17

Question 1

what envr challenges do lichens face?

Answer 1

light

cold

fire

Question 2

what is an effect of developing in regions where light is strong?

Answer 2

heat must be dissipated

Question 3

how do lichens survive living in an envr where light is strong?

Answer 3

dry out to withstand heat & therefore, the heat won’t negatively affect the algal cell

fungi are resistant to heat

Question 4

what effect does permafrost have on lichens?

Answer 4

top is dry & bottom is moist b/c permafrost dries out & provides enough moisture so the algal cell can remain living

enter a cryptobiotic state

Question 5

cryptobiotic state

Answer 5

all measurable metabolic processes stop (reproduction, development & repair) until envr conditions return to being suitable

Question 6

what effect does fire have on lichens?

Answer 6

permafrost melts

exposes envr to the loss of water

destroys vegetation

eliminates food sources

destroys animal habitats

changes nutrient composition

Question 7

when do lichens burn?

Answer 7

when substrate or soil is set on fire

Question 8

what component has a larger dependence on the other?

Answer 8

algal cells have a larger dependence on the lichen than the fungal cells do

Question 9

what process occurs in the algal component of the lichen?

Answer 9

nitrogen-fixing

Question 10

describe the formation of a lichen?

Answer 10

fungal hyphae penetrate algal cell wall

clusters of algae meshed within fungal hyphae

Question 11

what are the thallus components of a fruticose lichen?

Answer 11

algal layer

solid central strand

medulla

cortex

Question 12

medulla in fruticose lichens

Answer 12

composed of fungal hyphae in assoc with algal cells

Question 13

what are the thallus components of a foliose lichen?

Answer 13

medulla

Gonidial layer (algal layer)

upper cortex

lower cortex

Question 14

where do the agal & fungal cells interact?

Answer 14

algal layer

Question 15

medulla in foliose lichens

Answer 15

fungal layer assoc with upper cortex

Question 16

how do lichens survive a cold state?

Answer 16

maintain the same moisture as the atm around them through poikilohydric nature

Question 17

poikilohydric nature

Answer 17

connect water tissue level with that of the envr, coupled with the ability to survive dehydration without physiological damage

Question 18

how do lichens survive on permanently frozen ground without roots or a cuticle?

Answer 18

acquire nutrients from the atm

Question 19

secondary compounds

Answer 19

protect against light, excess moisture or parasitism

formed by fungal cells

Question 20

describe Peltigera

Answer 20

contain green algae & cyanobacteria

Question 21

what are the mechanisms that lichens use to gain nutrients from the envr?

Answer 21

atm uptake

uptake from below (soil, substrate)

use incoming light

Question 22

what feature of a lichen enable them to survive in a cold & dry envr?

Answer 22

poikilohydric nature

Question 23

what feature of apothecia are useful in the survival of lichens?

Answer 23

apothecia are ornamented with cilia which function to maintain an atm of higher humidity, hold moisture in the air

Question 24

how do the sexual propagules of lichens disperse?

Answer 24

wind

Question 25

soredia

Answer 25

algal cell wrapped in hyphae

Question 26

isidia

Answer 26

branch of the lichen thallus

Question 27

rhizine

Answer 27

fungal, function is to move water along the surface of the medula

(like a root)

Question 28

thamnolia

Answer 28

coral fungus