USABO Plant Form and Function Exam Questions with Complete Solutions 100%
Solved| Grade A+
apical dominance the tendency for primary plant growth to be concentrated at the tip of the
shoot, a property stemming from the inhibitory activity of the apical bud on axillary bud growth
leaf primordium a finger-like projection along the flank of a shoot apical meristem, from
which a leaf arises
mesophyll leaf cells specialized for photosynthesis; in C3 and CAM plants, they are located
between the upper and lower epidermis while in C4 plants, they are located between the
bundle-sheath cells and the epidermis
vascular ray a radial file of mostly parenchyma cells that connects the secondary xylem and
phloem; serves as a shuttle for water and nutrients
heartwood the dense inner part of a woody plant, consisting of older layers of secondary
xylem
sapwood the soft outer layers of recently formed wood between the heartwood and the
bark, consisting of functional secondary xylem
bark all tissues external to the vascular cambium, consisting of the secondary phloem and
layers of periderm
lenticel a small raised area in the bark of woody stems and roots that enables gas exchange
between the internal tissues and external environment
meristem identity gene a plant gene that promotes the switch from vegetative growth to
flowering
, organ identity gene a plant homeotic gene that uses positional information to determine
which emerging leaves develop into which types of floral organs
ABC hypothesis a model of flower formation identifying three classes of organ identity genes
that direct formation of the four types of floral organs; accounts for the phenotypes of mutants
lacking A, B, or C gene activity, with one addition: where A gene activity is present, it inhibits C,
and vice versa
calyx the outermost whorl of sepals
corolla the second outermost whorl of petals
androecium the second innermost whorl of stamens
gynoecium the innermost whorl of carpels
phyllotaxy the arrangement of leaves on a stem specific to each species
apoplast in plants, everything external to the plasma membrane of a plant cell
symplast in plants, the continuum of cytoplasm connected by plasmodesmata between
cells.
water potential the potential energy of water per unit volume relative to pure water in
reference conditions; predicts the direction in which water will flow
Solved| Grade A+
apical dominance the tendency for primary plant growth to be concentrated at the tip of the
shoot, a property stemming from the inhibitory activity of the apical bud on axillary bud growth
leaf primordium a finger-like projection along the flank of a shoot apical meristem, from
which a leaf arises
mesophyll leaf cells specialized for photosynthesis; in C3 and CAM plants, they are located
between the upper and lower epidermis while in C4 plants, they are located between the
bundle-sheath cells and the epidermis
vascular ray a radial file of mostly parenchyma cells that connects the secondary xylem and
phloem; serves as a shuttle for water and nutrients
heartwood the dense inner part of a woody plant, consisting of older layers of secondary
xylem
sapwood the soft outer layers of recently formed wood between the heartwood and the
bark, consisting of functional secondary xylem
bark all tissues external to the vascular cambium, consisting of the secondary phloem and
layers of periderm
lenticel a small raised area in the bark of woody stems and roots that enables gas exchange
between the internal tissues and external environment
meristem identity gene a plant gene that promotes the switch from vegetative growth to
flowering
, organ identity gene a plant homeotic gene that uses positional information to determine
which emerging leaves develop into which types of floral organs
ABC hypothesis a model of flower formation identifying three classes of organ identity genes
that direct formation of the four types of floral organs; accounts for the phenotypes of mutants
lacking A, B, or C gene activity, with one addition: where A gene activity is present, it inhibits C,
and vice versa
calyx the outermost whorl of sepals
corolla the second outermost whorl of petals
androecium the second innermost whorl of stamens
gynoecium the innermost whorl of carpels
phyllotaxy the arrangement of leaves on a stem specific to each species
apoplast in plants, everything external to the plasma membrane of a plant cell
symplast in plants, the continuum of cytoplasm connected by plasmodesmata between
cells.
water potential the potential energy of water per unit volume relative to pure water in
reference conditions; predicts the direction in which water will flow
