plant function slides

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Plant Function

AP Biology Rapid Learning Series

Rapid Learning Centerwww.RapidLearningCenter.com/© Rapid Learning Inc. All rights reserved.

Wayne Huang, PhDAndrew Graham, PhDElizabeth James, PhD

Casandra Rauser, PhD Jessica Habashi, PhD

Sara Olson, PhDJessica Barnes, PhD



Learning Objectives

Pl t N t iti

By completing this tutorial, you will learn about:

Plant Nutrition

Plant Hormones

Plant Defense

Plant Reproduction

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Plant Function Concept Map

Air

Plant reproductionPlant GrowthSoil

Air

Plant Hormones

CytokininsCytokininsABAs

GAS Ethylene

Auxin

Regulated byFlower structureFlower structure

Seed Development

pathogensInsects

pathogens

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Growth promotionPhototropismPhototropism

GravitropismGravitropism

Apical DormancyApical Dormancy



Plant Nutrition

Plants obtain their nutrients from soil and air.

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Plant Nutritional SourcesThe major source of plant

nutrition is fixation of atmospheric CO2 using

photosynthesis to produce simple sugar

Photosynthesis is the source of energy to make sugars.

simple sugar.

Soil and water are also sources of

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nutrition. They provide an

anchorage as well as minerals and

nutrients.



Nutrient Classes

Nonmineral nutrients from air and water, carbon, hydrogen and oxygenhydrogen and oxygen.

Mineral nutrients from soil include macronutrients

which are required in large quantities.

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quantities.

Micronutrients are required in small

quantities.

Macronutrients Primary macronutrients

include: nitrogen, phosphorus and

potassium.

Secondary macronutrients include: calcium, magnesium

and sulfur.

Nitrogen

Calcium

Phosphorus

Potassium

MagnesiumMagnesium Sulfur

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Phosphorus

Primary Secondary



7 Micronutrients

There are 7 micronutrients. These are needed in small amounts.

Copper (Cu)

Iron (Fe) Boron (B)

Zinc (Zn)

Molybdenum (Mo)

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Chloride (Cl)

Manganese (Mn)

Molybdenum (Mo)

Obtaining Nutrients

Plants get nutrients from soil (roots) or air

(leaves and stems).

Macronutrients are usually not sufficient in cultivated soil and need to be added as fertilizer.

Natural plant communities recycle nutrients for use by other organisms.

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Other ways to get nutrients include:• Nitrogen fixation by bacteria.• Carnivorous feeding.• Symbiotic association with fungi.• Parasitic plants.



TranspirationTranspiration is the evaporation of

excess water from aerial parts of a plant. This is done by leaves,

stems, flowers and fruits.

Root absorbs minerals and water from soil

Water and solute are transported up through plants via xylem

The driving force is the

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The driving force is the evaporation from leaves via guard cells

This process is called transpiration

Transportation of Carbohydrates

Leaves make carbohydrates to ysupport plant life –sugar source

Carbohydrates are transported down via phloem in vascular tissue to where they

b d

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can be used –sugar sink



Plant Hormones

Plant Growth and Development

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Plant Hormones

Five major types of hormones that control plant growth and development.

A hormone is a chemical messenger between cells. They signal target cells to change a physiological activity.

1. Auxin2. Gibberellins

(GA)3. Cytokinins4. Ethylene5. Abscisic

Acid (ABA)

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AuxinAuxins are produced by apical tissues and developing leaves and they stimulates downward

growth.

Auxins function at the cell level by stimulating cell

elongation and cell division.

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The most important auxin is indole-3-acetic acid

(IAA).

Auxin FunctionsAuxinAuxins are plant hormones that are

involved in the coordination of many growth and behavior processes in

the plant’s life cyclethe plant s life cycle.

Auxins are used to promote the growth of roots as

well as flowering, setting fruits and preventing premature fruit drop.

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Auxins act by stimulating or inhibiting the expression

of specific genes.



Apical Dominance

Apical dominance is the inhibition of lateral buds by auxin

Dormant lateral bud

lateral buds by auxin from the apical bud.

Auxin is broken down as it moves down stem, so its concentration decreases.

Apical bud removed

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Removal of apical bud releases apical dominance

Phototropism

Phototropism: when illuminated from one direction, the shoot proceeds to grow in that direction.

When illuminated, Auxin accumulates on the shady side of a plant

This stimulate elongation of

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gcells from the shady side and bend the plant to the light



GravitropismPlant growth and its movements

respond to gravity. This is known as gravitropism.

When a plant is put into a horizontal position plant shoots will bend upward

because auxin accumulatesbecause auxin accumulates on the lower part of the stem called negative gravitropism.

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Plant roots will respond by bending down which is known as positive gravitropism. This is because of the accumulation of starch granules in the root

caps.

Cytokinins – Adenine Derivatives Cytokinins stimulate plant cell

differentiation. Notice the difference in these two plants of

treated versus untreated.

Cytokinin Function• Stimulate cell division• Major source: roots

and apical meritstem• Opposite to auxin:

1)Move upward; 2)

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) o e up a d; )promote growth of lateral buds

• Prevents leaf senescence

• Essential for plant cell culture.



Gibberellins

Gibberellins promote stem elongation, as well as in “bolting” which is sudden stem

elongation. It breaks the dormancy of seeds and stimulates flowering mature plantsand stimulates flowering mature plants.

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There are more than 30 structurally

related compounds.

Abscisic AcidIt is a major plant stress

hormone. Abscisic acid is a plant hormone involved in

adscission (shedding) of plant parts and in bud dormancy.

