CET Biology 12

Carbohydrates provide 4.1 kcal/g, proteins provide 5.65 kcal/g, and fats provide 9.45 kcal/g. This explains why fats are the most energy-dense macronutrients at over twice the caloric density of carbohydrates. Option D is incorrect as these are standard physiological fuel values.

Meconium is the earliest stool of an infant, composed of materials ingested during the time the infant spends in the uterus.

As part of the aging process, calcium deposits often accumulate in the walls of arteries (arteriosclerosis) and cartilage, leading to increased stiffness.

The hypothalamus contains the hunger (appetite) and satiety centers, which regulate food intake and energy balance.

 Osteomalacia, a disease of the bones in adults, is due to dietary deficiency of calcium and vitamin D. Measures to prevent and treat osteomalacia usually revolve around intake of vitamin D and calcium supplements.

During pregnancy, the fetus requires significant amounts of iron for blood production and calcium for bone development, often leading to deficiencies in the mother if not supplemented.

Depolarization occurs when the membrane potential becomes less negative (or more positive) inside the cell relative to the outside, typically due to an influx of sodium ions.

 Glaucoma is a term describing a group of ocular (eye) disorders that result in optic nerve damage.

One gram of hemoglobin can bind approximately 1.34 ml of oxygen, often rounded to 1.3 ml in textbook contexts.

The Bohr effect states that high CO2 concentrations increase hydrogen ion concentration (lower pH), which decreases hemoglobin's affinity for oxygen, facilitating oxygen release in tissues.

The heart muscle (myocardium) has a long refractory period, which acts as a recovery phase, preventing the muscle from entering a state of sustained contraction (tetanus) and allowing it to rest between beats.

In adults, red bone marrow is found in the spongy bone of the ribs, sternum, vertebrae, pelvis, and the proximal ends of the femur and humerus.

Chyme is the semifluid mass of partly digested food and digestive secretions that is formed in the stomach and intestine during digestion.

The end organs of Ruffini are specialized sensory receptors located in the skin that respond specifically to heat. They are distinct from receptors for pressure (Pacinian corpuscles), cold (Krause end bulbs), and touch (Meissner's corpuscles).

 The treatment of snakebite by antivenin is an example of artificially acquired passive immunity.

The Aqueduct of Sylvius is a canal located in the midbrain that connects the third and fourth ventricles of the brain, not a structure found in the ear. The other options correctly pair a tissue or organ with a specific anatomical structure found within it.

Streptokinase is a thrombolytic medication used to break down blood clots in the coronary circulation during a heart attack. It functions by activating plasminogen into plasmin, which degrades fibrin.

Human placentas are classified as chorio-allantoic (derived from both membranes), deciduate (part of the uterine lining is shed at birth), and haemochorial (maternal blood directly bathes the chorionic villi). Since all these descriptions apply to the human placenta, the correct answer is all of the above.

The primary oocyte completes its first meiotic division within the secondary follicle (also known as the Graafian follicle) just before ovulation. The primary follicle contains only the primary oocyte arrested in prophase I.

Glisson's capsule is the connective tissue sheath that covers the liver and extends into its interior to divide the parenchyma into lobules. It is a defining anatomical feature of the liver.

Hypertension is frequently referred to as the silent killer because it often presents with no symptoms until significant damage has occurred to organs like the heart, brain, or kidneys.

Albumin is the most abundant plasma protein and is primarily responsible for maintaining the blood colloidal osmotic pressure, which prevents fluid from leaking out of the blood vessels into tissues.

Pyrogens are substances that induce fever. Endogenous pyrogens, such as interleukin-1, are released by activated white blood cells (specifically macrophages) in response to infection or inflammation.

The scrotum is a pouch of skin that hangs outside the abdominal cavity, keeping the testes at a temperature slightly lower than the body temperature, which is essential for successful spermatogenesis.

The hypothalamus acts as the body's thermostat, regulating internal temperature by triggering mechanisms like sweating or shivering to maintain homeostasis.

The 3rd cranial nerve is the oculomotor nerve, the 6th is the abducens nerve, and the 11th is the spinal accessory nerve. Option D correctly identifies these.

Oxyntic cells secrete HCl (A-III), Goblet cells secrete mucus (B-I), Chief cells secrete proenzymes like pepsinogen (C-IV), and Parenchymal cells of the liver secrete bile (D-II). This matches option C.

The trigeminal nerve (cranial nerve V) is the primary sensory nerve for the face and jaw. Its mandibular branch is responsible for the sensation in the lower teeth and jaw.

Cleavage involves rapid mitotic divisions that increase the number of cells (blastomeres) without increasing the overall size or mass of the embryo. Therefore, the statement that it brings an appreciable increase in the mass of protoplasm is incorrect.

Progesterone is the primary hormone responsible for maintaining the uterine lining and supporting pregnancy. It is often called the pregnancy hormone.

Vitamin K deficiency leads to hemorrhagic disease (B), Vitamin D deficiency causes rickets (D), Vitamin B1 deficiency causes beri-beri (A), and Vitamin A deficiency causes keratomalacia (C). This matches option C.

Ptyalin (salivary amylase) functions optimally in a slightly alkaline or neutral pH. Lime juice is acidic; therefore, it lowers the pH of the mouth, which inhibits or reduces the action of ptyalin on starch.

Aldosterone hormone is responsible for Conn’s disease. Most people have high blood pressure which may cause poor vision or headaches. Occasionally, there may be muscular weakness, muscle spasms, tingling sensations or excessive urination.

The cornea is an avascular tissue, meaning it lacks blood vessels. It receives oxygen directly from the air and nutrients from the aqueous humor to maintain its transparency.

 Gluconeogenesis is formation of glucose from sources other than carbohydrate.