Correct Answer: A

Rationale: The correct answer is A: Ribosome. Ribosomes are the organelles responsible for protein synthesis in the cell. They are the cellular machinery where translation, the process of assembling proteins from amino acids based on mRNA sequences, occurs. Ribosomes can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum. The nucleus (choice
B) houses DNA but is not directly involved in protein synthesis. Mitochondria (choice
C) are responsible for energy production through cellular respiration, not protein synthesis. The Golgi apparatus (choice
D) is involved in modifying, sorting, and packaging proteins for secretion, not in the synthesis of proteins.

Correct Answer: B

Rationale: The correct answer is B: Vein. Veins carry blood back to the heart from various parts of the body, functioning as the vessels that return blood to the heart. Arteries, on the other hand, carry blood away from the heart to different parts of the body to deliver oxygen and nutrients. Capillaries are tiny blood vessels where the exchange of gases, nutrients, and waste products occurs between the blood and tissues. Lymphatic vessels are part of the lymphatic system, responsible for maintaining fluid balance and aiding in immunity.
Therefore, the correct choice is B as it directly relates to the blood flow back to the heart.

Correct Answer: A

Rationale: The correct answer is 'Abdominal.' The peritoneum primarily lines the abdominal cavity, providing support and protection to abdominal organs. It is a serous membrane that covers the abdominal organs and the abdominal wall, aiding in their function and protection.
Choice B, 'Dorsal,' is incorrect because the peritoneum does not primarily line the dorsal cavity.
Choice C, 'Ventral,' is incorrect as the peritoneum is not primarily associated with the ventral cavity.
Choice D, 'Thoracic,' is incorrect because the peritoneum primarily lines the abdominal cavity and is not primarily found in the thoracic cavity.

Correct Answer: D

Rationale: The correct answer is D: Hair follicle. Hair follicles are structures in the skin responsible for producing hair. They are specialized structures that contain the hair root and the bulb, where hair growth originates. Sudoriferous glands produce sweat, sebaceous glands produce sebum, and melanocytes are responsible for producing melanin, the pigment that gives hair and skin their color.

Choices A, B, and C are incorrect because sudoriferous glands produce sweat, sebaceous glands produce sebum, and melanocytes produce melanin, respectively, but they are not responsible for producing hair.

Correct Answer: B

Rationale: The correct answer is B: Red blood cell. Red blood cells, also known as erythrocytes, are responsible for carrying oxygen from the lungs to the body's tissues. They contain hemoglobin, a protein that binds to oxygen and transports it throughout the body. White blood cells (
Choice
A) are part of the immune system and help fight infections, not involved in carrying oxygen. Platelets (
Choice
C) are responsible for blood clotting, not oxygen transport. Plasma (
Choice
D) is the liquid component of blood that carries various substances like nutrients and waste products, but it does not directly carry oxygen.