BIO 172, CH. 28 Plant Structure and Growth Test with Answers
1. Primary growth, which occurs at apical Part A - Ditterentiating between primary
meristems, results in the elongation of growth and secondary growth.
roots and shoots. In roots, primary growth
increases water and nutrient absorption
by increasing the root surface area ex-
posed to the soil. In shoots, primary
growth adds height and leaves, which in-
crease the plant's exposure to and absorp-
tion of light.
Secondary growth occurs at two types of
lateral meristem: vascular cambium and
cork cambium. Vascular cambium adds
thickness to a woody plant by adding
secondary xylem (wood) and secondary
phloem. This increases vascular flow and
provides additional support. Cork cam-
bium produces the external covering of
woody plants.
Woody plants, which can live for many
years, experience both primary and sec-
ondary growth. Herbaceous (nonwoody)
plants, on the other hand, generally live
only one year and experience only prima-
ry growth. (Recent research indicates that
some herbaceous plants undergo a small
amount of secondary growth in the late
growing season, but generally speaking,
herbaceous plants are composed of a pri-
mary plant body only.)
1/7
, BIO 172, CH. 28 Plant Structure and Growth Test with Answers
2. Primary growth occurs at apical meristems Part B - Labeling primary growth structures
in the tips of roots and shoots and in the
axillary buds of shoots. Primary growth Primary growth is growth in length that oc-
generates the primary plant body, which curs at the tips of roots and shoots and in
consists of dermal, ground, and vascu- the axillary buds of shoots. Label the follow-
lar tissues. (Leaves, for example, are com- ing diagram of a plant, the cross section of
posed of all three types of tissue.) Note its stem, and the longitudinal section of its
that primary xylem and primary phloem root. Note that the term zone of maturation
are produced by apical meristems. is equivalent to the term zone of ditterentia-
tion.
The primary growth in a root occurs be-
hind the protective root cap in three differ-
ent zones:
the zone of cell division, which contains
the apical meristem and adds new cells
the zone of elongation, where cells elon-
gate and push the root tip farther into the
soil
the zone of differentiation, or zone of mat-
uration, where cells differentiate into dis-
tinct cell types, becoming vascular, dermal,
or ground tissue
3. Where growth is seasonal, the yearly Part C - Analyzing tree growth rings
growth patterns of woody plants give the Part complete
appearance of rings in the wood. In spring, As you have already learned, the lateral
secondary xylem cells are large with thin meristems are responsible for secondary
cell walls and appear as wide, light bands. growth in woody plants. One type of lat-
In the late summer and fall, the cells are eral meristem, the vascular cambium, adds
small with thick cell walls and appear as girth to woody plants by adding secondary
narrow, dark bands. A light band and a vascular tissues. The secondary xylem, com-
2/7
1. Primary growth, which occurs at apical Part A - Ditterentiating between primary
meristems, results in the elongation of growth and secondary growth.
roots and shoots. In roots, primary growth
increases water and nutrient absorption
by increasing the root surface area ex-
posed to the soil. In shoots, primary
growth adds height and leaves, which in-
crease the plant's exposure to and absorp-
tion of light.
Secondary growth occurs at two types of
lateral meristem: vascular cambium and
cork cambium. Vascular cambium adds
thickness to a woody plant by adding
secondary xylem (wood) and secondary
phloem. This increases vascular flow and
provides additional support. Cork cam-
bium produces the external covering of
woody plants.
Woody plants, which can live for many
years, experience both primary and sec-
ondary growth. Herbaceous (nonwoody)
plants, on the other hand, generally live
only one year and experience only prima-
ry growth. (Recent research indicates that
some herbaceous plants undergo a small
amount of secondary growth in the late
growing season, but generally speaking,
herbaceous plants are composed of a pri-
mary plant body only.)
1/7
, BIO 172, CH. 28 Plant Structure and Growth Test with Answers
2. Primary growth occurs at apical meristems Part B - Labeling primary growth structures
in the tips of roots and shoots and in the
axillary buds of shoots. Primary growth Primary growth is growth in length that oc-
generates the primary plant body, which curs at the tips of roots and shoots and in
consists of dermal, ground, and vascu- the axillary buds of shoots. Label the follow-
lar tissues. (Leaves, for example, are com- ing diagram of a plant, the cross section of
posed of all three types of tissue.) Note its stem, and the longitudinal section of its
that primary xylem and primary phloem root. Note that the term zone of maturation
are produced by apical meristems. is equivalent to the term zone of ditterentia-
tion.
The primary growth in a root occurs be-
hind the protective root cap in three differ-
ent zones:
the zone of cell division, which contains
the apical meristem and adds new cells
the zone of elongation, where cells elon-
gate and push the root tip farther into the
soil
the zone of differentiation, or zone of mat-
uration, where cells differentiate into dis-
tinct cell types, becoming vascular, dermal,
or ground tissue
3. Where growth is seasonal, the yearly Part C - Analyzing tree growth rings
growth patterns of woody plants give the Part complete
appearance of rings in the wood. In spring, As you have already learned, the lateral
secondary xylem cells are large with thin meristems are responsible for secondary
cell walls and appear as wide, light bands. growth in woody plants. One type of lat-
In the late summer and fall, the cells are eral meristem, the vascular cambium, adds
small with thick cell walls and appear as girth to woody plants by adding secondary
narrow, dark bands. A light band and a vascular tissues. The secondary xylem, com-
2/7
