Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > Unit 4: Plant Biology > Flashcards

Unit 4: Plant Biology Flashcards

1
Q

Major events in history of (plant) life

A

4550 MY: Earth forms
3500 MY: photosynthesis appears
1500 MY: 1st plastid; plants and red algae diverge
500 MY: Colonization of land: plants, fungi, animals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Features of all plants

A

1) Starch as main energy-storage molecule
2) Chlorophyll b
- Chl a: all photosynthetic eukaryotes
- Chl b: accessory pigment; passes energy to chl a
- Chl b absorbs slighly different wavelengths
3) Cellulose is a major component of cell wall
- Polysaccharide: unbranched glucose residues
4) Thylakoids in stacks (“grana”)
- Thylakoids are membranes inside chloroplast - contain chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Ancestors of land plants

A

Charophytes are the closest relatives of land plants
- Evidence:
1) both nuclear and chloroplast genes
2) structure
- Land plants are not descended from modern charophytes, but share a common ancestor with them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Features of charophyte and land plants

A
  • Cell plate and phragmoplast (short microtubules)
  • Plasmodesmata (extensions of the cell membrane through pores in cell wall)
  • Sperm structure
  • Peroxisome enzymes
  • Rose-shaped cellulose synthesizing complexes
  • Sporopollenin: durable polymer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Sporopollenin

A
  • Durable polymer
  • Found in walls of:
    1) plant spores
    2) pollen
  • chemically inert
  • stable
  • persists in the environment
    protects from desiccation, decay, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The move to land: potential advantages

A
  • Air filters less sunlight than water. There’s more light for photosynthesis
  • Air has more CO2 than water. There’s more fuel for photosynthesis
  • Early terrestrial habitats lacked pathogens or predators/herbivores
  • Terrestrial soil is richer in nutrients than aquatic soil
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Land Plants Adaptations

A
  • Air not as supportive as water: Turgor (positive pressure); cell walls with lignin; xylem; stems
  • Lose water: Cuticle; Vascular tissue; Roots; Stomates
  • Reproduction harder: sperm cannot swim in air, young not dispersed easily, eggs and embryos might dry out: Egg and embryo retained on parent; Sporopollenin; protected embryo; seed coat; pollen; flower; fruit
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Features of all LAND plants

A
  • Cuticle
  • Sporopollenin
  • Multicellular, jacketed sex organs = “gametangia” (antheridia, archegonia)
  • Embryophyte condition (Zygote retained in maternal tissue)
  • Alternation of generations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Antheridium

A
  • Male sex organ (haploid)
  • Produces sperm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Archegonium

A
  • Female sex organ
  • Produces egg
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Alternation of generations

A
  • Definition: MULTICELLULAR haploid and diploid stages
  • Gametophyte is haploid and multicellular
  • The 2 generations: Sporophyte (diploid, makes spores by mitosis) and Gametophyte (haploid, makes gametes by mitosis)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A green alga WITHOUT alternation of generations

A
  • Chlamydomonas (chlorophyta)
  • Most of life: single cell, haploid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How did alt of gen. originate?

A
  • Zygote delays meiosis and divides and grows
  • Result: Multicellular diploid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Spore

A

In land plants, meiosis produces spores:
- Single-cell that can divide to produce a multicellular organism (often with protective coat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Gamete

A

Single-cell that can unite with another gamete to produce a diploid zygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Land plants: 4 major divisions

A

1) Bryophyta: the mosses
2) Pterophyta: ferns, horsetails, etc.
3) Coniferophyta: the conifers
4) Anthophyta (angiosperms)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Bryophyta (the mosses)

A
  • Around 15,000 species
  • Low growing
  • Confined to damp areas
  • Swimming sperm
  • No true vascular tissue (rudimentary vascular system)
  • No true leaves
  • Gametophyte dominant
  • Homosporous (1 spore size)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Moss lifecycle

A
  • Spores from sporangium give rise to two “buds” which eventually become a bisexual gametophyte
  • female part of gametophyte has archegonia, male part of gametophyte has antheridia
  • Fertilization occurs within archegonium
  • zygote becomes embryo which becomes a young sporophyte, which eventually matures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Pterophyta (ferns, horsetails, etc.)

