Lecture 2: The dermal system

Question 1

What are the 6 types of cells

Answer 1

parenchyma
epidermis
collenchyma
scelerenchyma
sieve tube elements
vessel elements

Question 2

What is the dermal system comprised of?

Answer 2

shoots: epidermis (derived from protoderm)
root: rhizodermis

Question 3

How many layers are the parts of the dermal system?

Answer 3

single cell

Question 4

Where is the dermal system derived from?

Answer 4

protoderm meristem

Question 5

What is the purpose of the dermal system?

Answer 5

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

Question 6

What kind of dermis is the upper epidermis

Answer 6

adaxial epidermis

Question 7

what kind of dermis is the lower epidermis

Answer 7

abaxial dermis

Question 8

What 2 zones is the rhizodermis divided into?

Answer 8

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

Question 9

how do epidermal cells divide?

Answer 9

anticlinally

Question 10

define anticlinally

Answer 10

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

Question 11

What is the main job of the epidermis?

Answer 11

protective barrier

Question 12

what are the things the epidermis controls (5)

Answer 12

water loss
gas exchange
leaf temperature
invading organisms
compound exchange

Question 13

How is the leaf temperature controlled?

Answer 13

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

Question 14

What are the 4 components of the epidermis

Answer 14

cuticle
epidermal cells
stomatal and subsidiary cells
trichomes

Question 15

What is the cuticle made of?

Answer 15

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

Question 16

where is epicuticular wax not found

Answer 16

root hairs

Question 17

What does the form and thickness of the epicuticular wax influence

Answer 17

• 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

Question 18

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

Answer 18

strong barrier from the outside

Question 19

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

Answer 19

lipstick
car wax
dental floss
disposable cups
floor polish

Question 20

What is the purpose of the cuticle

Answer 20

absorbs UV-B light
reflects light
cools surface
conserves water

Question 21

what are xerophytes?

Answer 21

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

Question 22

What are the properties of the cuticle?

Answer 22

water repellence

cooling

Question 23

what damages the cuticle layer?

Answer 23

pollutants, wind

Question 24

Where is cuticle not usually found?

Answer 24

roots

Question 25

Describe the characteristics of epidermal cells | underneath the cuticle

Answer 25

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

Question 26

Describe stomata

Answer 26

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

Question 27

What is the stomata organization in monocots

Answer 27

in rows

Question 28

what is the stomata organization in dicots

Answer 28

stomata regularly placed

Question 29

What are subsidiary cells? | - size and presence depends on species

Answer 29

flank stomata | may ASSIST in opening and closing

Question 30

How is the stomata developed (2 steps)

Answer 30

1. ) unequal division of guard cell mother cells | 2. ) the smaller cell divides into two guard cells

Question 31

What does the pore diameter of the stomata control?

Answer 31

- CO2 levels - humidity - water stress - temperature - wind

Question 32

What is the function of the stomata

Answer 32

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

Question 33

When is a stomata open? turgid or flaccid?

Answer 33

turgid cells

Question 34

When is the stomata closed?

Answer 34

flaccid cells

Question 35

What are trichomes?

Answer 35

- hairs ( star shaped, branched, unbranched) - scales - root hairs facilitate water and mineral uptake

Question 36

How do trichomes vary?

Answer 36

- single cell or multicellular - glandular or non glandular - functional when dead or alive

Question 37

What are trichomes for? - prevent dessication

Answer 37

- reflects solar radiation - lower leaf temperature - decrease water loss - absorb water and minerals (on roots and leaves) - secrete salt - insect resistance - exude compounds

Question 38

What are trichomes made of?

Answer 38

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

Question 39

What is the role of invaginations on a plant?

Answer 39

increases the surface area ; also where compounds are secreted out

Question 40

What are the protective functions of trichomes

Answer 40

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

Question 41

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

Answer 41

lycopersicon esculentum | - susceptible to aphid attacks

Question 42

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

Answer 42

lycopersicon pennelli | - aphid attacks

Question 43

Why is the wild tomato resistant to aphid attacks?

Answer 43

it secretes triacylglucose secreted from glandular trichomes

Question 44

what does Dioecious mean?

Answer 44

has 2 genders

Question 45

What kind of resin does Cannabis sativa produce?

Answer 45

THC (tetrahydrocannabinol) from its glandular trichomes

Question 46

In which gender is the concentration of THC greater?

Answer 46

on female flowers | - especially from hot, dry areas (Colombia, Mexico, India)

Question 47

Where is Cannabis sativa originally from?

Answer 47

from China; Dioecious annual

Question 48

What are the properties of Cannabis sativa?

Answer 48

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

Question 49

What are the medicinal uses of Cannabis sativa?

Answer 49

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

Question 50

What are the effects of cannabis

Answer 50

sense of calmness euphoria perception of time and space distorted