Download

Plant Adaptations






Advertisement
/ 56 []
Download Presentation
Comments
jacob
From:
|  
(4284) |   (0) |   (0)
Views: 81 | Added:
Rate Presentation: 0 0
Description:
Plant Adaptations. Outline: Photosynthesis and respiration Environmental controls on photosynthesis Plant adaptations to: High and low light Water limitation Nutrient availability Readings: Chapter 6. Conditions and Resources.
Plant Adaptations

An Image/Link below is provided (as is) to

Download Policy: Content on the Website is provided to you AS IS for your information and personal use only and may not be sold or licensed nor shared on other sites. SlideServe reserves the right to change this policy at anytime. While downloading, If for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.











- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -




Plant adaptationsSlide 1

Plant Adaptations

Outline:

Photosynthesis and respiration

Environmental controls on photosynthesis

Plant adaptations to:

High and low light

Water limitation

Nutrient availability

Readings: Chapter 6

Conditions and resourcesSlide 2

Conditions and Resources

  • Conditions are physical / chemical features of the environment

    • E.g. Temperature, humidity, pH, etc.

    • Not consumed by living organisms (but may still be important to them)

  • Resources are consumed

    • Once used, they are unavailable to other organisms

    • Plants: sunlight, water, mineral nutrients, …

    • Animals: prey organisms, nesting sites, …

Plant resourcesSlide 3

Plant Resources

  • Plants are autotrophs - make their own organic carbon form inorganic nutrients

    • Need light, ions, inorganic molecules

  • Plants are sessile

    • Grow towards nutrients

Plant adaptationsSlide 4

PHOTOSYNTHESIS

Conversion of carbon dioxide into simple sugars

6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O

LIGHT

Plant adaptationsSlide 5

Light reactions

Plant adaptationsSlide 6

Dark reactions

carboxylation

Plant adaptationsSlide 7

Photosynthetically Active Radiation, PAR

Plant adaptationsSlide 8

RESPIRATION

C6H12O6 + 6O2 6CO2 + 6H2O + ATP

Plant adaptationsSlide 9

Net photosynthesis = Photosynthesis - Respiration

Plant adaptationsSlide 10

Photosynthesis involves gas exchange

Plant adaptationsSlide 11

  • Controls on photosynthesis

    • Light

    • Water

    • Nutrients

    • Temperature

1 lightSlide 12

1. Light

Plant adaptationsSlide 15

PAR

TradeoffSlide 17

Tradeoff

  • Shade plants grow better in the sun than in the shade,

  • but sun plants grow faster than shade plants in direct sun

Shade plant

Sun plant

Tradeoff1Slide 18

Tradeoff

  • Shade plants survive well in either sun or shade

  • Sun plants cannot tolerate shade

Shade plant

Sun plant

Plant adaptationsSlide 19

  • 9 tree species of Macaranga from Borneo, Malaysia

Phenotypic plasticitySlide 20

Phenotypic plasticity

  • Most plants have the ability to alter their morphology (within limits) in response to light conditions

