Quiz 2 Stems, flowers, and leaves

What are the main functions of a plant stem?

Stems support leaves, transport water upward through the plant, and transport food (mainly sugars) from the leaves to other parts of the plant. Some modified stems also function in food storage, defense, and photosynthesis.

What is the shoot system?

The shoot system consists of the stems and leaves of a plant. These structures work together to support photosynthesis and transport materials.

What is a node?

A node is the region of a stem where one or more leaves are attached.

What is an internode?

An internode is the portion of the stem located between two nodes.

What are the three types of leaf arrangements?

• Alternate: Leaves are attached individually at different points along the stem.

• Opposite: Leaves are attached in pairs.

• Whorled: Three or more leaves are attached at the same node.

What is an axillary bud?

An axillary bud is located in the axil, the angle between the petiole and the stem. It may develop into a branch or contain tissues that develop into flowers.

What is a terminal bud?

A terminal bud is located at the tip of a stem or twig. It contains meristematic tissue that produces new cells, allowing the stem to increase in length.

What is the apical meristem, and what is its function?

The apical meristem is a region of actively dividing cells located at the tip of a stem. Its primary function is to increase the length of the stem through cell division.

What protects the apical meristem before the growing season?

The apical meristem is protected by bud scales and leaf primordia, which are tiny embryonic leaves that eventually develop into mature leaves.

What are the three primary meristems that develop from the apical meristem?

• Protoderm: Produces the epidermis.

• Procambium: Produces primary xylem and primary phloem.

• Ground meristem: Produces the cortex and pith.

What are the five primary tissues of a stem?

The five primary tissues are the epidermis, primary xylem, primary phloem, cortex, and pith. They develop while the stem increases in length.

What is the vascular cambium?

The vascular cambium is a layer of actively dividing cells located between the xylem and phloem. It produces secondary xylem and secondary phloem, contributing to an increase in stem girth.

What is the cork cambium?

The cork cambium, also called the phellogen, is a meristematic tissue that produces cork cells. These cells form protective outer bark tissue that reduces water loss and protects against mechanical injury.

What is the difference between primary and secondary growth?

Primary growth increases the length of the plant through the activity of apical meristems. Secondary growth increases the thickness or girth of the plant through the activity of the vascular cambium and cork cambium.

What is a stele?

A stele is the central cylinder of a stem consisting of primary xylem, primary phloem, and the pith when present.

What is a protostele?

A protostele is the simplest type of stele. It consists of a solid core of conducting tissues in which the phloem usually surrounds the xylem.

What is a eustele?

A eustele is a type of stele in which the primary xylem and primary phloem are arranged in distinct vascular bundles. It occurs in most flowering plants and conifers.

What is the difference between monocots and dicots?

Monocots have one cotyledon (seed leaf), scattered vascular bundles in the stem, and generally parallel leaf veins. Dicots have two cotyledons, vascular bundles arranged in a circular pattern, and generally netlike leaf veins.

What is an herbaceous stem?

An herbaceous stem is a nonwoody stem that is often green. Its tissues are primarily composed of primary tissues, although some secondary growth may occur.

What is the difference between spring wood and summer wood?

Spring wood is produced early in the growing season and generally contains larger vessel elements. Summer wood is produced later and contains smaller or fewer vessel elements and more tracheids.

What are annual rings?

Annual rings represent one year's growth of secondary xylem in a woody stem.

What is the difference between heartwood and sapwood?

Heartwood is the older, darker wood located toward the center of the stem. It no longer conducts materials but provides strength and support. Sapwood is the younger, lighter-colored xylem near the vascular cambium that still conducts water.

What are tyloses?

Tyloses are protrusions of parenchyma cells into the cavities of vessels or tracheids. They may block these conducting cells and contribute to the formation of heartwood.

What is the difference between hardwood and softwood?

Hardwood comes from woody dicot trees, while softwood comes from cone-bearing trees such as pines. According to the notes, softwood primarily contains tracheids rather than vessel elements.

What are specialized stems? Give examples.

Specialized stems are modified to perform functions such as storage, spreading, climbing, or photosynthesis. Examples include rhizomes, runners, stolons, tubers, bulbs, corms, and cladophylls.

What are the main functions of leaves?

Leaves capture light energy for photosynthesis, allow gas exchange, regulate water loss, perform respiration, and may help dispose of accumulated metabolic waste when shed.

What is the petiole?

The petiole is the stalk that attaches the leaf blade to the stem.

What is the lamina?

