Title: Plant Structure and Function
Course: Question Banks

Q: The ________ results in the characteristic “square” shape of plant cells.
- plasma membrane (Incorrect. Animal and plant cells both have plasma membranes and animal cells aren’t shaped like squares.)
- central vacuole (Incorrect. The central vacuole helps give plant cells their shape but is not the key reason they appear like squares.)
- cell wall (Correct. The cell wall is rigid due to its cellulose and lignin; it shapes and supports plant cells, causing them to appear square-like.)
A: cell wall

Q: The high lignin concentration in ________ cells make these cells very strong, and tissues of these cells appropriate for making rope.
- parenchymal (Incorrect. Parenchymal cells are thin-walled and involved in photosynthesis and energy storage; they are not particularly strong.)
- collenchymal (Incorrect. These cells tend to have irregularly thickened walls, and are more “stringy.”)
- sclerenchymal (Correct. These cells have a high lignin concentration, making their walls very thick and strong.)
A: sclerenchymal

Q: The ________ store the pigments that give flower petals their bright colors.
- chloroplasts (Incorrect. Chloroplasts hold the pigments that give plant leaves their colors.)
- vacuoles (Incorrect. Vacuoles are storage vesicles, but they do not store pigments.)
- chromoplasts (Correct. Chromoplasts are organelles prevalent in flower petals; they make and store the pigments that give flowers their colors.)
A: chromoplasts

Q: ________ tissues continue to grow throughout the life of a plant.
- Dermal (Incorrect. Dermal tissues are differentiated permanent tissues that cover and protect the plants.)
- Vascular (Incorrect. Vascular tissues are differentiated permanent tissues that transport water, minerals, and sugars throughout plants.)
- Meristem (Correct. Meristems are regions of continuous growth and cell division in plants.)
A: Meristem

Q: The opening and closing of a stoma is controlled by ________ cells.
- trichome (Incorrect. Trichomes are hair-like structures that reduce water loss above ground, increase solar reflectance, and store defensive compounds.)
- tracheids (Incorrect. Tracheids are xylem cells with thick lignified cell walls that conduct water.)
- guard (Correct. A guard cell is found on each side of a stoma; these cells control the opening and closing of these pores, and thus regulate the uptake of carbon dioxide and release oxygen and water vapor.)
A: guard

Q: The ________ is ground tissue towards the interior of the vascular tissues.
- cortex (Incorrect. The cortex is the layer of tissue between the vascular tissue and epidermis.)
- phloem (Incorrect. Phloem is vascular tissue, not ground tissue.)
- pith (Correct. The pith is towards the interior of the vascular tissue in a stem or root.)
A: pith

Q: The ________ system is generally above ground in plants.
- root (Incorrect. The root system is usually underground in plants.)
- apical meristem (Incorrect. Apical meristem tissues are found at the tips of both stems and roots.)
- shoot (Correct. The shoot system, both vegetative and reproductive parts, generally grow above ground in plants.)
A: shoot

Q: Stems arise from ________ tissue.
- dermal (Incorrect. Dermal tissue is a part of the stem, in the form of epidermis, but it does not overall give rise to stems.)
- vascular (Incorrect. Vascular tissue makes up the xylem and phloem channels inside the stem, but not the overall stem.)
- ground (Correct. Stems, and other plant organs, arise from ground tissue.)
A: ground

Q: A modified stem that grows horizontally underground is a ________.
- stolon (Incorrect. Stolons run almost parallel to the ground, or may be slightly below the surface.)
- tubers (Incorrect. Tubers are modified stems that store starch; they are often underground but do not grow horizontally.)
- rhizome (Correct. Rhizomes are modified stems growing horizontally underground that have nodes and internodes.)
A: rhizome

Q: The ________ is usually found between the base of a leaf and the stem and may give rise to flowers.
- bulb (Incorrect. A bulb is a modified stem below ground that stores nutrients.)
- apical bud (Incorrect. An apical bud is found at the tip of the shoot.)
- axillary bud (Correct. An axillary bud is found in the axil where it can give rise to a branch or a flower.)
A: axillary bud

Q: The lamina is the ________.
- attachment point where a leaf meets the stem (Incorrect. Some leaves attach to stems with a petiole; others attach directly to the stem.)
- midline of the leaf that produces veins (Incorrect. This is the midrib.)
- widest part of the leaf (Correct. This is also called the leaf blade.)
A: widest part of the leaf

