exam 1 Flashcards
(320 cards)
1
Q
what is DNA?
A
material of inheritance that is common to all organisms
2
Q
what is evidence that all organisms evolved from a single common ancestor?
A
DNA is common to all organisms
3
Q
what is the most accurate measure of relatedness?
A
how similar genomes are
4
Q
what was the first genetic material that was widely compared?
A
rRNA sequences
5
Q
life depends on ______ synthesis.
A
protein
6
Q
what functions to make proteins?
A
ribosomes
7
Q
genes for rRNA evolve _________.
A
very slowly
8
Q
why were rRNA the first widely compared sequences?
A
the length of the sequences are ideal and they evolve very slowly
9
Q
_____ confirmed many previous classification schemes.
A
sequencing
10
Q
what is archaea more closely related to?
A
eukaryotes
11
Q
what are eukaryotes?
A
cells with a nucleus
12
Q
what are prokaryotes?
A
cells without a nucleus
13
Q
archaea were originally thought to be what?
A
a type of bacteria
14
Q
what are the 3 domains of life?
A
bacteria, archaea, and eukarya
15
Q
why are dyes used to visualize bacteria?
A
bacteria are hard to see even at 100X
16
Q
what is gram staining?
A
using violet, then red dye
17
Q
what does gram positive mean?
A
the cell wall of a bacteria takes up the violet dye (and looks purple)
18
Q
what does gram negative mean?
A
the cell wall of a bacteria is underneath an outer membrane (and appears pink from the red counterstain)
19
Q
what is (and isn’t) gram staining useful for?
A
useful for identification, but not for phylogenies
20
Q
how does gram staining work?
A
the purple dye sticks to the peptidoglycan in the cell wall when it is on the outside of the cell, but not when it is between layers of membranes
21
Q
where are prokaryotes found?
A
everywhere on earth, even in extreme environments
22
Q
what are the 3 shapes of bacteria?
A
coccus (spheres), bacillus (rods), and helix (spiral)
23
Q
what are ways that bacteria can move?
A
by using flagella, twisting, or gliding (and some don’t move)
24
Q
how do bacteria communicate?
A
by chemicals or light
25
what is quorum sensing?
bacteria monitor the amount of their specific species of bacteria there are, and can tell when there is a minimum amount present to form a biofilm
26
what is a biofilm formation?
aggregation of bacteria to protect the bacteria (hard for antibiotics to work)
27
prokaryotes are often ____cellular.
uni
28
even though prokaryotes are often single celled, they often live in _____.
colonies
29
how do prokaryotes reproduce?
fission (asexual reproduction)
30
what is horizontal/lateral gene transfer?
genetic material moves between organisms, not through generations
31
what is vertical gene transfer?
genetic material moves generation to generation, like in multicellular organisms
32
what is DNA transfer by conjugation?
DNA (a plasmid) from a living donor cell is transferred to a recipient cell via a pilus
33
what is DNA transfer by transformation?
DNA is released into the environment by a dead cell, and is then taken up by a living recipient cell
34
what is DNA transfer by transduction?
DNA is transferred from a donor cell to a recipient cell via a virus
35
what effect does lateral gene transfer have on phylogenies?
it complicates them
36
True or False: all prokaryotes require oxygen for survival.
False- some live in oxygen-free environments
37
what are obligate anaerobes?
organisms that must be in environments without oxygen
38
what are obligate aerobes?
organisms that must be in environments with oxygen
39
what are facultative anaerobes?
organisms that can be in environments that do or do not have oxygen
40
what are photoautotrophs?
organisms that feed themselves using light
41
what are photoheterotrophs?
organisms that harvest energy from light but rely on sugars made by organisms for food
42
what are chemoheterotrophs?
organisms that feed on other organisms
43
what are chloroplasts evolved from?
symbiotic cyanobacteria
44
what type of organisms was responsible for converting Earth's atmosphere to aerobic in the ancient past?
photoautotrophs
45
what are decomposers?
organisms that break down dead bodies- they return carbon to the soil and atmosphere
46
what are nitrogen fixers?
organisms that convert N2 from the atmosphere into NH3 (ammonia)
47
what are nitrifying bacteria?
