Plant Structure and Growth Lecture Notes

A comprehensive set of question-and-answer flashcards covering major concepts from the lecture on plant structure, growth, and tissue systems.

What agricultural development helped early civilizations to grow and spread?

The domestication of wild grasses and other seed plants.

Which three cereal grains became staple foods for humans worldwide?

Wheat, rice, and corn.

Besides food, list three other materials humans obtain from plant parts such as leaves, stems, or bark.

Lumber, fibers (for paper or clothing), and pharmaceuticals (also rubber, cork, etc.).

In botanical terminology, what does Morphology refer to?

The shape and overall appearance of body parts.

What is meant by Anatomy in plant science?

The physical structure of body parts.

Define Physiology in the context of plants.

The study of how plant parts function, including nutrient acquisition, transport, reproduction, and defense.

What are the two major components of a seed plant’s body plan?

The root system (underground) and the shoot system (above ground).

Why do roots and stems grow in different directions?

To capture resources from both soil and air while performing integrated functions.

What is a plant organ?

A structure containing two or more tissue types with a definite form and function.

What functions does the root system perform?

Anchors the plant, provides structural support, absorbs water and minerals, and stores carbohydrates.

Name the repeating components that make up the shoot system.

Stems, leaves, axillary buds, and flowers.

What type of growth stops once an organ reaches a certain size?

Determinate growth.

What type of plant growth can continue throughout a plant’s life?

Indeterminate growth.

Why must roots have vast surface areas?

To absorb enough water and dissolved minerals for growth and cellular maintenance.

What is a taproot system, and give an example.

A single main root adapted for deep penetration and storage; e.g., carrots or dandelions.

What kind of root system do grasses typically have?

A fibrous root system.

Where do adventitious roots originate?

From the stem of a young plant, later forming part of a fibrous root system.

What protects the root apical meristem as it pushes through soil?

The root cap.

Which root cells sense gravity and help guide the root tip downward?

Certain gravity-responsive cells within the root cap.

What is the Quiescent Center inside some root caps?

A clump of slowly dividing meristem cells that can become active if the root cap is injured and also synthesize hormones controlling root development.

Where does most root lengthening occur?

In the zone of elongation, where cells expand as vacuoles fill with water.

In which root zone do cells differentiate into specialized tissues?

The zone of maturation.

Which primary meristem gives rise to xylem and phloem?

The procambium.

What tissue fills much of a young root and stores starch?

The cortex, derived from the ground meristem.

How is the stele arranged in dicot roots?

As a central solid core running through the center of the root.

What additional tissue separates cortex and pith in many monocot roots?

The stele forms a ring that divides ground tissue into cortex and pith.

What is the exodermis, and what is its possible role?

A narrow band of cells beneath the epidermis that may limit water loss and regulate ion uptake.

Which root layer acts as a selectively permeable barrier to the stele?

The endodermis.

Which root tissue can become meristematic again to form lateral roots?

The pericycle.

What specialized epidermal outgrowths greatly increase root surface area?

Root hairs (a type of trichome).

What are stomata and where are they commonly found?

Pore-like openings, mainly in leaf epidermis, that regulate gas exchange.

Which two specialized cells surround each stoma and control its aperture?

Guard cells.

Give two key adaptations of leaves for photosynthesis.

A thin, broad blade for light capture and abundant stomata for CO₂ uptake.

What two mesophyll layers are typical of dicot leaves?

Palisade mesophyll (compact, chloroplast-rich) and spongy mesophyll (loosely arranged with air spaces).

Which mesophyll layer has more chloroplasts?

Palisade mesophyll.

What is the role of xylem in a leaf?

To bring water to photosynthetic tissues.

What is the main function of the phloem in leaves?

To transport carbohydrates out of the leaf, often to roots.

Where in the chloroplast do light-dependent reactions occur?

The thylakoid membranes.

What drives the bulk flow of water from roots to leaves?

Negative pressure (tension) generated by transpiration pulling water up through the xylem.

List three primary functions of stems.

Mechanical support, housing vascular tissue for transport, and potential storage of water/food.

What is a node on a stem?

The point where one or more leaves attach to the stem.

Define Apical Dominance.

Suppression of lateral bud growth by hormones released from the terminal bud.

What is heartwood and how does it differ from sapwood?

Inner, dead xylem that stores defensive compounds and is stronger; sapwood is outer, wet xylem that still conducts water.

Which meristem produces secondary xylem and phloem in stems?

The vascular cambium (a lateral meristem).

Why do dicots typically show secondary growth whereas most monocots do not?

Dicots possess lateral meristems for stem thickening; monocots generally lack them.

Name the three tissue systems in plants and give one key function of each.

Dermal (protection), vascular (transport), and ground (storage and photosynthesis).

Which ground-tissue cell type is living, thin-walled, and capable of division?

Parenchyma.

What distinguishing feature do collenchyma cells possess?

Unevenly thickened, stretchable primary cell walls that provide flexible support.

Why are mature sclerenchyma cells rigid and dead?

They have thick, lignified secondary walls that cannot stretch, and the cells die at maturity.

What key difference distinguishes xylem vessels from phloem sieve-tube elements?

Xylem vessels are dead, hollow, and lignified; sieve-tube elements are living but lack nuclei and rely on companion cells.