Bio Exam 3 > General > Flashcards

General Flashcards

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1
Q

What pigments do plants use for photosynthesis?

A

Chlorophyll a & b, with carotenoids as accessory pigments.

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2
Q

What is the storage form of sugar in plants?

A

Starch.

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3
Q

What are plant cell walls composed of?

A

Cellulose and pectin.

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4
Q

What structure helps align cell division in plant cells?

A

The phragmoplast (perpendicular microtubules relative to the division plane).

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5
Q

Which green alga is a strong candidate ancestor of land plants mentioned in lecture?

A

Spirogloea musicola.

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6
Q

List two stress-response features found in Spirogloea that preadapted plants to land.

A

Transcription factors for stress, hormone signaling, cell wall remodeling, disease resistance, desiccation tolerance (any two).

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7
Q

What are the major challenges plants faced when moving onto land?

A

Drought, high irradiance/UV, freezing, anchoring, and structural support out of water.

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8
Q

Define hyphae and mycelium.

A

Hyphae are threadlike fungal filaments; mycelium is the mass of hyphae forming the fungal body.

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9
Q

What are mycorrhizae and their mutual benefits?

A

Fungus-root symbioses: plants gain mineral/water uptake; fungi receive carbon.

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10
Q

Differentiate ectomycorrhizae and arbuscular (endo)mycorrhizae.

A

Ecto surround roots but don’t penetrate cells; endo penetrate cells (mostly Glomeromycetes).

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11
Q

What is sporopollenin (as discussed for Zygnematophyceae)?

A

A tough outer coat on zygospores providing desiccation resistance.

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12
Q

How do fungi feed?

A

Externally digesting heterotrophs: secrete enzymes and absorb nutrients.

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13
Q

What is the dikaryon stage in fungi?

A

A stage with two genetically distinct nuclei (n + n) per cell before karyogamy.

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14
Q

What is unusual about fungal mitosis?

A

Nuclear (closed) mitosis with spindle plaques inside the nucleus.

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15
Q

Name one example of fungal carnivory from lecture.

A

Nematophagous fungi that trap/immobilize nematodes for nitrogen.

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16
Q

What life cycle pattern do nonvascular plants exhibit?

A

Haplodiplontic alternation of generations.

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17
Q

Which stage is dominant in bryophytes?

A

Gametophyte is dominant; sporophyte is dependent on the gametophyte.

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18
Q

List the three bryophyte groups.

A

Mosses, liverworts, hornworts.

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19
Q

Do nonvascular plants have true leaves or vascular tissue?

A

No, they lack both true leaves and xylem/phloem.

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20
Q

What do bryophytes require for fertilization?

A

Water (flagellated sperm).

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21
Q

What early adaptations reduce desiccation in some nonvascular plants?

A

Waxy cuticle and stomata (in moss and hornwort sporophytes).

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22
Q

Do nonvascular plants have central veins?

A

Sort of—proto-vascular strands not fully lignified or well differentiated for sugar/water flow.

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23
Q

Summarize the nonvascular plant life cycle.

A

Gametophyte (1N) produces gametes → fertilization → sporophyte (2N) → meiosis → spores (1N) → gametophyte.

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24
Q

Why are fungi important to early land plants?

A

Mycorrhizal partnerships improved nutrient/water uptake and soil formation.