NH3 -> NO2 -> NO3
48
what is denitrifying?
organic nitrogen is converted to N2
49
True or False: all prokaryotes are harmful in the form of pathogens.
False- some are beneficial, and some are neutral, and some are unknown
50
what is an example of beneficial prokaryotes?
legume roots house nitrogen-fixing bacteria
51
what is an example of harmful prokaryotes?
agrobacterium in plants that causes crown galls
52
the human body harbors ____ bacterial cells as human cells.
4X
53
Only a tiny percentage of prokaryotes are ________.
pathogens
54
how do pathogens cause disease?
invade the body, evade the immune system, multiply, and produce toxins
55
what are endotoxins?
they expose the host to the pathogen when bacteria lyse (when the immune system kills the bacteria)
56
what are exotoxins?
they are released by living bacteria (an active pathogen- the immune system can't fight it well)
57
which form of toxin can the human body tolerate more?
endotoxins
58
what are some symptoms of endotoxins?
fever, vomiting
59
what are some symptoms of exotoxins?
they are highly poisonous or fatal
60
what are viruses?
small molecules composed of protein-coated DNA or RNA, encoding a small number of proteins
61
what is the best evidence that viruses are not alive?
they are acellular
62
though viruses are not alive, they ______
mutate, evolve, interact with other organisms, and are derived from other organisms
63
how are viruses classified?
based on nucleic acid type (DNA or RNA)
64
what are positive sense RNA viruses?
the genome is also a template for translation
65
what are some examples of positive sense RNA viruses?
rhinovirus, polio, covid
66
what are negative sense RNA viruses?
the complement to the genome is the template for translation
67
what is RNA-dependent RNA polymerase?
it makes the complementary strand upon infection, which is the template for translation
68
what are examples of negative sense RNA viruses?
rabies, measles, mumps
69
what is an RNA retrovirus?
RNA is used to make a DNA copy (reverse of the normal flow of info) via reverse transcriptase, then pro-viral DNA is integrated into the host's genome
70
which virus type is specific to vertebrate animals?
RNA retrovirus
71
what is an example of an RNA retrovirus?
HIV
72
what are examples of DNA viruses?
smallpox, herpes, and a bacteriophage
73
what are main features of eukaryotes?
they have an organized nucleus (with linear chromosomes and a membrane), and contain organelles
74
what are organelles?
membranes associated with specialized functions
75
what do vesicles do?
move materials in and out of the cell
76
what does cellular movement in eukaryotes rely on?
predation, changing shapes, and an increase in size
77
which organelles are believed to have originated via endosymbiosis?
chloroplasts and mitochondria
78
eukaryotes have a _______ relationship with prokaryotes.
symbiotic
79
what is characteristic of eukaryotic DNA molecules?
they are linear with multiple origins of replication and carry many genes and regulatory regions
80
all eukaryotes have a ______ life cycle.
sexual
81
gametes have _____ the normal chromosome number because of meiosis.
1/2
82
what is the fusion of gametes called?
fertilization
83
what increases diversity?
sex
84
what produces variations in life cycles?
haploid and diploid phases can be persistent or brief that depend on timing of meiosis and fertilization
85
what are large eukaryotes?
plants, animals, and fungi
86
what are small eukaryotes?
protists (usually single-celled)
87
multicellularity allows for what?
specialization (increased efficiency), greater size, and mortality
88
what are the 3 main superkingdoms?
plants, animals and fungi, and protists
89
characteristics of opisthokonts
single flagellum on the back end of the cell
90
what organisms are opisthokonts?
animals, fungi, and choanoflagellates
91
opisthokonts are _____cellular
uni and multi-
92
what are choanoflagellates?
cells that can be colonial, which can be believed to be the first step toward multicellularity
93
what could be considered to be the ancestor to animals?
choanoflagellates
94
what are main characteristics of fungi?
cell wall made of chitin, absorptive heterotrophy (they digest food in the environment then reabsorb the molecules it needs for cellular respiration), feeding on living or dead organisms
95
why are fungal infections in animals difficult to treat?
