USABO PLANT FORM AND FUNCTION EOC EXAM QUESTIONS WITH
SOLUTIONS 2025 GRADED A+
✔✔vascular cambium - ✔✔a cylinder of meristematic tissue in woody plants that adds
layers of secondary vascular tissue
✔✔cork cambium - ✔✔a cylinder of meristematic tissue in woody plants that replaces
the epidermis with thicker, tougher cork cells
✔✔primary meristem - ✔✔one of the three meristematic derivative of the apical
meristem
✔✔protoderm - ✔✔the primary meristem that develops into dermal tissue
✔✔procambium - ✔✔the primary meristem that develops into vascular tissue
✔✔ground meristem - ✔✔the primary meristem that develops into ground tissue
✔✔root cap - ✔✔a cone of cells at the tip of a plant root that protects the apical
meristem; secretes mucilage, an extracellular polysaccharide that lubricates the soil
around the tip of the root
✔✔endodermis - ✔✔in plant roots, the innermost layer of the cortex that surrounds the
vascular cylinder
✔✔pericycle - ✔✔the outermost layer in the vascular cylinder, from which lateral roots
arise
✔✔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
✔✔solute potential - ✔✔a component of water potential that is inversely proportional to
the molarity of the solution
✔✔pressure potential - ✔✔a component of water potential that quantifies the physical
pressure on a solution; can be positive, zero, or negative
SOLUTIONS 2025 GRADED A+
✔✔vascular cambium - ✔✔a cylinder of meristematic tissue in woody plants that adds
layers of secondary vascular tissue
✔✔cork cambium - ✔✔a cylinder of meristematic tissue in woody plants that replaces
the epidermis with thicker, tougher cork cells
✔✔primary meristem - ✔✔one of the three meristematic derivative of the apical
meristem
✔✔protoderm - ✔✔the primary meristem that develops into dermal tissue
✔✔procambium - ✔✔the primary meristem that develops into vascular tissue
✔✔ground meristem - ✔✔the primary meristem that develops into ground tissue
✔✔root cap - ✔✔a cone of cells at the tip of a plant root that protects the apical
meristem; secretes mucilage, an extracellular polysaccharide that lubricates the soil
around the tip of the root
✔✔endodermis - ✔✔in plant roots, the innermost layer of the cortex that surrounds the
vascular cylinder
✔✔pericycle - ✔✔the outermost layer in the vascular cylinder, from which lateral roots
arise
✔✔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
✔✔solute potential - ✔✔a component of water potential that is inversely proportional to
the molarity of the solution
✔✔pressure potential - ✔✔a component of water potential that quantifies the physical
pressure on a solution; can be positive, zero, or negative
