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My BIO DAT Prep > Plants > Flashcards

Plants Flashcards

1
Q

Collenchyma

A
  • ground tissue that provide extra mechanical support to the plant, especially where the plant is actively growing
  • thick but flexible cell walls
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2
Q

Imbibition

A
  • The absorption of water by the seed
  • begins the process of germination in plants
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3
Q

Casparian strip

A

Helps regulate the type and amount of substances that can enter through the roots and travel to the rest of the plant (via vascular tissue)

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4
Q

What cells make up the phloem

A

Sieve cells and companion cells

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5
Q

Sieve cells

A

Long cells with pores that allow substances to flow through them
They lack organelles in order to transport sugars

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6
Q

Companion cells

A

Have the organelles needed in order to carry out metabolic functions (loading sieve cells with sugars to transport)
Companion cells connect to sieve cells via plasmodesmata (gap between cells that connect their cytoplasms)

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7
Q

What structures make up the xylem

A

Tracheids and vessel elements

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8
Q

Tracheids

A
  • Long, thin cells that connect to one another via their tapered ends
  • Water flows through pits found at the ends of tracheid cells
  • Also provides structural support (along with allowing the flow of water throughout the plant)
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9
Q

Vessel elements

A
  • Shorter and stouter than tracheid cells
  • Maintain contact with other vessel elements
  • Water flows through perforations between vessel elements (perforations are better than pits because water flows more efficiently)
  • Also provides structural support (along with allowing the flow of water throughout the plant)
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10
Q

Pith

A

Tissue found at the center of the root or stem
Stores and transports materials throughout the plat (functionally similar to vascular tissue)
Made up of parenchyma (ground tissue)

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11
Q

Dermal tissue of a plant

A

Found on the outer layer of the plant
Provides protection to the inside of the plant
Helps regulate how the plant is affected by the external environment

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12
Q

What is the function of the casparian strip

A

Regulates type and amount of substances that enters roots of the plant due to the fact that it is made up fatty, waxy substances that make it impenetrable (substances are forced into the cytoplasm of the root cell and forced to flow through the plasma membrane)
Helps filter substances coming in through the cell wall

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13
Q

What causes the opening of the stomata?

A

Low concentration of CO2 inside the plant which occurs during the daytime (photosynthesis occurring)
Plants need more CO2 to carry out photosynthesis
This causes the stomata to open (more carbon dioxide rushes in)

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14
Q

How does the stomata open?

A

K+ ions diffuse into guard cells —> this causes a higher concentration of solute within the guard cells which leads to water rushing into the guard cells making them turgid (swollen)

Swollen guard cells = open stomata

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15
Q

What causes the closing of the stomata?

A

High concentration of CO2 inside the plant (happens at night when photosynthesis is not occurring), the plant does not need [CO2] for photosynthesis causing plant to close stomata

High temperatures cause plants to close their stomata because they want to prevent transpiration (evaporation of water from the plant) so they close their stomata and water stays in the plant

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16
Q

How does the stomata close?

A

K+ ions leave the guard cells —> this causes the outside of the guard cells to have a higher concentration of solute which leads water to rush out of the guard cells, making them *flaccid (shrunken)**

Shrunken guard cells = closed stomata

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17
Q

Functions of auxins

A
  • Promote plant growth and elongation of cells by increasing proton concentration in primary cell walls
  • enzymes are activated that loosen cellulose fibers, increasing cell wall plasticity and thus tugor pressure expands cells to grow
  • function with cytokinins to promote cell differentiation and division
  • one of the main hormones responsible for plant tropisms (growth in a certain direction: phototrophism, gravitropism and thigmotrophism)
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18
Q

Function of cytokinins

A
  • can regulate cell differentiation and division
  • stimulates cytokinesis
  • stimulates and influences the direction of organogenesis
  • stimulate the growth of lateral buds which weakens the apical dominance created by auxins (growth of apical meristem)
  • delay senescence (aging) in plants
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19
Q

Functions of gibberllins

A
  • promote cell growth (stem elongation and flower)
  • elimination of dormancy of a seed –> promote germination
  • promote flowering and fruit production
  • inhibition of agining in leaves
  • can work with auxins to stimulate growth
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20
Q

Function of abscisic acid

A
  • Function in times of plant stress
  • Promotes/maintains seed dormancy (prevents premature opening), closes stomata (during drought), inhibits growth, forms scales
  • The dormancy caused by this hormone can be broken by an increase in gibberllin or environmental stimuli (such as temperature or light)
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21
Q

What type of plants are bryophytes?

