How can you differentiate between a bacterial and viral infection based solely on symptoms?

Correct Answer: A

Rationale: It is impossible to differentiate between a bacterial and viral infection based solely on symptoms because many symptoms overlap between the two types of infections. Symptoms like fever, cough, and others can be present in both bacterial and viral infections. Additional diagnostic tests such as cultures or blood tests are often needed to determine the cause of the infection accurately. Relying only on symptoms can lead to misdiagnosis and inappropriate treatment. Choices B, C, and D are incorrect because they oversimplify the differentiation process and do not encompass the complexity of symptoms associated with bacterial and viral infections. While it is true that bacterial infections may respond to antibiotics and some differences in symptoms may be observed between bacterial and viral infections, these are not definitive indicators without proper diagnostic tests.

Correct Answer: C

Rationale: Epinephrine, also known as adrenaline, is the hormone produced by the adrenal glands that prepares the body for a 'fight or flight' response. It increases heart rate, dilates airways, and mobilizes energy stores to provide the body with the necessary resources to respond to a perceived threat or stressor. Cortisol, although produced by the adrenal glands, is not responsible for the 'fight or flight' response; it is involved in regulating metabolism, immune response, and stress. Aldosterone, another hormone produced by the adrenal glands, primarily regulates electrolyte and fluid balance. Insulin, produced by the pancreas, is responsible for regulating blood sugar levels and is not directly involved in the 'fight or flight' response.

Correct Answer: C

Rationale: Refraction is the change in direction of light as it moves from one medium to another, such as air to water or glass. This change occurs due to variations in the speed of light in each medium, causing the light rays to bend. When light passes through different mediums, it changes its path, a phenomenon known as refraction. Choice A, Diffraction, refers to the bending of waves around obstacles and the spreading of waves when passing through small openings, not the change in direction of light when moving between mediums. Choice B, Reflection, is the bouncing back of light rays from a surface into the same medium, not the change in direction when transitioning between different mediums. Choice D, Dispersion, involves the separation of light into its constituent colors based on their different wavelengths, not the change in direction of light when passing through different mediums.

Correct Answer: D

Rationale: B cells are responsible for producing antibodies as part of the adaptive immune response. When activated by a specific antigen, B cells differentiate into plasma cells that secrete antibodies to target and neutralize pathogens. Natural killer cells are primarily involved in killing infected or cancerous cells, phagocytes engulf pathogens, and helper T cells assist in activating other immune cells. Therefore, the correct answer is B cells because they play a crucial role in antibody production, a key component of the adaptive immune response.

Correct Answer: A

Rationale: The work done is calculated using the formula: Work = Force x Distance x cos(theta), where theta is the angle between the force and the direction of motion. In this case, the force and the direction of motion are in the same direction, so cos(theta) = 1. Therefore, Work = 20 N x 5 m x 1 = 100 Joules. Since the force and distance are given and are in the same direction, the work done can be directly calculated without needing to know the object's mass. Choice A, 100 Joules, is the correct answer as calculated. Choice B and C are incorrect as they do not correspond to the correct calculation. Choice D is incorrect because knowing the object's mass is not necessary to calculate work in this scenario, as work is dependent on force, distance, and the angle between them, not mass.

Correct Answer: C

Rationale: The correct answer is Helium (C). Electronegativity is the tendency of an atom to attract electrons towards itself in a bond. Helium, as a noble gas, has a very low electronegativity because its outer electron shell is already full and stable, resulting in minimal attraction for additional electrons. Oxygen (A), Fluorine (B), and Chlorine (D) are all non-noble gas elements that have higher electronegativity values compared to Helium due to their electron configurations and tendencies to attract electrons.

Correct Answer: B

Rationale: When unpolarized light passes through a polarizing filter, the filter only allows light waves oscillating in a specific direction to pass through while blocking light waves oscillating in other directions. Since unpolarized light consists of light waves oscillating in all possible directions, when it passes through a polarizing filter, only half of the light waves (those oscillating in the direction allowed by the filter) are transmitted. As a result, the intensity of the transmitted light is reduced by half. Choice A is incorrect because the light is not completely absorbed; choice C is incorrect because the polarizing filter affects the transmitted light; and choice D is incorrect because the intensity does not double, but rather decreases by half due to the selective transmission of light waves in a specific direction by the polarizing filter.

Correct Answer: A

Rationale: A lysosome is a membrane-bound organelle found in animal cells that contains digestive enzymes. These enzymes are responsible for breaking down various cellular components, such as proteins, lipids, carbohydrates, and even foreign particles like bacteria. This breakdown process is crucial for maintaining cell health and function by recycling and disposing of cellular waste. Options B, C, and D are incorrect because lysosomes are not involved in transporting proteins and lipids throughout the cell (option B), protein synthesis (option C), or cellular respiration (option D). Lysosomes primarily function as the cell's 'recycling center' by breaking down and processing cellular materials.

Correct Answer: B

Rationale: The trachea is the correct scientific term for the windpipe, a tube that carries air from the larynx to the bronchi. It is an essential part of the respiratory system, enabling the passage of air to and from the lungs. The pharynx is the region behind the mouth and nasal cavity, acting as a passageway for air and food. The epiglottis is a cartilage flap that shields the trachea during swallowing to prevent food from entering the airway. Bronchioles are smaller airways that branch off from the bronchi within the lungs, further dividing and distributing air within the lungs.