A
  • Around 20,000 species, most tropical
  • Appeared around 400 mya
  • Vascular tissue
    —-Xylem and phloem
    —-Support and supply
  • Swimming sperm
  • Sporophyte dominant
  • Homosporous or heterosporous
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Fern reproduction

A
  • Sporangium opens and disperses spores
  • Spore develops into a gametophyte
  • Gametophyte has a male part (at back) with antheridia and a female part (at front) with archegonia
  • Zygote develops within archegonium, new sporophyte, mature sporophyte (fern leave), back to sporangium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Spore sizes

A

Homospory: 1 size of spore from meiosis
Heterospory: 2 sizes of spore from meiosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Homosporous spore production

A

1) Sporangium on sporophyll
2) Single type of spore
3) Typically a bisexual gametophyte
4) Eggs and sperm
Mosses and most Ferns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Heterosporous spore production

A

1) Megasporangium on megasporophyll
2) Megaspore
3) Female gametophyte
4) Eggs
1) Microsporangium on microsporophyll
2) Microspore
3) Male gametophyte
4) Sperm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Seed plants

A
  • Seed plants have both seeds and pollen
  • Seed:
    —-Embryo + nutrition + seed coat
  • Develops from ovule:
    —–Novel structure appearing in seed plants
    —–Site of female meiosis
    —–Thus contains female gametophyte, female sex organs, egg and embryo
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Ovule

A
  • Micropyle at top
  • Integument (2n) on outside
  • Megasporangium (=nucellus) (2n)
  • Just after meiosis in megasporangium: single functional megaspore (1n): will become megagametophyte (1n)
  • Ovule becomes the seed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Seeds and pollen

A
  • Seed:
    1) Embryo + nutrition + seed coat
    2) Develops from ovule
  • Pollen
    1) Mature male gametophyte
    2) Few cells in size
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Coniferophyta (conifers)

A

~550 species
* Reproductive
organs in cones
* Sporophyte
dominant
* Heterosporous
* Microgametophyte = pollen!
* Megagametophyte
—–within ovule
—–makes egg & the nourishes embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Conifer lifecycle

A
  • Mature sporophyte (2n) has Ovulate cone and Pollen cone
    1) Pollen cone has microsporangia, with microsporocytes in them, meiosis happens to produce pollen grains (n)
    2) Ovulate cone has ovule, with integument, megasporangium (2n) with megasporocyte (2n)
    3) Pollen grain enters the ovule through pollen tube (pollination BEFORE female meiosis!)
    4) inside ovule is one surviving megaspore (n), which become megagametophyte
    4) Archegonium in inside ovule, so is female gametophyte
    5) sperm nucleus (n) and egg nucleus (n) meet, after pollen enters through pollen tube
    6) seed coat forms around embyro (2n) with food reserves (n)
    7) 2 seeds form, grows into seedling, becomes mature sporophyte
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Nutrition for embryo in conifers

A

The megagametophyte provides nutrition for the embryo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Conifer gametophytes

A

megagametophyte:
1) Makes egg in archegonium
2) Nourishes embryo
Microgametophyte
1) Pollen grain (makes sperm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Gymnosperms

A
  • A plant that has seeds unprotected by an ovary or fruit
  • Gymnosperms include the conifers, cycads and ginkgo
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Angiosperms

A
  • A plant that has flowers and produces seeds enclosed within a carpel
  • Includes herbaceous plants, shrubs, grasses, and most trees
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Jack Pine: Slow reproduction in conifers

