Flagella are the primary organelles of locomotion in motile algae. These whip-like appendages extend from the cell surface and beat in a coordinated fashion to propel the organism through an aqueous medium. While cilia are structurally similar, flagella are the standard terminology used for algal motility.
1142
The vegetative plant body of Laminaria is typically differentiated into how many distinct regions?
The sporophytic thallus of Laminaria is generally differentiated into two main regions: the holdfast, which anchors the plant to the substrate, and the lamina (or blade), which is the flattened, photosynthetic portion. Sometimes a stipe is also considered, but the primary structural division is often cited as two.
1143
What is the specialized root-like structure used by Phaeophyta for attachment to substrates?
The holdfast is a root-like structure found at the base of the thallus in many brown algae. Unlike true roots, it does not absorb nutrients or water but serves exclusively to anchor the organism firmly to rocks or other substrates in the marine environment.
1144
Which of the following describes the motility of unicellular algal genera?
Unicellular algae exhibit diverse strategies for movement. Some species, such as Chlamydomonas, possess flagella and are motile, allowing them to navigate their environment. Conversely, many other unicellular algae, such as Chlorella, lack flagella and are non-motile, relying on water currents for dispersal. Therefore, both conditions exist within the group.
1145
Which generations are produced during a diplohaplontic life cycle?
A diplohaplontic life cycle, also known as alternation of generations, involves two distinct multicellular phases: the haploid gametophyte generation, which produces gametes, and the diploid sporophyte generation, which produces spores via meiosis. Both phases are integral to the completion of the life cycle.
1146
What term is used to describe a chain of cells in filamentous algae or bacteria?
In phycology and microbiology, a trichome refers to a single row of cells connected end-to-end, often found in filamentous cyanobacteria like Anabaena or Oscillatoria. The trichome is frequently enclosed within a mucilaginous sheath, forming the complete filament structure observed in these organisms.
1147
Which of the following bacterial shapes are commonly associated with the presence of flagella?
Motility is a common trait among many bacterial species, and flagella are the primary organelles of locomotion. Both bacilli (rod-shaped bacteria) and spiral-shaped bacteria (such as spirilla and spirochetes) frequently possess flagella to facilitate movement in their respective environments. This motility allows these bacteria to exhibit chemotaxis, moving toward favorable conditions or away from toxic substances, which is essential for their survival and colonization.
1148
In a typical eukaryotic algal cell, the nucleus is primarily embedded within which cellular component?
The nucleus is a membrane-bound organelle that resides within the cytoplasm of eukaryotic cells. It is suspended in the cytosol, which is the fluid component of the cytoplasm. The nucleus contains the cell's genetic material and serves as the control center for cellular activities, including metabolism and reproduction.
1149
Which chemical agents are commonly used to achieve sterilization or disinfection against bacteria?
Both iodine and chlorine are potent oxidizing agents used as chemical disinfectants. They effectively disrupt bacterial cell membranes and denature essential proteins, thereby inhibiting growth or killing the microorganisms. They are widely used in water treatment and medical antisepsis.
1150
Which ploidy level characterizes the gametophyte generation in plants and algae?
The gametophyte is the haploid phase in the alternation of generations life cycle. It produces gametes through mitosis, which then fuse during fertilization to form a diploid zygote, eventually developing into the sporophyte generation.
