DAT Practice Test (Survey of Natural Sciences)

Question 1

Which organelle in a eukaryotic cell makes transport vesicles for exocytosis?

Accepted Answer

Golgi Body

Answer

The Golgi apparatus, or Golgi body, is responsible for modifying, sorting, and packaging proteins and lipids into vesicles for secretion or delivery to other organelles. Specifically, it forms transport vesicles that carry processed materials to the cell membrane for exocytosis, the process of releasing substances outside the cell. The Smooth Endoplasmic Reticulum is involved in lipid synthesis and detoxification, while ribosomes synthesize proteins, and mitochondria produce ATP.

Question 2

The reaction quotient (Q) for a reaction involving nitrogen monoxide within a sealed flask was determined to be 1.1 × 10² at one point. Which reaction is most likely taking place in the flask if the amount of NO gas in the flask increased after this point?

Accepted Answer

N2(g) + O2(g) ↔ 2NO(g) Kc = 4.2 × 102

Answer

The reaction quotient (Q) compares the relative amounts of products and reactants present in a reaction at any given time to the equilibrium constant (Kc). If Q < Kc, the reaction will proceed in the forward direction (towards products) to reach equilibrium. The problem states that the amount of NO gas increased, meaning the reaction shifted to the right (towards products). For this to happen, Q must be less than Kc. Option A has Q (1.1 × 10²) < Kc (4.2 × 10²), indicating a shift to the right, which would increase NO.

Question 3

When reacted with benzene, which of the following will produce an ortho/para configuration?

Accepted Answer

2 of the below

Answer

Ortho/para directors are substituents that direct incoming electrophiles to the ortho and para positions on a benzene ring and are typically activating groups or halogens. Activating groups, like alkyl groups (-CH3) or groups with lone pairs (e.g., -NH2, -OH), donate electron density to the ring. Halogens (-Cl) are deactivating but are also ortho/para directors due to resonance effects. Both -Cl and -CH3 are ortho/para directors, making '2 of the below' the correct choice, as -NO2 and -COOH are meta directors.

Question 4

In humans, cystic fibrosis is a recessive disease. What is the probability that a kid would be born with the condition if one parent is a carrier of the trait and the other parent is homozygous dominant, according to the principles of classical Mendelian genetics?

Accepted Answer

0%

Answer

Let 'c' represent the recessive allele for cystic fibrosis and 'C' represent the dominant normal allele. A carrier parent has genotype Cc, and a homozygous dominant parent has genotype CC. When these parents cross (Cc x CC), the possible offspring genotypes are CC and Cc, each with a 50% probability. Since cystic fibrosis is a recessive disease, an individual must have two recessive alleles (cc) to express the condition. Therefore, none of the offspring will be 'cc', meaning the probability of a child being born with cystic fibrosis is 0%.

Question 5

The cytosol's typical pH is at 7.2. The majority of enzymes in the lysosome, on the other hand, are only active at pH 5. This implies that

Accepted Answer

protons are actively pumped into the lysosome

Answer

Lysosomes are acidic organelles, with a typical pH of around 5, which is significantly lower than the cytosol's pH of 7.2. This acidic environment is crucial for the optimal activity of lysosomal enzymes, which are hydrolytic enzymes designed to break down waste materials. To maintain this low pH, protons (H+ ions) are actively pumped into the lysosome from the cytosol, requiring energy. This ensures that the enzymes function efficiently within the lysosome and are largely inactive if they accidentally leak into the cytosol, preventing cellular damage.