorsal) and front (ventral) surface can be determined
The groups separated based on radial symmetry are
Hydra, Corals, Anemones, and Jellyfish – Phylum Cnidaria \n Comb jellies – Phylum Ctenophora\n Note: This is a relatively minor phylum and we will not \n cover any of the details.
Hydra, Corals, Anemones, and Jellyfish – Phylum Cnidaria
Mostly marine\n –Tissues present – including a nerve net\n –May reproduce sexually or asexually by budding \n –Only two germ layers form in the early embryo\n –Simple sac–like body with a gastrovascular cavity (see fig. 23–7)\n two types of body plan\n Polyp or medusa\n –Tentacles with nematocyst armed cnidocytes (see fig. 23–8)
Germ layers are the
layers of cells in the early embryo that lead to all tissues and organs.
The three possible germ layers are:
endoderm – interior lining of the organs\n mesoderm – muscles, skeleton and circulatory system\n ectoderm – outer coverings
The Cnidarians are missing the
mesoderm
The two germ layers present in Cnidarians lead to the
inner and outer body layers.
All the remaining phyla in the Kingdom Animalia except cnidarians have
bilateral symmetry and three germ layers.
Some species (Sea Urchins and Starfish) have
radial symmetry as adults but have bilateral symmetry in the larval stages.
With bilateral symmetry
cephalization also appears.
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