Plant Responses to the Environment Flashcards
What are abiotic components?
Components of an ecosystem which are non-living
What are alkaloids?
Organic nitrogen-containing bases that have important physiological effects on animals.
Give examples of alkaloids.
Nicotine
Quinine
Strychnine
Morphine
What are biotic components?
Components of an ecosystem that are living.
What is a pheromone?
Any chemical substance released by one living thing, which influences the behaviour or physiology of another living thing.
What are tannins?
Phenolic compounds, located in cell vacuoles or in surface on wax plants.
What is tropism?
A directional growth response in which the direction of the response is determined by the direction of the external stimulus.
What are the plants responses to threats form herbivores?
Tannins
Alkaloids
Pheromones
How are tannins a defense?
They are toxic to microorganisms and larger herbivores.
Where annins found in the leaf of the plant?
They are found in the upper epidermis.
What do annins do to the leaves?
Make them taste bad.
What do annins do in the roots of plants?
Prevent infiltration by pathogenic microorganisms.
What are alkaloids derived from?
Amino acids
Where are alkaloids found in the plant?
In the growing tips and flowers, and peripheral cell layers of stems and roots.
How are alkaloids a deterrent to animals?
They are a feeding deterrent as they taste bitter.
What is phototropism?
Shoots grow towards the light, enabling them to photosyntheise
What is geotropism?
Roots grow towards the pull of gravity
Why do plants perform geotropism?
It anchors them into the soil and helps them to take up water/minerals.
What is chemotropism?
On a flower, pollen tubes grow down the style, attracted by the chemicals, towards the ovary where fertilisation can take place.
What is thigmotropism?
Shoots of climbing plants, such as ivy, wind around other plants or solid structure to gain support.
What is a positive tropic response?
If a plant responds towards the stimulus.
What is a negative tropic response?
If a plant responds away from a stimulus.
What are non-directional responses towards a stimulus called?
Nastic response.
The sensitive plant responds to touch. What is this called?
Thigmonasty
How do hormones cause an effect in cells?
They bind reversibly to complimentary receptors on target cells plasma membrane causing a reaction to happen inside the cell.
What does the hormone cytokinins cause?
Promotes cell division
Delay leaf senescence
Overcome apical dominance
Promote cell expansion
What does the hormone abscisic acid cause?
Inhibits seed germination and growth
Causes stomatal closure when the plant is stressed by low water availability
What do auxins do?
Promote cell elongation
Inhibit the growth of side shoots
Inhibit leaf abscission (leaf fall)
What do gibberellins do?
Promote see germination and the growth of stems
What does ethene do?
Promotes fruit ripening
Give three methods that hormones use to move around the plant.
Active transport
Diffusion
Mass flow in the phloem sap or xylem vessels.
