Plant Cells, Tissues, Morphology & Growth [Chapters 35-37]

Lecture 1

What are the major similarities between green algae and plants?

Eukaryotic, cellulose cell walls, chlorophylls A & B, starch for energy storage, and high genetic similarities

What is the most abundant organic molecule in plant and algal cell walls?

Cellulose

What pigments are found in green algae and plants?

Chlorophylls A & B

What is the major energy storage molecule in green algae and plants?

Starch

Are green algae considered plants?

No, they are protists

What is the dominant generation in nonvascular plants (Bryophyta)?

The gametophyte is larger and photosynthetic

What happens when gametes meet in nonvascular plants?

They create a sporophyte, which is smaller

Why can't nonvascular plants grow tall?

They lack veins and vascular tissue

What is the dominant generation in vascular plants?

The sporophyte

What allows vascular plants to transport substances long distances?

Vascular tissues (xylem and phloem)

What makes primitive vascular plants primitive?

They do not make seeds

What structure forms in Selaginella (spikemosses) during reproduction?

A strobilus (specialized reproductive structure)

What is the photosynthetic generation in ferns?

The sporophyte (ferns are considered as vascular plants)

What are three examples of gymnosperms (lack the protective outer covering which surrounds the seeds)?

Cycads, Ginkgo, and Conifers (pine)

What structures do gymnosperms use for reproduction?

Strobili

What are defining features of angiosperms?

They produce flowers and fruits (fruits house seeds)

What type of plants are most important nutritionally for humans?

Monocots (e.g., grasses and grains)

What type of seed do monocots have?

One cotyledon

What type of seed do dicots have?

Two cotyledons

Which plants gave rise to monocots?

Dicots, such as water lilies

What are the two main parts of a plant?

The shoot system (above ground) and root system (below ground)

What is the thickest root connected to the stem called?

The primary root

What do primary and secondary growth refer to?

• Primary growth = plant gets longer

• Secondary growth = plant gets wider

What type of cells are responsible for primary growth?

Meristematic cells (stem cells)

What protects the root apical meristem?

The root cap, which stays the same size

What substance helps lubricate root growth (produced by the root caps)?

Mucilage

What is the difference between shoot and root apical meristems?

The shoot tip has no protective cap (interacts with air), while the root tip does

What are the small early leaves near the shoot tip called?

Leaf primordia

Where are the youngest parts of a plant found?

At the tips (not the base)

What is a bud formed by the shoot apical meristem?

Axillary bud (can include axillary buds for branching or bulbs for asexual reproduction)

What tissue initiates lateral roots?

The pericycle (also becomes meristematic)

What tissues grow from the pericycle?

Xylem (to the inside), phloem (to the outside), epidermis, and ground tissue

What moves with root growth but does not grow?

The root cap

What is the function of the lamina?

It is the site of photosynthesis

What is the petiole?

The stalk attaching the blade to the stem

What are stomata and where are they mostly located?

Pores in the epidermis, mostly on the bottom of leaves

What are veins in leaves?

Vascular bundles

What is the space between a leaf and the stem called?

The leaf axil

What is found in the leaf axil?

An axillary bud (with a shoot apical meristem)

What is a cotyledon?

A seed leaf found in the embryo of monocots (have 1) or dicots (have 2)

What is the outermost tissue in young roots?

The epidermis (1 cell layer thick and alive)

What is the central vascular region in roots called?

The stele

What surrounds the stele and can become meristematic?

The pericycle

What tissue transports water from root to shoot?

Xylem (xylem sap = mineral water)

What tissue transports sugar from source to sink?

Phloem (phloem sap = sugar water using sucrose)

What is the sugar alcohol used by some plants for transport?

Sorbitol

What is the vascular arrangement in young dicot stems?

Vascular bundles in a ring, with xylem inside and phloem outside

What are the inner and outer layers of a dicot stem?

Pith (center), cortex (beneath epidermis)

What is the vascular arrangement in young monocot stems?

Scattered/dispersed vascular bundles with ground tissue (no cortex or pith)

What happens to the center cells in some young monocot stems?

They undergo apoptosis (programmed cell death)

Where is food stored in a plant?

In the ground tissue

Where does most metabolism (photosynthesis, starch storage) occur in plants?

Ground tissue (Parenchyma)

Which way does xylem flow? Which way does phloem flow?

• Xylem: Root → Shoot

• Phloem: Shoot → Root

What is the external to internal tissue arrangement in a young dicot root?

Epidermis → Cortex (ground tissue) → Endodermis → Pericycle → Xylem (center) → Phloem (between xylem arms)

What is the external to internal tissue arrangement in a young monocot root?

Epidermis → Cortex → Endodermis → Pericycle → Ring of xylem and phloem → Central pith