Biology 1011 Flashcards
Why are plants important?
- for the conversion of the sun’s energy
- agriculture
-drugs, fossil fuels, clothing, etc - biodiversity
What is botany? What does a botanist study?
Botany is the study of plants, however it ranges from evolution, ecology, genetics, anatomy, physiology, etc
What are drugs in relation the the plant?
-A plants secondary compounds, not necessarily useful for metabolism, growth, or development.
- Produced as a poison or deterrent from being eaten, human use them for other things.
What is a plant?
A group of organisms which share characteristics
What does the cladogram of a plant look like?
3 major groups, chlorophyta, charophyte, and embryophyta
What are green algae from the cladogram of plants?
Both chlorphyta and charophytes are green algae
What are embryophyta on the cladogram?
These are land plants
What are shared characteristics of all plants?
- starch as main energy storage molecule
- chlorophyll b, absorbs different wavelengths than a
- Cellulose as a major component of cell wall
- Thylakoid in states (grana)
Why can’t sugar be an effective storage molecule?
It is too absorbent of water
Describe starch as a plant feature
Polysaccharide (carbohydrate) of glucose residue
- 20 % amylose, 80% amylopectin
- starch is not absorbent, easily metabolized, and not very reactive
What is chlorophyll b in respect to plant features?
Chlorphyll as is all photosynthetic eukaryotes, and chlorophyll b is an accessory pigment which passes energy to chlorophyll a because b absorbs different wavelengths of light from the sun
What is cellulose in respect to plant features?
Polysaccharide which is a major component of the cell wall
- most common organic polymer,
What are thylakoids in respect to plant features?
- grana
- membranes inside chloroplast, contain chlorophyll
What are the closest ancestors of land plants?
- Charophytes are the closest relative of land plants
- a type of green algae
What is evidence that charophytes are the closest ancestor to land plants?
They have the same chloroplast and nuclear DNA
- similar anatomical structure
NOTE: land plants share a common ancestor with modern charophytes
What are the similar structures between charophytes and land plants?
- cell plate
- plasmodesmata -extensions of cell membrane through pores in cell wall
- structure of flagellated sperm
- peroxisome enzymes
- rosette shaped cellulose synthesizing complexes
- sporopollenin in spore walls
What is sporopollenin?
- durable polymer
- found in walls of plant spores and pollen
- chemically inert: stable, persists in environment
- essentially protects pollen from external factors (temperature, acidity, etc), protects from decay
What are the advantages of plants moving to dry land (embryophyta)?
- air filters less sunlight than water
-air has more co2 than water - early terrestrial habitats lacked pathogens of predators
- soil is richer
What were some challenges/adaptation in moving to land from embryophyta?
- land is not supportive –> turgor, cell walls, stems
- lose water on land –> vascular tissue, roots, stomates
- reproduction harder on land –> egg and embryo retained on parent
What are some features of land plants?
1) cuticle - a waxy covering
2) multicellular, jacketed sex organs = gametangia
3) Embryophyte condition - zygote retained in maternal tissue (fertilized egg develops on mother)
4) alternation of generations
What are gametangia?
plant sex organs
a) antheridium : male sex organ in land plants that makes sperm
b) archegonium : female sex organ that produces eggs
What are the two kinds of gametangia ?
antheridium and archegonium
What is a gametophyte?
the haploid phase of the plant, has haploid gametes
- makes gametes by mitosis
What happens when the gametophyte is fertilized?
Produces a zygote which form a sporophyte
What is a sporophyte?
- diploid phase of the plant, produces haploid
- makes spores by meiosis
What is alternation of generations?
- a process plants undergo in which there is a regular alternation between two distinct forms (gametophyte and sporophyte)
NOTE: spores undergo mitosis to form the gametophyte which is haploid. When gametes fuse they form a zygote which undergoes mitosis, which undergoes meiosis to form spores.
What is different about green algae in terms of alternation of generations?
-Green algae does not have alternation of generation, multicellular haploid but not multicellular diploid
describe the structure of the plant cell
- cell wall, inner membrane, vacuoles, plasmodesmata, cytosol
What is plasmodesmata?
- an extension of cell membrane through pores in cell wall
- a feature found in both charophytes and embryophytes
when do plants appear in the history of life?
- 1500 million years ago plants split from red algae in marine and moist environments
- 500 million years ago the colonization of dryer environments (consider the adaptations to plants when this occurred!)
What are the major events in history of plant life?
earth forms, photosynthesis, plastids appear, colonization of plants, fungi, and animals
How long ago did the earth form?
4.6 billions years ago
How long ago did photosynthesis appear?
3500 million years ago
When did the 1st plastid appear?
700-1500 million years ago
What are the 4 main components of the plant phylogram?
red algae, chlorophytes, charophytes, and embryophytes (land plants)
What is an alternation of generations?
- multicellular haploid and diploid stages
- seen in all land plants
What are gametophytes?
- multicellular haploid stage, makes gametes through mitosis
What are sporophyte?
Multicellular diploid, makes spores through meiosis
What are the two alternating generations found in the alternation of generations?
Gametophytes and sporophytes
What differentiates animals life cycle from plant life cycles?
Animal life cycles have unicellular stages where haploid cells fertilize, which then undergo mitosis, which eventually undergo mitosis to form haploid gametes
- plant life cycles are multicellular
How do plant life cycles work in detail?
