Plant Form and Function

Plant Form and FunctionLearning Goal: How are plants structurally adapted for survival?

Concept 3: Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)

Refer to pg 219-222 in HoltzclawCh 39 in Campbell Media resources

Get your

Evolution

question

ready!

Checkpoint Next Class: Concept 1: Analyzing the structure,

growth, development and nutrition of plants (Ch 35, 37)

Concept 2: Analyzing the reproduction of angiosperms and modifications through biotechnology (Ch 38)

Concept 3: Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)

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Try This!Which of the following constitute

plant macronutrients?A. Potassium, oxygen, hydrogen and

zincB. Carbon, oxygen, nitrogen and

copperC. Carbon, oxygen, nitrogen, and

hydrogenD. Carbon, boron, nitrogen, and

chlorineE. Phosphorus, oxygen, nitrogen and

iron

Try This!Which of the following constitute

plant macronutrients?A. Potassium, oxygen, hydrogen and

zincB. Carbon, oxygen, nitrogen and

copperC. Carbon, oxygen, nitrogen, and

hydrogenD. Carbon, boron, nitrogen, and

chlorineE. Phosphorus, oxygen, nitrogen and

ironCHNOPS!!

Try This!In double fertilization, how is the

endosperm formed?A. The fusing of two sperm and an

egg B. From the epidermisC. From the fertilization of the eggD. From the zygote during

developmentE. From the fusing of a sperm with

two polar bodies

Try This!In double fertilization, how is the

endosperm formed?A. The fusing of two sperm and an

egg B. From the epidermisC. From the fertilization of the eggD. From the zygote during

developmentE. From the fusing of a sperm

with two polar bodies

From Last Class… Free Response

Page 820 in Campbell – Assess next class◦# 12 Evolution ConnectionWith respect to sexual reproduction, some

plant species are fully self-fertile, others are fully self-incompatible, and some exhibit a “mixed strategy” with partial self-incompatibility. These reproductive strategies differ in their implications for evolutionary potential. How, for example, might a self-incompatible species fare as a small founder population or remnant population in a severe population bottleneck (see Ch 23), as compared with a self-fertile species?

From Last Class… Free ResponseFree Response – Evolution

ConnectionSmall populations of self-incompatible species,

whether due to being founding populations or to bottleneck, would be at a disadvantage relative to self-fertile species. Small populations already have significant challenges in avoiding extinction. Adding the fact that they cannot perform sexual reproduction independently of other organisms merely adds to the list of challenges.

Beginning Developing Accomplished ExemplaryDoes not demonstrate a basic understanding of concept. Substantial errors throughout.

Basic understanding of concepts. Errors and inconsistency reveal some missing elements.

Solid understanding of concepts. Most answers are correct. Few errors.

Complete and in depth understanding of concepts. Answers are correct, with elegant connections.

Concept 3: Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)

Concept 3: Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)You must know: The three steps to a signal transduction

pathwayThe role of auxins in plantsThe survival benefits of phototropism and

gravitropismHow photoperiodism determines when

flowering occurs

Try This!Both plants and animals respond to

environmental stimuli. Which of the following statements are true and which ones are false?

A. The processes by which plants and animals perceive environmental changes are equally complex.

B. The processes by which plants and animals perceive environmental changes are often homologous.

C. Unlike animal hormones, plant hormones act only locally.

D. Both plants and animals have physiological cycles called circadian rhythms.

Try This!Both plants and animals respond to

environmental stimuli. Which of the following statements are true and which ones are false?

A. The processes by which plants and animals perceive environmental changes are equally complex. TRUE

B. The processes by which plants and animals perceive environmental changes are often homologous. TRUE

C. Unlike animal hormones, plant hormones act only locally. FLASE

D. Both plants and animals have physiological cycles called circadian rhythms. TRUE

Try This!What are the morphological

differences in dark-grown plants and light-grown plants?

Try This!What are the morphological

differences in dark-grown plants and light-grown plants?◦Dark- grown have

long stems underdeveloped roots unexpanded leaves shoots lack chlorophyll

But,

WHY?

How does this potato change its growth when there is light?

How does this potato change its growth when there is light?

Via the Signal Transduction Pathway!

How does this potato change its growth when there is light?

Via the Signal Transduction Pathway!◦ The signal (light) is transduced to a response

(greening)

Signal Transduction - ReviewReceptionTransductionResponse

Signal Transduction - ReviewReception: Receptors undergo changes

in shape due to an environmental stimulus◦ Ex) phytochrome proteins changing in response

to light

Signal Transduction - ReviewTransduction: Amplification of signal

through a multistep pathway◦ Allows small signal to produce large cellular

response Uses protein kinases (phosphorylation cascade)

and second messengers (Ca2+ and cAMP)

Signal Transduction - Review Response: Two ways response is

accomplished:1. Transcriptional Modification:

• ↑ or ↓ mRNA production (turning genes on/off)2. Post-Translational Modification:

• Activates existing enzyme molecules

Signal TransductionFor example, affected proteins

for this potato exposed to light include:◦Photosynthesis enzymes◦Plant growth hormones

Auxin levels lower to slow stem growth (focus on leaf growth)

So…. What was AUXIN?A plant hormone…

Yes, plants have hormones too!

Examples of Plant HormonesAuxins – stimulate elongation of cells

within young developing shoots

Cytokinins – stimulate cell division

Gibberellins – stimulate stem elongation, pollen, fruit, seed development

Abscisic acid – promotes stomatal closure during drought stress

Ethylene (gas!) – fruit ripening, leaf abscission

Plant HormonesHormones: chemical

messengers that coordinate the different parts of a multicellular organism

Tropism: Plant growth response toward or away from a stimulus◦Phototropism◦Gravitropism

How does this benefit survival?

Phototropism - Mechanism

Phototropism - Mechanism

Phototropism - Mechanism

Actions of hormones…Photoperiodism – physiological

response to a photoperiod (relative lengths of day and night)◦Example: Flowering

Short day plants Long day plants Day-neutral plants

Circadian rhythms – physiological cycles that have a frequency of about 24 hours

Responses to Mechanical StimuliMimosa Plant

Herbivore Defense

Video Clip

Think:Illustrate this statement with an

example: “A plant generally responds to environmental cues by adjusting its pattern of growth and development.”

How do plants detect and defend themselves against herbivores and environmental stresses?

Do you know? The three steps to a signal

transduction pathwayThe role of auxins in plantsThe survival benefits of phototropism

and gravitropismHow photoperiodism determines when

flowering occurs

Checkpoint Next Class: Concept 1: Analyzing the structure,

growth, development and nutrition of plants (Ch 35, 37)# 12, 13, 15, 16, 20, 21, 24 in Holtz

Concept 2: Analyzing the reproduction of angiosperms and modifications through biotechnology (Ch 38)#5, 22, 23 in Holtz

Concept 3: Analyzing how plants detect and defend themselves against herbivores and environmental stresses (Ch 39)# 1, 2, 7, 8, 9, 10, 11, 14, 25 in Holtz

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