many fungicides are toxic to animal cells because of how closely related animals and fungi are
96
what are single-celled fungi?
yeasts
97
what are hyphae?
strands of fungi together that make up mushrooms (look kind of like roots)
98
what are the 2 main parts of mushrooms?
underground- mycelium
aboveground- fruiting body (makes spores in gills)
99
what are fungal plant pathogens?
rusts and smuts
100
fungi can be beneficial, what is an example?
symbiosis of mycorrhizal fungi that allow trees to take up more minerals from the soil
101
what are lichens?
fungus + green algae or cyanobacterium
102
characteristics of amoebozoans
use pseudopods for motility and have a flexible membrane
103
what are 3 examples of amoebazoans?
amoeba, physarum, and dictyostelium
104
what is amoeba?
a lobosean that lives in fresh water; eats via phagocytosis and is a scavenger and predator
105
what is physarum?
a plasmodial slime mold found in forests; they disperse, then aggregate to form fruiting bodies and form spores by meiosis, they are scavengers that move by cytoplasmic streaming
106
what is dictyostelium?
a cellular slime mold with amoeba-like single cells that aggregate into a "slug" when dry or starved; the cells are retained and form spores
107
amoebazoans are _____cellular.
(mostly) uni
108
characteristics of rhizarians
unicellular aquatic organisms with long pseudopods (that look kind of like roots)
109
what are 2 types of rhizarians?
foraminiferans and radiolarians
110
what are foraminiferans?
have an external shell of calcium carbonate, and are a source of limestone when they decompose over time; pseudopods ensnare plankton for food
111
what are radiolarians?
have glassy endoskeletons made of silica and include some of the largest unicellular eukaryotes; can have photosynthetic endosymbionts (dinoflagellates)
112
characteristics of archaeplastids
land plants
113
what are some examples of archaeplastids?
red algae, green algae
114
what chlorophyll does red algae use?
chlorophyl a and phycoerythrin
115
what chlorophyll goes green algae use?
chlorophyl a and b
116
characteristics of stramenophiles?
they have unequal flagella
117
what are 2 types of stramenophiles?
diatoms and brown algae
118
what are diatoms?
single celled organisms with silica in cell walls that are aquatic and photosynthetic; filtration via diatomaceous earth
119
what is brown algae?
can be multicellular (sea palms and giant kelp) that are photosynthetic (chlorophyll a and c + brown pigments); source of emulsifiers of ice cream
120
where do chloroplasts in green algae and land plants come from?
cyanobacterium endosymbiosis
121
what is a clue to endosymbiosis leading to chloroplast formation?
more than one membrane surrounding the chloroplast
122
what is serial endosymbiosis?
more than 2 membranes around the chloroplast (derived from red algae)
123
characteristics of alveolates
single celled organisms, with sacs under the cell membrane
124
what is paramecium?
ciliate (body covered in cilia for motility) that live in fresh water
125
what are dinoflagellates?
have 4 membrane chloroplasts and can cause red tides (large algal growth)
126
what is plasmodium?
parasite that causes malaria with life cycles in mosquitoes and human blood; has nonfunctional chloroplasts
127
what are examples of alveolates?
paramecium, dinoflagellates, and plasmodium
128
characteristics of excavates
unicellular and often lacking mitochondria; named for the surface groove
129
what are examples of excavates?
giardia, euglena, and trypanosome
130
what is giardia?
a diplomonad parasite with many flagella and no mitochondria; in freshwater and causes giardiasis
131
what is euglena?
a euglenid photosynthetic organism with a flagellum on the front; if in the dark, it eats
132
what is a trypanosome?
a kinetoplastid parasite that causes sleeping sickness
133
what are characteristics of an animal?
multicellular, heterotrophic, internal digestion, motility (via muscles and skeleton)
134
True or False: Animals are monophyletic.
