Phloem carries sugars, amino acids, and other organic molecules from photosynthetic and storage tissues to other parts of the plant.
Sieve tubes are long, narrow tubes that transport organic materials in plants. They are associated with companion cells that help them perform their functions, such as loading and unloading substances and providing energy for transport.
Translocation is the movement of organic molecules through the phloem from source to sink.
Pressure and water potential aid translocation by creating a pressure gradient that drives the movement of materials from source to sink. Water moves from areas of high potential to low potential, and pressure is created by the buildup of solutes in the phloem.
Aphid stylets can be used to measure phloem transport rates because they are thin, flexible structures that can penetrate plant tissues and extract sap without damaging the phloem.
Radioactively-labelled CO2 can be used to measure phloem transport rates by tracing the movement of labeled carbon through the phloem.
Meristems are regions of actively dividing cells in plants that give rise to new tissues and organs.
Apical meristems are located at the tips of roots and shoots and are responsible for primary growth.
These regions are important because they generate new plant tissues and organs that are necessary for growth and development.
Cell division causes the growth of new plant tissue.
Tropism refers to the growth or movement of a plant in response to an external stimulus, such as light or gravity.
Two tropisms are phototropism, where the plant responds to light, and gravitropism, where the plant responds to gravity. In phototropism, the plant grows towards the light source, and in gravitropism, the plant responds by growing either towards or away from gravity.
The main group of plant hormones are auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
The main functions of plant hormones are to regulate growth and development, coordinate responses to environmental cues, and maintain physiological homeostasis.
Auxin influences gene expression by binding to a receptor and activating a signaling pathway that leads to changes in gene expression and cellular function.
Micropropagation is a method of asexual reproduction in which small pieces of plant tissue are used to produce new plants.
It is done by culturing the plant tissue on a nutrient-rich medium under sterile conditions to promote growth and development.
Micropropagation is done to produce large numbers of genetically identical plants for research, commercial purposes, or conservation.
External factors that can affect gene expression and flowering include temperature, light intensity and quality, and photoperiod (the duration of day and night).
Phytochrome triggers flowering in short-day plants by promoting the expression of flowering genes when the night is longer than a critical length. In long-day plants, phytochrome promotes flowering when the night is shorter than a critical length.
Pollination is the transfer of pollen from the male to the female reproductive structures of a flower.
Fertilization is the fusion of male and female gametes to form a zygote.
Seed dispersal is the process by which seeds are spread from the parent plant to new locations.
Flowering can be induced out of season by manipulating photoperiod or by using chemicals such as gibberellins.
Germination is the process by which a seed begins to grow into a new plant.
The conditions required for germination include moisture, oxygen, and appropriate temperature.
Gibberellins are synthesized at the start of germination and promote seed germination, stem elongation, and fruit development.