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Plant cells are the basic structural and functional units of organisms within the kingdom Fungi.
Answer: False
This statement is incorrect. Plant cells are the fundamental structural and functional units of organisms within the kingdom Plantae, characterized by their photosynthetic capabilities.
Chitin is the primary structural component of the primary cell walls in plant cells.
Answer: False
This statement is false. While chitin is a key structural polysaccharide in fungal cell walls, plant cell walls are primarily composed of cellulose, hemicelluloses, and pectin.
Lignin is a component primarily found in the primary cell walls of rapidly growing plant cells.
Answer: False
This statement is false. Lignin is a complex polymer that is deposited in the secondary cell walls of certain plant cells, providing rigidity, strength, and waterproofing. It is not typically found in primary cell walls, especially not in rapidly growing cells.
The primary cell walls of plant cells are composed of cellulose, hemicelluloses, and pectin.
Answer: True
This statement is accurate. These three polysaccharides are the principal components that form the flexible and extensible primary cell walls of plant cells.
Suberin is secreted by plant cells to form secondary wall layers inside the primary cell wall.
Answer: True
This statement is accurate. Suberin is a complex polymer deposited in the secondary cell walls of certain cells, particularly in roots and periderm, providing waterproofing and protection.
Which of the following is a key distinguishing feature of plant cells compared to many other eukaryotic cells?
Answer: A large central vacuole regulating turgor pressure.
The presence of a large central vacuole, which plays a critical role in maintaining turgor pressure and cellular homeostasis, is a significant distinguishing feature of mature plant cells compared to many other eukaryotic cell types.
According to the source, what are the main components of the primary cell walls of plant cells?
Answer: Cellulose, hemicelluloses, and pectin.
The primary cell walls of plant cells are primarily constructed from a complex matrix of cellulose microfibrils embedded in a matrix of hemicelluloses and pectin.
How do plant cell walls differ fundamentally from fungal cell walls?
Answer: Plant walls contain cellulose; fungal walls contain chitin.
The fundamental difference lies in their primary structural polysaccharide: plant cell walls are predominantly composed of cellulose, whereas fungal cell walls are primarily made of chitin.
What is the role of lignin when secreted into plant cell walls?
Answer: To provide rigidity, strength, and waterproofing.
Lignin, when deposited in secondary cell walls, imparts significant rigidity, mechanical strength, and resistance to water penetration, contributing to structural support and preventing desiccation.
A large central vacuole in plant cells primarily functions to store genetic material.
Answer: False
This assertion is inaccurate. The primary functions of the large central vacuole include maintaining turgor pressure, storage of water, ions, and waste products, and contributing to cell growth, rather than storing genetic material, which is housed within the nucleus.
Chloroplasts are responsible for storing starch and fats within plant cells.
Answer: False
This statement is false. While chloroplasts are involved in photosynthesis and can transiently store starch, the primary storage of starch occurs in amyloplasts, and fats are stored in elaioplasts. Chloroplasts' main role is photosynthesis.
The tonoplast is the cell wall component responsible for providing flexible support in growing stems.
Answer: False
This statement is false. The tonoplast is the membrane surrounding the large central vacuole, playing a role in turgor pressure and storage. Flexible support in growing stems is primarily provided by collenchyma cells.
Which of the following is NOT listed as a function of the large central vacuole in plant cells?
Answer: Synthesizing proteins for the cell.
The large central vacuole is involved in turgor maintenance, storage, and waste breakdown, but protein synthesis is a function carried out by ribosomes in the cytoplasm and on the endoplasmic reticulum.
The tonoplast membrane is associated with which organelle?
Answer: Large central vacuole
The tonoplast is the selectively permeable membrane that encloses the large central vacuole in plant cells, regulating the transport of substances between the cytoplasm and the vacuole.
Parenchyma cells are highly specialized, differentiated cells incapable of further division.
Answer: False
This statement is incorrect. Parenchyma cells, while differentiated, retain totipotency and are capable of division and redifferentiation, playing crucial roles in various plant functions.
Collenchyma cells provide rigid support to mature plant tissues due to their heavily lignified secondary walls.
Answer: False
This statement is false. Collenchyma cells provide flexible support to growing plant organs through thickened, yet flexible, primary cell walls, often at the corners. Rigid support in mature tissues is typically provided by sclerenchyma cells with lignified secondary walls.
Sclerenchyma cells are living cells at functional maturity, providing flexible support.
Answer: False
This statement is incorrect. Sclerenchyma cells are characterized by thickened, lignified secondary walls, rendering them non-living (dead) at functional maturity. They provide rigid support, not flexible support.
Sclereids, or stone cells, contribute to the gritty texture found in some fruits and leaves.