A

Nonvascular plants: they do not have vascular tissue or roots
Examples: mosses, liverworts, hornworts

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22
Q

General characteristics of bryophytes

A
  • They must remain small and short due to the fact that they have no vascular tissue
  • They are found in moist habitats
  • They grow horizontally in order to be near water and nutrients
  • They contain rhizoids (hair-like projections) which aid in water absorption and provide minor anchoring
23
Q

Life cycle of bryophytes

A

Spend most of their life in the gametophyte stage (haploid, produces gametes)
Gametes produced posses flagellated sperm (motile, thy are able to travel through the moist environment and fuse with other gametes to produce a zygote)
Sporophyte stage uses spores as their dispersal unit
Contain reduced sporophyte which depends on and is attached to the gametophyte

24
Q

Nitrifying bacteria

A

Convert ammonia and ammonium into nitrites (NO2-) and nitrites into nitrates (NO3-)

25
Q

Nitrogen-fixing bacteria

A

Found in the root nodules of legumes
Fix atmospheric nitrogen (N2) into organic nitrogen: ammonia (NH3) and ammonium (NH4+)

26
Q

Detritus

A

Formed by dead and decaying plants and animals
Are decomposed back into the soil to contribute a nitrogen source (provides soil with nitrates)

27
Q

Denitrifying bacteria

A

Convert nitrates back into atmospheric nitrogen

28
Q

Low concentration of carbon dioxide inside a plant

A

Happens during the daytime - light is available to carry out photosynthesis and constant photosynthesis depletes the concentration of carbon dioxide levels inside the plant

29
Q

What life cycle do seedless tracheophytes spend most of their life in?

A

Sporophyte stage (they have independent gametophyte and sporophyte stages)

30
Q

Examples of seamless tracheophytes:

A

Fern, club moss, quillworts and horsetail

31
Q

What does the pressure flow hypothesis explain?

A

The movement of sugar in the phloem in relation to the movement of water

32
Q

Pressure flow hypothesis general steps

A

1) Source cells in the leaves produce sugar and load sugar into the phloem at the leaves
2) sugar concentration inside phloem cells increases, creating a gradient that pulls water from xylem into these phloem cells
3) turgor pressure is created in the phloem which results in a bulk flow movement of the sugar and water from the source (leaves) down to the sink (roots)

33
Q

What is the main driving force for water entry into roots?

A

Root pressure builds up in roots and produces an osmotic gradient which drives water from the soil into the roots and the osmotic pressure pushes the column of water in the xylem upwards

34
Q

translocation in plants:

A
  • movement of carbohydrates through the phloem from the source (leaves) to the sink (site of carbohydrate utilization)
  • movement described by the pressure-flow hypothesis
35
Q

cohesion

A
  • the attraction between like substances (ex: attraction b/w many water molecules)
  • this allows water within the xylem cells to behave as a single, polymer-like column from the roots to the leaves
36
Q

what affect does transpiration have on the pressure inside the plant?

A

transpiration causes evaporation of water from a plant which causes negative pressure (tension) to develop within the leaves and the xylem

37
Q

cohesion-tension theory:

A
  • theory explaining water movement
  • major contributor of water movement within a plant
  • consists of: transpiration, cohesion and bulk flow
38
Q

cotyledons:

A

storage tissue that provides nutrition to the devoloping seedling

39
Q

cotyledons in dicots vs. monocots

A

dicots: 2 cotyledons
monocots: 1 cotyledon

40
Q

leaf venation and structure in dicots vs. monocots:

A

dicots: broad leaf with network/branching pattern of veins
monocots: long, narrow leaf with parallel veins

41
Q

flower parts in dictos vs. monocots

A

dicots: flower parts in multiples of 4 or 5s
monocots: flower parts in multiples of 3s

42
Q

vascular bundles in dicots vs. monocots:

A

dicots: orgnized in a ring
monocots: scattered

43
Q

root system in dicots vs. monocots:

A

dicots: taproot (large, single root)
monocots: fibrous root system with many fine roots

44
Q

ground tissue:

A
  • provide structural support to the plant
  • make up most of the plants mass
  • three types: parenchyma, collenchyma and sclerenchyma
45
Q

parenchyma tissue

A
  • most common ground tissue
  • thin cell walls
  • function: storage, photosynthesis, and secretion
  • ex: mesophyll cells
46
Q

sclerenchyma:

A
  • thicker cell walls than collenchyma
  • provide mechanical support
  • tissue produces lignin, a strengthening polymer
47
Q

what are the vascular tissues in plants?

A

xylem and phloem, which together form vascular bundles

48
Q

root cap

A
  • aka root tip
  • protects the apical meristem behind it
  • secretes polysaccharides that moisten the soil, permitting root growth
49
Q

zone of cell division

A
  • formed from the dividing cells of the apical meristem
  • zone right above the apical meristem
50
Q

zone of elongation

A
  • newly formed cells from the zone of division absorb water and elongate
  • responsible for our perception of plant growth
51
Q

zone of maturation

A
  • the cells differenciate and mature into the xylem, phloem, parenchyma and epidermal cells (root hairs may grow here too)
52
Q

what plants undergo secondary growth?

A

conifers and woody dicots

53
Q

where are auxins produced?

A

at the tips of shoots and roots (apical meristem)

54
Q

auxin is a modified ____ amino acid

A

tryptophan

My BIO DAT Prep (24 decks)

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