True- the common ancestor is thought to resemble colonial choanoflagellates
135
the earliest and simplest animals are ______.
marine
136
what are sponges?
they lack tissues and have cup-shaped body; inner surface composed of chaonocytes (flagella beat to draw water through pores to central cavity)
137
what are diploblastic animals?
have 2 body layers and distinct organ systems; noncentralized nerve net; aquatic (body supported by water)
138
diploblastic animals have a central _______ cavity, meaning what?
gastrovascular; a single opening is both the mouth and anus
139
what are ctenophores?
comb jellies
140
what are cnidarians?
jelly fish and corals
141
jelly fish and comb jellies have _________ and _______ symmetry.
2 body layers in embryo; radial
142
more complex animals have _______ and ________ symmetry.
3 embryonic layers; bilateral
143
what is the difference between deuterostomes and protostomes?
the first embryonic opening becomes the mouth in protostomes, but it becomes the anus in deuterostomes and the mouth develops later
144
what is the hollow ball of cells in early embryo?
blastula
145
most animals are __________.
invertebrates
146
what are the 3 major animal clades?
lophotrochozoans, ecdysozians, and deuterostomes
147
what are examples of lophotrochozoans?
bryozoans, molluscs, and annelids
148
what are lophotrochozoans?
have a common, free-living larval form (trochophore) and a feedng apparatus (lophophore)
149
what are examples of ecdysozoans?
arthropods and nematodes
150
what are ecdysozoans?
shed exoskeleton to grow
151
what are examples of deuterostomes?
echinoderms, hemichordates, and vertebrates
152
what are the most successful animals?
arthropods (10^18 at present- most species-rich)
153
what are the most complex of the ecdysozoans?
arthropods
154
why have arthropods been successful?
the body is supported by an exoskeleton (made of chitin), segmented body plan, and paired, jointed appendages
155
what are 4 types of arthropods?
crustaceans, hexapods, myriapods, and chelicerates
156
what are crustaceans?
marine and terrestrial organisms (lobster)
157
what are hexapods?
terrestrial organisms- insects (grasshopper)
158
what are myriapods?
insects like millipedes
159
what are chelicerates?
have distinct mouth parts (horseshoe crab, spiders)
160
what are some simpler ecdysozoans?
tardigrades and nematodes
161
what are molluscs?
they have a foot for moving, internal organs ("visceral mass"), and a mantle that secretes shell
162
what are types of lophotrochozoans?
gastropods, bivalves, and cephalopods
163
what are gastropods?
organisms with one shell (ex: snail)
164
what are bivalves?
organisms with 2 shells (ex: clams)
165
what are cephalopods?
lophotrochozoans with no exterior shell (ex: octopus)
166
what are annelids?
lophotrochozoans with segmented bodies (earthworms and leeches)
167
what are flatworms?
lophotrochozoans with simple bodies and often lack digestive tracts; most are internal parasites (flukes and tapeworms)
168
what are rotifers?
lophotrochozoans that have a ciliated corona (sweeps food into their mouth); some species only have females
169
what are bryozoans?
lophotrochozoans that can be colonial
170
simpler animals have ______ symmetry.
radial
171
more advanced animals have _____ symmetry;.
bilateral
172
________ evolved from a bilateral ancestor but exhibit radial symmetry as adults.
echinoderms
173
characteristics of echinoderms
"spiny body"; most are radially symmetric as adults, larvae are bilaterally symmetric, and they move and feed using "tube feet"
174
characteristics of chordates
dorsal, hollow nerve cord (CNS), a postanal tail for movement, a notochord for flexible support (sometimes just embryonic), and pharyngeal slits for gas exchange
175
what are examples of chordates?
lancets, tunicates, and vertibrates
176
half of all vertebrate species are __________.
ray finned fish
177
vertebrates possess ______, which was the first important innovation.
jaws
178
what are the ancestors of tetrapods?
lobe-fins
179
what are some jawed fishes?
cartilaginous fish (sharks and rays), bony fish (ray finned), and lobe-fins
180
what are the most primitive tetrapods?
amphibians
181
characteristics of amphibians
moist skin (breathe through it), require water to lay eggs (eggs have no shell), and have wet habitats
182
what are some examples of amphibians?
frogs, salamanders, and caecilians
183
what are vertebrate innovations?
internal skeleton, bony vertebrae, jointed fins, nares (to breathe air), terrestrial limbs, and amniotic eggs
184
what are amniotic eggs?
