Nokea
Which macromolecule will always contain nitrogen?
- A. Fatty acid
- B. Protein
- C. Lipid
- D. Carbohydrate
Correct Answer: B
Rationale: The correct answer is B: Protein. Proteins always contain nitrogen, as it is a key element in amino acids, the building blocks of proteins. Fatty acids (choice A), lipids (choice C), and carbohydrates (choice D) do not always contain nitrogen. Fatty acids consist of long chains of hydrocarbons, lipids are mainly composed of carbon, hydrogen, and oxygen, and carbohydrates are composed of carbon, hydrogen, and oxygen as well, but not nitrogen.
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Which part of the brain is responsible for controlling involuntary actions like breathing and heart rate?
- A. Cerebellum
- B. Medulla oblongata
- C. Cerebrum
- D. Thalamus
Correct Answer: B
Rationale: The correct answer is the Medulla oblongata. This region of the brain is located in the brainstem and is responsible for controlling vital autonomic functions such as breathing, heart rate, and blood pressure. The Cerebellum (Choice A) is primarily involved in coordination and balance. The Cerebrum (Choice C) is responsible for higher brain functions like thinking and voluntary muscle movement. The Thalamus (Choice D) acts as a relay station for sensory information but is not primarily responsible for controlling involuntary actions like breathing and heart rate.
Which blood type is known as the universal donor?
- A. Type A
- B. Type B
- C. Type AB
- D. Type O
Correct Answer: D
Rationale: Type O blood is known as the universal donor because it lacks antigens on the surface of red blood cells. This characteristic makes it compatible with all blood types during transfusions. Type A, Type B, and Type AB blood types have specific antigens that can cause adverse reactions if transfused to an incompatible recipient.
From which of the following germ layers does the nervous system develop?
- A. Ectoderm
- B. Endoderm
- C. Gastroderm
- D. Mesoderm
Correct Answer: A
Rationale: The correct answer is A: Ectoderm. The nervous system develops from the ectoderm, which is the outermost of the three germ layers. The ectoderm gives rise to structures such as the skin, hair, nails, and the entire nervous system. Choices B, C, and D are incorrect because the endoderm gives rise to the lining of the gut and associated organs, the gastroderm is not a recognized germ layer, and the mesoderm forms structures like muscles, bones, blood, and the circulatory system, but not the nervous system.
What is the best tool to measure the volume of a solid?
- A. Triple beam balance
- B. Measuring wheel and mathematical formula
- C. Graduated cylinder
- D. Measuring wheel
Correct Answer: C
Rationale: A graduated cylinder is the most suitable tool to measure the volume of both liquids and solids. It works by measuring the displacement of water when the solid is submerged in the graduated cylinder. Choice A, the triple beam balance, is used to measure mass, not volume. Choice B, using a measuring wheel and mathematical formula, is typically used to measure distance or area, not volume. Choice D, a measuring wheel, is used to measure distance, making it inappropriate for measuring the volume of a solid.
Which of the following structures prevents food from entering the windpipe?
- A. Pharynx
- B. Esophagus
- C. Larynx
- D. Epiglottis
Correct Answer: D
Rationale: The epiglottis is the structure that prevents food from entering the windpipe by covering the trachea during swallowing. When food is swallowed, the epiglottis folds over the opening of the trachea to ensure that food goes down the esophagus and not into the airway. The pharynx is a shared pathway for both food and air, leading to the esophagus and larynx respectively. The esophagus is the muscular tube that carries food from the throat to the stomach. The larynx is responsible for producing sound and protecting the airway during swallowing, but the epiglottis is specifically designed to prevent food from entering the windpipe.