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
131
Which component of the nephron is classified as non-tubular?
Answer:
renal corpuscle
The nephron consists of the renal corpuscle and the renal tubule. The renal corpuscle, comprising the glomerulus and Bowman's capsule, is the filtration unit and is not considered a tubule. The remaining parts, including the proximal convoluted tubule, loop of Henle, and distal convoluted tubule, constitute the tubular system.
132
What is the standard frequency for hemodialysis treatments for patients with chronic kidney failure?
Answer:
three times
For patients with end-stage renal disease, standard hemodialysis is typically performed three times per week. This frequency is necessary to effectively remove waste products and excess fluid from the blood that the kidneys can no longer filter.
133
What is the typical width of a human kidney?
Answer:
5 cm
The human kidney is a bean-shaped organ that typically measures approximately 10 to 12 cm in length, 5 to 6 cm in width, and 3 to 4 cm in thickness in an average adult.
134
What biological process enables an organism to maintain a relatively stable internal environment despite external fluctuations?
Answer:
Homeostasis
Homeostasis is the physiological process by which living systems maintain a stable internal environment, such as temperature, pH, and solute concentration, within a narrow range suitable for survival. This is achieved through various regulatory mechanisms, primarily negative feedback loops, which detect deviations from a set point and initiate corrective responses to restore balance.
135
What is the biological term for the physiological state that enables certain animals to survive extreme dehydration?
Answer:
Anhydrobiosis
Anhydrobiosis is a unique biological adaptation that allows an organism to survive the loss of almost all its body water. During this state, the organism enters a dormant phase, often involving the synthesis of protective molecules like trehalose to stabilize cellular structures until environmental conditions improve and water becomes available again for rehydration.
136
Excessive intake of which vitamin is associated with an increased risk of kidney damage and the formation of kidney stones?
Answer:
Vitamin C
High doses of Vitamin C (ascorbic acid) can lead to increased urinary oxalate excretion. Since oxalate is a primary component of many kidney stones, excessive supplementation may significantly elevate the risk of stone formation and potential renal complications in susceptible individuals.
137
Under what physiological condition does the kidney perform less filtration and increase the rate of water reabsorption?
Answer:
shortage of water
When the body experiences a water shortage, the hypothalamus triggers the release of antidiuretic hormone (ADH). This hormone increases the permeability of the collecting ducts in the kidneys, promoting greater water reabsorption into the bloodstream to maintain homeostasis and prevent further dehydration, while reducing the volume of filtrate processed.
138
What is the term for the funnel-shaped structure that collects urine from the renal pyramids?
Answer:
renal pelvis
The renal pelvis is a large, funnel-shaped cavity located in the kidney that serves as a reservoir for urine. It collects urine from the major calyces, which receive it from the renal pyramids, and directs it into the ureter for transport to the urinary bladder.
139
Which type of excretory system is characterized by a more complex, segmented organization suited to the organism's physiological requirements?
Answer:
Metanephridium
Metanephridia are more complex excretory organs found in many invertebrates, such as annelids. Unlike the simpler protonephridia, metanephridia consist of a ciliated funnel (nephrostome) that opens into the coelom, allowing for more efficient filtration and reabsorption of fluids and solutes.
140
Where is cuboidal epithelium, characterized by a single layer of cube-shaped cells, typically found in the human body?
Answer:
small glands and kidney tubes
Simple cuboidal epithelium is specialized for secretion and absorption. It is commonly found in regions such as the secretory portions of small glands and the lining of the renal tubules (kidney tubes), where it facilitates the transport and modification of fluids.