Q: The arrangement of leaves on a stem is ________.
- ikebana (Incorrect. This is the art of Japanese flower arranging.)
- venation (Incorrect. This is the arrangement of veins in a leaf.)
- phyllotaxy (Correct. Phyllotaxy describes the number and placement of a plant’s leaves.)
A: phyllotaxy

Q: The ________ reduces the rate of water loss from the surface of a leaf.
- number of trichomes (Incorrect. Trichomes help to deter herbivory.)
- guard cell (Incorrect. Guard cells control opening and closing of the stoma, where gas exchange occurs. This can help conserve water but is not the main mechanism to prevent water loss.)
- cuticle (Correct. This waxy layer helps minimize water loss from leaves.)
A: cuticle

Q: A(n) ________ root system has a main root that grows down vertically.
- adventitious (Incorrect. Adventitious roots emerge above ground from the shoot; no plant uses only adventitious roots.)
- fibrous (Incorrect. Fibrous root systems are a dense network of roots closer to the soil surface.)
- tap (Correct. A tap root system has a main root (the taproot) that grows down into the soil, often penetrating deeply.)
A: tap

Q: ________ increase the surface area of the root.
- Root caps (Incorrect. The root cap protects the tip of the root as it burrows in the soil.)
- Pericycles (Incorrect. Pericycle is the outermost layer of the root’s vascular tissue.)
- Root hairs (Correct. These extensions of root epidermal cells greatly contribute to absorption of water and minerals.)
A: Root hairs

Q: The ________ forces water and solutes into endodermal cells.
- stele (Incorrect. This is the inner portion of the root where the vascular tissues are arranged.)
- suberin (Incorrect. This is the waxy substance present on the walls of endodermal cells.)
- Casparian strip (Correct. This waxy region prevents water and solutes from slipping between cells in the root, ensuring that only materials required by the root pass through the endodermis.)
A: Casparian strip

Q: Water in plants move to equilibrate by moving from areas of ________ water potential to areas of ________ water potential.
- lower; higher (Incorrect. Water does not move from areas of lower water potential to higher.)
- shallower; deeper (Incorrect. Shallow and deep are not terms used to describe water potential in plants.)
- higher; lower (Correct. Just like with a concentration gradient, water moves from areas of higher water potential to areas of lower water potential in an attempt to equilibrate.)
A: higher; lower

Q: When a leaf opens its stomata, the turgor potential of the leaf will ________.
- stay the same (Incorrect. The turgor potential will not stay the same.)
- increase (Incorrect. The turgor potential will not increase.)
- decrease (Correct. Opening the stomata allows water to evaporate, which reduces the turgor (or pressure) potential.)
A: decrease

Q: ________ has a greater impact on taller plants.
- Matric potential (Incorrect. Matric potential does not have a greater impact on taller plants.)
- Turgor potential (Incorrect. Turgor potential does not have a greater impact on taller plants.)
- Gravity potential (Correct. Gravity potential increases as a water column increases. Taller plants have equally taller water columns, so gravity potential has a larger impact on taller plants.)
A: Gravity potential

Q: The main driver of water movement through xylem is ________.
- gravity potential (Incorrect. Gravity potential influences the process but is not the main driver.)
- humidity (Incorrect. Humidity can have an impact on this process but is not the main driver.)
- transpiration (Correct. The evaporation of water at the leaf surface results in the loss of this water. This generates the negative pressure that draws water up from the roots through the xylem tissue.)
A: transpiration

Q: Up to ________ percent of the water taken up by the roots may be lost to transpiration.
- 30 (Incorrect. This number is too low.)
- 60 (Incorrect. This is not the correct amount of water lost to transpiration.)
- 90 (Correct. Up to 90 percent of the water absorbed by a plant’s roots may be lost to transpiration from the leaves.)
A: 90

Q: ________ often have thicker waxy cuticles to reduce transpiration.
- Mesophytes (Incorrect. Mesophytes live in well-water environments and do not need extra protections to reduce transpiration.)
- Hydropytes (Incorrect. Aquatic plants do need special leaf adaptations for their watery environments, but one is not a thicker cuticle to combat transpiration.)
- Epiphytes (Correct. Despite living in humid environments, epiphytes have limited access to water since they grow on other plants. Therefore they have adaptations that reduce transpiration.)
A: Epiphytes

