UHS MDCAT 2022 past paper

Answer: A. A virus that infects bacteria

The term "bacteriophage" literally translates to "bacteria-eater." Therefore, it refers to a virus that specifically infects and replicates within bacteria. Option B is incorrect because viruses infect bacteria, not the other way around.

Answer: B. Active transport

The correct answer is B) Active transport because it is the only process that moves molecules against their concentration gradient, requiring energy. Option A) Passive transport and C) Facilitated diffusion move molecules down their concentration gradient, requiring no energy. Option D) Filtration is driven by pressure differences, not concentration gradients.

Answer: B. Non-heritable

The correct answer is **B) Non-heritable**. Acquired adaptations are changes an organism undergoes during its lifetime due to environmental influences or behavior, such as developing stronger muscles through exercise. These changes do not alter the organism's DNA, meaning they cannot be passed down to offspring. Option A is incorrect because heritable traits are determined by genes, which are not modified by acquired adaptations.

Answer: C. Ovulation stage

The correct answer is C) Ovulation stage. A surge in luteinizing hormone (LH) triggers ovulation, the release of an egg from the ovary. This surge occurs around the midpoint of the menstrual cycle. The menstrual stage (A) involves shedding of the uterine lining and low hormone levels. The proliferative stage (B) is characterized by rising estrogen levels to prepare the uterine lining. The secretory stage (D) follows ovulation and is dominated by progesterone.

Answer: C. 67.8 × 50 / 100

The partial pressure of a gas in a mixture is calculated by multiplying its mole fraction by the total pressure. The percentage composition given directly represents the mole fractions of each gas. Therefore, to find the partial pressure of H₂, we multiply its percentage (67.8%)

Answer: B. Regular tetrahedron

In VSEPR theory, the AB4 type molecule with no lone pairs has four electron domains that arrange themselves as far apart as possible, leading to a tetrahedral electron geometry. This arrangement results in a **regular tetrahedron** molecular shape. A tempting wrong answer would be Trigonal, as it only considers three electron domains.

Answer: A. Adduct

Phenol reacting with formaldehyde under appropriate conditions leads to the formation of a polymer like Bakelite. This process involves the addition of phenol to formaldehyde, forming an intermediate species where both molecules are linked together before further polymerization. Options B, C, and D represent ions that are not the primary product of this specific reaction between phenol and formaldehyde.

Answer: D. 2.1 s

The angular velocity ($\omega$) is given as 3.0 rad/s. One revolution is equal to $2\pi$ radians. The time period (T) for one revolution is calculated by dividing the total angle of a revolution by the angular velocity: $T = \frac{2\pi}{\omega}$. Plugging in the values, $T = \frac{2\pi}{3.0 \text{ rad/s}} \approx \frac{6.28}{3.0} \approx 2.09$ seconds, which is approximately 2.1 s.

Answer: B. 4W

The energy stored in a capacitor is given by the formula $W = \frac{Q^2}{2C}$. If the charge is doubled to $2Q$, the new energy becomes $W' = \frac{(2Q)^2}{2C} = \frac{4Q^2}{2C} = 4W$. Option A is tempting because one might incorrectly assume energy scales linearly with charge.

Answer: D. all of these

The hydrogen atom's line spectrum includes spectral lines across the ultraviolet, visible, and infrared regions. The Lyman series falls in the ultraviolet, the Balmer series in the visible, and the Paschen, Brackett, and Pfund series extend into the infrared. Therefore, all these regions contain spectral lines of the hydrogen atom.