Exam 3 Flashcards
What made plants move onto land?
Combination of new opportunities available on land, such as unfiltered sunlight, more CO2 available, more nutrients, and few herbivores and pathogens on land.
What were some challenges of new land plants?
There was less water on land, and gravity caused plants difficulty.
what were adaptations which caused charophytes to move to land?
-charophytes already lived in shallow freshwater ponds, so a somewhat similar environment to land.
-charophytes contain sporopollenin, which is a durable polymer which prevents charophyte zygotes from drying out.
What are shared features of charophytes and land plants?
Both contain rings of cellulose synthesizing proteins, which are rings in the plasma membrane which produce cellulose in the cell wall. They both have a similar structure of flagellated sperm, and contain sporopollenin.
what are some innovations of land plants, in NO DETAIL?
alternation of generations, multicellular dependent embryos, sporangia, sporopollenin, waxy cuticle, and apical meristems.
What plants have alternation of generations
Plants are multicellular haploid and diploid organisms. They are not present in charophytes, but they are present in some algae.
what is the difference between charophytes and chlorophytes?
Chlorophytes are mostly freshwater plants, can be multicellular or unicellular, have two flagella, and use both types of reproduction. They have over 7500 species.
Charophytes are algae most closely related to land plants. They have shared traits with land plants and are important in plant evolution.
How are multicellular, dependent embryos an innovation of plants?
the embryos are retained within a gametophyte.
explain sporangia
Sporangia is an enclosure found in sporophytes. They are multicellular organ which produce haploid spores.
what are gametophytes
gametophyte is stage in the life cycle of plants and algae that undergo alternation of generations. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes
what is sporopollenin
sporopollenin is a substance present in spores which protects against harsh conditions, especially desiccation (drying out)
what is the waxy cuticle
a waxy cuticle is the covering of wax and other polymers. It protects plants from drying out and protects against bacterial infections.
what are apical meristems
apical meristems are regions at the tips of plant roots and shoots which experience cell division. Cell division in these regions is continuous during a plants life, and increase ability to obtain resources.
what are some facts about early land plants?
-fossil evidence shows that plants were on land 470 mya.
-spores and tissue fossils have been extracted from 450 mya rock
-large plant structures appeared in fossil record 425 mya
-by 400 mya, many diverse plants lived on land
unique traits of early land plants
-specialized tissues for water transport
-stomata
-branched sporophytes
-lacked true roots and leaves
what are sporophytes
the diploid, multicellular, spore producing phase in plant and algae.
what are nuclearids?
organisms which are most closely related to fungi. Most consume algae or cyanobacteria. They live in soils and freshwater habitats.
what are fungi?
fungi are a large group of organisms which have over 100k organisms described, with an estimated 1.5 million left to describe. They can be found all over the world in diverse habitats, including marine, terrestrial, and freshwater.
importance of fungi
-help with ecosystem function and health
-agriculture
-food industry
-medicine
-culture
characteristics of fungi
-reproduce both ways
-contain no chloroplasts
-have cell walls and vacuoles
-contain chitin in cell wall (besides fungi, only arthropods contain chitin)
-every group except chytrias have lost the posterior flagellum
fungal nutrition
-fungi are heterotrophs. They break down nutrients and recycle nutrients
-produce hydrolytic enzymes (enzymes which break down molecules from the environment into simpler forms)
-the fungi then absorb these simpler molecules
-fungi can be decomposers, parasites, and mutualists
fungi morphology
yeast- single cell form of fungi, less than 1% have this form
filament- multicellular, most fungi grow as filaments and yeast
hypha (p. hyphae)- tubular, cylindrical, thread-like filament. 2-10 um in diameter, and grows at tips and bifurcations (branching)
mycelium (p. mycelia)- fuzzy mold. Networks of hyphae which result from apical and branching growth. Increase the surface area for absorption.
spore producing structures- have variety and diversity. Some are mycelial structures, and use both types of reproduction. spores are haploid.
specialized hyphae
what are specialized hyphae
haustorium. Haustorium can be a parasitic or mutualistic structure at the tips of hyphae. Hyphae break down the host cell wall and the haustorium develop adjacent to the plasma membrane. They DO NOT kill the host
Where is haustorium observed?
