plant+response+analysis

In the space below post your analysis of the section fo the textbook relating to plant repsonses. Clearly try to show the followining points.

Key terms Key concepts Any relevant diagrams that are important How does the information link to other areas of the course? What questions do you have to ask?

**Hormones and guard cells**

 * __Key Terms__**
 * Stomata** - tiny epidermal pores through which gas exchange occurs in plants; each stoma is bound by two guard cells
 * Guard cells** - pairs of highly specialised epidermal cells which form stomata and regulate the degree of opening of the stomatal pore in plants
 * Transpiration** - evaporation of water from plant shoots mainly through stomata in leaves and due largely from heat from the sun; draws water up xylem vessels from roots.
 * Xylem** - tissue responsible for the transport of water and minerals from soil to leaves in vascular land plants.
 * ABA** - abscisic acid - a growth inhibiting plant hormone associated with leaf and fruit fall, as well as bud and seed dominancy. it 'may' also be involved in stomatal movements

-Many commercially available synthetic substances that mimic natural plant hormones have been made to control the development and growth of plants. -However these tend to take years to break down (are persistent), have damaging effects on organisms (are toxic) and bioaccumulate in food chains. one example is DDT. -ABA is a naturally occurring hormone that is non-toxic and only needed in low concentrations developed to help with water loss from plants by transpiration through stomata. -Plants negative feedback mechanism: as transpiration increases, levels of ABA increase, causing the stomata to partially close. This reduces transpiration which causes ABA levels to drop and stomata to open again. -As naturally occurring products are expensive to produce and are broken down rapidly by the plant, cheaper products with the same biological effects that don't break down as quickly tend to be used more often in farming practices.
 * __Key Concepts__**

Plants have negative feedback response, too.
 * __Relevance__**


 * E.B, A.K, S.B**

**Sensing and Responding In Plants**
__**Key Terms:**__ Phototropism - Growth in response to light
 * Geotropism**- Growth in response to gravity
 * Apical Dominance** - Inhibition of lateral branches
 * Ripening of fruit** - Conversion of starches to sugar
 * Abcission** - Shedding of leaves and fruit

//Plants growth regulators are hormones:// - Communication between different paarts of plants are important for timng of growth, water balance and direction of plants. - Communication takes place by the control of hormones (Auxin, Gibberellin, Cytokinins, Abscisic Acid and Ethylene) - Plants do not have an endocrine system which is equivalent to the human endocrine system. //Environmental Cues// - Plants have to survive in the environment in which their spore germinates sending their roots into the soil. - Plants have to therefore deal with the environemtn in which they are permanently fixed to. - Their environment controls their timing and method of growth - Plants respond to gravity, light and temperature. //Sensing// - Plants do not have a difference between their extracellular fluids and their external enviroments They respond to; __Physical Factors:__ Direction and wavelength of light, temperature, gravity, touch etc... __Chemical Factors:__ Water, carbon dioxide, oxygen, specific chemicals (ethylene gas) etc...
 * __Key Concepts:__**

- Hormones in both humans and plants detect change and can control certain parts of the body/plant. Each hormone has a specific role and controls a specific site causing an action and sometimes, having a visible result.
 * __Relevance:__**

TY, AJ, SO (I bet that was confusing!)

Pg 146 – 147 __Key terms__

**Chemical factors**: water, carbon dioxide
__Key concepts__ __Relevance__ Plants also have hormones which regulate different responses.
 * In plants hormones regulate growth by being produced by sensitive cells (in various parts of the plant)
 * Coordination of plant responses are controlled internally by hormones.
 * Hormones responsible for: **phototropism**, **geotropism**, **apical dominance**, **ripening of fruit** and **abscission**.
 * Environment provides cues for stages in plant growth. eg. Seed germination occurs when conditions are ideal.
 * Plants are sensitive to environmental factors (**physical** and **chemical factors**)
 * A plant becomes responsive to a stimulus when the stimulus causes a sensitive cell to produce a particular hormone, hormone travels through phloem to a responsive tissue.
 * Directionality important in plant sensing and responding
 * Direction from which stimulus (physical or chemical) comes affects the direction of the response to the stimulus.
 * eg. Stimulus: light ; plant response is growing towards it.
 * eg. Stimulus: gravity; roots grow downwards

__Diagram__

sorry for the bad quality! :)

xoxo DV and GR**
 * you know you love us,

=Response & Growth of Cells & Photoperiodism=

Key Terms

 * Positive Tropism**: a plants growth response **towards** source of light - stimuli (sun)
 * Negative Tropism**: a plants growth response **away** from source of light - stimuli (sun)
 * Negative/Positive Phototropism**: movement or growth in response to lights or colors of light.
 * Auxin**: Plant hormone that regulates stem and root growth in plants.

