The immune response can be categorized into two main branches:

Correct Answer: A

Rationale: - The immune response can be broadly categorized into two main branches: the humoral immune response and the cellular immune response. - The humoral immune response involves the production of antibodies by B cells and is primarily responsible for defending against extracellular pathogens such as bacteria and viruses in the bloodstream and tissues. - The cellular immune response involves the activation of T cells, which can directly kill infected cells or help coordinate the immune response. This branch is crucial for combating intracellular pathogens like viruses and some bacteria. - Options B, C, and D do not accurately represent the main branches of the immune response and are therefore incorrect.

Correct Answer: B

Rationale: A) Community refers to all the populations of different species living and interacting in a particular area. Since the question specifies organisms of the same species, community is not the correct answer. B) Population is a group of organisms of the same species living in a particular area. This term specifically refers to individuals of the same species and their interactions within a defined area. C) Ecosystem includes all the living organisms (biotic factors) and non-living components (abiotic factors) in a particular area and their interactions. While populations are part of an ecosystem, the term 'ecosystem' is broader and includes multiple populations. D) Habitat refers to the specific environment where an organism lives, including the physical and biological factors. It is the place where a population or individual organism resides, but it does not specifically refer to a group of organisms of the same species.

Correct Answer: B

Rationale: The correct answer is B: Neutralization. When an acid and a base react, they neutralize each other's properties, resulting in the formation of water and a salt. Choice A, 'Precipitation,' refers to the formation of a solid from a solution during a chemical reaction. Choice C, 'Oxidation-reduction,' involves the transfer of electrons between reactants. Choice D, 'Photolysis,' is a reaction where a compound is broken down into smaller components by light energy. Therefore, the most appropriate term for a reaction between an acid and a base is neutralization.

Correct Answer: B

Rationale: Chest pain or discomfort is the most common symptom of angina pectoris. This pain is often described as squeezing, pressure, heaviness, tightness, or pain in the chest. Fever and chills, sudden onset of severe shortness of breath, and numbness or tingling in the extremities are not typical symptoms of angina pectoris. The pain associated with angina is usually triggered by physical or emotional stress and typically subsides with rest or medication, distinguishing it from other conditions.

Correct Answer: A

Rationale: Polymers are large molecules formed by repeating units called monomers. These monomers link together to form long chains or networks, giving polymers their unique properties such as flexibility, strength, and durability. Choice B is incorrect because polymers are not simple organic molecules with low boiling points, but rather complex structures formed by polymerization. Choice C is incorrect as polymers are not necessarily highly reactive compounds, and they are not exclusively used in industrial processes. Choice D is incorrect because polymers can have varying solubilities and structures depending on their composition and properties.