The lamina is the flattened blade of a leaf. It contains a network of veins and is the main surface involved in capturing light for photosynthesis.

What is the difference between simple and compound leaves?

A simple leaf has one undivided blade, while a compound leaf has a blade divided into separate leaflets.

What is the difference between pinnately and palmately compound leaves?

Pinnately compound leaves have leaflets arranged along a central rachis. Palmately compound leaves have leaflets attached at the same point at the end of the petiole.

What are stipules?

Stipules are small thornlike, leaflike, or scalelike appendages sometimes located at the base of the petiole.

What is the difference between petiolate and sessile leaves?

Petiolate leaves have a petiole, while sessile leaves are attached without a petiole.

What is phyllotaxy?

Phyllotaxy is the arrangement of leaves on a stem. The three main arrangements are alternate, opposite, and whorled.

What is venation?

Venation refers to the arrangement of veins within a leaf blade. Examples include pinnate, palmate, parallel, netlike, and dichotomous venation.

What is pinnate venation?

Pinnate venation occurs when a leaf has one main vein, called the midvein or midrib, with smaller secondary veins branching from it.

What is palmate venation?

Palmate venation occurs when several primary veins spread outward from the base of the leaf blade.

What is parallel venation?

Parallel venation occurs when the primary veins run alongside one another. It is commonly found in monocot leaves.

What is reticulate venation?

Reticulate venation is a netlike arrangement of veins commonly found in dicot leaves.

What are the three main internal regions of a leaf?

• Epidermis

• Mesophyll

• Veins (vascular bundles)

What is the epidermis of a leaf?

The epidermis is the outer protective layer covering the upper and lower surfaces of a leaf.

What are stomata?

Stomata are tiny pores, commonly found in the lower epidermis, that regulate gas exchange between the leaf and its environment.

What are guard cells, and what do they do?

Guard cells surround stomatal pores and control their opening and closing by changing their turgidity. This helps regulate gas exchange and water loss.

What gases move through stomata during photosynthesis?

Carbon dioxide enters the leaf through the stomata, while oxygen produced during photosynthesis exits into the atmosphere.

What is mesophyll tissue?

Mesophyll is the internal tissue of a leaf that contains large amounts of chloroplasts and performs photosynthesis.

What are the two types of mesophyll?

Palisade mesophyll and spongy mesophyll. Both contain chloroplasts that are involved in photosynthesis.

What are bulliform cells?

Bulliform cells are large specialized cells found in grass leaves, located on either side of the main vein according to the notes.

What adaptations help desert plants conserve water?

Desert plants may have thick cuticles, sunken stomata, fewer stomata, dense hairs, succulent leaves, thick-walled cells beneath the epidermis, or leaves modified into spines.

Why are cactus leaves modified into spines?

Spines help reduce excessive water loss and protect the plant from herbivores. The stem takes over much of the photosynthetic function.

What are the characteristics of submerged aquatic leaves?

They typically contain reduced amounts of vascular tissue, large air spaces, and mesophyll that is not differentiated into palisade and spongy layers.

What are storage leaves?

Storage leaves are modified leaves that store water or carbohydrates. Water-storing leaves may contain large parenchyma cells with vacuoles, while onion bulb leaves store carbohydrates.

What is leaf abscission?

Leaf abscission is the process by which leaves are shed from a plant. It occurs because of changes in the abscission zone near the base of the petiole.

What is a deciduous plant?

A deciduous plant is a plant that sheds its leaves seasonally.

What is the primary function of a flower?

Flowers are specialized reproductive structures of flowering plants. They contain structures involved in pollen production, pollination, and the development of seeds and fruits.

What is a peduncle?

A peduncle is the stalk supporting a flower or flower cluster.

What is a pedicel?

A pedicel is a smaller stalk that supports an individual flower.

What is the receptacle?

The receptacle is the enlarged upper portion of the flower stalk where the floral structures are attached.

What are sepals, and what is their function?

Sepals are usually green structures that protect a developing flower while it is still a bud. All the sepals together form the calyx.

What is the corolla?

The corolla is the collective name for all the petals of a flower. Petals often help attract pollinators.

What is the perianth?

The perianth consists of the calyx (sepals) and corolla (petals) together.

What is a stamen?

The stamen is a male reproductive structure consisting of a filament and an anther. The anther produces pollen grains.

What is the androecium?

The androecium is the collective term for the male reproductive structures, or stamens, of a flower.

What is a pistil?

A pistil is a female reproductive structure composed of the stigma, style, and ovary.