Q: Translocation occurs via the ________ of plants.
- mesophyll (Incorrect. Translocation does not move sugars from sources via mesophyll.)
- xylem (Incorrect. Transpiration drives the movement of water from roots via the xylem.)
- phloem (Correct. Translocation moves sugars from sources to growing parts of the plants via the phloem.)
A: phloem

Q: ________ connect the mesophyll cells that produce photosynthates to the phloem for transpiration to the closest sink.
- Sieve plates (Incorrect. Sieve plates with pores connect the phloem sieve-tube elements.)
- Companion cells (Incorrect. Companion cells produce energy for STEs.)
- Plasmodesmata (Correct. These cytoplasmic channels connect to the phloem sieve-tube elements.)
A: Plasmodesmata

Q: Photosynthates are directed to ________ during vegetative growth.
- seeds (Incorrect. Photosynthates move to seeds and fruits during reproductive development.)
- tubers (Incorrect. Photosynthates move to tubers for storage.)
- leaves (Correct. Photosynthates move to leaves and shoots during vegetative growth.)
A: leaves

Q: The inactive form of phytochrome, ________, is triggered by far-red light.
- P_fr (Incorrect. P_fr is the active form of phytochrome, and is triggered by red light.)
- Pi (Incorrect. There is no Pi form of phytochrome.)
- P_r (Correct. P_r is the inactive form of phytochrome, and is triggered by exposure to far-red light.)
A: P_r

Q: Plants use the phytochrome system to ________.
- open or close leaves (Incorrect. This is a plant response controlled by phototropins, not phytochromes.)
- trigger formation of a flower bud (Incorrect. Day-neutral plants do not use the phytochrome system to control flowering)
- grow away from shade and towards light (Correct. Shaded areas will have more far-red light, which triggers in inactive Pr, slowing growth.)
A: grow away from shade and towards light

Q: Phototropism is a response to ________ wavelengths of light.
- far-red (Incorrect. This is part of the photomorphogenesis and photoperiodism responses.)
- red (Incorrect. This is part of the photomorphogenesis and photoperiodism responses.)
- blue (Correct. Directional bending toward or away from a light source by a plant is in response to the blue wavelength of light.)
A: blue

Q: ________ ensures that roots grow into soil and shoots grow toward sunlight.
- Phototropism (Incorrect. This is directional bending of a shoot only in response to light signals.)
- Thigmotropism (Incorrect. This is the movement of a plant subjected to constant directional pressure.)
- Gravitropism (Correct. This ensures shoots usually sprout up from the ground and roots grow into soil.)
A: Gravitropism

Q: The response to gravity is controlled by ________.
- IAA (Incorrect. IAA is the plant hormone that dictates the response to gravity, but it must be triggered by another cellular response.)
- calcium ions (Incorrect. Calcium signaling is a step in the cascade that triggers a specific response to gravity, but the release of these ions is triggered by something else.)
- amyloplasts (Correct. These plastids contain starch granules that settle downward in response to gravity. This initiates a signaling cascade that controls the directional response to gravity.)
A: amyloplasts

Q: A high concentration of IAA in response to gravity stimulates cell elongation in ________.
- roots (Incorrect. High concentration of IAA inhibits cell elongation in roots.)
- leaves (Incorrect. Leaves do not respond to gravitational signals.)
- shoots (Correct. High concentration of IAA triggers cell elongation, which causes the shoot to grow up.)
A: shoots

Q: What is thigmotropism?
- the force that ensures shoots usually sprout up from the ground and roots grow into soil (Incorrect. This is gravitropism.)
- the directional bending of a shoot only in response to light signals (Incorrect. This is phototropism.)
- the movement of a plant subjected to constant directional pressure (Correct. Thigmotropism controls the winding of tendrils around a support frame.)
A: the movement of a plant subjected to constant directional pressure

Q: A Venus flytrap closing upon an insect is an example of a ________ response.
- thigmomorphogenetic (Incorrect. This would be exemplified by a tree trunk becoming thicker when constantly bent in the wind.)
- thigmotropic (Incorrect. This would be exemplified by a morning glory growing up a fence pole.)
- thigmonastic (Correct. The trap snaps shut regardless of which trigger hair an insect touches.)
A: thigmonastic

