Response in flowering plants

What causes stomata to open?

High water levels low levels of carbon dioxide

What is meant by tropism?

growth response of a plant to a stimulus

What are the types of tropisms?

Phototropism Geotropism Thigmotropism Hydrotropism Chemotropism

What is meant by Phototropism?

growth of a plant in response to light

What is meant by Geotropism?

growh of a plant in response to gravity

What is meant by Thigmotropism?

growth of a plant in response to touch

What is meant by Hydrotropism?

growth of a plant in response to water

What is meant by Chemotropism?

growth of a plant in response to chemicals

Where are growth regulators secreted?

Apical meristems

What is a growth regulator?

a chemical that controls the growth of plants

What is an example of growth regulator that causes growth(growth promotors)?

IAA

What is growth regulator that inhibits the growth of plants?

Ethene Abscisic Acid

What is the most common type of auxin?

IAA

What growth regulator is used for Apical Dominance?

IAA (most common of auxin)

Explain the term positively phototrophic

Growth towards light

Explain the mechanism of phototropism

Light illuminates one side of stem IAA is produced in meristimatic tissue of shoot tip IAA diffuses down the shaded sided of the stem causes faster elongation on the shaded side results in bending towards light

Give two examples of the use of growth regulators

Ethene used to ripen fruit Auxins used to produce seedless fruit

What are physical adaptations of Plant adaptations?

Thorns - discourage animals Bark - physical barrier Waxy Cuticle - prevent excess water loss Stinging hairs - discourage animals

How are growth regulators transported around a plant?

by diffusion

Describe how you set up the experiment to investigate the effect of indoleacetic acid (IAA) growth regulator on plant tissue

set up different concentrations of IAA by serial dilution in 7 bottles Bottle 8 acts as control with only distilled water and NO IAA Place acetate grid inside grid use 5 raddish seeds per petri dish Place filter paper on seeds Place cotton wool soaked in IAA on top of filter paper in each Store on their sides at 25°C in an incubator for 2-3 days

What is a result of too high concentration on IAA?

Inhibit plant growth

Describe how you measured the effect of IAA on the plant tissue?

Using grid acetate to measure length of tissue

Describe the results of your investigation of the effect of IAA on plant tissue

More root growth in low concentration More shoot growth in high concentration

Name a suitable plant tissue you used in the investigation of the effect of IAA on the growth of plant tissue

Radish seeds

Why was the filter paper wetted in the experiment to investigate the effect of IAA growth regulator on plant tissue?

holds the seeds in position

Why was the cotton wool soaked in IAA the experiment to investigate the effect of IAA growth regulator on plant tissue?

Ensures seeds contact with that concentration of IAA for duration of experiment

Why are petri dishes stored on its side in the experiment to investigate the effect of IAA growth regulator on plant tissue?

Allows shoots to grow up and roots to grow down; makes it easier for measuring

Why is IAA first dissolved in ethanol in the experiment to investigate the effect of IAA growth regulator on plant tissue?

as IAA does not easily dissolve in water

What are (commercial) uses of two growth regulators?

Herbicides Fruit ripening Seedless fruit

Describe how seeds contribute to the formation of fruit

Produce growth regulators

Give one way seedless fruits may develop

Spray with growth regulators

What is the precise benefit to the plant of being positively phototropic

Absorb more light More photosynthesis

Write a note on the mechanism of phototropism

Auxin produced in shoot tip/ Plant shoot exposed to more light on one side/ Auxin diffuses down the shaded side of the shoot/ causing more elongation in shaded cells/ Shoot bends towards the light

What is an auxin?

A plant growth regulator

Name one Chemical way plants can protect themselves

Heat shock proteins Growth regulators

What to plants do in response to Wilting?

Close stomata

Give two ways in which growth regulators in plants are similar to hormones in animals

Made at one site & function at another Chemical Transport slow

Name a group of substances which control responses to external stimuli in plants

Growth regulators

What does it mean to be Positively Phototropic?

Growth towards light

What is a plant response to wilting?

Close stomata

How does unequal concentration of auxin affect growth of shoots?

Higher auxin concentration results in higher rate of cell division

What gas influences the diameter if stomata

Carbon dioxide