DUHS MDCAT 2024 past paper, Code C

Answer: B. Hypothalamus

The hypothalamus contains neurosecretory cells that produce releasing and inhibiting hormones. These hormones travel through the hypophyseal portal system to the anterior pituitary, regulating its hormone secretion. While other brain regions like the pons and midbrain are involved in various nervous system functions, they do not directly control the anterior pituitary via releasing and inhibiting hormones.

Answer: D. Setae and muscles

Segmented worms, like earthworms, use a complex system of muscles working against their hydrostatic skeleton to move. Bristles called setae, located on each segment, anchor the worm to the ground, allowing for effective leverage and propulsion. While segmentation is characteristic of these worms, it is the combined action of muscles and setae that actually facilitates locomotion.

Answer: E. 20 and 32 respectively

Deciduous teeth, also known as milk teeth, are 20 in number. Permanent teeth, which replace the deciduous teeth, are typically 32 in number. Therefore, option E accurately states this count.

Answer: B. Spinal cord

The spinal cord is the primary pathway for information traveling between the brain and the rest of the body, and it is housed within the vertebral column. While the brainstem is part of the central nervous system and connects the brain to the spinal cord, it is not the cable extending down the backbone.

Answer: A. Hemoglobin

Hemoglobin, a protein found in red blood cells, is specifically designed to bind and transport oxygen from the lungs to the body's tissues. While proteins are a broad category, hemoglobin is the precise molecule responsible for this vital function. Hormones, lipids, and antibodies have entirely different roles in the body.

Answer: D. Zn

Zinc deficiency directly impacts taste and smell, leading to a loss of appetite and subsequent weight loss. While iron deficiency can cause fatigue and reduced appetite, it doesn't as directly affect taste perception as zinc does.

Answer: E. Linear

The AX2 designation with a 180° bond angle indicates two electron groups around the central atom, with no lone pairs, and they are positioned as far apart as possible. This geometry results in a straight line, hence linear. While a bent shape (B) has two electron groups, it arises from a bond angle less than 180° due to lone pairs, making it incorrect here.

Answer: B. Boltzmann constant

The ratio of the molar gas constant (R) to Avogadro's number (Na) is indeed the Boltzmann constant (k). This relationship arises because the molar gas constant is the gas constant per mole, and Avogadro's number is the number of entities per mole, so dividing them gives the constant per entity. Coulomb's constant is related to electrostatics and is therefore incorrect.

Answer: A. J kg⁻¹ K⁻¹

The SI unit for specific heat capacity is Joules per kilogram per Kelvin (J kg⁻¹ K⁻¹). This is because specific heat capacity is defined as the amount of heat energy required to raise the temperature of 1 kilogram of a substance by 1 Kelvin. Option B uses grams instead of kilograms, and options C and D use Celsius instead of Kelvin, which are not the standard SI units for mass and temperature difference, respectively.

Answer: D. Although he was very ill, he managed to write a letter to his son

Option D correctly joins the two independent clauses with the subordinating conjunction "although," creating a complex sentence. Option B is incorrect because it creates a run-on sentence by joining two independent clauses without proper conjunction or punctuation.