Key Concepts
Stimulus [light/sun] detected by the tip of a growing shoot and the response [bending of shoot towards the light] occurs below the tip. Response is brought out by Auxin which is released from the tip of the plant. Auxin is mevoed to the shaded part of the plant where it increases the rate of growth cells.
 * Response & Growth of Cells**

Key Terms

 * Photoperiodism**: plants ability to measure the length of day and night and if there are any changes.

**Key Concept**

 * 'Day Neutral' plants are roses, snap dragons, tomatoes and many weeds -->This means they flower over day lengths.
 * 'Short Day' --> flower in spring and late summer (longer nights)
 * 'Long Day' --> flower in late spring and early summer (shorter nights)
 * Auxin goes to shoot tips and other parts of the plants which stimulates flowering.

=SS, LR & DR.=

**Stomata – **tiny pores/openings found on the surface of plant leaves (and more abundantly on the undersurface of leaves), which are responsible for regulation of gases, and involve gas exchange of O2 and CO2, (as well as of water); each stoma is bounded by two ‘guard cells **’. ** **Turgor – **a state of high internal fluid (ie. water) pressure, resulting from water entering rigid plant cells (via osmosis). **Turgid – **a state of swollen-ness of a plant cell, as a result of an overload of water intake.   **
 * <span style="font-size: 24pt; color: red; font-family: 'Arial','sans-serif'; mso-ascii-theme-font: minor-bidi; mso-hansi-theme-font: minor-bidi; mso-bidi-theme-font: minor-bidi; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-AU; mso-fareast-language: EN-AU; mso-bidi-language: AR-SA; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi; msofareastfontfamily: 'Times New Roman'; msoansilanguage: EN-AU; msofareastlanguage: EN-AU; msobidilanguage: AR-SA;">PLANT REGULATION **
 * __Key Terms: __**
 * Guard Cells – **cells surrounding stomata openings. [ à <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;"> more on the __function__ of guard cells (and stomata) further on… ]
 * <span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Hypotonic – **__<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">less __<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> solute concentration in the external environment.
 * <span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Hypertonic – **__<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">more __<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> solute concentration in the external environment.
 * <span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Autotrophs – **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">organisms that make their own organic molecules from inorganic molecules, meaning they are able to produce their own energy, (rather than rely on another organism); eg. Photosynthetic organisms, such as plants.
 * <span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Photosynthesis – **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> …everyone knows this… right?
 * <span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Abscisic Acid (ABA) – **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">a plant hormone responsible for growth inhibition, associated with leaf/fruit fall, and dormancy of bud/seed (temporarily inactive); also involved in stomatal movements.
 * __<span style="font-size: 14pt; font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">Key Concepts: __**
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">A characteristic that __separates__ plants from other living organisms is their **autotrophic photosynthetic properties**. Along with this specialised function, plants contain different structures (eg. chloroplasts in some cells).
 * __<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Three things __<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> which plants regulate with somewhat proficiency are: CO2, H20 and 02. Noticeably, H20 and CO2 are reactants of photosynthesis, and 02 is a product. These regulatory mechanisms involve a structure in the plant found on leaves, known as stomata.
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">Here is a picture for you to admire:

