Topic 6 - Plant Structures And Their Functions - Definitons And Concepts 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
What is phototropism?
A plant’s growth response to light.
Define plant tropism.
The growth response of a plant to a stimulus.
What is positive plant tropism?
The growth of a plant towards a stimulus.
Who are producers in an ecosystem?
Photosynthetic organisms (e.g. green plants or algae) at the start of the food chain.
What are root hair cells?
Specialised cells responsible for the uptake of water and minerals from the soil.
What is the function of root hairs?
They provide a large surface area for absorption.
What are rooting powders used for?
To stimulate the growth of roots in cuttings, enabling rapid plant cloning.
What is the spongy mesophyll layer?
A type of loosely packed mesophyll tissue specialised for gas exchange.
What are stomata?
Small holes found on the surface of a plant that control water loss and gas exchange.
What is translocation in plants?
The movement of sugars and amino acids up and down a plant via the phloem.
What is transpiration?
Water loss from plant leaves and shoots via diffusion and evaporation.
What factors affect the rate of transpiration?
Light intensity, temperature, and air flow.
What is the upper epidermis in plants?
A layer of transparent cells that allows light to strike the palisade mesophyll tissue.
What is a vascular bundle?
Part of the transport system in vascular plants that consists of xylem and phloem tissue.
What is the function of the waxy cuticle?
To reduce water loss from the surface of leaves.
What is xylem?
A transport tissue in plants that is specialised to transport water and dissolved minerals from the roots to the leaves.