Abscisic acid is involved in the closing of stomata. It inhibits fruit ripening and encourages

seed dormancy by inhibiting celly seed dormancy by inhibiting cell growth.

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In winter preparation abscisic acid is produced in the terminal buds and slows

growth and protects buds during the cold.



Ethylene

Function

The only gas form of plant hormone, produced by fruit.

Promote fruit ripening

Stimulates senescence and abscission in leaves and fruits

Minor functions:

Sprouting of potato buds;

H2C=CH2 Ethylene

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p g p ;

Seed germination;

Flower formation in some species

What Plant Hormone Trigger Growth?

Do you know what plant hormone is involved in

promoting growth?

If you said auxin, cytokinin and

gibberellins you arep g g gibberellins you are right.

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Plant Defense

How plants cope with stress and insects

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Plant Defense

There are two basic strategies of plant

defense: physical and chemical barrier.

Physical barriers against herbivores include:

• Cuticle: a layer of wax onchemical barrier. Cuticle: a layer of wax on the surface of leaves• Trichomes: extension of plant cells• Spines which are modified leaves.• Bark

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Chemical barriers: secondary metabolites or chemical toxins that could cause problems for the predator.

These chemicals include isoprenes, phenolic compounds and alkaloids.



Systemin Response Plant response to wound: systemin

S th i f S th i fSynthesis of Systemin

Plants under attack

Proteinase inhibitorsSynthesis of

Proteinase inhibitors

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Systemin is a signal molecule for plants to sense the wound and triggers a series of biochemical reaction to release proteinase inhibitors which are toxic to insects.

Plant Defense to Pathogens

Virus Infection

Cell Death

■ Gene-for-Gene TheoryTo every pathogen avirulence (avr) gene, there is a

corresponding R gene (resistance gene) in plant to trigger

Hypersensitive Response (HR)

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HR

HR is commonly followed by a slower response that leads to systemin acquired resistance (SAR). SAR occurs when a hormone, which may be salicylic acid, travels from the infection site to nearby tissues and triggers the expression of a specific set of genes.



How Does a Plant Respond to Injury?

How do plants respond to being

wounded?

It mounts a systemin response involving

signaling from wounded? systemin.

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Plant Reproduction

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Sexual and Asexual ReproductionPlants can reproduce

asexually and sexually.Yes, sexual reproduction involves male gametes (sperms) and female gametes (eggs) which combine to

create a zygote.

In asexual reproduction offspring are produced

by mitosis and are genetically identical to

the parent.

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Female structures house the embryo

during development.

Life Cycle of a Flowering Plant

Seeds

Seed germination

Seed production

32/42Seedling

Seed germination

Pea plant

Adult plant with flowers



Flowers are Reproductive Organs

PedalStigma Carpel

(female organs)

Filament

AntherSteman(male organs)

Ovary (female organs)

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Sepal

Formation of Gametes

Microspores --> Pollens

Megaspores --> EggsMeiosis

Mother Cell (2N)

3

Meiosis

Pollen Mother Cell

Pollen Pollen Pollen Pollen

Pollen Grain

Pollen Grain

Pollen Grain

Pollen Grain

2N

1Nmegaspores degenerate, 1 survives

3 times mitosis then cell dividing

1N egg cell

2N t l ll

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GrainGrainGrainGrain

1N

Embryo sac in ovaryPollen grain in anther

2N central cell1N egg cell



Pollination

Pollination: Pollen from male organs are transferred to surface of stigma

Sperms meet megaspores (eggs)1 Self-pollination

2 Self-pollination, same plant but different flower

3 Cross-pollination

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pDifferent plants

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Formation of ZygotesPollen tube grows, two sperm cells are delivered into ovary

One sperm fertilize one of the 6 eggs, one fertilizes the central cell

Fertilized egg develops into 2N zygotes and fertilized central cell develop into endosperm (3N)

Zygotes attach to parental plant to acquire nutrients which is to be stored in cotyledons

1N 1N1N 1NCentral cell (2N)

Ovary

3N3N

3N 3NEndosperm(3N)

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1N 1N

1N

1N

1N Egg cell (1N)

Pollen tube

2 sperm nuclei

3N (3N)Embryo (2N)

Double pollination



Seed StructureZygotes grow and differentiate, acquiring and

store food in cotyledons and seed forms.

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How are Seeds Developed?

How does a seed develop?

Double pollination.Pollination of eggs forms

the embryo.

Acorn

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Pollination of the central cell forms the endosperm



Question: Review____ is the evaporation of excess water from aerial parts of a plant.

___________Transpiration

D dA i ti l t ___________

___________

Downward

Apical dominance

Auxins stimulate _____ growth.

_______ is the inhibition of lateral buds by auxin from the apical bud.

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___________Cytokinins_____ stimulate plant cell differentiation.

____ promote stem elongation and bolting. ___________Gibberellins

Plant nutrients

Macronutrients

Plant nutrients

Macronutrients

Learning Summary

Plant defense

Natural barrier

Plant defense

Natural barrierMacronutrients

micronutrients

Macronutrients

micronutrients

Pl t th dPl t th d

Against wound

Against pathogen

Against wound

Against pathogen

Plant reproductionPlant reproduction

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Plant growth and development

Plant hormones

Plant growth and development

Plant hormones

Flowers

Zygotes

Seeds

Flowers

Zygotes

Seeds



Congratulations

You have successfully completed the core tutorial

Plant Function

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