1. Lysosomes are known as "suicide bags" of the cell. What enzymes do they contain?

A. Hydrolytic enzymes
B. Ligases (bonding enzymes)
C. Transferases (molecule transfer)
D. Oxidoreductases (redox reactions)

Correct answer: A

Rationale: Lysosomes are membrane-bound organelles containing hydrolytic enzymes responsible for breaking down various macromolecules, cellular waste, and foreign substances. These enzymes perform hydrolysis, a process where water molecules are used to break down larger molecules into smaller components. This function earned lysosomes the nickname 'suicide bags' as they can initiate cell death (apoptosis) by releasing their enzymes when needed. Ligases, transferases, and oxidoreductases are enzymes with different functions such as forming bonds, transferring molecules, and catalyzing redox reactions, respectively, which are not typically found in lysosomes. Therefore, the correct answer is A: 'Hydrolytic enzymes.'

2. Which of the following is NOT a method of sterilization?

A. Autoclave
B. UV light
C. Chemical disinfectants
D. Boiling water

Correct answer: D

Rationale: Rationale: A) Autoclave: An autoclave is a method of sterilization that uses high pressure and steam to kill microorganisms, making it an effective way to sterilize equipment and materials. B) UV light: UV light is a method of sterilization that damages the DNA of microorganisms, preventing them from reproducing and causing infections. C) Chemical disinfectants: Chemical disinfectants are used to kill or inactivate microorganisms on surfaces, but they may not always achieve sterilization, which is the complete destruction of all microorganisms. D) Boiling water: Boiling water is a method of disinfection rather than sterilization. While boiling water can kill many microorganisms, it may not be effective against all types of bacteria, viruses, and spores, making it unsuitable for achieving sterilization. Therefore, the correct answer is D) Boiling water, as it is not a method of sterilization

3. What is the main reason why elements in Group 18 (Noble gases) are generally unreactive?

A. They have high atomic masses
B. They lack valence electrons
C. Their outermost electron shells are completely filled
D. They exist as single atoms, not molecules

Correct answer: C

Rationale: Noble gases have their outermost electron shells filled with 8 electrons, achieving a stable configuration with minimal urge to gain or lose electrons, making them less prone to chemical reactions.

4. What is the difference between a pure substance and a mixture?

A. Pure substances have fixed composition, mixtures don't.
B. Mixtures have fixed composition, pure substances don't
C. Pure substances are always solids, mixtures can be any state
D. Pure substances are always elements, mixtures are always compounds

Correct answer: A

Rationale: Rationale: - Pure substances have a definite and constant composition, meaning they are made up of only one type of atom or molecule. This composition does not vary. - Mixtures, on the other hand, are composed of two or more substances physically combined. The components of a mixture can be present in varying proportions, leading to a variable composition. - Option A correctly distinguishes between pure substances and mixtures based on the fixed composition of pure substances and the variable composition of mixtures.

5. The feedback loop is a crucial concept in endocrine regulation. In a negative feedback loop, high levels of a hormone can:

A. Further stimulate the release of the same hormone
B. Inhibit the release of the hormone or its production
C. Have no effect on the hormone's regulation
D. Increase the need for another hormone entirely

Correct answer: B

Rationale: In a negative feedback loop, high levels of a hormone signal the body to stop producing more of that hormone in order to maintain homeostasis. This is a self-regulating mechanism to prevent excessive levels of the hormone. Option B is correct because in this scenario, the high levels of the hormone will inhibit its further release or production. This feedback loop helps ensure that hormone levels stay within a narrow range, preventing overstimulation or imbalance in the endocrine system. Options A, C, and D are incorrect as they do not align with the concept of negative feedback regulation in endocrine systems.

6. Stretch marks occur when

A. The dermis layer becomes inflamed
B. The dermis layer becomes inflamed
C. The dermis layer tears due to rapid stretching
D. Sebaceous glands become clogged

Correct answer: C

Rationale: Stretch marks occur when the dermis layer tears due to rapid stretching. During periods of rapid growth or weight gain, the skin may stretch beyond its capacity, causing the dermis layer to tear and resulting in the formation of stretch marks. Inflammation or clogged sebaceous glands do not directly cause stretch marks, making options A, B, and D incorrect. It is important to understand the physiological process behind stretch marks to identify the correct answer.