Answer: True
This statement is accurate. Sclereids are a type of sclerenchyma cell known for their irregular shapes and hard, lignified walls, which impart grittiness to tissues like the flesh of pears or the surface of some leaves.
The tunica layers of the shoot apex are responsible for producing the vascular tissues of the plant.
Answer: False
This statement is false. The tunica layers (L1 and L2) of the shoot apex primarily give rise to the epidermis. The corpus (L3 layer) is responsible for producing the internal tissues, including the vascular tissues.
Chlorenchyma cells are primarily involved in water transport within the plant.
Answer: False
This statement is false. Chlorenchyma cells are specialized parenchyma cells containing chloroplasts, and their primary role is photosynthesis, not water transport.
Which type of plant cell is described as undifferentiated and analogous to stem cells in animals?
Answer: Meristematic cell
Meristematic cells are undifferentiated plant cells characterized by continuous division and differentiation, analogous to stem cells in animals, responsible for plant growth.
Parenchyma cells are characterized by which feature?
Answer: Thin, permeable primary walls and totipotency.
Parenchyma cells are typically distinguished by their thin, flexible primary cell walls and their inherent totipotency, allowing them to divide and differentiate into various cell types.
Which of the following best describes sclerenchyma cells at functional maturity?
Answer: Dead cells with thickened, lignified secondary walls.
At functional maturity, sclerenchyma cells are characterized by their thick, lignified secondary walls, which provide rigid support, and they are typically dead, lacking protoplasts.
Which of the following cell types are components of sclerenchyma tissue?
Answer: Sclereids and fibres
Sclerenchyma tissue is composed of two primary cell types: sclereids (e.g., stone cells) and fibres, both of which possess thick, lignified secondary walls providing structural support.
What is the significance of chlorenchyma cells?
Answer: They are specialized parenchyma cells primarily responsible for photosynthesis.
Chlorenchyma cells are a type of parenchyma cell distinguished by their abundant chloroplasts, making them the primary sites for photosynthesis within the plant.
Xylem tissue is primarily responsible for the transport of sugars throughout the plant.
Answer: False
This statement is false. Xylem tissue is primarily responsible for the transport of water and dissolved minerals from the roots upwards. The transport of sugars is the principal function of phloem tissue.
Phloem sieve tube elements contain nuclei and ribosomes to support their metabolic functions.
Answer: False
This statement is false. Mature sieve tube elements in phloem lack essential organelles, including nuclei and ribosomes. Their metabolic support is provided by associated companion cells.
Vessel elements and tracheids are both types of cells found in phloem tissue.
Answer: False
This statement is false. Vessel elements and tracheids are the primary water-conducting cells found in xylem tissue, not phloem.
Companion cells provide metabolic support to sieve tube elements because sieve tube elements lack essential organelles.
Answer: True
This statement is accurate. Mature sieve tube elements are enucleated and lack other vital organelles, necessitating metabolic support from the closely associated companion cells.
Vessel elements are found in the xylem of gymnosperms but not in flowering plants.
Answer: False
This statement is false. Vessel elements are a characteristic feature of xylem in angiosperms (flowering plants) and are absent in most gymnosperms, where water transport relies primarily on tracheids.
The presence of xylem tracheids is a defining characteristic of vascular plants (Tracheophytes).
Answer: True
This statement is accurate. The evolution of tracheids, enabling efficient water transport, was a critical step in the development of vascular plants.
What is the primary function of xylem tissue?
Answer: Transport of water and minerals from roots upwards.
The principal role of xylem tissue is the unidirectional transport of water and dissolved mineral nutrients from the root system to the aerial parts of the plant.
Tracheids are a key feature defining which group of plants?
Answer: Vascular Plants (Tracheophytes)
The presence of xylem tracheids, which facilitate efficient water transport, is a defining characteristic that distinguishes vascular plants (Tracheophytes) from other plant lineages.
How do xylem vessel elements differ from tracheids, according to the text?
Answer: Vessel elements lack end walls, forming continuous tubes, primarily in flowering plants.
A key distinction is that vessel elements, which form efficient conducting tubes, typically lack end walls and are prevalent in angiosperms, whereas tracheids possess intact end walls and are found in both gymnosperms and angiosperms.
What is the main substance transported by phloem tissue?
Answer: Sugars (primarily sucrose)
Phloem tissue is primarily responsible for the translocation of photosynthetically produced sugars, predominantly sucrose, throughout the plant.
The functional relationship between sieve tube elements and companion cells involves:
Answer: Companion cells supporting the metabolic functions of sieve tube elements.
Companion cells are metabolically active and provide essential support, including loading sugars and maintaining the functionality of sieve tube elements, which lack key organelles.
Plasmodesmata are rigid structures that prevent any communication between adjacent plant cells.
