Chapter 3: Botany Quiz

Transpiration is the process by which water vapor is lost from the leaves of plants through stomata. Stomata are tiny openings on the surface of leaves that allow for gas exchange. When the stomata open to allow carbon dioxide in for photosynthesis, water vapor also escapes. This loss of water vapor helps to regulate the plant's temperature and maintain its internal water balance. Therefore, transpiration is the correct answer as it accurately describes the loss of water vapor through stomata.

The Casparian strip, found in the endodermal cells of plant roots, is a waxy barrier that plays a crucial role in controlling the movement of water and minerals into the vascular system (xylem). By forcing water and dissolved substances to pass through the selectively permeable cell membranes, the Casparian strip ensures that harmful substances are filtered out, maintaining the plant's internal environment. This function is vital for plant health and nutrient transport.

The endosperm in angiosperms functions in the nourishment of the embryo. The endosperm is a tissue that develops in the seed after fertilization and provides nutrients to the developing embryo. It is rich in starch, proteins, and other substances that support the growth and development of the embryo. This nourishment is essential for the embryo to develop into a fully formed plant.

Flowers and fruits have likely contributed the most to the evolutionary success of angiosperms compared to other land plant groups. Flowers attract pollinators, increasing the chances of successful reproduction through cross-pollination. Fruits protect and disperse seeds, aiding in their dispersal to new locations. These reproductive structures have allowed angiosperms to adapt to various environments and efficiently reproduce, giving them a competitive advantage over other plant groups.

During germination in most angiosperm seeds, food for the growing embryo is provided by the endosperm. The endosperm is a tissue that is formed inside the seed during development and contains a rich supply of nutrients such as starch, proteins, and oils. It serves as a source of energy and nourishment for the developing embryo until it is able to produce its own food through photosynthesis or by absorbing nutrients from the soil. The endosperm is eventually consumed by the growing embryo as it uses up the stored nutrients for growth and development.

Abscisic Acid (ABA) is the plant hormone primarily responsible for inducing seed dormancy and inhibiting seed germination. It plays a critical role in helping plants survive unfavorable conditions by delaying germination until the environment is suitable. ABA also regulates other stress responses, such as stomatal closure during drought. Unlike gibberellins, which promote germination, ABA's action ensures seeds remain dormant during periods of stress, safeguarding the plant's reproductive success.

The correct answer is "a tree during a 24-hour period under normal environmental conditions" because the given description mentions that the rate of transpiration, stem flow, and leaf water potential are measured in a tree over a 24-hour period. This implies that the measurements are taken continuously throughout the day and night, providing a comprehensive understanding of the tree's water dynamics under normal environmental conditions.

Parenchyma is the correct answer because it is a versatile and unspecialized type of plant tissue that can divide and differentiate into other types of plant tissues. It is found in all parts of the plant and performs various functions such as storage, photosynthesis, and secretion. Due to its ability to divide and differentiate, parenchyma tissue can give rise to other types of plant tissues, including sclerenchyma, collenchyma, xylem, and phloem.

Ethylene is a plant hormone that regulates fruit ripening. When fruits are placed in closed paper bags, the ethylene gas produced by the fruits gets trapped inside the bag. This high concentration of ethylene accelerates the ripening process by activating enzymes that break down starches into sugars, softening the fruit and enhancing its flavor.

Archegonia is the correct answer because it is the structure in which only female gametes are produced. Antheridia and stamens are structures that produce male gametes. Protonemata are the filamentous structures in mosses and liverworts that produce both male and female gametes. Flowers are reproductive structures in angiosperms that can produce both male and female gametes. Therefore, archegonia is the only structure listed that exclusively produces female gametes.

Root hairs are extensions of epidermal cells. The epidermis is the outermost layer of cells in the root, and root hairs are specialized structures that extend from the epidermal cells. These root hairs increase the surface area of the root, allowing for better absorption of water and nutrients from the soil.

Adhesion refers to the attraction between water molecules and the walls of xylem vessels. This attraction allows water to be held against gravity, preventing it from falling back down the plant. It helps in the upward movement of water from the roots to the leaves. Adhesion is an important factor in maintaining the continuous flow of water and nutrients in plants.

The movement of water to the top of a 15-meter tree is best explained by transpiration and cohesion. Transpiration is the process by which water is evaporated from the leaves of a plant, creating a suction force that pulls water up from the roots. Cohesion refers to the attraction between water molecules, allowing them to stick together and move as a continuous column up the xylem vessels of the tree. These two processes work together to transport water from the roots to the top of the tree against gravity.

