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Biology

Key Terms

BiologyKey Terms

accessory fruit
fruit derived from tissues other than the ovary
aggregate fruit
fruit that develops from multiple carpels in the same flower
aleurone
single layer of cells just inside the seed coat that secretes enzymes upon germination
androecium
sum of all the stamens in a flower
antipodals
the three cells away from the micropyle
apomixis
process by which seeds are produced without fertilization of sperm and egg
coleoptile
covering of the shoot tip, found in germinating monocot seeds
coleorhiza
covering of the root tip, found in germinating monocot seeds
cotyledon
fleshy part of seed that provides nutrition to the seed
cross-pollination
transfer of pollen from the anther of one flower to the stigma of a different flower
cutting
method of asexual reproduction where a portion of the stem contains notes and internodes is placed in moist soil and allowed to root
dormancy
period of no growth and very slow metabolic processes
double fertilization
two fertilization events in angiosperms; one sperm fuses with the egg, forming the zygote, whereas the other sperm fuses with the polar nuclei, forming endosperm
endocarp
innermost part of fruit
endosperm
triploid structure resulting from fusion of a sperm with polar nuclei, which serves as a nutritive tissue for embryo
endospermic dicot
dicot that stores food reserves in the endosperm
epicotyl
embryonic shoot above the cotyledons
exine
outermost covering of pollen
exocarp
outermost covering of a fruit
gametophyte
multicellular stage of the plant that gives rise to haploid gametes or spores
grafting
method of asexual reproduction where the stem from one plant species is spliced to a different plant
gravitropism
response of a plant growth in the same direction as gravity
gynoecium
the sum of all the carpels in a flower
hypocotyl
embryonic axis above the cotyledons
intine
inner lining of the pollen
layering
method of propagating plants by bending a stem under the soil
megagametogenesis
second phase of female gametophyte development, during which the surviving haploid megaspore undergoes mitosis to produce an eight-nucleate, seven-cell female gametophyte, also known as the megagametophyte or embryo sac.
megasporangium
tissue found in the ovary that gives rise to the female gamete or egg
megasporogenesis
first phase of female gametophyte development, during which a single cell in the diploid megasporangium undergoes meiosis to produce four megaspores, only one of which survives
megasporophyll
bract (a type of modified leaf) on the central axis of a female gametophyte
mesocarp
middle part of a fruit
micropropagation
propagation of desirable plants from a plant part; carried out in a laboratory
micropyle
opening on the ovule sac through which the pollen tube can gain entry
microsporangium
tissue that gives rise to the microspores or the pollen grain
microsporophyll
central axis of a male cone on which bracts (a type of modified leaf) are attached
monocarpic
plants that flower once in their lifetime
multiple fruit
fruit that develops from multiple flowers on an inflorescence
nectar guide
pigment pattern on a flower that guides an insect to the nectaries
non-endospermic dicot
dicot that stores food reserves in the developing cotyledon
perianth
(also, petal or sepal) part of the flower consisting of the calyx and/or corolla; forms the outer envelope of the flower
pericarp
collective term describing the exocarp, mesocarp, and endocarp; the structure that encloses the seed and is a part of the fruit
plumule
shoot that develops from the germinating seed
polar nuclei
found in the ovule sac; fusion with one sperm cell forms the endosperm
pollination
transfer of pollen to the stigma
polycarpic
plants that flower several times in their lifetime
radicle
original root that develops from the germinating seed
scarification
mechanical or chemical processes to soften the seed coat
scion
the part of a plant that is grafted onto the root stock of another plant
scutellum
type of cotyledon found in monocots, as in grass seeds
self-pollination
transfer of pollen from the anther to the stigma of same flower
senescence
process that describes aging in plant tissues
simple fruit
fruit that develops from a single carpel or fused carpels
sporophyte
multicellular diploid stage in plants that is formed after the fusion of male and female gametes
suspensor
part of the growing embryo that makes connection with the maternal tissues
synergid
type of cell found in the ovule sac that secretes chemicals to guide the pollen tube towards the egg
tegmen
inner layer of the seed coat
testa
outer layer of the seed coat
vernalization
exposure to cold required by some seeds before they can germinate
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