Definitons And Concepts - Topic 6⬆️ Flashcards
What are auxins?
A group of plant hormones that inhibit growth in plant roots and stimulate growth in shoot tips
Auxins are involved in plant tropisms and are used in rooting powders and selective weedkillers.
Define biomass.
The total mass of organic material, measured in a specific area over a set period.
What is ethene?
A hormone that stimulates ripening in fruit.
What are gibberellins?
Plant hormones that regulate germination and flowering
They can be used commercially to control flower and fruit formation or to produce seedless fruits.
What is gravitropism?
A plant’s growth response to gravity.
What are guard cells?
Cells that surround the stomata and change shape depending on the volume of water
They control the rate of transpiration by becoming turgid or flaccid, opening or closing the stomata.
What does the inverse square law state?
Light intensity is inversely proportional to the square of the distance from the light source.
What is lignin?
A material that strengthens the walls of xylem cells.
Define limiting factor.
A variable that limits the rate of a particular reaction.
What is the lower epidermis?
A layer of cells on the leaf’s lower surface that contains stomata and guard cells.
What is negative plant tropism?
The growth of a plant away from a stimulus.
What is the palisade mesophyll layer?
The main photosynthetic tissue in plants located below the upper epidermis
It receives the most light so contains the greatest concentration of chloroplasts.
What is phloem?
A transport tissue found in plants that is specialised to transport sugars from the leaves to the rest of the plant in both directions.
Define photosynthesis.
An endothermic reaction that converts light energy into chemical energy.
What is the overall equation for photosynthesis?
6C0, + 6H,0 → CH,206 + 60г
