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Biosci 102 Plant structure and function > Lecture 2: The dermal system > Flashcards

Lecture 2: The dermal system Flashcards

1
Q

What are the 6 types of cells

A 
parenchyma
epidermis
collenchyma
scelerenchyma
sieve tube elements
vessel elements
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2
Q

What is the dermal system comprised of?

A

shoots: epidermis (derived from protoderm)
root: rhizodermis

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3
Q

How many layers are the parts of the dermal system?

A

single cell

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4
Q

Where is the dermal system derived from?

A

protoderm meristem

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5
Q

What is the purpose of the dermal system?

A

protects the inner part of the plant from water loss, gas exchange, herbivores, pathogens

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6
Q

What kind of dermis is the upper epidermis

A

adaxial epidermis

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7
Q

what kind of dermis is the lower epidermis

A

abaxial dermis

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8
Q

What 2 zones is the rhizodermis divided into?

A

zone of maturation (root hairs are; when root gets older)
zone of elongation
zone of cell division

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9
Q

how do epidermal cells divide?

A

anticlinally

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10
Q

define anticlinally

A

division of cells, 90 degrees to surface of plant (new cell wall is 90 degrees to surface of plant)

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11
Q

What is the main job of the epidermis?

A

protective barrier

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12
Q

what are the things the epidermis controls (5)

A 
water loss
gas exchange
leaf temperature
invading organisms
compound exchange
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13
Q

How is the leaf temperature controlled?

A

-regulated by the amount of sun energy that
penetrates the leaf
- the amount of air movement that occurs around the leaf (influences water loss)

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14
Q

What are the 4 components of the epidermis

A

cuticle
epidermal cells
stomatal and subsidiary cells
trichomes

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15
Q

What is the cuticle made of?

A 
epicuticular wax (smooth, glandular, ridged)
cuticle proper ( cutins - fatty acids)
pectin rich layer (polysaccharides; like a cement)
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16
Q

where is epicuticular wax not found

A

root hairs

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17
Q

What does the form and thickness of the epicuticular wax influence

A
  • influences the amount of sun energy that comes into the leaf
  • impacts on the ability of bacteria to penetrate the epidermal cells
  • also affects the ability of insects to penetrate the epidermal cells
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18
Q

together what does the epicuticular wax, cuticle proper and pectin rich layer form?

A

strong barrier from the outside

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19
Q

What are examples of the uses of epicuticular wax when harvested?

A 
lipstick
car wax
dental floss
disposable cups
floor polish
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20
Q

What is the purpose of the cuticle

A

absorbs UV-B light
reflects light
cools surface
conserves water

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21
Q

what are xerophytes?

A

grow in the desert

  • xero meaning dry, phyte meaning plant
  • control water loss & over absorption (the cuticle)
  • cuticle is thick and has heavy wax layers
22
Q

What are the properties of the cuticle?

A

water repellence

cooling

23
Q

what damages the cuticle layer?

A

pollutants, wind

24
Q

Where is cuticle not usually found?

A

roots

25
Q

Describe the characteristics of epidermal cells

underneath the cuticle

A 
elongated or isodiametric
often have wavy outline (absorbs stresses)
lack chlorophyll (except shade plants)
26
Q

Describe stomata

A

the pores are bordered by GUARD CELLS
- aerial (most abundant on leaves) 500- 1000 mm^2 common
contain chloroplasts

27
Q

What is the stomata organization in monocots

A

in rows

28
Q

what is the stomata organization in dicots

A

stomata regularly placed

29
Q

What are subsidiary cells?

- size and presence depends on species

A

flank stomata

may ASSIST in opening and closing

30
Q

How is the stomata developed (2 steps)

A
  1. ) unequal division of guard cell mother cells

2. ) the smaller cell divides into two guard cells

31
Q

What does the pore diameter of the stomata control?

A
  • CO2 levels
  • humidity
  • water stress
  • temperature
  • wind
32
Q

What is the function of the stomata

A
  1. ) control water loss via transpiration (allows the plant to pull the water from the roots)
  2. ) allow entry of CO2
  3. ) allow exit of CO2
33
Q

When is a stomata open? turgid or flaccid?

A

turgid cells

34
Q

When is the stomata closed?

A

flaccid cells

35
Q

What are trichomes?

A
  • hairs ( star shaped, branched, unbranched)
  • scales
  • root hairs facilitate water and mineral uptake
36
Q

How do trichomes vary?

A
  • single cell or multicellular
  • glandular or non glandular
  • functional when dead or alive
37
Q

What are trichomes for?

  • prevent dessication
A
  • reflects solar radiation
  • lower leaf temperature
  • decrease water loss
  • absorb water and minerals (on roots and leaves)
  • secrete salt
  • insect resistance
  • exude compounds
38
Q

What are trichomes made of?

A

contain cellulose +/- lignin, cutin; may have crystals

39
Q

What is the role of invaginations on a plant?

A

increases the surface area ; also where compounds are secreted out

40
Q

What are the protective functions of trichomes

A

decrease transpiration
reflect light and UVB
secrete chemicals
absorb water and minerals

41
Q

what is the name given for the cultivated species of tomatoes? What is it susceptible to?

A

lycopersicon esculentum

- susceptible to aphid attacks

42
Q

What is the name given for the wild species of tomatoes? What is it resistant to?

A

lycopersicon pennelli

- aphid attacks

43
Q

Why is the wild tomato resistant to aphid attacks?

A

it secretes triacylglucose secreted from glandular trichomes

44
Q

what does Dioecious mean?

A

has 2 genders

45
Q

What kind of resin does Cannabis sativa produce?

A

THC (tetrahydrocannabinol) from its glandular trichomes

46
Q

In which gender is the concentration of THC greater?

A

on female flowers

- especially from hot, dry areas (Colombia, Mexico, India)

47
Q

Where is Cannabis sativa originally from?

A

from China; Dioecious annual

48
Q

What are the properties of Cannabis sativa?

A 
Smoked or ingested
hallucinogen
attributed medical benefits
impairs short term memory
fat soluble, so remains in body for days after inhalation
49
Q

What are the medicinal uses of Cannabis sativa?

A

nausea and vomiting; particularly with chemotherapy
wasting and severe weight loss, in people with HIV/AIDS
asthma
epilepsy
glaucoma
appetite stimulant
pain relief

50
Q

What are the effects of cannabis

A

sense of calmness
euphoria
perception of time and space distorted

Biosci 102 Plant structure and function (9 decks)

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