Plant responses to the enviroment

List 3 chemical defences in plants.

1. Tannins-toxic,located in upper epidermis+makes leaf taste bad.Located in roots=stop pathogenic miuoorganisms from entering.2.Alkaloids-Derived from amino acids,bitter taste+toxic.3.Pheromones-chemicals when released by an individual,affect another

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What makes the Alkaloids toxic?

The amine group

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List 2 plants respond to stimuli

1.Predation from herbivores=Rapid growth/spines and thorns/toxins in tissues 2. Wear shortage/low temperatures=arrested growth or domancy.

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what is the definition of Tropism?

A directional growth response of a plant, determined direction by the direction of the external stimulus.

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what does 'positive' and 'negative' tropism mean?

'positive'= towards a stimulus. /. 'negative'=away from a stimulus

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list the 5 main types of tropisms?

1.Phototropism(light)-shoots=positive,roots=negative2.Geotropism(gravity)-roots=positive,shoots=negative 3.chemotropism(chemical)-pollen tubes=positive 4.hydrotropism(water)roots=positive 5.Thigotropism(solid surfaces)-shoots of climbing plant=ivy

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Definition of 'Nasties'?

Non-directional responses to environmental stimuli = Nasties (mastic responses)

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List the five main plant hormones (plant growth factors)?

1. Auxins 2.Gibberellins 3.Ethene 4.cytokinins 5. Abscissic acid (ABA)

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List the effects of Cytokinins.

promote cell division, delay leaf senescence, overcome apical dominance, promote cell expansion.

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List the effects of Gibberellins.

Promote seed germination+ growth of stems

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List the effects of Ethene.

Involved to help fruit ripen+ promotes leaf abscission

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List the effects of Auxins.

promote cell elongation, inhibits growth of side-shoots, inhibit leaf abscission (leaf fall). Involved in phototropism+ apical dominance(inhibits the growth of side shoots).

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List the effects of Abscisic acid (ABA)

Inhibits seed germination+ growth, causes stomatal closure when the plant is stressed by low water avilability.

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List the 3 main ways hormones move around the plant?

1. active transport 2.diffusion 3. Mass flow in the phloem sap or in xylem vessels.

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Definition of Antagonists?

Work opposite to each other, work against each other (i.e-Auxin+Ethene)

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Definition of Synergists?

Work together. Help each other

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List 3 similarities of plant +animal hormones

1.Chemical messenger 2. Act on target cells/tissues 3. Can only bind to specific receptors on cell surface membrane with complementary shapes.

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List 3 difference of plant +animal hormones

1. Produced in a variety of tissues(not endocrine glands) 2. Transported by mass flow in phloem or in xylem vessels (rather than blood). 3. produced in very small quantities.

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How might thigmonastic responses in plants help them survive?

1. Discourage insects from feeding on the plant. 2. Climb higher towards the higher light intensities.

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What is the difference between tropic and nastic responses?

Tropic = directional / nastic = non-directional

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Explain why only certain tissues in a plant respond to a particular plant hormone.

Target tissue will have necessary complementary-shaped receptors on their cell surface membranes, where the particular hormone molecule can bind.

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Definition of Biotic + Abiotic

Biotic: (living) Abiotic: (non-living)

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What's Photoperiod?

response to day length, influencing their flowering. 1) short-day plants= flower in Spring +Autumn(need a lone period without light) 2) long day plants= flower in summer.

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What is the difference between tropic and a nastic response?

Tropic= directional + Nastic= non-directional

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List one similarity + difference between auxin + an animal hormone (insulin)?

Similarity= Acts on target tissues with complementary receptor (containing nitrogen)+ Difference= Auxin is NOT a protein or steroid

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Plant responses to the enviroment

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