A
  • Male cones:
    —-takes a year to develop and pollinate
  • Female cones:
    —-takes a year to be pollinated, another year for female meiosis to occur
    —-After 2 years, matures into woody cone with mature seeds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Seed Plants evolution

A

1) Gymnosperms (seed, pollen)
2) Angiosperms (flower)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Angiosperm terrestrial revolution

A
  • Appeared around 150 mya then exploded into many species
  • Today over 85% of plant, animal, and fungal species live on land rather than in the sea
    — Half live in tropical rainforests
  • An explosive boost to terrestrial diversity occurred from 100-50 mya
    — The biosphere expanded to a new level of productivity
    — Coincided with innovations in flowering plant biology and evolutionary ecology, including
    1) Their flowers and efficiencies in reproduction;
    2) Coevolution with animals, especially pollinators and herbivores;
    3) Photosynthetic capacities
    4) Adaptability; the ability to modify habitats
  • The rise of angiosperms triggered a macroecological revolution on land and drove modern diversity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Anthophyta (angiosperms)

A
  • 300,000 (named),
    400,000 (estimated) species
  • Reproductive organs in flowers
  • Sporophyte dominant
  • Heterosporous
  • Microgametophyte = pollen!
  • Megagametophyte: 8 nuclei
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Flower structure

A
  • 4 whorls of modified leaves
  • sepal (leaves on outside)
  • petal (coulourful outside)
  • Stamen (male part), stem is called filament, top is anther
  • Carpel (female part), ovary on bottom, stem is style, stigma on top
  • Ovules inside the ovary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Hermaphroditic

A
  • A flower with both female and male sex organs
  • 85% of angiosperm species have co-sexual = hermaphroditic flowers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Monoecy

A

Separate male and female flowers on the same individual plant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Dioecy

A

Male and female sex organs on different individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Pollination

A
  • Definition: arrival of pollen on stigma (flowering plants) or on receptive female cone (conifers)
  • Occurs only in seed plants
  • Conifers: wind
  • Flowering plants:
    –insects
    –birds
    –bats
    –wind
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Pollination in angiosperms

A
  • Reward for pollinators:
    a) Nectar (sugar water)
    b) Pollen
  • Advertisement by plant
    a) Showy flower
    b) Possibly odor
  • Both reward and advertisement are costly
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Pollination syndromes

A
  • Integrated sets of floral traits (e.g., morphology, colour, odour, size, rewards) associated with particular pollinator groups
  • An example of convergent evolution: The traits have evolved separately many times. Can thus occur in unrelated plant species
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Pollination by bees

A

Syndrome:
- Shape: various: can be highly specialized or not
- Color: various, including yellow, blue, orange (not red)
Odor: none or highly specialized

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Pollination by bats or moths

A

Syndrome:
- Shape: tubular, open at night
- Color: yellow or white
- Odor: strong and sweet
- Nectar: large quantity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Pollination by birds

A

Syndrome:
- Shape: tubular
- Color: red most common, also yellow
- Odor: none
- Nectar: large quantity, often weak (20% sugar)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Pollination by wind

A

Syndrome:
- Shape: not showy (very reduced petals)
- Odor: none
- Nectar: none
- Pollen: very large quantity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Deceit pollination

A
  • Plant provides no reward, instead is colorful and tricks pollinator into taking pollen with no reward
  • Ex: Pink lady’s slipper orchid: bee enters bottom, has to exit through top where pollen packets (pollinia) and stigma are located
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Angiosperm lifecycle

A

1) Mature flower on sporophyte
2) Anther in flower has microsporangium, with microsporocytes, go through meiosis and make microspores
3) microspore has a generative cell and a tube cell
4) male gametophyte is in pollen grain (n)
5) Pollen grains enter through pollen tube through stigma, pollen tube extends through the style toward the ovule
6) 2 Sperm in the pollen grains fertilizes megaspore in ovary and central cell
7) Ovule (2n) in ovary goes through meiosis and forms megaspore (n)
8) 2 cells join together to form central cell and get fertilized by one sperm, other sperm fertilizes egg
9) female gametophyte (embryo sac) consists of antipodal cells, central cell, synergids, eggs (n)
10) zygote forms, and endosperm (3n), which feeds the embryo
11) results in embryo (2n), endosperm (3n), and seed coat (2n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Double fertilization

