Botany Exam 2

Functions of roots

▪ Anchoring the plant firmly to a substrate
▪ Absorbing water and minerals
▪ Producing hormones

Fleshy taproots

Plant’s main site of carbohydrate storage during winter

Radicle

embryonic root

Fibrous root system

▪ Mass of many similarly sized roots
▪ Adventitious in nature

Adventitious roots

Do not arise on pre-existing roots or from the radicle

Many eudicots undergo _____ growth

Secondary

Most monocots cannot undergo _____ growth

Secondary

Root grow from an ______ ______ at the tip

Apical meristem

Root apical meristem is protected by the ____ ___

Root cap

Behind the root cap and root apical meristem is the ____ __ _______

Zone of elongation

Region in which many of the epidermal cells extend out as narrow trichomes

Root hair zone

Root regions top to bottom

Maturation region, elongation region, meristematic region, root cap

Mitotically inactive central region

quiescent center

Innermost layer of cortical cells differentiates
into a cylinder called the

endodermis

Casparian strips

control the minerals that enter the xylem

Apoplastic transport

diffusion through the cell walls and intercellular spaces

Symplastic transport

absorption into the cytoplasm of a cortical cell and then transferal from cell to cell, probably through plasmodesmata

Cylinder of tissue, interior to the cortex, forms the

Stele

Pericycle

irregular region of parenchyma cells between the vascular tissue and the endodermis where lateral roots are produced

Endodermal cells that are slow to mature and have only the Casparian strip are called

Passage cells

Prop roots

adventitious roots that can grow extensively through the air

Buttress roots

▪ Tall, plate-like roots of some
tropical trees
▪ Upper side grows more rapidly
than other parts of the root.
▪ Brace the trunk from being
blown over by wind

Aerial roots of orchids have a specialized
epidermis called a

velamen

Mycorrhizae

symbiotic associations between the roots of seed plants and soil fungi.

Ectomycorrhizal relationship

fungal cells penetrate between the outermost root cortex cells but never penetrate the cell wall. Typically in woody species

Endomycorrhizal associations

fungal cells penetrate the root cortex and cell walls but not the plasma membrane

Haustoria

highly modified roots of parasitic plants

Vascular cambium

one of the meristems that produces the secondary plant body

Vascular cambium cells keep diving and produce

fascicular cambium

Some mature parenchyma cells between vascular bundles ____ mitosis

Resume

Vascular cambia are ____ found in leaves, but never in flowers, fruits, or seeds.

rarely

Two types of cells in vascular cambia

Fusiform, Ray

cells of secondary xylem

▪ Tracheids
▪ Vessel elements
▪ Fibers

cells of secondary phloem

▪ Sieve cells
▪ Sieve tube members
▪ Companion cells
▪ Fibers

---

____ ______ divide and develop similarly, but form xylem or phloem parenchyma that function:
▪ In storage
▪ Albuminous cells (in gymnosperms)

Ray initials

Growth rings appear due to the differential
growth of ___ _____ and ____ ____

Early (spring) wood; late(summer) wood

Ring porous

Ring-porous species have vessel cells in a range of sizes

Center of a log

Heartwood

Outer wood

Sapwood

What is a tylosis?

A tylosis forms a plug from adjacent parenchyma cells

Reaction wood

Produced in response to lateral stress

As circumferential stretching increases and older sieve elements die…

some storage parenchyma cells undergo cell division.

In a few species, the cork cambium may produce a cell or two to the inside that mature into a layer of parenchyma called

Phelloderm

The layers of cork cells and the phelloderm (if any) are known as

Periderm

All tissues outside the innermost cork cambium
comprise the

Outer bark

All secondary phloem between the vascular
cambium and the innermost cork cambium is the

inner bark

These regions of aerenchymatous
cork are

lenticels

Vascular cambium arises when

parenchyma cells between the primary xylem and phloem become mitotically active.

Because they produce different secondary bodies, it is called

anomalous secondary growth

This type of secondary phloem, located between two bands of xylem, is

included phloem

Columns of some parenchyma cells produce narrow cells that differentiate into

secondary vascular bundles

Fragmentation

one of the most common methods of asexual reproduction

▪ A large vining plant grows to several meters in length.

Sporophytes

are diploid and produce haploid spores by meiosis.

Gametophytes

are haploid and produce gametes by mitosis

syngamy

the union of two gametes for the generation of a
zygote

Complete flowers

have all four floral appendages: sepals, petals, stamens, carpels

Incomplete flowers

lack at least one appendage.

Sepals

are the outermost floral appendage

Petals

are located above the sepals on the receptacle

Stamens

occur above the petals

Carpels

collectively, are the gynoecium.
▪ Stigma catches pollen grains.
▪ Style elevates the stigma.
▪ Ovary is where megaspores are produced.

nucellus

the central part of a plant ovule containing the embryo sac

megasporocyte

megaspore mother cell

Plasmogamy

fusion of the protoplasts of the gametes

Karyogamy

fusion of the nuclei

double fertilization

both sperm nuclei undergo fusions

Radicle

embryonic root

Epicotyl

embryonic stem

Hypocotyl

root/shoot junction

A mature seed in which endosperm is abundant is an

albuminous seed

If endosperm is sparse or absent at maturity, the seed is

exalbuminous

Cross-pollination

by pollen from a different individual.

Self-pollination

by pollen from the same flower or another on the same plant.

Monoecy

the condition of having staminate flowers located on the same plant as the carpellate.

Actinomorphic flowers

Most flowers are radially symmetrical

Zygomorphic flowers

Flowers that coevolved with animals are often bilaterally symmetrical, like their pollinators.

Determinate inflorescences

The apex is converted to a flower, which tends to open before the lower flowers.

Indeterminate inflorescences

The lowest or outermost flowers open first, and new flowers are being initiated at the apex

Photoautotrophs

gather energy directly from light

Heterotrophs

must take in organic molecules and respire them for energy

Cytochromes

are intrinsic membrane proteins

▪ They contain a cofactor, heme, which holds an iron atom.

Plastoquinones

like cytochromes, transport electrons over short distances within a membrane.

Plastocyanin

is a small protein that carries electrons on a copper atom

Light-dependent reactions

water and light are used to create ATP and NADPH

Stroma reactions

ATP and NADPH interact with CO2 and produce carbohydrate

pigment

any material that absorbs certain wavelengths

Action spectrum

shows which wavelengths are most effective at
powering a photochemical process

Accessory pigments

molecules that strongly absorb wavelengths not
absorbed by chlorophyll-a.