Phenotypic plasticity1Slide 21

Phenotypic plasticity

  • Sun and shade leaves can exist within the same tree

More deeply lobed --> More rapid heat loss

Plant adaptationsSlide 22

  • Sun leaf

  • thicker

  • more cell layers

  • more chloroplasts

  • Shade leaf

  • flat

  • thin

  • larger surface area / unit weight

Plant adaptationsSlide 23

  • Shade leaves

  • Horizontal leaves, single layer

  • Low saturation point

  • Low compensation point

  • Produce less RUBISCO

  • Low respiration

  • More chlorophyll

  • Light availability limits photosynthesis rate

  • Sun leaves

  • Leaves at many angles

  • High saturation point

  • High compensation point

  • Produce more RUBISCO

  • High respiration

  • Less chlorophyll

  • RUBISCO availability limits photosynthesis rate

2 waterSlide 24

2. Water

Transpiration

For transpiration to occurSlide 25

For transpiration to occur

atmosphere < leaf <root<soil

Water potentialSlide 26

Water potential

w = p ++m

p= = hydrostatic pressure

 = = osmotic pressure

m= = matric pressure

StomataSlide 27

Stomata

  • Reduction in soil  --> stomata close

  • Species differ in tolerance to drying soils

Strategies for droughtSlide 28

Strategies for drought

  • Avoiders

    • Short lifespan

    • Wet season

    • Seeds survive drought

    • Drought deciduous species

      • Leaves shed in dry season

Strategies for drought1Slide 29

Strategies for drought

  • Tolerators

    • Leaves transpire slowly

    • Change orientation of leaves

    • Sunken stomata

      • E.g. pines

    • More efficient photosynthesis

      • E.g. C4 --> reduces photorespiration

      • E.g. CAM --> stomata open at night

Plant adaptationsSlide 31

CAM

photosynthesis

C4

photosynthesis

Plant adaptationsSlide 32

C4

Plant adaptationsSlide 33

CAM

Plant adaptationsSlide 34

CAM

Plant adaptationsSlide 35

% of grasses that are C4

Water absorptionSlide 36

Water absorption

  • Root hairs increase surface area

Plant adaptationsSlide 38

  • Structure of the root system varies between species, depending on the amt. of soil moisture in their env’t

  • Individual species show phenotypic plasticity

    • wet soil --> shallow roots near surface (greater oxygen availability)

    • dry soil --> deep roots

3 nutrientsSlide 39

3. Nutrients

  • Macronutrients – needed in large amounts (e.g. C, H, O, … N, P, K, Ca, Mg, S)

  • Micronutrients – trace elements (e.g. Fe, Mn, B)

  • Micro/macro refer to the quantity needed

Plant adaptationsSlide 40

Table 6-1

Nutrient uptake ratesSlide 41

Nutrient uptake rates

  • Reach plateau with increasing nutrient concentration

Plant adaptationsSlide 42

Maximum growth rate of a plant reflects N availability in its natural habitat. A. stolonifera occurs on more nitrogen-rich soils than A. canina.

Evergreen leavesSlide 44

Evergreen leaves

  • Plants adapted to nutrient-poor conditions tend to have evergreen leaves

4 effects of temperatureSlide 45

4. Effects of temperature

= Condition

  • Increase temperature --> increase biochemical reaction rate

  • At high temperature,

    enzymes denature

    --> death

Plant adaptationsSlide 46

  • Gross photosynthetic rate increases up to a point with increasing temperature

  • Respiration rate also increases with temperature.

  • Net photosynthesis is maximal at a point slightly below that at which gross photosynthesis is maximal

Plant adaptationsSlide 47

Leaf temperature

  • > 95% of sunlight absorbed by a leaf becomes heat

  • Cooling of leaves:

    • Transpiration

    • Convection (movement of cool air around a leaf)

C4 plantsSlide 50

C4 plants

  • Have higher temperature optima than C3

Phenotypic plasticity2Slide 51

Phenotypic plasticity

  • Individual species can modify their Topt according to the changing seasons

    = acclimatization

Plant adaptationsSlide 53

  • Response to cold

  • Chilling injury - near, > 0 oC

  • - cell membranes rupture

  • Freezing - < 0 oC

  • - ice inside cells = death

  • - ice outside cells = dehydration

    • (may survive)

    • may kill juveniles only

Plant adaptationsSlide 54

Saguaro cacti (S.W. United States) store large amounts of water; they can tolerate short periods of freezing temperatures

Plant adaptationsSlide 55

  • CLOSER TO HOME

  • Freeze-tolerant plants: frost hardening

    • When T decreases – plants synthesize sugars, amino acids, other molecules to act as antifreeze.

  • Winter – deciduous plants

    • Lose leaves in autumn

    • Leaves very efficient in summer – high photosynthesis rate

    • Leaves can’t survive freezing

    • Costly in energy, nutrients to rebuild leaves

  • Chilling breaks seed dormancy for temperate/boreal spp.

  • Germinates only in spring

Plants are phenotypically plasticSlide 56

Plants are phenotypically plastic


Copyright © 2014 SlideServe. All rights reserved | Powered By DigitalOfficePro