Sister chromatids are held together by a
centromere
centrosome
centriole
kinetichore
The Correct Answer is A
A. centromere: The centromere is the region of a chromosome where sister chromatids are tightly joined after DNA replication. It plays a critical role in ensuring proper alignment and separation of chromatids during cell division.
B. centrosome: The centrosome is an organelle that organizes microtubules and helps form the mitotic spindle during cell division. It is not responsible for holding sister chromatids together.
C. centriole: Centrioles are cylindrical structures within the centrosome that aid in spindle fiber formation. They assist in chromosome movement but do not act as the attachment site between sister chromatids.
D. kinetochore: The kinetochore is a protein complex assembled on the centromere that attaches to spindle fibers. It facilitates chromatid movement but is not the structure that holds sister chromatids together.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. collagen, elastin, and reticular fibers:These are the main types of fibers found in connective tissue, providing strength, elasticity, and support, but they do not represent all three main components.
B. ground substance, fibers, and cells:Connective tissue is composed of cells (such as fibroblasts, macrophages, and adipocytes), fibers (collagen, elastin, reticular), and ground substance (a gel-like material that fills the extracellular space). These three components work together to provide support, strength, and a medium for nutrient and waste exchange.
C. alveoli, fibrous capsule, and secretory cells:These structures are specific to glands or organs like the lungs, not general components of connective tissue.
D. fibroblasts, chondroblasts, and osteoblasts:These are specific types of connective tissue cells responsible for producing matrix in different connective tissues, but they do not account for fibers and ground substance, so they are not the three main components
Correct Answer is A
Explanation
A. accumulate the melanin granules on their superficial portion, forming a UV-blocking pigment layer:Keratinocytes take up melanin granules produced by melanocytes and position them above the nucleus. This arrangement shields nuclear DNA from harmful UV radiation, reducing the risk of mutations and cellular damage.
B. provide the melanocyte with nutrients necessary for melanin synthesis:Nutrients for melanocyte function are delivered through blood supply in the dermis rather than directly by keratinocytes. Keratinocytes do not supply essential substrates for melanin production.
C. maintain the appropriate pH in order for the melanocyte to synthesize melanin granules:pH balance in the skin is regulated mainly by sweat and sebaceous secretions. Keratinocytes do not directly control melanocyte pH for melanin synthesis.
D. maintain the appropriate temperature so the product of the melanocyte will not denature:Temperature regulation is largely a function of dermal blood flow and sweat glands. Keratinocytes do not control melanocyte temperature or prevent denaturation of melanin.
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