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
191
What is the fundamental structural and functional unit of the human kidney?
Answer:
nephron
The nephron is the microscopic structural and functional unit of the kidney. Each kidney contains over a million nephrons, which are responsible for filtering blood, reabsorbing essential substances, and secreting waste products to form urine, thereby maintaining homeostasis in the body.
192
What proportion of the initial glomerular filtrate is typically reabsorbed back into the blood?
Answer:
0.99
The kidneys filter a massive volume of blood daily, producing approximately 180 liters of glomerular filtrate. Of this, about 99% is reabsorbed back into the peritubular capillaries, ensuring that essential water, glucose, and electrolytes are conserved, while only about 1% is excreted as urine.
193
What is the biological term for the process by which metabolic waste products are eliminated from an organism?
Answer:
Excretion
Excretion is a vital physiological process in all living organisms responsible for the removal of metabolic waste products, such as urea, carbon dioxide, and excess salts, which are generated during cellular metabolism. This process is essential for maintaining internal homeostasis and preventing the toxic accumulation of substances within the body's tissues and fluids.
194
Which male animal is known to experience temporary sterility during the summer months due to environmental temperature sensitivity?
Answer:
rabbit
Rabbits are known to be sensitive to high ambient temperatures. In males, heat stress can impair spermatogenesis, leading to a condition of temporary sterility during hot summer months. This physiological response is an adaptation to prevent reproductive failure under unfavorable environmental conditions.
195
Following their accumulation in the collecting ducts of the testes, where are sperm cells transported next?
Answer:
epididymis
After spermatogenesis occurs within the seminiferous tubules of the testes, sperm cells move into the collecting ducts and are subsequently transported to the epididymis. The epididymis is a coiled tube where sperm undergo maturation and are stored until they are ready for ejaculation.
196
What is the primary functional unit of the kidney responsible for filtration and urine formation?
Answer:
nephron
The nephron is the microscopic structural and functional unit of the kidney. Each kidney contains approximately one million nephrons, which perform the essential tasks of filtering blood, reabsorbing necessary nutrients, and secreting waste products to maintain homeostasis.
197
What is the approximate average weight of a healthy human kidney?
Answer:
120 grams
The average weight of a healthy adult human kidney is typically cited in anatomical literature as approximately 120 to 150 grams. Among the provided choices, 120 grams is the standard reference value often used in biological textbooks for a single kidney.
198
Approximately how many nephrons are contained within each human kidney?
Answer:
one million
The nephron is the functional unit of the kidney responsible for blood filtration and urine formation. Each healthy human kidney contains approximately one million nephrons, totaling about two million nephrons per individual, which collectively filter the entire blood volume multiple times daily.
199
Which historical scholar is credited with authoring a significant treatise concerning kidney diseases?
Answer:
Abu Nasr al-Farabi
Abu Nasr al-Farabi, a prominent polymath of the Islamic Golden Age, contributed extensively to various fields, including philosophy and medicine. Historical records attribute to him early scholarly works discussing the nature and treatment of renal conditions, reflecting the medical knowledge of that era.
200
The hilus is a distinct indentation or depression located on the medial border of which organ?
Answer:
kidney
The renal hilus is the concave medial border of the kidney where the renal artery, renal vein, lymphatics, nerves, and the ureter enter or exit the organ. It serves as the primary gateway for the vascular and structural connections of the kidney.