A

2 sperm nuclei in pollen
– 1 fertilizes egg, embryo (2n, diploid)
– 1 fertilizes central cell, endosperm (3n, triploid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Pollen growth

A
  • Pollen lands on stigma: pollination
  • Pollen tubes grow down style toward ovules
52
Q

Angiosperm ovules and ovaries

A
  • Ovules become seeds
  • Ovaries become fruit
53
Q

Nourishing the embryo

A

Conifers: megagametophyte (1n)
Angiosperms: endosperm (3n)

54
Q

Seed components

A
  • seedcoat (2n)
  • endosperm (3n)
  • Embryo (2n)
    — cotyledons (embryonic leaves)
    — hypocotyl (embryonic stem)
    — radicle (embryonic roots)
55
Q

2 systems in vascular plants

A
  • shoots
  • roots
56
Q

Evolutionary adaptations of stems

A

1) Iris rhizome:
- Rhizomes grow underground
- Vertical shoots emerge from axillary buds at nodes
2) Strawberry stolon
- stolons grow along surface
- plantlets form at nodes: asexual reproduction
3) Potato tuber (stolon or rhizomes)
- storage
- ‘eyes’ are axillary buds at nodes

57
Q

Evolutionary adaptations of roots

A

1) Prop roots
- Hala tree
- unstable soils
2) Storage roots
- beet
3) green roots
- Orchid
4) Pneumatophores
- mangrove
5) “strangling” aerial roots
- strangler fig

58
Q

Plant cell walls

A
  • Cellulose microfibrils
  • adjacent, parallel cellulose molecules
  • extracellular = outside of membrane
  • Composed mostly of cellulose (polysaccharide of glucose units)
  • 2 kinds:
    1) primary wall - thin, in all cells
    2) secondary wall - thicker, in some cells (strength)
58
Q

Functions of plant cell wall

A
  1. determines & maintains cell shape
  2. provides support and mechanical strength (allows
    plants to get tall, hold out thin leaves to obtain light)
  3. prevents the cell membrane from bursting (i.e.,
    resists water pressure)
  4. controls the rate and direction of cell growth and
    regulates cell volume
  5. ultimately responsible for the plant architectural
    design
  6. physical barrier to: (a) pathogens and (b) water in
    suberized (waxy) cells. However, remember that
    the wall is very porous and allows the free passage
    of small molecules.
59
Q

Plant cell wall composition

A

3 kinds of polysaccharides:
1. Cellulose
- polymer (chain) of up to 25,000 glucose molecules
- around 36 chains bond to make microfibril
2. Cross-linking glycans (hemicellulose) - bond with cellulose
3. Pectin - jellylike: glue

60
Q

Cells sticking together

A

Middle lamella:
- Material between cells
- Made of pectic substances

61
Q

The 3 tissue systems in vascular plants

A
  1. Dermal tissue
    - single layer; secretes cuticle (waxy)
  2. Vascular tissue
    - xylem and phloem; support and supply
  3. Ground tissue
    - bulk of young plant; fills space between dermal and vascular tissues; mostely parenchyma; storage, photosynthesis, support
62
Q

Plant cell types

A

1) Dermal tissue
- Epidermis
2) Ground tissue
- parenchyma
- collenchyma
- sclerenchyma
3) Vascular tissue
- Tracheids and vessel elements
- Sieve elements

63
Q

Epidermal cells

A
  • Outermost cells
  • single layer (single sheet) covering leaves, stems, and roots of non-woody plants or plant parts
    Functions:
    – waterproofing
    – protection from pathogens: viruses, bacteria, fungi
    Other specialized roles
    – hairs (trichomes)
    – nectary
    – guard cells: gas exchange
64
Q

Cuticle

A

Cuticle protects against:
- water loss
- pathogens
- ultraviolet (UV) radiation

65
Q

Secretory trichomes

A

Projections on plant surface, secrete oils, hinder crawling insects etc.

