Biology MCQs
Topic Notes: Biology
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
51
During plant cytokinesis, what structure is formed when vesicles accumulate at the equatorial plane of the cell?
Answer:
cell plate
In plant cells, cytokinesis differs from animal cells due to the presence of a rigid cell wall. Golgi-derived vesicles containing cell wall materials migrate to the center of the dividing cell and fuse to form a structure known as the cell plate. This plate eventually expands outward to fuse with the existing plasma membrane and cell wall, effectively separating the two daughter cells.
52
What is the biological process by which undifferentiated embryonic cells specialize into mature, functional cell types?
Answer:
cell differentiation
Cell differentiation is the developmental process by which a less specialized cell, such as an embryonic stem cell, undergoes changes in gene expression to become a more specialized cell type with distinct structural and functional characteristics. This process is essential for the formation of tissues and organs in multicellular organisms.
53
During the process of cell division, which cellular component undergoes division first?
Answer:
nucleus
The nucleus, containing the cell's genetic material, must divide first to ensure each daughter cell receives a complete set of chromosomes. This process, called karyokinesis, precedes cytokinesis, the division of the cytoplasm.
54
Karyokinesis is defined as the division of which cellular component?
Answer:
nucleus
Karyokinesis refers specifically to the process of nuclear division during the cell cycle. It involves the separation of the replicated chromosomes into two distinct nuclei, which typically precedes cytokinesis, the division of the cytoplasm. This process ensures that each daughter cell receives an identical set of genetic material.
55
Which of the following cellular components is not typically considered a primary phase or product of mitosis?
Answer:
vacuoles
Mitosis is the process of nuclear division. While the cytoplasm divides during cytokinesis, vacuoles are organelles that are distributed between daughter cells but are not a defining phase or product of the mitotic process itself.
56
During anaphase, what structures are separated to form the new genetic components of the daughter cells?
Answer:
sister chromatids
During the anaphase stage of mitosis, the centromeres split, allowing the sister chromatids to be pulled apart toward opposite poles of the cell. Once separated, these individual chromatids are officially referred to as daughter chromosomes.
57
What is the name of the complex protein structure located at the centromere to which spindle fibers attach during cell division?
Answer:
kinetochores
Kinetochores are specialized protein complexes assembled on the centromeric DNA of chromosomes. They serve as the attachment sites for spindle microtubules, ensuring the proper segregation of sister chromatids during mitosis and meiosis.
58
What is the classification of a metaphase chromosome that possesses a centrally located centromere?
Answer:
Metacentric
Chromosomes are classified based on the position of the centromere. A metacentric chromosome has its centromere located in the middle, resulting in two arms of approximately equal length, which gives the chromosome a characteristic V-shape during the metaphase stage of cell division.
59
Which cellular process results in the formation of two daughter cells?
Answer:
mitosis
Mitosis is the process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two genetically identical daughter cells. This mechanism is crucial for growth, tissue repair, and asexual reproduction in multicellular organisms.
60
Which biologist is credited with the initial observation and description of cell division via mitosis?
Answer:
Walther Flemming
Walther Flemming, a German biologist, was a pioneer in cytogenetics. In the 1870s and 1880s, he conducted extensive microscopic studies on salamander cells and coined the term 'mitosis' to describe the process of nuclear division, providing the first detailed account of the stages involved.