Phototropism is the phenomenon in which plants bend or grow towards a light source. It is mediated by the plant growth substance called auxin. Auxin is a hormone that is responsible for regulating plant growth and development. In the case of phototropism, auxin is produced in higher concentrations on the shaded side of the plant, causing the cells on that side to elongate and the plant to bend towards the light. Therefore, auxin is the plant growth substance that mediates phototropism in plants.

Cambium is an actively dividing tissue in plants. It is responsible for the growth in diameter of stems and roots. It produces new cells that differentiate into xylem and phloem, which are responsible for the transport of water, nutrients, and sugars throughout the plant. The cambium is located between the xylem and phloem in the vascular bundles of plants.

Auxin is primarily responsible for cell elongation, gravitropism, and apical dominance in plants. It promotes cell elongation by loosening the cell wall, allowing the cells to expand. It also plays a crucial role in gravitropism, which is the growth response of plants to gravity. Auxin accumulates on the lower side of the plant, causing the cells to elongate and bend upwards. Additionally, auxin suppresses the growth of lateral buds, promoting apical dominance. Overall, auxin regulates various aspects of plant growth and development.

Flowering plants are capable of fertilization in the absence of water because the process of pollination and fertilization occur through the pollen tubes delivering the sperm to the eggs. This means that the sperm does not need to rely on water for transportation to reach the eggs, allowing fertilization to occur even in dry conditions.

Expansion and greening of the first true foliage leaves will be the last to occur in the development of a seedling. This is because after the seed germinates and the root emerges, the seedling will focus on establishing a strong root system and absorbing nutrients from the soil. Once the root system is established, the plant can then allocate resources towards the growth and development of the foliage leaves. Expansion and greening of the foliage leaves indicate that the seedling is mature and capable of photosynthesis, which is essential for its survival and growth.

Guttation is the correct answer because it refers to the exudation of water droplets from the tip of a leaf or stem. This process occurs when the water pressure in the roots is high and causes water to be pushed up through the xylem vessels and out of special structures called hydathodes. Guttation typically occurs during the night or early morning when transpiration rates are low and the soil is saturated with water.

Photoperiodism is the physiological response of plants to the length of day and night. In the case of tobacco, cocklebur, and certain lettuce seeds, their flowering and germination are primarily induced by photoperiodism. This means that these plants require specific periods of light and darkness in order to initiate these processes. Temperature, negative feedback, circadian rhythms, and lunar phases do not play a significant role in triggering flowering or germination in these particular plants.

Both xylem and phloem are produced as secondary growth by the vascular cambium. The vascular cambium is a layer of meristematic tissue in the stems and roots of plants that is responsible for the production of secondary xylem and phloem. Secondary growth occurs in woody plants and is responsible for the increase in girth or thickness of the plant. The vascular cambium produces new xylem cells towards the inside of the stem and new phloem cells towards the outside. Therefore, both xylem and phloem are produced as secondary growth by the vascular cambium.

The influence of gibberellin on cell expansion is least likely to be a factor in the movement of water through a terrestrial plant. Gibberellin is a hormone that primarily affects plant growth and development, including cell elongation. However, water movement in plants is mainly driven by factors such as cohesion of water molecules, capillary action, root pressure, and the evaporation of water from the leaves through transpiration. While gibberellin may indirectly affect water movement by influencing cell expansion, it is not a direct factor in the movement of water through a plant.

Sieve-tube elements are the cells in plants that are responsible for the translocation of the greatest quantity of organic nutrients. These cells form a part of the phloem tissue, which is responsible for the transport of sugars and other organic molecules throughout the plant. Sieve-tube elements have specialized sieve plates that allow for the movement of nutrients from cell to cell. This makes them the most efficient cells for long-distance transport of organic nutrients in plants.

The correct answer is the force of transpirational pull. The rate of flow of water through the xylem is regulated by the force of transpirational pull. Transpiration, the loss of water vapor through the stomata in leaves, creates a negative pressure or tension that pulls water up from the roots through the xylem vessels. This force of transpirational pull is responsible for the movement of water and dissolved minerals from the roots to the rest of the plant.

The movement of materials in the phloem of plants is driven by a difference in osmotic potential between the source and the sink. This means that there is a difference in solute concentration between the area where the materials are being produced (source) and the area where they are being used or stored (sink). This difference in concentration creates a pressure gradient that allows the materials to flow from the source to the sink. Gravity, root pressure, transpiration of water through the stomates, and adhesion of water to vessel elements are not the driving forces for phloem movement.