66
Q

Parenchyma cells

A

1) Functions
- Many; often specialized
- Most metabolic processes (photosynthesis, storage, secretion, food storage)
2) Features
- A type of ground tissue (when in stems and roots)
- Usually lack secondary wall
- Can often divide and differentiate at maturity
3) Examples
- Fruit flesh
- Endosperm
- Pith and cortex of stems and roots
- Chloroplast-laden cells inside leaves

67
Q

Collenchyma cells

A

1) Functions
- Support, esp. of young and growing organs
2) Features
- A type of ground tissue
- Thick, uneven primary wall
- No secondary wall
- Always occur just below epidermis
- Often occur in strands
- Alive at maturity: can elongate
3) Examples: Celery leaf midrib petiole (the ribs we feel on a celery stalk are each underlaid by a strand of collenchyma

68
Q

Stem cross section

A

Top: epidermis
Underneath: (ground tissue), collenchyma at top, parenchyma underneath
Middle: Vascular tissue

69
Q

Sclerenchyma cells

A

1) Functions
- Support, protection, (of tissues no longer elongating)
2) Features
- A type of ground tissue
- Thick secondary wall of lignin (a rigid polymer)
- Cannot elongate at maturity (may be dead)
- 2 forms: fibers and sclereids
3) Examples
- Burlap (jute fibers)
- Nutshell (sclereids)
- leaves of water lilies (sclereids)

70
Q

Water conducting cells of the xylem: tracheids and vessel elements

A

1) Functions
- Support and supply of water and minerals
2) Features
- Dead at maturity
- Secondary wall lignified, often spiral
- Two kinds: tracheids and vessel elements
- A type of vascular tissue
3) Pits
- Holes in secondary wall where only primary wall remains
- Allow water passage
- In both tracheids and water elements

71
Q

Programmed cell death

A

1) Cytoplasmic streaming
2) Secondary wall formed
3) Death (vacuole implodes)

72
Q

Lignin

A
  • Class of complex organic polymers (NOT a polysaccharide)
  • 2nd most abundant natural polymer, after cellulose
  • Deposited in cells walls; fills spaces and binds cellulose, hemicellulose and pectin
  • Gives strength to wood and bark
  • Can occur in cell walls of non-woody plants
  • Human uses:
    —Wood: 20-33% lignin by dry weight
    —Rope, clothing, rugs, … (schelenchyma fiber)
    —Paper - lignin removed to leave cellulose
    —Artificial vanillin
73
Q

Sugar conducting cells of the phloem: sieve-tube elements

A

1) Functions
- Transport sugars (esp. sucrose), other organic compounds, some minerals
2) Features
- A type of vascular tissue
- Alive at maturity
- With companion cell (parenchyma)

74
Q

Meristems

A

Plants grow from meristems:
- Ultimate source of all parts of the mature sporophyte
- Undifferentiated
- Retain “forever” the ability to divide

75
Q

Types of location of meristems

A

1) Apical meristems (AM)
- Root AM and shoot AM
- Primary growth
2) Lateral meristems
- Vascular cambium and cork cambium
- Secondary growth
- Only in conifers and woody eudicots
- Make wood and bark

76
Q

Apical meristem: shoot

A
  • Leaf primordia
  • Shoot apical meristem
  • young leaf
  • developing vascular strand
  • axillary bud meristems
77
Q

Apical meristem growth of tissues

A
  • Source of primary growth of both root and shoot
  • Makes 3 other meristems:
    1) Protoderm (epidermis) makes dermal tissue
    2) Procambium makes vascular tissue
    3) Ground meristem makes ground tissue
78
Q

