1. What is the waxy or oily substance produced by sebaceous glands that helps lubricate the skin and hair?

A. Keratin
B. Melanin
C. Sebum
D. Sweat

Correct answer: C

Rationale: The correct answer is C: Sebum. Sebum is a waxy or oily substance produced by the sebaceous glands in the skin. It helps lubricate and waterproof the skin and hair, preventing them from drying out. Keratin is a protein found in the skin, hair, and nails, providing structure and strength. Melanin is a pigment that gives color to the skin, hair, and eyes. Sweat is produced by sweat glands and helps regulate body temperature by cooling the skin through evaporation. In this question, sebum specifically refers to the substance produced by sebaceous glands, making it the correct answer.

2. Which phenomenon describes the separation of light into its component colors when passing through a prism?

A. Refraction
B. Diffraction
C. Dispersion
D. Reflection

Correct answer: c

Rationale: Dispersion occurs when light passes through a prism, causing different wavelengths (colors) to separate due to their varying speeds through the medium.

3. What is the main function of lysosomes?

A. Breaking down and recycling cellular waste
B. Storing carbohydrates
C. Synthesizing lipids
D. Transcribing DNA into mRNA

Correct answer: A

Rationale: The main function of lysosomes is to break down and recycle cellular waste. Lysosomes contain digestive enzymes that help break down old or damaged organelles, foreign substances, and cellular debris. This process, known as autophagy, helps maintain cellular health and proper functioning. Storing carbohydrates (option B) is not a function of lysosomes; carbohydrates are typically stored in the form of glycogen in the cytoplasm or as starch in plant cells. Synthesizing lipids (option C) is primarily done by the endoplasmic reticulum and not by lysosomes. Transcribing DNA into mRNA (option D) is a function of the nucleus and not the lysosomes. Therefore, the correct answer is A: breaking down and recycling cellular waste.

4. A ball is thrown upwards. At the peak of its trajectory, which of the following forces is acting on the ball?

A. Gravity only
B. Gravity and air resistance only
C. Neither gravity nor air resistance
D. All of the above

Correct answer: C

Rationale: At the peak of its trajectory, the ball has momentarily stopped moving upwards and has not yet started to fall back down. Therefore, there is no longer a net force acting on the ball at that instant. Gravity is acting downwards, but since the ball is not moving, the force of gravity is balanced by an equal and opposite force, resulting in a net force of zero. Similarly, air resistance only affects the ball when it is in motion, so at the peak where the ball momentarily stops, there is no air resistance force. Therefore, at the peak of its trajectory, neither gravity nor air resistance is acting on the ball, making option C the correct answer.

5. Which sentence uses the correlative conjunction "either/or" correctly?

A. You can either come to the party or stay home.
B. Either she will go to the concert, or he will.
C. I'm not sure whether I should go swimming or running.
D. He likes both pizza and pasta, so he can have either.

Correct answer: A

Rationale: Option Aa uses "either/or" to present two exclusive options.

6. During embryonic development, all tissues originate from

A. Epithelial tissue only
B. Muscle tissue only
C. Connective tissue only
D. Embryonic germ layers

Correct answer: D

Rationale: During embryonic development, all tissues originate from the three primary embryonic germ layers: ectoderm, mesoderm, and endoderm. These layers give rise to all the different types of tissues found in the body. The ectoderm forms the skin and nervous system, the mesoderm gives rise to muscle, bone, and connective tissues, while the endoderm develops into the lining of the digestive and respiratory systems. Therefore, option D is the correct answer as it encompasses the comprehensive origin of all tissues in the body during embryonic development.