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BIOL 366 > Lecture 22- Plant Adaptations I > Flashcards

Lecture 22- Plant Adaptations I Flashcards

1
Q

What are some limitations to northern plants?

A
  • Short growing season
  • Drought
  • Infertile soil
  • Frost heaving
  • Permafrost
  • Snow abrasion
  • Strong winds
  • Episodic herbivory
  • Low pollinatory frequencies
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2
Q

What part of the short growing season limits northern plants?

A
  • Short time to put out leaves
  • Short time to release seeds
  • The temperature is consistently low, never really gets warm
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3
Q

What part of drought limits northern plants?

A
  • Low levels of precipitation
  • Low soil moisture levels because its frozen
  • Dry conditions
  • High winds draw out the moisture of the plant
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4
Q

What is frost-heaving and what does it do?

A
  • Where the soil freezes and shifts
  • It is a disturbance of the soil that changes local patterns and hydrology
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5
Q

What is snow abrasion?

A

The mechanical damage done by snow (Weight or high winds in snow)

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6
Q

What part of strong winds limits northern plants?

A
  • Mechanical damage
  • Increased risk of evapotranspiration
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7
Q

Episodic herbivory puts pressure on what?

A

Pockets of localized pressure on plants

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8
Q

What part of low pollinator frequencies limits northern plants?

A
  • Their reproductive success
  • Not lots of pollinator species and in low frequencies
  • Success rate of the plants is much lower
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9
Q

The treeline determines what?

A

Where trees can and cannot grow

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10
Q

Treelines are determined by?

A
  • Lack of summer warmth
  • Restricted photosynthesis
  • Permafrost = shallow rooting depth, so doesnt support tall verticle growth
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11
Q

What do you find above the treeline?

A

Higher abundance of small non-woody plants

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12
Q

In the north, annual growth is devoted to _____

A

Essentials
* Photosynthetic efforts being put into roots and leaves
* Little energy for woody tissue growth

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13
Q

What are the different types of environments found in the north?

A
  • Deserts, semi-desert
  • Ice caps, glaciers, moist tundras, wet tundras
  • Shrublands, heaths
  • Bogs, marshes, salt marshes and aquatic environments
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14
Q

Microhabitats allow for what in the north?

A
  • Allows for localized variation in species composition
  • Variations in topography, soil moisture and soil temperature
  • Changes in temperature, moisture, snow cover, etc
  • Small scale
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15
Q

What happens if you shift a plant in the north?

A

Moving a plant a few centimeters might easily put it into a habitat type for which it is ill adapted to

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16
Q

What are the three types of plant life strategies?

A
  1. Annuals
  2. Biennials
  3. Perennials
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17
Q

What is an annual life strategy?

A

The plant has its whole life cycle in one year

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18
Q

Which plant life strategy is the worst and most ill adapted to the north?

A

Annual

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19
Q

What is a biennial life strategy?

A

The plant has its entire lifecycle in two years

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20
Q

What do biennials do in year 1 and year 2?

A
  • Year 1 = Leaves and roots
  • Year 2 = Flowers and seeds
21
Q

List the plant life strategies from lowest to highest commonality

A
  1. Annuals
  2. Biennials
  3. Perennials
22
Q

What are perennial life strategies?

A

They are plants that are slow growing that live for many years

23
Q

What do perennials invest in the first year?

A

Invest into growth of roots

24
Q

A perennial ____ reproduce for several years

A

May not

25
Q

The majority of plants in the Arctic was what plant life strategy?

A

Perennial

26
Q

Perennials generally flower every year except _____

A

In the first year

27
Q

Describe a perennial root system in the north

A
  • Many have rhizomes (for reproduction)
  • Roots are important for stabilization
  • Deep root system
  • Long lived root system
  • Often have a large tap root
  • Predominantly storing carbohydrates they need to keep growing
28
Q

What are some issues that northern plants face?

A
  • Acclimation and freezing of temperatures
  • Desiccation
  • Water supply in winter
  • Evergreen leaves
  • Mechanical problems
  • Reproductive strategies
29
Q

What is acclimation?

A

It is a reversible change in morphology or physiology in response to environmental change

30
Q

Plants must tolerate ____ without injury because there are no avoidance mechanisms

A

Freezing

31
Q

How do plant tissues freeze?

A
  • Undergo a multi-step process
  • 1st exotherm indicates ice formation in the water conducting xylem cells
  • Water freezes in water conducting cells
  • Ice crystals continue to grow as water gets drawn out of the cells
  • 2nd exotherm coincides with cell death and intracellular freezing
  • If you get freezing within the cells, it will expand and will rupture the cell wall and cause death
32
Q

What happens to the plant if cooling is fast enough?

A
  • Withdrawl of water from the cells cannot keep pace with rate of freezing
  • Ice formation may occur inside cells and cause death
  • Can cause a lot of splitting and rupturing of cells
  • Cant move the water out of cells fast enough
33
Q

When do plants acclimate to freezing?

A

In late summer to early fall when the temperature starts to drop a little bit

34
Q

Describe the process of plant tissue acclimation to freezing

A
  • Growth cessation = stop growing (growth hormone)
  • Start to move sugar out of the leaves and into the roots which changes the concentration gradient inside the plant
  • Alteration of cellular membranes = triggered by growth inhibitors
  • The growth inhibitor makes the cell membrane more permeable so water can just flow out of the cells very quickly
  • Now water will no longer be freezing inside of the cells and causing them to rupture
35
Q

What universal growth inhibitor increases permeability of cell membranes?

A

Abscisic acid (ABA)

36
Q

What is critical for plant tissue acclimation to freezing?

A

Increased permeability of the cell membrane

37
Q

Freezing injuries often occur where on plants?

A

Branch stubs, bark

38
Q

Freezing injuries can cause ____ pressure

A

Selective pressure

39
Q

When are freezing injuries most likely to occur?

A

During the growing season (late spring frost)

40
Q

Desiccation is driven by what?

A
  • High winds
  • Water vapour loss in winter (low atmospheric humidity)
  • Low soil moisture
41
Q

Water loss is influenced by ____ differences between the leaf and outside air

A

Temperature

42
Q

What is the rate of water loss?

A

Difference between water vapour concentration between internal atmosphere of leaf and outside air

43
Q

The intracellular air spaces in leaves are near ____ humidity

A

100%

44
Q

What are some morphological adaptations for desiccation?

A
  • Short stature
  • Cushion grown form
  • Hairs
  • Evergreen leaves
45
Q

What improvement does short staure offer to the plant?

A
  • Keeps plant closer to warmth of earth
  • Reduces tissue exposed to high winds
  • Short stature keeps them in this boundary layer between the ground and the air
  • Keeps them lower then the bulk of the wind
46
Q

What improvements does cushion growth offer to the plant?

A
  • Exposed tissues reduced = less water loss
  • Air trapped inside cushion is warmer
  • Elongated taproot to replenish water loss
  • Can help other plants
47
Q

What is a negative to cushion growth?

A

Could be susceptible to heat damage if the temperature outside is high

48
Q

What improvements do hairs offer to the plant?

A
  • Trap air close to the plant
  • Warmer temperatures adjacent to tissues
  • Reduce air flow across leaf surface
49
Q

Evergreen leaves are a waxy cuticle over the leaf that ____

A

Reduced water loss

BIOL 366 (33 decks)

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