Eudicot vs. monocot shoots

A
  • Eudicot: phloem and xylem (vascular bundle) in a ring around the pith, cortex on outside of ring
  • Monocot: Vascular bundles scattered throughout the ground tissue
79
Q

Root apical meristem and development

A

1) Top:
- Procambium/vascular cylinder
- Protoderm/epidermis
- Ground meristem/cortex
2) Bottom:
- Root cap/protoderm initial (RCP)
- Columella initial (CI)
- Columella root cap

80
Q

Young roots parts

A
  • Endodermis is innermost layer of cortex
  • Stele or Vascular cylinder is all cells inside endodermis; arise from procambium
81
Q

Eudicot vs. monocot roots

A

Eudicot:
- vascular tissue in an X shape in middle
- endodermis than cortex on outside
Monocot:
- Core of parenchyma cells
- Xylem and phloem in a ring around core
- Endodermis then cortex on outside

82
Q

Lateral root

A
  • Originates in pericycle (outermost layer of the vascular cylinder)
  • Grows out through cortex and epidermis
83
Q

Structure of primary (non-woody) roots - summary

A

1) Root cap - protects
2) Root hairs - epidermal cells, increase absorption area
3) Endodermis - innermost layer of cortex; surrounds vascular cylinder
4) Vascular cylinder (stele) - center of root; contains vascular tissues (xylem and phloem) and some ground tissue
5) Pericycle - between vascular cylinder and endodermis; origin of lateral roots

84
Q

Secondary growth

A

Produces:
- Wood
- Bark
Occurs in:
- Conifers
- Woody eudicots

85
Q

Cambium

A
  • The cork cambium adds secondary dermal tissue
  • The vascular cambium adds secondary xylem and phloem
86
Q

Vascular cambium

A
  • Vascular cambium is a meristem!
  • VC produces:
    1) Secondary xylem to inside (wood)
    2) Secondary phloem to outside
    3) More VC (to increase in circumference)
    4) Rays - parenchyma for lateral transport
87
Q

Wood: aok

A
  • Wood is secondary xylem
  • Lignin (polymer) in secondary walls of tracheids and vessel elements
  • Heartwood (middle, dead) vs. sapwood, (outside, alive)
88
Q

Lignin

A
  • Class of complex organic polymers (NOT a
    polysaccharide)
  • 2nd-most abundant natural polymer, after
    cellulose
  • Deposited in cell walls; fills spaces and binds
    cellulose, hemicellulose & pectin
  • Gives strength to wood & bark
  • Can occur in cell walls of non-woody plants
    (palm trees, bamboo, wheat straw, …)
  • Human uses:
  • Wood: 20–33% lignin by dry weight
  • Rope, clothing, rugs, … (sclerenchyma
    fibers)
  • Paper—lignin removed to leave cellulose
  • Artificial vanillin
89
Q

What protects woody plants?

A

Cork cambium (aka phellogen)
- New lateral meristem
- Arises from cylinder of cortex cells outside the vascular cambium and secondary phloem
- Produces the “periderm”: 3 layers:
1) Phelloderm to inside (some woody species)
* Thin layer of living parenchymal cells
2) Cork cambium itself
3) Cork to outside
* Suberized, dead cells
* Protects woody plant (there is no more epidermis)

90
Q

3 cell compartments

A
  • Cytoplasm: all material inside cell membrane
  • Cytosol: the part of the cytoplasm excluding organelles
  • Cell wall: part of the cell surrounding the membrane, made of cellulose
91
Q

Cellulose

A
  • Main component of cell walls
  • Highly absorbent (hydrophilic)
  • Polysaccharide (polymer)
  • Most abundant organic compound on earth
92
Q