Q: ________ tissue in particular is strengthened in a thigmomorphogenetic response.
- Phloem (Incorrect. Phloem is not particularly strengthened in response to wind pressure.)
- Meristem (Incorrect. The meristematic region of tendrils is very touch sensitive, but that is a thigmotropic response.)
- Xylem (Correct. Xylem is strengthened to add stiffness to resist the wind’s force on trees.)
A: Xylem

Q: The first line of defense in plants is ________.
- toxic compounds (Incorrect. Toxic compounds are a secondary defense for most plants.)
- volatile compounds (Incorrect. Volatile compounds may be released to attract parasitoids that will then attack insects already damaging a plant.)
- intact bark or waxy cuticle (Correct. Bark or a waxy cuticle serve as a physical barrier protecting plants.)
A: intact bark or waxy cuticle

Q: Thorns are modified ________, while spines are modified ________.
- stems; leaves (Incorrect. This is not the origin of thorns.)
- roots; stems (Incorrect. This is not the origin of thorns or spines.)
- branches; leaves (Correct. Thorns and spines both discourage animals by causing physical damage and/or inducing rashes and allergic reactions.)
A: branches; leaves

Q: Many secondary metabolites produced as defense responses in plants are made to ________.
- kill the animal that ingests them (Incorrect. Only a few secondary metabolites, like cyanide, are actually lethal.)
- attract pollinators (Incorrect. Those substances would not be produced as defense responses.)
- discourage predators (Correct. Quite a few of the secondary metabolites plants use in their defense are produced to discourage predators from ingesting them.)
A: discourage predators

Q: New xylem is produced by ________.
- ground meristem (Incorrect. Ground meristem produces ground tissue.)
- protoderm (Incorrect. Protoderm produces new epidermis.)
- procambium (Correct. Procambium gives rise to new xylem and phloem.)
A: procambium

Q: ________ replaces the epidermis of stems with bark.
- Procambium (Incorrect. Procambium gives rise to new xylem and phloem and is a type of primary meristem.)
- Vascular cambium (Incorrect. Vascular cambium adds secondary xylem and phloem, adding to the diameter of a plant.)
- Cork cambium (Correct. One layer of bark is cork; hence the name cork cambium.)
A: Cork cambium

Q: Growth rings in trees are layers of ________.
- ground tissue (Incorrect. Ground tissue is a type of primary growth, so would not be “captured” as a growth ring.)
- bark (Incorrect. Bark is the outermost layer of a tree trunk only, though it does have sublayers such as inner bark and cork.)
- secondary xylem (Correct. Secondary xylem is the main tissue in what we call growth rings; each ring is added on top of the previous, increasing the diameter of the plant.)
A: secondary xylem

Q: Primary growth is due to cell division of the ________.
- lateral meristem (Incorrect. This is secondary growth.)
- axillary buds (Incorrect. Axillary buds form along branches and stems but will not normally grow out.)
- apical meristem (Correct. Primary growth refers to lengthening of the roots and stems. All plants undergo primary growth.)
A: apical meristem

Q: Herbaceous plants do not have secondary growth because they lack ________.
- apical meristem (Incorrect. All plants undergo primary growth, which is the result of cell division in the shoot apical meristem.)
- axillary buds (Incorrect. Axillary buds form along branches and stems but will not normally grow out. When they do, it is due to a primary growth mechanism.)
- lateral meristem (Correct. Lateral meristem controls secondary growth.)
A: lateral meristem

Q: Autumn wood has ________ than spring wood.
- a larger internal diameter (Incorrect. This is not the key difference between autumn and spring wood.)
- spongier cork (Incorrect. Cork is present in the bark layer, not the secondary xylem layer which makes up autumn and spring wood.)
- a thicker cell wall (Correct. This makes autumn wood denser than spring wood.)
A: a thicker cell wall

Q: ________ are most abundant in growing tissues where they can promote mitosis.
- Gibberellins (Incorrect. Gibberellins stimulate shoot elongation and fruit and flower maturation, but not cell division.)
- Abscisic acid (Incorrect. ABA is most active in response to stress conditions, where it induces dormancy.)
- Cytokinins (Correct. Cytokinins are most amount where plants actually grow, in roots, embryos and fruits.)
A: Cytokinins

