BISC Final Exam Quiz: MCQ!

Transpiration is the process of water evaporation from plant parts, such as leaves, stems, and flowers. It occurs through small openings called stomata on the surface of the plant. As the water evaporates, it creates a pulling force that helps in the transportation of water and nutrients from the roots to the rest of the plant. Transpiration also helps in cooling the plant and maintaining its temperature.

Epidermal cells secrete a waxy cuticle. The waxy cuticle is a protective layer that covers the outer surface of the epidermis of plants. It helps to reduce water loss by forming a barrier against evaporation. Additionally, the waxy cuticle also provides protection against pathogens, UV radiation, and mechanical damage. Therefore, epidermal cells are responsible for the secretion of the waxy cuticle, which plays a crucial role in the survival and adaptation of plants.

Humus is the correct answer because it refers to the decomposition of organic matter in the soil. It is a dark, organic material that is rich in nutrients and helps improve soil fertility. Humus is formed through the breakdown of dead plant and animal material by microorganisms. It helps to retain moisture in the soil, promotes root growth, and enhances the overall health of the soil ecosystem.

When guard cells swell, it causes the stoma (plural: stomata) to open. Stomata are tiny openings on the surface of leaves that allow for gas exchange, including the intake of carbon dioxide and the release of oxygen during photosynthesis. The swelling of guard cells, which surround each stoma, is triggered by the accumulation of potassium ions and water. This swelling causes the guard cells to bend and create an opening, allowing gases to enter and exit the leaf. Therefore, the correct answer is "a stoma opens."

Both macronutrients and required elements are correct answers for the given question. Carbon, hydrogen, and oxygen are essential elements that plants require in large quantities for their growth and development. These elements are considered macronutrients because plants need them in relatively large amounts. Additionally, these elements are also classified as required elements because they are necessary for plants to carry out essential metabolic processes.

The correct answer is mycorrhiza. Mycorrhiza is a mutually beneficial association between a root and a fungus. In this symbiotic relationship, the fungus helps the plant in absorbing nutrients, particularly phosphorus, from the soil, while the plant provides the fungus with carbohydrates produced through photosynthesis. This association is essential for the growth and survival of many plant species, as it increases their access to nutrients and enhances their ability to withstand environmental stressors.

Sieve tubes are part of the phloem. The phloem is responsible for transporting sugars and other organic molecules from the leaves to other parts of the plant. Sieve tubes are specialized cells found in the phloem that form long tubes for the transport of these substances. They are interconnected by sieve plates, which allow for the movement of materials between cells. Therefore, the correct answer is phloem.

Guard cells pump ions into their cytoplasm in response to light to open stomata. This ion pumping causes an increase in osmotic potential within the guard cells, leading to the uptake of water. As a result, the guard cells become turgid and the stomata open, allowing for gas exchange and transpiration.

The transport of photosynthetically produced sugars from leaves to roots occurs by pressure flow and differences in source and sink solute concentrations. Pressure flow is a mechanism in which sugars are transported from areas of higher concentration (source) to areas of lower concentration (sink) through specialized cells called sieve tubes. This process is driven by the pressure generated by the active transport of solutes into the sieve tubes. Additionally, the differences in solute concentrations between the source (leaves) and sink (roots) create a gradient that facilitates the movement of sugars.

The Casparian strip is a specialized structure found in the endodermal cells of plant roots. It forms a waterproof barrier that forces water and solutes to move through the cells, rather than around them. This helps regulate the movement of water and nutrients into the plant, preventing any unwanted substances from entering.

The vascular cylinder consists of cells of the endodermis, which is the innermost layer of the cortex in the root, as well as the xylem and phloem. The endodermis is responsible for regulating the movement of water and nutrients into the vascular tissue, while the xylem and phloem are responsible for transporting water, minerals, and sugars throughout the plant. Therefore, the correct answer is b and d.

Water transport from roots to leaves occurs mainly because of transpiration, tension, and cohesion of water. Transpiration is the process by which water evaporates from the leaves, creating a suction force that pulls water up through the xylem vessels. Tension refers to the negative pressure created by transpiration, which helps in the upward movement of water. Cohesion of water molecules allows them to stick together, forming a continuous column of water in the xylem vessels. These three factors work together to facilitate the movement of water from the roots to the leaves.

Abscisic acid is a hormone produced by plants in response to stress, such as drought or dry soil conditions. When soil is dry, the concentration of abscisic acid increases in the plant cells. This hormone signals the guard cells surrounding the stomata to collapse against one another, resulting in the closure of stomata. This helps to prevent water loss through transpiration and conserve water within the plant. Therefore, the correct answer is abscisic acid.

Tracheids are part of xylem, which is responsible for transporting water and minerals from the roots to the rest of the plant. Tracheids are elongated cells with tapered ends that are involved in water conduction. They have thick secondary cell walls and are dead at maturity. Tracheids, along with vessel elements, make up the two main types of water-conducting cells in xylem tissue.