Nokea
Which part of the eye controls the amount of light that enters the eye?
- A. Cornea
- B. Iris
- C. Retina
- D. Lens
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.
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Which structure in the heart is responsible for pumping oxygenated blood to the body?
- A. Right ventricle
- B. Left ventricle
- C. Left atrium
- D. Right atrium
Correct Answer: B
Rationale: The left ventricle is the chamber responsible for pumping oxygenated blood from the heart to the body. It receives oxygen-rich blood from the left atrium and contracts to push this blood out to the rest of the body through the aorta. The right ventricle pumps deoxygenated blood to the lungs for oxygenation, making choices A, C, and D incorrect for this function. Therefore, the correct answer is B, the Left ventricle.
What type of bond is present in salt?
- A. Ionic
- B. Nonpolar covalent
- C. Polar covalent
- D. Peptide
Correct Answer: A
Rationale: The correct answer is 'Ionic.' Ionic bonds are formed in salts through the transfer of electrons between atoms, leading to the attraction between positively and negatively charged ions. This results in a stable ionic compound, such as common table salt (sodium chloride). Nonpolar covalent, polar covalent, and peptide bonds are not typically found in salts. Nonpolar covalent bonds involve the equal sharing of electrons, polar covalent bonds involve unequal sharing of electrons, and peptide bonds are specific to proteins, not salts.
Which of the following statements regarding the working of the heart is not correct?
- A. The atria contract, and the valves open to allow blood into the ventricles.
- B. The heartbeat begins when the heart muscles relax, and blood flows into the atria.
- C. The valves close to stop blood from flowing backward.
- D. The ventricles contract, forcing blood to leave the heart.
Correct Answer: B
Rationale: The correct answer is B because the heartbeat actually begins when the heart muscles relax, allowing the chambers to fill with blood. The contraction phase follows, which propels blood out of the heart. The other statements are accurate in describing the normal sequence of events in the heart's functioning: the atria contract to push blood into the ventricles, the valves close to prevent backflow of blood, and the ventricles contract to pump blood out of the heart.
What type of tissue is found in the outermost layer of skin?
- A. Muscle tissue
- B. Connective tissue
- C. Epithelial tissue
- D. Nervous tissue
Correct Answer: C
Rationale: The correct answer is C: Epithelial tissue. Epithelial tissue forms the outermost layer of the skin, providing protection against external factors. It serves as a barrier and helps in preventing water loss and entry of pathogens into the body. Choice A, Muscle tissue, is incorrect as muscle tissue is responsible for movement, not skin structure. Choice B, Connective tissue, is incorrect as it provides support and structure to the body but is not the main component of the outermost layer of the skin. Choice D, Nervous tissue, is incorrect as nervous tissue is responsible for transmitting signals within the body, not for the outermost layer of the skin.
What is the primary function of ribosomes in a cell?
- A. Protein synthesis
- B. DNA replication
- C. Cell division
- D. Lipid synthesis
Correct Answer: A
Rationale: The correct answer is A: Protein synthesis. Ribosomes are the cellular organelles responsible for protein synthesis. They read the messenger RNA (mRNA) and translate the genetic information into specific proteins. This process is essential for building and maintaining the structures and functions of the cell. Choice B, DNA replication, is incorrect because ribosomes are not involved in replicating DNA; that process occurs in the nucleus. Choice C, cell division, is incorrect as ribosomes are not directly involved in cell division but rather in protein synthesis. Choice D, lipid synthesis, is also incorrect as ribosomes are not responsible for synthesizing lipids, which primarily occurs in the endoplasmic reticulum and other organelles.