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
281
How many guard cells are typically associated with a single stoma?
Answer:
two
A stoma is a microscopic pore found on the epidermis of leaves and stems, which is flanked by a pair of specialized epidermal cells known as guard cells. These two guard cells regulate the opening and closing of the stomatal aperture by changing their turgor pressure, thereby controlling gas exchange and transpiration rates in the plant.
282
Which of the following plant structures are considered vegetative parts, as opposed to reproductive parts?
Answer:
all of above
In botany, vegetative parts are the non-reproductive organs of a plant. These include the roots, stems, and leaves, which are responsible for growth, nutrient uptake, and photosynthesis, whereas flowers, fruits, and seeds are classified as reproductive structures.
283
Which type of plant tissue is primarily responsible for providing structural flexibility and mechanical strength?
Answer:
support tissues
Support tissues, such as collenchyma and sclerenchyma, are specialized plant tissues that provide structural integrity. Collenchyma offers flexible support to growing plant parts, while sclerenchyma provides rigid strength to mature tissues, ensuring the plant can withstand environmental stresses and maintain its form.
284
What is the term for the cytoplasmic channels that traverse the cell walls of adjacent plant cells, facilitating intercellular communication?
Answer:
Plasmodesmata
Plasmodesmata are microscopic channels that penetrate the cell walls of plant cells, connecting the cytoplasm of adjacent cells. These structures form a continuous network known as the symplast, which allows for the direct transport of water, nutrients, and signaling molecules between cells, bypassing the cell wall barriers.
285
What is the structural composition of sclerenchyma tissues in plants?
Answer:
rigid secondary cell walls
Sclerenchyma cells provide structural support to plants. They are characterized by thick, rigid secondary cell walls that are heavily lignified. These cells are typically dead at maturity, providing the necessary mechanical strength to withstand environmental stresses and maintain plant architecture.
286
Plant tissues are primarily classified into which two categories based on their structure and functional capabilities?
Answer:
meristematic and permanent tissues
Plant tissues are broadly categorized into meristematic tissues, which consist of actively dividing cells responsible for growth, and permanent tissues, which are derived from meristematic cells and have differentiated to perform specific functions such as support, protection, or conduction within the plant body.
287
In the human skeletal system, where are collagen fibers primarily located?
Answer:
matrix of cartilage
Collagen fibers are a critical structural component of the extracellular matrix in cartilage. They provide tensile strength and flexibility to the tissue, allowing it to withstand mechanical stress and support various skeletal structures throughout the human body.