ATI TEAS Practice Test Science

Correct Answer: C

Rationale: The correct answer is C: Chromosome. A chromosome is a structure composed of DNA and proteins that carries genetic information. It is the condensed form of DNA associated with structural proteins, not just a molecule of DNA or protein. Lysosomes are membrane-bound organelles containing digestive enzymes, not DNA and protein. Centrosomes are involved in cell division, not related to DNA and protein together. A genome refers to an organism's complete set of DNA, not specifically a molecule containing both DNA and structural protein.

Correct Answer: B

Rationale: Platelets play a crucial role in clotting blood to prevent excessive bleeding when injuries occur. They are responsible for initiating the coagulation process by forming clots at the site of injury, sealing the damaged blood vessels, and preventing further blood loss. Platelets do not primarily transport oxygen, fight infection, or transport nutrients. While red blood cells are responsible for carrying oxygen, white blood cells are involved in fighting infections, and nutrients are transported by plasma, platelets' main function is related to hemostasis and wound healing.

Correct Answer: B

Rationale: The correct answer is B: Mitochondria. Mitochondria are known as the powerhouses of the cell and are responsible for producing energy in the form of ATP through cellular respiration. ATP is the primary energy currency of the cell, powering various cellular activities. The nucleus (choice A) is responsible for housing the cell's genetic material but is not involved in ATP production. Ribosomes (choice C) are involved in protein synthesis, not energy production. The Golgi apparatus (choice D) is responsible for modifying, sorting, and packaging proteins for secretion, not for ATP production.

Correct Answer: B

Rationale: The iris is the correct answer as it controls the amount of light that enters the eye by adjusting the size of the pupil. The cornea is responsible for focusing light onto the retina, the retina detects light at the back of the eye, and the lens helps in further focusing light onto the retina. The iris, through changing the size of the pupil, regulates the amount of light reaching the eye, making it the part that controls the entry of light.

Correct Answer: A

Rationale: Hydroxyapatite is a mineral compound composed of calcium and phosphorus that plays a crucial role in strengthening the collagen matrix of bones, contributing to their structural integrity and hardness. It is a key component of bone tissue and provides the mineralization necessary for bone strength and density. Choice B is incorrect because the structural unit of a bone is the osteon or Haversian system, not hydroxyapatite. Choice C is incorrect as it describes cartilage, not hydroxyapatite. Choice D is incorrect as it refers to the epiphysis, which is not synonymous with hydroxyapatite.