L10.2 Desert Biome

Question 1

Where are deserts found

Answer 1

30˚ North and South of the equator

Question 2

What are the climatic conditions in a desert

Answer 2

Temperature can vary but rainfall is always low
Arid

Question 3

What are the soils like in deserts

Answer 3

Coarse with low water retention

Question 4

What are the 2 types of desert

Answer 4

Tropical and temperate

Question 5

What are the conditions in a tropical desert

Answer 5

High pressure and temperatures, intense solar radiation

Question 6

Where are temperate deserts found

Answer 6

Lie in rain shadow of mountains or inland

Question 7

What are the temperature conditions in a temperate desert in summer vs winter

Answer 7

High temp in summer
Below freezing in winter

Question 8

What is the mean rainfall in deserts

Answer 8

300mm per year

Question 9

What is the cloud cover like in deserts

Answer 9

Sparse

Question 10

What is the name given to the way water breaks down rocks

Answer 10

Evapotranspiration

Question 11

What is the landscape like in deserts

Answer 11

Uniform

Question 12

What is the goal behind the great green wall of Africa

Answer 12

Planting trees into the Saharha to decrease desertification

Question 13

How long have arid conditions existed

Answer 13

Since Devonian times, 420 MYA

Question 14

How does desert flora relect its long evolutionary history

Answer 14

Richness and uniquness

Question 15

Give an example od convergent evolution among desert flora

Answer 15

Cactaceae and Euphorbiaceae
No relation to eachother but experience same pressure

Question 16

Where are Cactaceae found

Answer 16

In America’s

Question 17

What are the areas of high biodiversity in savannas

Answer 17

Oases

Question 18

What are the 3 predominant plant types in savannas

Answer 18

Therophyte annuals
Succulent
Non-succulent

Question 19

What is growth like in therophyte annuals

Answer 19

Dormant for a long period then short quick growth

Question 20

What are the 4 main adaptations for savanna plants

Answer 20

Drought escape
Drought evade
Drought endure
Drought resist

Question 21

What is drought escape

Answer 21

Avoid drought by being in seed form until rainfall
Germinate and grow when moisture is available

Question 22

What kind of plants use drought escape

Answer 22

Therophytes - short lived annual herbs occuring after rains, creat seasonality

Question 23

What plants use the drought evade stratergy and how does it work

Answer 23

Perennials, non-succulents (grasses, shrubs, trees0
Growth only active in moist conditions, roots can lie dormant until rain occurs
Still exist at other times, just dont grow

Question 24

Wha plants use the drought endure method

Answer 24

Mainly perennials
Non-succulent (shrubs and trees) with deeper root systems

Question 25

What adaptations do drought evade plants have
(What are there roots and leaves like, what do they have in their cell wall)

Answer 25

High root:shoot ration
Shed leaves in dry season
Cell wall impregnated with waxy fars (prevent transpiration)
Varnish like coating over leaves
Thick hairy cuticles

Question 26

Whay kind of plants use the drought resist stratergy

Answer 26

Succulents

Question 27

What adaptations do drought resistant plants have
(Roots, stems, cell wall, leaves)

Answer 27

Shallow roots, lateral and thin
Swollen stems
Cell walls impregnated with waxy fats
Spines as leaves - reduce transpiration and reduces temperature

Question 28

What type of photosynthesis do drought resistant plants use

Answer 28

CAM

Question 29

Describe the root system of a tree vs a cactus

Answer 29

Tree: long complicated roots searching for more water
Cactus: horizontal roots, when it raisn it can collect water immediately

Question 30

What happens in CAM photosynthesis and why do it

Answer 30

Carbon dioxide fixation at night
Reactions seperated in time
Lower temperatures at night reduce water loss
Stomata closed during day, no water loss

Question 31

What is the point of the rib or accordion like structure of cacti

Answer 31

Allows for rapid volumetric expansion, serves as a mechanism to enhance water storage
Stretch without tearing plant tissue

Question 32

Why do some succculents grow close ogether, give an example plant

Answer 32

Clustering creates microclimate, better for trapping moisture
Lithops

Question 33

When do ephermal therophytes germinate

Answer 33

After sufficient rain

Question 34

When do zerophytic shrubs grow

Answer 34

Can be active thoughout the year in seasonal deserts

Question 35

Other plant adaptations to arid environments

Answer 35

Extensive lateral root systems
Reduced leaves or spines
Thick waxy xuticles
Leaf hairs
Regulation of leaf temp to maintain photosynthetic efficienct
Salt glands or sacraficial leaves
C4 photosynthesis
CAM photosynthesis

Question 36

Give an example of plants with salt glands and ehy they have them

Answer 36

Salty soils
Chenopodiaceae

Question 37

What plants use C4 photosynthesis

Answer 37

Halophytic shribs and perennial grasses

Question 38

What pants use CAM photosynthesis

Answer 38

Succulents

Question 39

How productive are deserts

Answer 39

Not very

Question 40

Give an example of niche partitioning in deserts

Answer 40

Differential root systems

Question 41

Where do annuals grow in deserts

Answer 41

In association with established perennials

Question 42

What human activities can effect deserts

Answer 42

Urban encrochment
Irrigation
Agriculture
Settlement
Oil drilling