What is the gynoecium?

The gynoecium is the female reproductive portion of a flower and consists of one or more pistils.

What is the function of the stigma?

The stigma receives pollen during pollination.

What is the function of the style?

The style connects the stigma to the ovary.

What is the function of the ovary?

The ovary contains the ovules and develops into a fruit after fertilization in typical fruit development.

What happens to ovules after fertilization?

Fertilized ovules develop into seeds.

What is a superior ovary?

A superior ovary occurs when the calyx and corolla are attached to the receptacle below the ovary. This arrangement is described as hypogynous.

What is an inferior ovary?

An inferior ovary occurs when the receptacle grows around the ovary and the calyx and corolla attach above it. This arrangement is described as epigynous.

What is parthenocarpy?

Parthenocarpy is the development of fruit without fertilization. Some bananas develop this way.

What are the three layers of the pericarp?

• Exocarp: The outer skin.

• Mesocarp: The middle layer, which may be fleshy.

• Endocarp: The innermost layer surrounding the seed.

What are the two main types of fruits based on their texture at maturity?

Fleshy fruits and dry fruits. Fleshy fruits have a mesocarp that is at least partly fleshy, while dry fruits have a dry mesocarp.

What is a simple fleshy fruit?

A simple fleshy fruit develops from a flower containing a single pistil.

What is a drupe?

A drupe is a simple fleshy fruit with a seed enclosed in a hard, stony endocarp. Examples include cherries, plums, olives, and apricots.

What is a berry in botanical terms?

A berry is a fleshy fruit in which the entire pericarp is fleshy and the fruit commonly contains multiple seeds.

What are the three types of berries discussed in the notes?

True berries, pepos, and hesperidia.

What is a true berry?

A true berry has thin skin and a relatively soft pericarp at maturity. Examples include tomatoes, grapes, and peppers.

What is a pepo?

A pepo is a berry with thick skin. Examples include pumpkins, cucumbers, watermelons, and cantaloupes.

What is a hesperidium?

A hesperidium is a berry with leathery, oil-containing skin and juice-filled sacs. Examples include oranges, lemons, limes, and grapefruit.

What is a pome?

A pome is a fleshy fruit with a papery or leathery endocarp around the seeds. Examples include apples and pears.

What are dry fruits?

Dry fruits have a dry mesocarp at maturity. They are divided into dehiscent and indehiscent fruits.

What is a dehiscent fruit?

A dehiscent fruit is a dry fruit that splits open at maturity to release its seeds.

What is an indehiscent fruit?

An indehiscent fruit is a dry fruit that does not split open at maturity to release its seed.

What is a follicle?

A follicle is a dry, dehiscent fruit that splits open along one side. Examples include milkweed and columbine.

What is a legume?

A legume is a dry, dehiscent fruit that splits along two sides. Examples include beans, lentils, and peas.

What is a capsule?

A capsule is a dry, dehiscent fruit formed from at least two carpels. It can split in several ways to release its seeds. Examples include orchids, lilies, and poppies.

What is a botanical nut?

A nut is a one-seeded dry fruit with a thick, hard pericarp. Examples include hazelnuts and hickory nuts.

What is a grain (caryopsis)?

A grain is a dry fruit in which the pericarp is tightly united with the seed. Examples include corn, oats, and rice.

What is a samara?

A samara is a dry fruit with a winglike extension of the pericarp that helps with seed dispersal.

What is a schizocarp?

A schizocarp is a fruit that separates into one-seeded segments at maturity. In the parsley family, the twin fruit separates into two segments called mericarps.

What is an aggregate fruit?

An aggregate fruit develops from several pistils within a single flower. The individual fruitlets mature together as a cluster. Examples include raspberries, blackberries, and strawberries.

What is a multiple fruit?

A multiple fruit develops from several individual flowers within one inflorescence.

Hilum

concave side of an ordinary kidney bean

In humans you have the placenta in plants you have _______?

Hilum

What is the micropyle, and where is it located?

The micropyle is a tiny pore located next to the hilum of a seed.

What happens when a bean sead is soaked in water for an hour or two?

The seed swells , causing the seed coat to split. Once the seed coat is removed, two halves called cotyledons can be seen.

What is the plumule?

The embryonic shoot that develops into the shoot system of a plant.

Where are the cotyledons attached in a seed embryo?

Just below the plumule.

What is the epicotyl?

The short portion of the embryonic stem located above the cotyledons.

What is the hypocotyl?

The portion of the embryonic stem located below the attachment point of the cotyledons