Unit 1 - Lesson 6: Plant Growth And Development Flashcards
Define plant hormones.
A group of chemicals that affect the rate of cell division, elongation and differentiation
What produces plant hormones?
Any growing tissue
What are the 3 stimulatory hormones?
Auxins, Gibberellins, Cytokinins
Where are auxins found?
Leaves, seeds, root tips
Where are gibberellins found?
Young shoots and developing seeds
Where are cytokinins found?
Root tips
What do auxins do?
Stimulate cell division and elongation in stems/roots. Regulate cell expansion in response to light and gravity.
What do gibberellins do?
Stimulate cell elongation and seed germination
What do cytokinins do?
Stimulate cell division, prevents the ageing of leaves
What are the 2 types of inhibitory hormones?
Abscisic acid (ABA) and Ethylene (Ethene)
Where is ABA found (within plants and types of plants)?
Mature leaves and plants under stress
Where is ethylene found? When?
Found throughout the plant, especially when ageing, ripening and under stress
What does ABA do?
Induces/ maintains seed dormancy, inhibits shoot growth, closes stomata
What does Ethene do?
Promotes fruit ripening
What are tropisms?
The growth response of plants to external stimuli
What is phototropism? What causes it and how does it affect plant growth?
The growth response to light, caused by an unequal distribution of auxin. Less auxin on side closest to light source, cells on the other side of light elongates, that side of stem becomes longer, stem curves in direction of the light.
Wha5 is thigmotropism? Give an example.
The growth response to mechanical stimuli (e.g contact with an object, another organism, wind, etc.). Example: vines that twist around nearby structures (fences, trees)
What is gravitotropism? What type of gravitotropism do roots and stems demonstrate?
The growth response to gravity. Roots demonstrate positive gravitotropism (grow down into soil to anchor plant and get water/nutrient, grows with the force of gravity). Stems demonstrate negative gravitotropism (grow up against gravity to get max. light exposure)
What is a mastic response? Give an example.
A plant’s movement in response to stimulus not associated with the direction of the stimulus. This is not a growth response, is reversible, and can be repeated. Example: a flower opens during the day and closes at night to conserve heat.
What are macronutrients? Give 2 examples.
Nutrients needed in larger amounts. Examples include nitrogen, calcium, potassium, etc.
What are micronutrients? Give 2 examples.
Nutrients needed in smaller amounts p. Examples include iron, copper, iron, etc.
What soil pH do must plants thrive in?
6-7, slightly acidic
What soil pH do fewer plants survive in?
7-8, slightly basic