The correct answer is "Cells on the dark side of the stem elongate more than those on the lighted side." This explanation suggests that the mechanism by which a plant stem grows towards light is that the cells on the dark side of the stem elongate more than those on the lighted side. This allows the stem to bend towards the light source, as the elongation of cells on the dark side causes the stem to curve in that direction.

Anthocyanin is not a plant-growth regulator. It is a pigment responsible for the red, purple, and blue colors in plants. Plant-growth regulators, on the other hand, are chemicals that regulate various aspects of plant growth and development, such as hormone-like substances. Ethylene, indoleacetic acid, abscisic acid, and cytokinins are all examples of plant-growth regulators.

Plant stems bend toward a light source because of cell elongation on the side of the stem away from the light source. This is known as phototropism. The cells on the side of the stem that is away from the light source elongate, causing the stem to bend towards the light. This response allows the plant to maximize its exposure to light for photosynthesis.

Phytochrome is a plant pigment that is responsible for detecting changes in light. It plays a crucial role in the initiation of flowering in response to photoperiod, which refers to the duration of light and dark periods in a day. When phytochrome detects changes in the length of the dark period, it triggers the process of flowering. Therefore, phytochrome is the correct answer as it is directly involved in the regulation of flowering in plants based on photoperiod.

Sieve cells are considered living cells, unlike tracheids. Sieve cells are involved in transporting water and ions. They are found in vascular plants, which include all plants with specialized tissues for conducting water and nutrients. However, the specific location of sieve cells can vary within the plant, and they can be found in different parts such as the outer cortex or the center of the stem.

Girdling a tree by completely removing a ring of bark disrupts the process of translocation. Translocation is the movement of water and nutrients from the roots to the rest of the plant through the phloem. By removing the bark, the phloem is damaged, preventing the transport of sugars and other nutrients from the leaves to the rest of the tree. This can lead to nutrient deficiency and ultimately, the death of the tree.

The Casparian strip of the endodermal cells of a root functions to control the movement of materials into the vascular cylinder of the root. This strip is a waterproof barrier that forces water and solutes to pass through the endodermal cells, instead of between them. This selective movement of substances helps regulate the absorption of nutrients and water by the root, preventing the entry of harmful substances and allowing for the uptake of essential materials.

Leaf transpiration is the most important factor in the movement of water up a tall tree. Transpiration is the process by which water is evaporated from the leaves through small openings called stomata. This evaporation creates a pull or suction force that draws water up from the roots through the xylem vessels. As water molecules evaporate from the leaves, they create a continuous column of water that moves up the tree. This process is aided by cohesion and adhesion forces within the xylem vessels, allowing water to be transported against gravity. Therefore, leaf transpiration plays a crucial role in the movement of water up a tall tree.

The correct answer is haploid megaspores and microspores. Meiosis is a type of cell division that occurs in the reproductive cells of organisms, including angiosperms (flowering plants). During meiosis, the parent cell undergoes two rounds of division, resulting in the formation of four haploid cells called spores. In angiosperms, these spores are known as megaspores and microspores. Megaspores develop into female gametophytes, which produce eggs, while microspores develop into male gametophytes, which produce sperm. Therefore, the result of meiosis in angiosperms is the production of haploid megaspores and microspores.

The length of the dark period most directly controls the flowering response in short-day plants. Short-day plants require a specific duration of darkness in order to initiate the flowering process. When the dark period reaches a certain length, it triggers the production of flowering hormones in the plant, leading to the flowering response. Therefore, the length of the dark period is crucial for the flowering response in short-day plants.

The fruit produced by angiosperms aids in seed dispersal. This means that the fruit helps to spread the seeds away from the parent plant, increasing the chances of the seeds finding suitable conditions for germination and growth. By attracting animals to eat the fruit, the seeds can be carried to new locations and deposited in different environments. This increases the genetic diversity of the plant population and allows for colonization of new areas. Overall, the fruit serves as a mechanism for the plants to ensure the survival and propagation of their species.

The answer is valid because the table shows that the T group (defoliated leaves) consistently has lower water content compared to the C group (non-defoliated leaves) on all three summer days. This suggests that defoliation by gypsy moths does have an effect on the water content of the leaves. Therefore, the statement that defoliation by gypsy moths has no effect on the water content of next year's leaves is incorrect.

The correct answer is that a typical dicotyledon seed contains a first-foliage plumule formed at the apical meristem. This means that the seed contains the initial growth point for the first set of leaves, which will develop from the apical meristem. The plumule is responsible for the development of the shoot system in the plant. This is a characteristic feature of dicotyledon seeds, which have two cotyledons and undergo epigeal germination.