Answer: False
This assertion is incorrect. Plasmodesmata are cytoplasmic channels that traverse the cell walls of adjacent plant cells, facilitating direct intercellular communication and the transport of molecules.
The plant cuticle is secreted by root epidermal cells to prevent water loss.
Answer: False
This statement is false. The plant cuticle is a waxy layer secreted by the epidermal cells of aerial plant organs (stems and leaves) to prevent excessive water loss. Root epidermal cells typically lack a cuticle and are specialized for water and nutrient absorption.
Stomatal guard cells typically lack chloroplasts in most plant species.
Answer: False
This statement is false. In most plant species, stomatal guard cells are unique among epidermal cells in that they contain chloroplasts, which are essential for their role in regulating stomatal aperture.
The primary function of root hairs is to provide structural rigidity to the root.
Answer: False
This statement is false. Root hairs are specialized epidermal outgrowths that significantly increase the surface area of the root, thereby enhancing the absorption of water and dissolved mineral nutrients from the soil.
The primary function of the epidermis is nutrient storage within the plant.
Answer: False
This statement is false. The epidermis serves as a protective outer layer for the plant body. While some epidermal cells may store substances, its primary roles involve protection, regulation of gas exchange (via stomata), and absorption (via root hairs).
What is the function of plasmodesmata within plant tissues?
Answer: To facilitate the direct exchange of nutrients and hormones between adjacent cells.
Plasmodesmata are specialized channels that traverse the cell walls of adjacent plant cells, enabling direct cytoplasmic connections for the passage of signaling molecules, nutrients, and metabolites.
What is the primary role of the plant cuticle?
Answer: Preventing excessive water loss from aerial surfaces.
The plant cuticle is a hydrophobic, waxy layer that covers the epidermis of aerial organs, significantly reducing transpirational water loss and protecting against pathogens.
Which specialized epidermal cells contain chloroplasts and regulate stomatal opening?
Answer: Stomatal guard cells
Stomatal guard cells are specialized epidermal cells that contain chloroplasts and regulate the opening and closing of stomata, thereby controlling gas exchange and transpiration.
What is the primary contribution of root hairs to the plant?
Answer: Increasing the surface area for water and nutrient absorption.
Root hairs are microscopic extensions of epidermal cells that dramatically increase the absorptive surface area of the root system, thereby enhancing the uptake of water and dissolved mineral nutrients.
Cell division in land plants involves the formation of a cell plate guided by a phragmoplast.
Answer: True
This statement is accurate. During cell division in land plants, the phragmoplast serves as a transient structure that directs the assembly of the cell plate, which ultimately develops into the new cell wall separating the daughter cells.
Flagella are commonly found in the somatic cells of mature conifers and flowering plants.
Answer: False
This statement is false. Flagella are typically found in the motile sperm cells of certain plant groups (e.g., bryophytes, pteridophytes), but not in the somatic cells of mature conifers or flowering plants.
Which structure serves as a scaffold for the formation of a cell plate during cytokinesis in land plants?
Answer: Phragmoplast
The phragmoplast, a dynamic assembly of microtubules and actin filaments, forms in the equatorial region of the dividing plant cell and serves as the structural framework for the deposition of the cell plate during cytokinesis.
Motile sperm cells with flagella are found in which group of plants mentioned?
Answer: Bryophytes and Pteridophytes
Bryophytes and pteridophytes are among the plant groups that produce motile sperm cells equipped with flagella, enabling them to swim towards the egg for fertilization.
Which plant group lacks motile sperm and flagella entirely?
Answer: Conifers and Flowering Plants
Conifers and flowering plants (angiosperms) are characterized by the absence of motile sperm; their male gametes are delivered via pollen tubes, thus lacking flagella.
The endosymbiotic theory suggests that plastids evolved independently within eukaryotic cells.
Answer: False
This statement is incorrect. The endosymbiotic theory proposes that plastids, such as chloroplasts, originated from prokaryotic endosymbionts that were engulfed by an ancestral eukaryotic cell and established a symbiotic relationship.
Tracheids first appeared in plant evolution during the Carboniferous period.
Answer: False
This statement is false. Tracheids, a key feature of vascular plants, first appeared during the Silurian period, over 425 million years ago, predating the Carboniferous period.
What is the evolutionary hypothesis for the origin of plastids?
Answer: They originated from prokaryotic endosymbionts.
The prevailing hypothesis, known as the endosymbiotic theory, proposes that plastids evolved from free-living prokaryotic organisms that were engulfed by an ancestral eukaryotic cell.
The evolutionary appearance of xylem tracheids was significant because it:
Answer: Enabled efficient water transport against gravity for terrestrial life.
The evolution of xylem tracheids represented a crucial adaptation for terrestrial life, providing an efficient mechanism for water transport against gravitational forces, which was essential for plant survival and diversification on land.