The Stoma: ** <span style="font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; mso-list: Ignore; msolist: Ignore;">§ <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">Plants can regulate their turgidity through some measures, however this is not yet fully understood. <span style="font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; mso-list: Ignore; msolist: Ignore;">§ <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">One technique involves the guard cells altering **concentration of potassium ions** within them. <span style="font-family: Wingdings; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi; mso-char-type: symbol; mso-symbol-font-family: Wingdings; msochartype: symbol; msosymbolfontfamily: Wingdings;">à <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;"> Greater potassium concentration __within__ the guard cells causes water to __rush into__ them (via osmosis) along the solute concentration gradient; whereas, greater potassium concentration __outside__ the guard cells causes water to __leave__ them (via osmosis). <span style="font-family: 'Courier New'; msofareastfontfamily: 'Courier New'; mso-list: Ignore; msolist: Ignore;">o **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Note: **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> This potassium concentration is altered through active transport. <span style="font-family: 'Courier New'; msofareastfontfamily: 'Courier New'; mso-list: Ignore; msolist: Ignore;">o **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Note 2: **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> The greater the amount of water that enters the guard cells, the greater their turgidity, and hence the greater the opening of the stoma. <span style="font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; mso-list: Ignore; msolist: Ignore;">§ <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">Another technique involves altering **concentration of glucose** in the guard cells. <span style="font-family: Wingdings; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi; mso-char-type: symbol; mso-symbol-font-family: Wingdings; msochartype: symbol; msosymbolfontfamily: Wingdings;">à <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;"> More glucose concentration __inside__ cell compared to outside cell (hypotonic) **<span style="font-size: 14pt; mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">= **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> more water __rushing in__ cell along osmotic gradient, causing turgor; and vice versa. <span style="font-family: 'Courier New'; msofareastfontfamily: 'Courier New'; mso-list: Ignore; msolist: Ignore;">o **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';">Note: **<span style="mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'; mso-bidi-font-family: 'Times New Roman';"> This glucose concentration inside the guard cell is altered by converting glucose into starch or starch into glucose. <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;"> <span style="font-family: Wingdings; msobidifontfamily: Wingdings; msofareastfontfamily: Wingdings; mso-list: Ignore; msolist: Ignore;">§ <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">The plant hormone: 'Abscisic Acid' is associated with __loss of turgidity__, which causes the stoma to close again. Gas Exchange: ** <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;"> <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">There's good __diagram__ on **page 122** which explains exactly when stomata are open and when they are closed, and to what stimuli; (this will depend on photosynthesis rate, for example).
 * The stomata is a kind of pore that can close and open in different degrees, which enables gasses to enter and leave the plant.
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">This regulation mechanism involves two guard cells that man the opening.
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">These guard cells are joined at their ends in pairs (look like lips), have thicker cell walls nearest to stomatal pore, and are surrounded by bands of inelastic cellulose fibres.
 * <span style="font-size: 16pt; font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">Open Close: **
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">The level of opening of the stomatal pore is dependent on the __turgidity__ of these guard cells.
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">As water rushes into the cell’s vacuoles when they are in __hypotonic__ fluid, the vacuole presses against the cell wall causing it to become __turgor__. As a consequence, the guard cells swell lengthwise, and the stoma consequently opens.
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">In contrast, when water leaves the guard cell when in a __hypertonic__ fluid, the guard cells are not stretched lengthwise, and therefore the stoma is closed (lips are shut).
 * <span style="font-size: 14pt; font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">So how does the plant regulate stoma opening? **
 * <span style="font-size: 14pt; font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">When stomata is __open__: CO2 and O2 is exchanged; water also leaves the leaves.
 * <span style="font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">When stomata is __closed__: CO2 and O2 cannot be exchanged; water cannot leave so freely through the stoma pore opening, (but it can diffuse out via osmosis).
 * <span style="font-size: 14pt; font-family: Times New Roman; msoasciifontfamily: 'Times New Roman'; msoasciithemefont: major-bidi; msohansifontfamily: 'Times New Roman'; msohansithemefont: major-bidi; msobidifontfamily: 'Times New Roman'; msobidithemefont: major-bidi;">One last thing... **

** Key terms **

 * ** Geotropism – plant response to gravity **
 * ** Positively geotropic – roots grow towards the pull of gravity **
 * ** Negatively geotropic – shoots grow away from the pull of gravity **
 * ** Thigmotropism – growth response, resulting from contact with a surface **
 * ** Sleep movements – plants close their flowers or petals and fold their leaves at night. **
 * ** Stomata – open and close due to stimuli – light, carbon dioxide **
 * ** Turgidity – how full with water effects it, the cells are full = very turgid **
 * ** Motor cells – **
 * ** Horticulture – growing plants **
 * ** Auxins – hormone that stimulates root development, can prevent natural pollination **
 * ** Dioxin – human made hormone toxic and not used any more **
 * ** Gibberellins – hormone that speeds up germination in spring **
 * ** Ethylene – gas used to ripen fruit, fruit loosening \ **
 * ** Synthetic hormones – are man made mimic natural ones **

** Key Concepts **

 * ** roots are positively geotropic and the shoots are negatively geotropic, meaning the roots grow downwards and shoots grow upwards (roots- due to amyloplasts) **
 * ** contact with surfaces can cause plants to grow in a certain direction eg vines grow around trees trunks **
 * ** carbon dioxide, light and humidity stimulate the stomata to open and close due to changes in the turgor of guard cells **
 * ** potassium moves out of the motor cells, and water flows through osmosis and the cells becomes less turgid **
 * ** this causes the leaflets to droop **
 * ** horticultures - may use synthetic hormones to inhibit or enhance a plant to produce a desired outcome eg ethylene, auxin produces seedless vegetables **

MG, MW, RN