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25
What habitats do nonvascular plants typically occupy?
Moist habitats due to reliance on water for reproduction.
26
What key innovation distinguishes vascular plants?
Vascular tissue: xylem (water/minerals) and phloem (sugars).
27
Name the three primary tissue systems in plants.
Dermal, ground, and vascular.
28
What are functions of dermal tissue?
Protection and water loss prevention (cutin/wax).
29
What are trichomes and their functions?
Epidermal outgrowths that reduce evaporation and deter herbivory.
30
What do root hairs do?
Increase root surface area for absorption.
31
Define parenchyma, collenchyma, and sclerenchyma.
Parenchyma: living, storage/photosynthesis; Collenchyma: living, flexible support; Sclerenchyma: dead at maturity, fibers/sclereids for strength.
32
What are tracheids and vessel elements?
Water-conducting xylem cells with lignified secondary walls; vessels are wider and more efficient.
33
What regulates stomatal opening?
Guard cells via turgor pressure.
34
Define homospory vs. heterospory.
Homo: one spore type (bisexual gametophyte); Hetero: micro- and megaspores (separate gametophytes).
35
What groups are seedless vascular plants?
Lycophytes and pterophytes (ferns).
36
Which life stage dominates in ferns?
Sporophyte.
37
What are apical meristems?
Regions producing primary growth: protoderm, procambium, and ground meristem.
38
What do lateral meristems produce?
Secondary growth: vascular cambium (secondary xylem/phloem) and cork cambium (outer bark).
39
Give an example of heterospory in lycophytes from lecture.
Selaginella (heterosporous); Lycopodium is homosporous; Isoetes heterosporous without strobili.
40
Summarize the cohesion-tension model.
Transpiration creates tension; cohesion/adhesion pull water up xylem via hydrogen bonding.
41
List environmental factors that affect transpiration rate.
Temperature, humidity, wind velocity, CO₂ concentration, stomatal aperture.
42
What do stomata do?
Allow CO₂ in and H₂O out; regulated by guard cells’ turgor.
43
Name leaf-level adaptations to water stress from lecture.
Thicker epidermis, fewer/inset stomata, trichomes, stomatal regulation.
44
What is bulk flow in plants?
Mass movement of fluids driven by pressure differences (xylem and phloem).
45
Describe the pressure-flow hypothesis.
Sugars move from sources to sinks via osmotic pressure, through living sieve tubes aided by companion cells.
46
What are sources and sinks in phloem transport?
Sources: photosynthetic tissues (chlorenchyma); Sinks: growing apices, roots, storage tissues.
47
What is the evolutionary significance of seeds?
Embryo protection, dormancy, delayed germination, and nutrient supply for establishment.
48
Define integument and micropyle.
Integument: protective layer forming seed coat; micropyle: opening for pollen entry.
49
How do seed plants avoid needing water for fertilization?
Pollen carries the male gametophyte to the ovule.
50
What do gymnosperm microstrobili produce?
Microsporangia with microspore mother cells → microspores → winged pollen (2 prothallial cells, 1 generative, 1 tube cell).
51
Outline the gymnosperm fertilization timeline from lecture.
Pollination in spring; after ~12 months, generative cell produces sperm; ~13 months, megagametophyte forms tissue from free nuclei; then fertilization and seed maturation.
52
What tissues make up xylem vs phloem?
Xylem: vessels/tracheids (dead at maturity); Phloem: sieve tubes/sieve cells with companion cells (living).
53
How does gymnosperm pollination work?
Open cone scales catch pollen; secretion draws pollen into micropyle; scales then close.
54
What is serotiny and why is it adaptive?
Seed release triggered by heat/smoke/fire; times dispersal to post-fire conditions.
55
What seed trait aids dispersal in pines?
Winged seeds.
56
Why are angiosperms so diverse?
Flowers/fruits, double fertilization, enclosed ovules, and coevolution with pollinators.
57
Define double fertilization (angiosperms).
One sperm + egg → zygote (2N); one sperm + polar nuclei → endosperm (3N).
58
What becomes of the ovary and integuments after fertilization?
Ovary wall → fruit; integuments → seed coat.
59
What does the stamen consist of and produce?
Anther (with microsporangia) and filament; produces pollen (male gametophyte).
60
What is inside the ovule?
Megasporangium with megaspore mother cell; via meiosis → megaspore → embryo sac.
61
What makes endosperm important evolutionarily?
Nutritive tissue that feeds embryo—key advancement improving seedling success.
62
Give two gymnosperm seed-dispersal strategies from lecture.
Winged seeds; serotinous cones opening after fire/heat/smoke.
63
Name the parts of a carpel.
Stigma, style, ovary; ovules inside ovary.
64
What is the embryo sac?
The mature female gametophyte (7 cells, 8 nuclei: egg, 2 synergids, 3 antipodals, 2 polar nuclei).
65
What tissue ‘screens’ vs. attracts pollen tubes?
Sporophyte (2N) tissue screens; gametophyte (1N) tissue attracts pollen tubes.
66
What two products result from double fertilization?
Diploid zygote and triploid endosperm.
67
How do small vs large seeds differ in germination needs?
Small seeds often surface-germinate aided by light; large seeds can germinate underground using stored reserves.
68
Monocot vs dicot: leaf venation.
Monocots: parallel; Dicots: net/reticulate.
69
Monocot vs dicot: stem vascular bundles.
Monocots: scattered; Dicots: ringed arrangement (with fibers/xylem/phloem).
70
What does the ovary wall develop into?
Fruit enclosing seeds.
71
What do integuments become?
Seed coat.
72
Be able to label a carpel: which opening do pollen tubes enter?
Micropyle.
73
Define pollination (angiosperms).
Transfer of pollen to the stigma (or receptive surface) of the ovule-bearing structure.
74
What is plant–pollinator coevolution?
Reciprocal adaptation enhancing pollination efficiency and pollinator reward.
75
What rewards do flowers provide pollinators?
Nectar (sugars) and pollen (protein).
76
One benefit and one risk of specializing on a pollinator?
Benefit: efficient/reliable pollination; Risk: vulnerability if pollinator declines.
77
Traits of bat-pollinated flowers?
Nocturnal opening, large/pale flowers, strong scent, abundant nectar.
78
How do wind-pollinated flowers differ?
Small, inconspicuous, unscented, produce copious lightweight pollen with large surface area.
79
What makes pollen so durable?
Sporopollenin in the outer wall.
80
How does pollen differ by dispersal mode?
Wind: small, light, sometimes air-catching shapes; Animal: larger, sticky/structured to adhere to animals.
81
How many pollen grains can plants produce per anther?
Ranges widely—~100 to ~70,000+ depending on species.
82
List main seed-dispersal modes with terms.
Autochory (self), anemochory (wind), hydrochory (water), zoochory (animals).
83
Define epizoochory vs endozoochory.
Epi: on the outside of animals (e.g., burrs); Endo: through animals’ guts (fruits).
84
Give two conservation case studies tied to dispersal/pollination from lecture.
Mauritius tree risk due to lost dispersers (e.g., dodo); Guam faunal losses from brown tree snake causing plant impacts.
85
Why move seeds away from the parent plant?
Reduces competition/density-dependent mortality; colonizes new sites.
Bio Exam 3
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