- Spores (haploid) divide by mitosis to form gametophytes, which become fertilized to zygote, which undergoes mitosis Ito form a sporophyte Diploid) which undergoes meiosis to form spores
What are spores?
single cell that can divide to produce a multicellular organism with a protective coat
What are gametes ?
Single cell that can unite with another gamete to produce a diploid zygote
Does algae undergo alternation of generations?
Algae does not (it has +/- cells for asexual reproduction), the rest of the phylogram does have alternation of generations
How did alternation of generations originate?
Zygote delays meiosis and divides, grows into multicellular diploid (sporophyte)
What are the 4 major divisions of land plants?
moss, ferns, conifers,
What are some characteristics of moss?
- 15000 species, low growing, confined to damp areas, no true leaves
Is moss gametophyte or sporophyte dominant?
The moss is gametophyte dominant (they are haploid plants, sporophytes grow from the gametophyte)
Is moss homosporous or heterosporous?
Homosporous (1 size of spore)
Describe the moss life cycle
-Mitotic production of gametes, fertilized to form diploid.
-Become sporophyte which creates spores by meiosis (sporophyte grows out of gametophyte)
Why can’t sporophytes grow independently?
The sporophytes are nutritionally dependant on the moss, they don’t have vascular tissue
What was the next significant evolutionary step after moss?
vascular tissue: supports organism and supplies organism through xylem and phloem
Describe ferns
200,000 species, appear 400 million years ago, have vascular tissue
Are ferns sporophyte or gametophyte dominant?
Sporophyte dominant (diploid)
Are ferns homosporous or heterosporous?
BOTH!
Describe the fern life cycle
- spores turn into gametophytes through mitosis, fertilized to produce zygote–> sporophyte (diploid) which creates spores through meiosis (bottom of lead has dusty spores)
What is homospory?
1 size of spore from meiosis, (mosses, most ferns)
What is heterospory ?
2 sizes of spore from meiosis
(some ferns, all seed plants )
Describe the phylogeny of land plants
mosses, then ferns, then seed plants
What do seed plants have ?
Seed plants have both seeds and pollen
What is a seed?
- embryo + nutrition +seed coat
- develops from ovule
- seed plant is site of female meiosis
What female parts are found in the seed?
female gametophyte, female sex organs, egg, and embryo
what is pollen?
- mature male gametophyte (travels through megagametophye to fertilize egg_
- few cells in size
Describe conifers
- 500 species, reproductive organs in cones
Are conifers gametophyte or sporophyte dominant?
Sporophyte dominant
Are conifers heterosporous or homosporous?
heterosporous
What are megagametophyteS?
makes egg in archegonium nourishes embryo
What are microgametophytes?
pollen grain (makes sperm)
What are gymnosperms?
naked seeds
What are seeds?
embryo nourished by megagametophyte
Are seed conifers slow or fast reproduction?
fast
what comes next on the phylogenetic tree after ferns?
gymnosperm, then angiosperms
What are angiosperms?
flowering plants
What is the most recent ancestor of the angiosperm?
Anthophyta are the most recent common ancestor
around how long ago did anthophyta first appear?
150 million years ago
What is the angiosperm terrestrial revolution?
The proposal that many diverse organisms showed major diversification fuelled by the angiosperm terrestrial revolution - promoted mass diversification of organisms, and vice versa
what percent of plants, animals, and fungi are found on land?
85%
What are the 3 tissue systems found in vascular plants?
1) Dermal tissue
2) Vascular tissue
3) Ground tissue
Describe dermal tissue, what does it form?
- single layer, secreted cuticle (waxy)
- forms the epidermis
Describe vascular tissue
- xylem and phloem, support and supply
Describe Ground tissue
- tissue other than dermal or vascular (all else), bulk of young plant, fills space between decal and vascular tissues, mostly parenchyma storage, photosynthesis and support
What cell types are made from ground tissue?
parenchyma
collenchyma
sclerenchyma
What cell types are made from vascular tissue?
- tracheids and vessel elements
- sieve elements
What are epidermal cells?
- outermost cells
- single layer covering leaves, stems, and roots of non woody plants
-functional for waterproofing, protection from pathogens - other roles: hairs, nectary, guard cells
What are some other roles for epidermal cells?
Form trichomes (hairs), nectary, and form guard cells (for gas exchange)
What is the cuticle?
- formed by epidermal cells, outermost part is wax
- protects against water loss, pathogens, UV radiation
What are secretory trichomes ?
- specialized hairs formed by epidermal cells, various functions
What are parenchyma cells ?
- type of ground tissue
- many functions, often specialised
- responsible for most metabolic processes
- usually lack secondary wall
- can divide and differentiate at maturity
Wht are the functions of collenchyma cells ?
- support, especially for young and growing organs
- type of ground tissue
What are the features of the collenchyma cells?
- thick, uneven primary wall
- no secondary wall,
- always occur below epidermis
-often occur in strands - alive at maturity: can elongate
What is the layering order of a stem?
epidermis, collenchyma, parenchyma, and vascular tissue
What is the function of a sclerenchyma cell?
- support, protection (of tissues no longer elongating)
- hard cell type
- ground tissue
What are the features of the sclerenchyma?
- type of ground tissue, thick secondary wall with lignin, cannot elongate at maturity, 2 forms: fibres and sclereid
Describe the trachea and vessel elements of the vascular tissue
- for support and supply of water and minerals
- dead at maturity
- secondary wall lignified, often spiral
- two kinds: tracheids and vessel elements