Haustorium is observed in Mycorrhiza (p. mycorrhizae). There is a beneficial association (mutualism) between plant roots and the fungus.
This is a mutual relationship because the fungus gives the plant phosphate ions and minerals, and the plant gives the fungi carbs and other organic nutrients.
lichen- beneficial association between algae and fungus
endophytes- beneficial association between plants and fungi
importance of mycorrhizae
the plant’s absorption of water and minerals increases. Mycelium has a large surface area. a higher root ratio improves the plant’s absorption abilities.
basic fungal lifecycle for asexual fungi
hyphae develop into spore-producing structures. Fungi and spores are haploid.
molds- these are conidiophores. conidium (spore) producing structures on the ends of the hyphae
yeasts- use budding and cell division to replicate. Use DNA replication.
basic fungal lifecycle for sexual fungi
haploid hyphae from two different myceliae find each other. They use pheremondes, and there are both positive and negative mating types.
the myceliae fuse through plasmogamy. Cytoplasms fuse but the nuclei don’t fuse. Both are haploid. (n+n)
heterokaryotic stage- mycelium contain different nuclei (from n+n)
dikaryotic stage- the pair of nuclei each from different parent move into the cell, but they do not fuse (n +n).
-ascomycota and basidiomycota
karyogamy- haploid nuclei fuse to become a diploid nuclei (2n). they zygote is transient.
spores- meiosis of zygote, haploid (n)
types of fungi
microsporidia, chytrids, zygomycetes, Glomeromycetes, ascomycetes, basidomycetes
what are plants?
dominants group of land organisms. VERY diverse, vary from 2mm to 300 ft. there are 290,000 known species, and some are aquatic.
how are plants classified?
classified broadly by if they contain vascular tissue into categories of nonvascular and vascular. Vascular plants produce seeds, and nonvascular plants produce spores.
vascular tissue
cells joined into tubes that distribute water and nutrients through plants. Roots require water and nutrients. `
nonvascular plants (bryophytes)
have no roots. Water and nutrients are acquired through the leaves. Water moves in the plants and within the cells through osmosis and diffusion.
spores v seeds
spores- haploid. have one cell and arises from a sporophyte through meiosis. fertilization occurs after dispersal.
seed- diploid cells, are multicellular. contains an embryo which is a union of gametes from gametophyes (n). fertilization occurs before dispersal.
bryophytes
-live in moist environments
-small in size and are simple
-gametophyte stage (n) dominant. the sporophyte depends on the gametophyte for nutrition.
-lacks true stem, roots, and leaves as there is no vascular system to transport water and nutrients. they absorb water and nutrients from the environment through osmosis and diffusion.
- require water for fertilization (sperm swim to the egg)
-produce spores for asexual reproduction and dispersal
nonvascular plants: liverworts
“leafy” and thalloid (simple and flat) form. lack stomata
stomata
stoma- allow exchange of o2 and CO2. H2O evaporation occurs through these pores and can close during dry conditions to prevent water loss.
nonvascular plants: mosses
about 12,000 species. 1mm-15cm. some are tall, more than 2m. Substrates include rocks, soils, acidic soils, logs and stumps, and bogs. Survive desiccation or freezing.
nonvascular plants: hornworts
horn-like sporophyte
vascular plants
-have alternation of generations. The sporophyte stage is dominant to the gametophyte stage.
-have a vascular system, meaning xylem and phloem in the leaves and roots and leaves.
-dominant sporophytes. 2n larger and more complex v the gametophyte n.
-vascular tissue- conductive tissues that allows for transport of water, minerals, and photosynthetic products throughout the plant. two types are xylem and phloem
xylem and phloem
xylem- flows upward, with water and minerals. has tracheids, which are tube shaped cells with cell walls strengthened with lignin. has vessels
phloem- cells arranged in tubes. carries sugars, amino acids, and other organic products in all directions within the plant.
vascular tissue
lignified tracheids have thick cell walls. allows for increasing morphological complexity, like branching.
leaves
photosynthetic organ of vascular plants. increase the surface area in plants and are classified in two types; microphylls and megaphylls
microphylls
small, spine-shaped leaves with one vein. Appeared 410 mya. Lycophtes.
megaphylls
all other vascular plants. highly branched. When surface area is increased, then photosynthetic productivity is also increased. Arose 370 mya.
roots
-anchor the plant
-absorb water and nutrients from the ground
-store food to be used later
-evolved from lower most subterranean portion of stems
seedless vascular plants
-have true vascular tissue, xylem and phloem
-most have roots with lignified tissue
-lack seeds
-gametophytes reduced v bryophytes. develop from spores beneath the soil surface, and are often colorless and small. Some have no chlorophyll and derive nutrients with aid of fungi.
-gametophytes-sperm use the flagella to swim to the egg. They live in moist environments as they need water for sperm to swim. reproduce and disperse through spores.
-2 main groups- lycophytes and monilophytes
lycophytes
-club mosses, spike mosses, quillworks
-moist temperate forests
-microphylls
-dichotomously branching roots
monilophytes (pterophytes)
-ferns, horsetails, whisk ferns
-more closely related to seed plants than to lycophytes
-megaphyll leaves (ferns and horsetails)
-roots that branch (ferns and horsetails)
traits of seed plants
sporophyte dominant, reduced gametophyes, heterospory, ovules, and pollen
gametophytes of seed plants
microscopic, and still develop from spores. But, the spores are retained within the sporangia, and not released into the environment. It derives nutrients and shelter from the sporophyte. It protects it from desiccation and UV radiation
heterospory
plants which have two kinds of spores. a megaspore, which is a female gametophyte. One megasporangium yields one megaspore. A microspore, which is a male gametophyte. One microsporangium yields many microspores.
ovules
megasporangium. retained within the sporophyte. the megasporangium is protected by an integument. An integument is sporophyte tissue. one layer for gymnosperms, and one layer for angiosperms. Overall, an ovule contains the megasporangium, the megaspore, and the integument.
pollen
pollen grain-develops from microspore and houses the male gametophyte (microgametophyte). pollen wall is made from sporopollenin, and pollen grain is dispersed by wind or animals.
pollination- transfer of pollen to portion of seed containing ovules. uses pollen tube, which emerges after pollen tube germination. it discharges sperm into the female gametophyte.
in pollination, water is not required for the sperm to swim long distances. That’s why there is nonmotile sperm in gnetophytes, conifers, and angiosperms. Pollen can disperse long distances by wind or animals.
Seeds
-contains an ovule an ovule has an egg and sperm (both n) which turns into a 2n zygote, then develops into a sporophyte, and eventually an embryo. the seed also contains a food supply.
-advantages over spores- have longer lifetimes and a protective coat. Can be dispersed using wind or animals. An embryo itself is an advantage because it has more genetic variation. Having stored food inside the seed allows for the sporophyte to germinate and grow using stored food.
pollination of seeds and pollen
seeds are more resistant, and can be dispersed in many more ways. Pollen are an airborne agent which brings gametes together.
types of seed plants
gymnosperms- have a naked seed. Cycadophyta, ginkgophyta, ghetophyta, coniferophyta
angiosperms- vessel seeds. Anthophyta, flowering plants.
history of seed plants
360 million years ago, the first seed plants emerged. These species are extinct now.
305 mya, the first gymnosperms emerged
140 mya, the first angiosperms emerged
gymnosperms
emerged towards the end of the Paleozoic era (305 mya). during the Mesozoic era (252 mya), gymnosperms began to become more prominent. Cycads emerged.
Animals
-heterotrophs that ingest and digest food.
-are multicellular. Have no cell walls, use collagen, and have nerve and muscle cells.
-reproduction-diploid condition is dominant, and sexual reproduction is common. Meiosis produces haploid gametes. Has a zygote.
history of animals
great diversity of animals, over 99% of species are extinct.
Ediacaran fossils from 565-550mya were first animals. They were sponges and cnidarians. Others do not appear to fit any living land animals.
porifera
sponges- basal animals which lack true tissues. They are monophyletic, most are marine, and sedentary. They are suspension (filter) feeders, and they are non-motile.
-they are specialized cells but lack true tissues.
choanocyte- has a flagella which moves water through pores, into a spongeoceol and out through an osculum. food particles become trapped, and phagocytosis occurs.
amoebocyte- pseudopodia, moves around through the mesophyll. Transports nutrients to other cells. Produces structural fibers and can become other sponge cell types.
regeneration- ability to replace lost/damaged body parts. Entire sponges can do this, as long as amoebocytes are present.
ctenophora
“comb jellies”
diploblastic- true tissues, with 2 primary germ layers from which tissues originate. these layers are called an endoderm and an ectoderm. They are symmetrical, and most are predators.
cnidaria
corals, jellyfish, and hydras. Are also diploblastic. They are radially symmetrical and both sessile and motile. emerged 560 mya.
morphology- have a gastrovascular cavity called a mouth anus.
2 types- polyps like sea anemone and hydras which do not move. Medusa like jellyfish which move freely. Some cnidarians can have both types through life changes.
nutrition- they are carnivores. They capture prey with tentacles and push food into the GV cavity. undigested food is expelled through the cavity.
cambrian explosion
-occurred in BC Canada. Fossils over half of our present-day animal phyla can be found here. This includes arthropods, chordates, and echinoderms. These animals are predators and have hard mineralized structures like spines and body armor
-they are bilaterally symmetrical, and most have a complete digestive tract
why decline in ediacaran diversity?
-predator prey speciation allowed predators to develop traits to help them kill prey, like skeletons, plates, and other defensive structures.
-increased oxygen meant higher metabolic rates and larger body sizes
-Hox genes- allowed for different body forms. These are a group of developmental genes that controls body plan of bilaterally symmetrical animals
animal body plans
have symmetry, tissues, and body cavities
animal symmetry
2 types, radial and bilateral. Animals with radial symmetry are sessile, and interact with environment from all directions. Other type is bilateral. They are motile and have cephalization, which means they have sensory organs at anterior end; they move head first into their environment.
animal tissues
tissues are collections of specialized cells which arise from germ layers. In animals, there are three germ layers.
ectoderm- outer covering of skin (epidermis) and nervous system
mesoderm- muscles, dermis, BV, bone, and other organs
endoderm- lining of digestive and respiratory tract, pancreas, and liver.
body cavities
3 types of body cavities.
“true” cavity- space between digestive tract and outer body wall. Formed from the mesoderm. These are called coelomates.
“false” body cavity- body cavity formed from mesoderm and endoderm. These are called pseudocoelomates.
no cavity- acoelomates
bilateria
majority of animal species are this, have bilateral symmetry, and are triploblastic (three germ layers)
3 clades- lophotrochazoa, ecdysozoa, deuterostomia. These dominated cambrian oceans, and majority were invertebrates.
lophotrochazoa
most diverse clade of bilateral animals. There are 18 phyla.
flatworms (platyhelminthes)
free living in aquatic and damp terrestrial habitats. they are predators and scavengers.
there are parasitic forms likes trematodes (flukes) , and cestodes (tapeworms)
molluscs
second most diverse animal phylum. Live in marine, freshwater, and terrestrial environments. Soft creatures with a hard protective shell made of calcium carbonate. reduced or lost in squids, slugs, and octopi.
Annelids
segmented worms. Live in marine freshwater, terrestrial. They have a true cavity, so they are coelomates.
ecdysozoa
has an external coat with a cuticle. It is tough and sheds as the animal grows. This molting is called ecdysis.
this order contains more known organisms than all other animals, protist, fungus, and plant groups combined. There are 8 phyla.
nematodes
roundworms
morphology- cylindrical body. pseudocoelomate which contains fluid under pressure and keeps the body straight. Provides rigidity.
Arthropods
10 to the 18th number of species. 1 million identified. 2/3 animals are arthropods.
they are ubiquitous, meaning they can be found anywhere. They are the most successful of the animal phyla.
origin- earliest fossils in the cambrian explosion. Have a segmented body, hard exoskeleton, and jointed appendages.
over time, there is a reduction in segments, and the appendages became more specialized. More efficient because of division of labor among body segments.
arthropod characteristics
cuticle- exoskeleton, composed of layers of protein and chitin
functions- support and protection. Attachment point for muscles. Impermeable for water.
molting ecdysis- must shed old exoskeleton to grow. expends energy to mold. Arthropod is susceptible to predation and desiccation during this time until the new exoskeleton hardens
specialized appendages- walking, feeding, sensory reception, reproduction, defense, jointed and paired
homeogenetic genes
hox genes- determine body plan and orientation, foundation and identity of body segments, express patterns like clusters from head to tail, overall help regulate development by turning developmental genes on and off.
small changes in regulatory sequence leads to major changes in later form
hexapods (insects)
ubiquitous
evolutionary adaptation-flight, gymnosperms, flowering plant associations
flight- have 1-2 pairs of wings on the thorax. These are cuticular extensions. Wings evolved once in insects because of heat collection, gliding, gills in aquatic habitats, and swimming apparatuses.
insect life cycles
metamorphosis
can be incomplete or complete. In incomplete metamorphosis, there is no major change in morphology, like grasshoppers and crickets. In complete metamorphosis, there are huge morphological changes, like flies and butterflies. Larvae is another example
importance of insects
-can be herbivores, predators, parasites, and decomposers.
-they are a food source for many animals and humans
-pollinators
-destroy crops and crop yields
-cause animal and human disease
life cycle of pine trees
pollen cones- smaller, have microspores which develop into male gametophytes, or pollen grains
ovulate cones- larger, megaspores that develop into female gametophytes
cycadophyta
cycads
2nd largest group of gymnosperms. Dioecious sporophytes with palm-like leaves. Have large cones and flagellated sperm
gingkophyta
gingko bilboa is the only species
deciduous, meaning lose leaves seasonally
gnetophyta
3 genera
angiosperms
phylum anthophyta
vascular seed plants with flowers, which are sexual reproductive structures that are pollinated by wind and animals.
have fruits, which contain seeds.
most diverse and geographically widespread of all plant groups. they are 90% of all plants, and appeared 130 mya.
flower structure
have 4 sporophyll rings
have sterile floral organs- outer part of bud, sepals, and petals
fertile floral organs- internal part of bud, stamens, and carpels
petals
attract pollinators, like insects, birds, and mammals
UV patterns in petals
wind pollinated flower have no petals or dull petals
fertile floral organs
stamen- made up of filament (support) and anther
anther- contains microsporangium. microsporocytes (2n)- meiosis- microspore (n)- pollen grain (microgametophyte or male gametophyte)
carpel-stigma (receive pollen), style, and ovary
ovary- contains megasporangium
megasporocyte (2n)- meiosis- megaspores (n)- female gametophyte
fruit
mature ovary, but can include other flower parts
ovary is fruit and ovules are the seeds. Mature fruit can be fleshy or dry.
fruit function
protect seeds and aid in dispersal
evolution of flowering plants
emerged 140 mya as the first angiosperms.
Around the time of the Mid-cretaceous period (100 mya)
flowering plant diversity
water lilies, star anise and relatives
magnolids- magnolias, laurels, black peppers
monocots- 70,000 spp. can be orchids, grasses, and others (lilies, daffodils, irises, amaryllis, and tulips)
importance of angiosperms
food- 80% of all calories consumed come from 6 crops- rice, wheat, maize, potatoes, cassava, and sweet potatoes. food source is also spices, coffee and tea.
can also be used for wood and lumber, medicines and botanical, flower industry, and landscape industry