Q: Which is the result of treating a plant with gibberellins?
- an induced state of dormancy (Incorrect. ABA induces seed dormancy)
- fruit ripening, flower wilting, and leaf fall (Incorrect. Auxins promote these changes in plants.)
- the production of plump, large seedless grapes (Correct. Treating maturing fruit with GA will promote larger fruit size.)
A: the production of plump, large seedless grapes

Q: Farmers can trigger uniform ripening times in fruit by treating plants with ________.
- jasmonates (Incorrect. These compounds are defensive hormones.)
- oligosaccharins (Incorrect. These compounds help defend against bacterial and fungal infections in plants.)
- ethylene (Correct. Ethylene promotes fruit ripening; ripening time can be controlled by applying this gas.)
A: ethylene

Q: After carbon, ________ is the most abundant element in plant cells.
- oyxgen (Incorrect. Oxygen is an important part of plant cells, but is not the second most abundant.)
- iron (Incorrect. Iron is a micronutrient in plant cells.)
- nitrogen (Correct. Nitrogen is the second most abundant element in plant cells; only carbon is more abundant.)
A: nitrogen

Q: ________ plays a key role in regulating nutrient transport.
- Magnesium (Incorrect. Magnesium plays a role in photosynthesis, not nutrient transport.)
- Oxygen (Incorrect. Oxygen plays a role in cellular respiration and in forming water.)
- Calcium (Correct. In plants, calcium plays a role in regulating nutrient transport, and supports many enzyme functions.)
A: Calcium

Q: A potassium ion pump supports ________.
- cellular respiration (Incorrect. A potassium ion pump is not involved in cellular respiration.)
- regulation of nutrient transport (Incorrect. Calcium is involved in regulating nutrient transport.)
- stomata regulation of water balance (Correct. Potassium plays a key role in the process by which stomata help maintain a healthy water balance.)
A: stomata regulation of water balance

Q: The most important source of biological nitrogen fixation is the symbiotic relationship between ________.
- soil fungi and legume plants (Incorrect. Fungi do not play a role in BNF.)
- soil bacteria and plant roots (Incorrect. Not all plant roots can participate in this type of symbiotic relationship.)
- soil bacteria and legume plants (Correct. Rhizobia symbiotically interact with legume roots to form nodules, where nitrogen fixation occurs.)
A: soil bacteria and legume plants

Q: Mycorrhizae involve a root host and a symbiotic ________.
- protist (Incorrect. Protists are not involved in forming mycorrhizae.)
- bacteria (Incorrect. Bacteria are not involved in forming mycorrhizae.)
- fungi (Correct. A mycorrhizae is a symbiotic relationship between a plant root and a fungus.)
A: fungi

Q: More than ________ percent of terrestrial plant roots contain endomycorrhizae.
- 60 (Incorrect. This is not the correct percentage.)
- 40 (Incorrect. This percentage is too small.)
- 80 (Correct. Endomycorrhizae are found in the roots of more than 80 percent of terrestrial plants.)
A: 80

Q: The Dutchmen’s pipe is a ________ plant that decomposes dead matter.
- epiphyte (Incorrect. An epiphyte grows on other plants but does not depend on the other plant for nutrients.)
- holoparasite (Incorrect. Holoparasitic plants obtain nutrients from living plant hosts.)
- saprophyte (Correct. There are only a few saprophytic plants in the world, but they lack chlorophyll and obtain nutrients from breaking down organic matter.)
A: saprophyte

Q: Define the term epiphyte.
- a plant that decomposes dead matter (Incorrect. This is saprophyte.)
- a plant that obtain nutrients from living plant hosts (Incorrect. Holoparasitic plants obtain nutrients, including water, from living plant hosts. They do not absorb moisture from the atmosphere.)
- a plant with specialized roots that absorb moisture from the atmosphere (Correct. An epiphyte grows on other plants but does not depend on the other plant for nutrients; its aerial roots absorb moisture directly from the atmosphere)
A: a plant with specialized roots that absorb moisture from the atmosphere

Q: ________ are fully photosynthetic but obtain water and minerals from a host.
- Lichens (Incorrect. A lichen is a symbiotic relationship between a fungus and an algae.)
- Insectivorous plants (Incorrect. Insectivorous plants obtain minerals from insect prey to compensate for lacks in their environment.)
- Hemiparasites (Correct. Hemiparasites can, and do, perform photosynthesis but they utilize a host for water and minerals.)
A: Hemiparasites