Water potential, Psi

A
  • Water potential energy
  • Unit: megapascal (MPa)
  • Potential refers to water’s capacity to perform work
  • Energy and entropy are intimately linked
  • Determines DIRECTION of movement of water
  • Water flows from regions of higher to lower water potential
  • Combines effects of solute concentration and pressure
  • Psi = 0 MPa for pure water at sea level and at room temp
93
Q

Plasmolysis

A
  • Plasmolysis is loss of water from cell by osmosis
  • Cell membrane now separated from cell wall
94
Q

Turgid

A
  • Put cell in PURE water
  • Cell membrane now pushing against cell wall: turgid
94
Q

How water enters roots: Lateral transport of H2O and minerals

A

1) Apoplast (apoplastic route): nonliving continuum outside cytosol, including
- Cell walls
- Xylem cells
- Extracellular spaces
2) Symplast (symplastic route) = continuum of cytosol connected by plasmodesmata

95
Q

The endodermis

A

Cylinder 1-cell thick
* Stele: all material inside endodermis
* Xylem & phloem
* Pith
* Pericycle (origin of lateral roots)
* Casparian strip
* Where primary wall & middle lamella were
* Waterproof & impermeable to ions: suberin
* All water & ions entering xylem must pass
through endodermal cells; must cross cell
membrane!

96
Q

Mycorrhizae (mycorrhizal fungi)

A
  • A mutualism between plants and fungi
  • Increase surface area
  • Aid absorption of minerals
  • Roots and fungus attach
97
Q

The pathway of water and minerals in a herbaceous plant

A
  1. Soil
  2. Root hair or mycorrhizae
  3. Cortex
  4. Endodermis
  5. Xylem
  6. Atmosphere
98
Q

How does water move up a plant?

A
  • Transpiration-cohesion-tension mechanism (transpiration pull)
  • Negative pressure (tension) at the air-water interface in the leaf is the basis of transpiration pull, which draws water out of xylem
99
Q

Water flow in xylem: Ascent of sap

A

Steps:
- Water evaporates from moist cells in leaf stomates (transpiration)
- Water potential is lowered at air-water interface, causing negative pressure (tension) in xylem
- Hydrogen bonds hold water molecules together (cohesion)
- Xylem under tension gradient: pressure potential lowest (most negative) at top
- Water is pulled up by pressure gradient
- Water and minerals enter root by osmosis

100
Q

Control of transpiration by stomates

A

1) Cues to open at dawn:
- light
- CO2 depletion
2) Dry conditions
- abscisic acid:
- Hormone
- causes K+ to leave guard cells
- stimulates stomate closure

101
Q

Open/closed stomata

A
  • When open, water flows in and guard cells are turgid
  • When closed, water flows out and guard cells are flaccid
102
Q

Phloem transport

A

What: Sugar in solution and other compounds
Where: Sieve-tube elements
How: Pressure-flow hypothesis
- from source to sink

103
Q

Pressure flow hypothesis

A

1) Sugar is actively transported into the sieve-tube members of the phloem. Water follows by osmosis.
2) Higher water pressure at the source forces the phloem sap to move toward the sink
3) Sugar is unloaded at the sink, and water returns to the source via the xylem

104
Q

Photosynthesis: the two stages and location

A

1) Light reactions (thylakoid)
2) Calvin cycle (dark reactions) (stroma)

105
Q

Calvin cycle

A
  • Makes sugar
  • Occurs in stroma of chloroplast
  • Uses NADPH and ATP from light reactions
  • Supplies light reactions with NADP+ and ADP
106
Q

Rubisco

A
  • Most abundant protein
  • Attaches O2 to RuBP
107
Q

C4 photosynthesis

A
  • Around 3% of species
  • PEP carboxylase = adds CO2 to PEP
  • Corn, sugar cane
108
Q

C4 vs. CAM

A

CAM: 10% of flowering plants, most succulents
- temporal separation of steps
- C4: spatial separation of steps

