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
261
Andreas Vesalius is historically recognized for his significant contributions to which scientific discipline?
Answer:
anatomy
Andreas Vesalius was a 16th-century physician and anatomist. His seminal work, 'De humani corporis fabrica', revolutionized the study of human anatomy by emphasizing direct observation and dissection, moving away from the reliance on ancient, often inaccurate, medical texts.
262
Which specialized plant cells are typically described as bean-shaped and regulate stomatal opening?
Answer:
guard cells
Guard cells are specialized epidermal cells that occur in pairs around stomata. By changing their turgor pressure, they regulate the opening and closing of the stomatal pore, thereby controlling gas exchange (carbon dioxide uptake and oxygen release) and the rate of transpiration, which is vital for plant survival.
263
At which specific location on a rhizome are the buds typically produced?
Answer:
nodes
Rhizomes are modified underground stems that grow horizontally. Like aerial stems, they possess nodes and internodes. The buds, which are responsible for vegetative propagation and the development of new shoots, are specifically located at the nodes of the rhizome.
264
What is the primary structural component of the cell wall in organisms belonging to the kingdom Plantae?
Answer:
cellulose
The cell wall of plants is primarily composed of cellulose, a complex polysaccharide consisting of long chains of glucose units. Cellulose provides structural support and rigidity to plant cells, allowing them to maintain their shape and withstand turgor pressure. Chitin is found in fungal cell walls, not plants.
265
Through which structures does gaseous exchange primarily occur in plants?
Answer:
stomata
Stomata are microscopic pores located primarily on the epidermis of leaves and stems. They serve as the primary sites for gas exchange, allowing carbon dioxide to enter for photosynthesis and oxygen and water vapor to exit. While guard cells regulate the opening and closing of these pores, the stomata themselves are the actual apertures through which the exchange of gases occurs.
266
Which plant is characterized by a bilobed leaf structure with a prominent midrib?
Answer:
Dionaea
Dionaea muscipula, commonly known as the Venus flytrap, features leaves that are modified into two distinct lobes hinged at a central midrib. This specialized structure allows the plant to snap shut rapidly when the sensitive trigger hairs on the leaf surface are stimulated by prey, facilitating its carnivorous feeding mechanism.
267
Botanically speaking, which part of the ginger plant is utilized as a spice?
Answer:
Stem
Ginger is botanically classified as a rhizome, which is a modified underground stem that grows horizontally. Rhizomes store nutrients and allow the plant to propagate vegetatively. Although they grow beneath the soil surface, they are distinct from true roots because they possess nodes, internodes, and scale leaves, confirming their classification as stems rather than roots.
268
What is the name of the small fluid-filled spaces within the matrix of cartilage where chondrocytes reside?
Answer:
lacuna
Lacunae are small, hollow cavities or spaces found in the extracellular matrix of cartilage and bone tissue. Chondrocytes, the primary cells of cartilage, are housed within these lacunae, where they maintain the surrounding matrix and facilitate nutrient exchange within the dense tissue structure.
269
What is the shape of the outer wall of guard cells in a stoma?
Answer:
convex
Guard cells are specialized plant cells that control the opening and closing of stomata. The outer wall of the guard cell is thin and convex, while the inner wall facing the stoma is thick and concave. This structural difference allows the cells to bow outward when turgid, thereby opening the stoma.
270
In an onion plant, where is the food primarily stored?
Answer:
Scale leaves
Onions are modified bulbs where the fleshy, thickened leaves, known as scale leaves, serve as the primary storage organs for carbohydrates and nutrients. These leaves are arranged in concentric layers around a short, compressed stem.