the offspring can withstand drying conditions- membrane layers that allow respiration without drying
185
what are amniotes?
reptiles and animals
186
characteristics of reptiles
amniotic egg to provide "private pond", scales (made of keratin, or feathers)
187
what are examples of reptiles?
turtles, tuataras, squamates (snakes), crocodilians, dinosaurs and birds
188
characteristics of mammals
mammary glands, sweat glands, 4 chambered heart, hair, and sometimes teeth
189
what are the three types of mammals?
prototherians, marsupials, and eutherians
190
what are prototherians?
mammals that lay eggs (platypus)
191
what are marsupials?
mammals whose newborns move to a pouch (kangaroos, possums)
192
what are eutherians?
mammals that are more developed at birth- the biggest mammal group (5000 species, 20 major groups)
193
what was the first step to multicellularity?
colonial organisms- multiple cells adhere, but they are not differentiated
194
what is the difference between multicellular and colonial organisms?
multicellular- more than one cell type
colonial- same type of cell, but many adhered together
195
around how long ago did the first eukaryotes appear in the oceans?
1.8-1.3 billion years ago
196
when did the first organisms appear on land?
around 1.2 billion years ago (they were protists and bacteria
197
when did the first multicellular land animals appear?
around 500 million years ago
198
what are 5 advantageous innovations of plants?
vascular tissue, leaves, roots, seeds, and flowers
199
what is vascular tissue in plants?
cells specialized for fluid transport that allowed for increase in height
200
what do leaves do in plants?
specialized organs for photosynthesis
201
what do roots do in plants?
allow for the uptake of water and minerals
202
what do seeds do for plants?
next generation dispersed with food, dormancy
203
what do flowers do for plants?
pollinators enable wide crossing and increases diversity
204
what is a sporophyte?
part of a plant that produces cells that undergo meiosis (and produce spores)
205
what is a gametophyte?
part of a plant that produces gametes and develops from spores
206
what is the dominant generation in nonvascular plants?
gametophyte (ephemeral sporophyte)
207
nonvascular plants are often ______ and life in ______ environments.
small; moist
208
what does the gametophyte look like in nonvascular plants?
only few cell types, and leaves are only a few cell layers thick; lacks seeds, leaves, stems, and roots
209
what is the dominant generation in vascular plants?
sporophyte (reduced gametophyte)
210
what conducts water over long distances in vascular plants?
tracheids
211
what are characteristics of vascular plants?
tracheids allow greater size and structural support, most have true roots, some reproduce via seeds
212
what might the first vascular plants have looked like?
stem only with no leaves or roots (rhizoids and rhizome held it in place), stem branches at tip ("dichotomous branching"), and reproduced via spores from sporangia
213
what were the 2 origins of leaves?
flattened sterile sporangia and fusions of side branches
214
how were microphylls formed?
from flattened sterile sporangia
215
how were megaphylls formed?
side branches fused (overtopping), and flat plates of tissue formed between small branches
216
what are plants that produce seeds called?
seed plants
217
what are plants that do not produce seeds called?
ferns
218
what are lycophytes?
"club mosses" (not real moss) that has microphylls and dichotomous branching; spores are produced in sporangia in the strobilus (no seeds)
219
what are characteristics of whisk ferns?
no leaves or roots with dichotomous branching
220
what are some characteristics of ferns?
true leaves and roots, with dominant gametophyte and sporophyte (both are photosynthetic and both can be seen)
221
what functions to seeds serve?
protect and nourish the embryo, and allow survival through unfavorable conditions
222
____% of Earth's biomass is made up of seed plants
80%
223
seed plants are _______.
vascular
224
what are the 2 groups of seed plants?
gymnosperms and angiosperms
225
what are gymnosperms?
plants that make "naked" seeds
226
what are angiosperms?
plants that make "covered" seeds- mostly flowers
227
True or False: Sperm do not swim in seed plants.
True- they are contained in pollen and are transferred as a packet
228
where do seeds come from in gymnosperms?
cones
229
what are some types of gymnosperms?
cycads, gnetales, ginkgo, conifers
230
where are seeds produced in an angiosperm?
in the ovary (in the flower)
231
what are the 2 major groups of angiosperms?
monocots and eudicots
232
angiosperms are _______ important for humans.
economically (food, fiber, building materials, drugs)
233
why are animal pollinators important for angiosperms?
they increase diversity and the production of successful alleles (attraction to the most attractive flowers)
234
what are major groups of eudicots?
daisies and relatives (cacti), legumes, roses
235
what are major groups of monocots?
palms, cereal grains and other grasses, lilies, orchids, irises
236
what is the difference between plant morphology and anatomy?
morphology- what you see externally
anatomy- internal organization (cell types in tissues)
237
plant ancestors were ________ and ______.
single-celled and aquatic
238
terrestrial plant life allowed for _______ complexity.
greater
239
what is an important special feature of plants?
they continually grow throughout their lives
240
what are the 2 organ systems in plants, and what organs are in them?
root system (contains roots), and shoot system (contains stems and leaves)
241
what are the 2 states of plant morphology?
vegetative (stems and leaves) and reproductive (flowers and fruits form)
242
what are the functions of plant roots?
anchorage, water and mineral absorption, and storage (starch)
243
what are the 3 root types?
tap roots, fibrous roots, and adventitious roots
244
what are the components of the shoot system in plants?
stem, leaf, and bud
245
where is the source of new growth in plants?
at tips of stems (terminal buds) and in axils of leaves (axillary buds)
246
what is unique about the organization of a plant?
it is modular- there are segments made of a leaf, a bud, and a stem
247
what are the functions of the stem?
support, transport, storage
248
what is the function of leaves?
photosynthesis
249
what does the flat morphology of leaves maximize efficiency for?
gas uptake and light absorption
250
True or False: Each leaf can have multiple axillary buds.
False- each leaf has only one
251
what modified plant leaf is made for support?
tendrils
252
what modified plant leaf is made for protection?
spines
253
what modified leaf is associated with flowering?
bracts
254
what modified leaf is made to protect buds in the winter?
bud scales
255
True or False: All plant organs have each type of tissue.
True
256
what is the dermal tissue system?
outer covering of the plant
257
what is the ground tissue system?
carries out photosynthesis, stores photosynthetic product, and helps support the plant
258
what is the vascular tissue system?
conducts water and solutes throughout the plant
259
what are the simplest land plants?
bryophytes
260
what are characteristics of bryophytes?
less-specialized anatomy- single-layer thickness of photosynthetic structures and non-vascular water conducting cells
261
what are the components of plant cells that are also in animal cells?
nucleus, mitochondria, ribosomes, golgi, endoplasmic reticulum, cytoplasm, and plasma membrane
262
what are special features of plant cells?
chloroplasts, large vacuole, cell wall, and plasmodesmata
263
what are plasmodesmata?
connections between plant cells
264
where are secondary walls added in plant cells?
inside of the primary cell wall
265
what are characteristics of parenchyma?
living cells with a primary cell wall made of cellulose; diverse metabolic processes
266
what are characteristics of sclerenchyma?
dead cells with thick secondary cell walls (strengthened with lignin) for support and rigidity
267
what are long and slender sclerenchyma called?
fibers
268
what are isodiametric sclerenchyma called?
sclereids
269
what are xylem?
plant tissue that conducts water
270
what are the 2 cell types in xylem?
tracheids and vessel elements (both dead) [also fibers and parenchyma]
271
what kinds of plants have tracheids?
all vascular plants
272
what kinds of plants have vessel elements?
angiosperm only (they have more elaborate cell walls)
273
what are phloem?
plant tissue that conducts food (sugars or sap)
274
what is the main transport cell of phloem?
sieve elements (ALIVE- lack nucleus, ribosomes, mito, and ribosomes) [also companion cells- provides metabolic help]
275
what two things make up plant vascular tissue?
xylem and phloem
276
where is the point of continuous cell division on a plant?
meristem (growing points at tips of root and shoot- in buds)
277
what is characteristic about meristem cells?
not differentiated and can still divide
278
what is vascular cambium?
between xylem and phloem in each vascular bundle
279
xylem cells have ____ walls, and phloem cells have ____ walls.
thick; thin
280
what is long distance water transport useful for?
bulk flow
281
how does water get into roots?
osmosis
282
True or False: Uptake of water by a plant cell is limited.
True- each cell's volume is enclosed by a cell wall, and cannot grow past that cell wall
283
what is turgor pressure?
cytoplasm that is full of water exerts pressure against the wall, and each other cell exerts pressure against all other cells
284
what regulates the uptake of ions?
the composition of the plasma membrane (selective membranes)
285
what are plant cell walls made of?
cellulose
286
how does water enter plant cells?
it can cross the wall and enter the cell by osmosis, or diffuse through the wall
287
what is an apoplast?
the area outside the plasma membrane where water can move
288
what is a symplast?
area inside cells that is open for water
289
how are symplasts connected?
plasmodesmata
290
what is the order of continuous symplastic water movement?
epidermis -> cortex -> endodermis -> xylem
291
what is the order of apoplastic water movement?
epidermis -> cortex -> endodermis
292
what is unique about endodermal cells?
they are "waterproofed" by a Casparian strip (made of lignin and wax) to block apoplastic water movement
293
how does water have to enter xylem?
it must cross a membrane at least twice (at least into and out of the endodermis, sometimes additional membranes before endodermis)
294
how fast can sap move in xylem? *****
15 m/h
295
True or False: water has to follow the rules of gravity.
False- it moves against gravity to get to the top point of the plant from the roots
296
what are the origins of force of water movement?
pushing (root pressure) and pulling
297
how far does pushing force move water?
1-2 m
298
where does primary water loss occur?
leaves
299
what is a unique property of water?
cohesion (due to hydrogen bonding)
300
why can mesophyll cells dry out?
they do not have a cuticle (made of wax) on the cell wall that prevents water loss
301
True or False- a film of water covers the plant intercellular space.
True- as the leaf dries out, the water film on each cell gets thinner
302
how does sap move in the phloem?
from source (where it is made or stored) to sink (where it is used or stored)
303
what propels phloem sap through the plant?
hydrostatic pressure- water from xylem is drawn in at the site of phloem loading
304
how is gas exchange between plant cells regulated?
epidermal "guard cells" around stomata
305
how do stomata open?
the guard cells fill with water and curve, opening the pore
306
how does water uptake by guard cells work?
ATP-driven proton pump: H+ moves out of guard cells and favors the uptake of K+ (with Cl- cotransported with it)
307
how does the proton pump turn on?
blue light (receptor in plasma membrane of guard cells), light fueling photosynthesis, and a circadian rhythm
308
how do stomata close?
when it is dark, the proton pump turns off and K+ and Cl- exit the guard cells; water stress produces abscisic acid which also turns off the proton pump
309
True or False: Plants are heterotrophs.
False- they are autotrophs, and are nourished by simple molecules from the environment
310
what provides nutrition to plants?
photosynthesis (forms carbohydrates), and the environment (C, H, and O) and "mineral elements"
311
how can it be determined which elements are required for plant growth and development?
by analyzing the elements that are present
312
how can it be determined which elements are required for plant growth and development?
by analyzing the elements that are present
313
in herbaceous plants, ____% of the plant is water.
80-85%
314
how much of the "dry weight" of plants are carbohydrates?
95%
315
how can you tell a plant is deficient in a nutrient?
it will show characteristic symptoms, such as change in color or less growth
316
which elements are required by plants?
carbon, hydrogen, oxygen, phosphorus, potassium, nitrogen, sulfur, calcium, iron, and magnesium
317
how can plants be parasites?
the roots of a parasitic plant grows into its host plant and takes the nutrients from the plant
318
what is often the most limiting mineral element?
nitrogen
319
why is nitrogen limiting in plants?
N2 is abundant in the atmosphere, and plants cannot use it in that form (nitrogen fixing bacteria must break the triple bond in N2 and form ammonia/ammonium)
320
what is an adaptation to ensure sufficient nitrogen?
bogs (in acidic soil with fewer nitrogen fixing bacteria and low N availability; leads to carnivory- venus fly traps)