109
Q

Plants’ response to herbivores

A

1) Physical defenses
- thorns
- trichomes
2) Chemical defenses
- distasteful compounds
- toxic compounds
3) Some plants “recruit” predatory animals that help defend against specific herbivores

110
Q

Hormone action

A
  • A hormone binds to a specific protein receptor, either
    embedded in the plasma membrane or in the
    cytoplasm
  • Receptor protein’s conformation thus changes
  • Stimulates the production of “relay molecules” in the
    cytoplasm
  • Relay molecules trigger various responses to the original signal
111
Q

Abscisic acid “ABA”

A
  • Hormone for stomate regulation
  • Dry conditions:
    ABA stimulates stomate closure: cause K+ to leave guard cells
112
Q

Ethylene (gas)

A
  • hormone in most plants
  • Major functions: Promotes:
    1) leaf abscission (shedding)
    2) Triple response in seedlings
    3) Fruit ripening
    4) Root hair production
    Stimulates auxin production
113
Q

Characteristics of fungi

A
  • Heterotrophs
  • Eukaryotic
  • Main body is haploid
  • Multicellular or
    unicellular
  • Yeast: unicellular without
    flagella
  • Cell wall made of chitin
  • Polysaccharide
  • Arthropod shells,
    cephalopod beaks, fish
    scales
  • External digestion of
    food
114
Q

Multicellular fungi

A
  • Basic unit is hypha
  • spore-producing structures
  • Mycelium = mass of hyphae
115
Q

2 kinds of hyphae

A

1) Septate hypha: septa with pores between nuclei
2) Coenocytic hypha (common): just nuclei and cell wall, no septa

116
Q

Spores in fungi

A
  • Haploid (1n)
  • Most <20 mm (rarely >100 mm)
  • Each contains nucleus, dehydrated cytoplasm &
    protective coat
  • Some can remain dormant for long periods
  • Produced by:
     Mitosis: Asexual reproduction
     Meiosis: Sexual reproduction
  • Purpose (functions):
     Move to new food source
     Avoid or “wait out” adverse environment
     New genetic combination (sexual repro.)
117
Q

Asexual reproduction: fungi

A

1) Spores in sporangia
2) Conidia (spores) in conidiophores
3) Budding

118
Q

Fungi phylum Chytridiomycota

A
  • 1,000 species
  • Single cells or colonies
    with hyphae
  • Flagellated spore
    (“zoospore”)
  • Haploid, Asexually
    produced
  • “zoo” because swims
  • Aquatic, soil
  • Decomposers, parasites, commensals (digestive)
  • Infect amphibians
119
Q

Fungi phylum Zygomycota

A
  • 1,000 species
  • Coenocytic (non-septate)
    hyphae
  • Decomposers, parasites,
    commensals
  • Mind control
120
Q

Fungo phylum Glomeromycota

A
  • 160 species
  • Non-septate
    hyphae
  • Asexual only (!!)
  • Obligate symbionts:
    mycorrhizae
121
Q

Fungi phylum Basidiomycota

A

30,000 species
* Decomposers &
ectomycorrhizal
* Long-lived dikaryotic
mycelium
* Multicellular (& some
yeasts)
* Septate mycelia
* Multicellular sexual
reproduction
* Fruiting body =
“basidiocarp”

122
Q

Fungi phylum Ascomycota

A
  • “Sac” fungi
  • 65,000 species
  • Multicellular or unicellular (yeast)
  • Multicellular asexual repro.: conidia
  • Multicellular sexual reproduction
  • Fruiting body = “ascocarp”
    (cup fungi, morels, truffles)
123
Q

Asexual reproduction in Ascomycota

A
  • Unicellular: yeast = budding
  • Multicellular: formation of conidia (spores) on conidiophores
124
Q

Sexual reproduction in Ascomycota

A
  • 8 spores in each ascus
  • Ascocarp = fruiting body

Biology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions