TEAS Practice Test Science

Correct Answer: C

Rationale: The correct answer is C: Mitochondria. Mitochondria are known as the powerhouse of the cell because they are responsible for producing ATP through cellular respiration. This process involves the breakdown of glucose to generate energy in the form of ATP. Ribosomes (A) are responsible for protein synthesis, the nucleus (B) houses the cell's genetic material, and the endoplasmic reticulum (D) is involved in protein synthesis and lipid metabolism, but not ATP production. Mitochondria's unique structure and enzymes make them the primary site for ATP production in the cell.

Correct Answer: B

Rationale: Hydrophobic proteins often provide structural support in the body. This is because hydrophobic proteins have non-polar amino acids that interact with each other to form stable structures. These proteins are commonly found in cell membranes, connective tissues, and structural proteins like collagen. They are crucial for maintaining the shape and integrity of cells and tissues. Incorrect Choices: A: Digestive enzymes - Hydrophobic proteins are not commonly involved in digestive processes. C: Carry oxygen molecules - Oxygen-carrying proteins like hemoglobin are typically hydrophilic, not hydrophobic. D: Store energy - Energy storage is usually performed by molecules like carbohydrates and lipids, not hydrophobic proteins.

Correct Answer: A

Rationale: The correct answer is A: Helicase. Helicase is responsible for unwinding the double-stranded DNA during replication by breaking the hydrogen bonds between the base pairs. This allows the DNA strands to separate and serve as templates for the synthesis of new DNA strands by DNA polymerase. Ligase is responsible for joining the DNA fragments together, nuclease is involved in DNA repair by cutting out damaged DNA, and polymerase is responsible for synthesizing new DNA strands based on the template strands. Therefore, only helicase directly unwinds the double-stranded DNA during replication.

Correct Answer: B

Rationale: The correct answer is B: Nephron. The nephron is the basic structural and functional unit of the kidney because it is responsible for filtering blood, regulating fluid balance, and producing urine. It consists of the glomerulus, tubules, and collecting ducts. The other choices, A: Neuron, C: Glomerulus, and D: Axon, are not correct as they do not perform the specific functions related to kidney physiology. Neurons are nerve cells, glomerulus is a part of the nephron, and axon is a part of a neuron.

Correct Answer: B

Rationale: The correct answer is B: Dendrite. Dendrites are the part of the neuron that receives signals from other neurons, allowing for communication between neurons. They contain receptors that bind to neurotransmitters released by neighboring neurons. The axon (A) is responsible for transmitting signals away from the cell body. The synapse (C) is the junction between two neurons where neurotransmitters are released. The myelin sheath (D) is a protective covering that insulates the axon and speeds up signal transmission but does not receive signals from other neurons.