Plant and Animal Development

• gymnosperms - are both male and female; that is, each reproductive organ is either male or female
• gymnosperms - they are a group of seed-producing plants that includes conifers, cycads, ginkgo, and gnetophytes
• angiosperms - a plant that has flowers and produces seeds enclosed within a carpel
• angiosperms - a large group and include herbaceous plants, shrubs, grasses, and most trees
• seed coat - seed is surrounded with this
• aleurone layer - which lies under the seed coat, functions as a kind of digestive organ in seed germination
• starchy endosperm - a food storage tissue that forms separately from the embryo while the seed is still attached to the parent plant
• coleorhiza - protects the future root as it grows out of the seed into the surrounding soil
• plumule - composed of the epicotyl, young leaves, and the shoot apical meristem.
• seed germination - the process by which a plant grows from a seed into a seedling.
• breaking the dormancy - the embryo emits a hormone called gibberellin, which diffuses through the seed
• monocots - the hormone then triggers the production of digestive enzymes by the aleurone
• dicots - the digestive enzymes are produced by the cotyledons
• early root emergence - this part of the root tip is known as the zone of division. It is an apical meristem, a growing tip of embryonic, differentiating tissue
• early root emergence - zone of elongation, which is responsible for most of the lengthwise growth of the root tip. Since new cells are constantly added to this zone by mitosis
• early root emergence - the older portions of the zone of elongation cease to grow and become incorporated into the zone of maturation, where tissue differentiation now begins
• primary meristems - give rise to differentiated tissues such as phloem and xylem
• primary meristems - eventually form differentiated tissues themselves, but in such a way as to produce lateral growth and increase in girth
• zygote - a fertilized egg that has the potential to give rise to all the diverse cell types of the complete individual
• cleavage - from one cell to many
• implantation - begins on the seventh day of embryonic development
• implantation - enzymes destroy some tiny maternal capillaries in the wall of the uterus
• in the grass seed, the cotyledon is a food-absorbing structure known as a scutellum
• the portion of the seedling below the cotyledons is known as hypocotyl. One of the structures included in it is the future root, or radicle
• the root hairs form in the zone of maturation of the growing root tip
• when the "hook" of a dicot seedling is exposed to light during germination, it reacts by straightening; the receptor substance that initiates this reaction is pigment known as phytochrome
• the growing nodes of embryonic tissue found at the shoot and root tips of a plant are its apical meristems
• movement of cells to form a tube such as the neural tube is an example of morphogenesis
• specialization of cells to form neurons or some other cell types is called cellular differentiation
• the rapid series of mitoses that converts the zygote to a morula is referred to as cleavage
• the cluster of cells that projects into the cavity of the blastocyst is the inner mass; it gives rise to the cell embryo
• the process by which the blastula becomes a three-layered embryo is called gastrulation
• the tissue layer that gives rise to the nervous system is the ectoderm
• the germ layer that gives rise to the lining of the digestive tract is the endoderm