OAT Optometry Admission Prep Exam Questions & Answers 2026 (21–30)

✓ Correct answer: D. Mitochondria

Mitochondria are the primary site of ATP production in eukaryotic cells through the process of oxidative phosphorylation. They are often called the 'powerhouse' of the cell because they generate most of the cell's supply of ATP through the electron transport chain and chemiosmosis.

✓ Correct answer: C. Movement of specific molecules down their concentration gradient using transport proteins without energy expenditure

Facilitated diffusion is a passive transport process that uses specific transmembrane proteins to help molecules move across the cell membrane down their concentration gradient without requiring energy. Unlike active transport, it does not work against concentration gradients and doesn't require ATP.

✓ Correct answer: B. Metaphase

During metaphase, the chromosomes align at the equator of the cell (the metaphase plate) with their centromeres in one plane. This alignment is crucial for the proper segregation of chromosomes during the subsequent anaphase phase.

✓ Correct answer: A. Adding nucleotides to the growing DNA strand

DNA polymerase is responsible for adding nucleotides to the growing DNA strand during replication. It can only add nucleotides to the 3' end of a growing DNA strand and requires a primer to initiate synthesis. It also has proofreading capabilities to ensure accurate replication.

✓ Correct answer: D. Fungi are heterotrophic and absorb nutrients

Fungi are heterotrophs that obtain nutrients by absorption, unlike plants which are autotrophs that make their own food through photosynthesis. Fungi secrete digestive enzymes into their environment and absorb the resulting nutrients.

✓ Correct answer: C. Alveoli

Alveolar type II cells in the alveoli produce pulmonary surfactant, a mixture of phospholipids and proteins that reduces surface tension and prevents the alveoli from collapsing during exhalation. This is crucial for efficient gas exchange in the lungs.

✓ Correct answer: B. Production of antibodies against specific antigens

B lymphocytes (B cells) are primarily responsible for producing antibodies as part of the humoral immune response. Once activated, they differentiate into plasma cells that secrete antibodies specific to the antigen that triggered the immune response.

✓ Correct answer: A. A, B, AB, and O

Individuals with blood type AB have neither anti-A nor anti-B antibodies in their plasma, making them universal recipients who can receive blood from all ABO blood types (A, B, AB, and O) without an adverse reaction, assuming Rh compatibility.

✓ Correct answer: D. Filtering blood and forming urine

Nephrons are the functional units of the kidney responsible for filtering blood, reabsorbing essential substances, and secreting wastes to form urine. This process involves glomerular filtration, tubular reabsorption, and tubular secretion.

✓ Correct answer: C. 9/16

Using the Punnett square for a dihybrid cross (AaBb × AaBb), the proportion of offspring with at least one dominant allele for both traits (A_B_) is 9/16. These individuals will display the dominant phenotype for both traits according to Mendelian genetics.