1. The largest bone in the human body is the:

A. Femur (thigh bone)
B. Tibia (shin bone)
C. Humerus (upper arm bone)
D. Scapula (shoulder blade)

Correct answer: A

Rationale: The correct answer is A: Femur (thigh bone). The femur is the longest and strongest bone in the human body, located in the thigh region. It plays a crucial role in supporting the body's weight and facilitating movement. The tibia (B) is commonly known as the shin bone and is located below the femur. The humerus (C) is the upper arm bone, and the scapula (D) is the shoulder blade. However, neither of these bones is the largest in the human body. Understanding the anatomy of the skeletal system is essential for identifying the largest bone in the body, which is the femur.

2. Fingernails and toenails are made primarily of:

A. Collagen (Collagen is found in the dermis)
B. Keratin
C. Melanin (Melanin provides pigment, not structure)
D. Sebum (Sebum is an oily substance)

Correct answer: B

Rationale: The correct answer is B: Keratin. Fingernails and toenails are primarily made of a tough protein called keratin. Keratin is a fibrous structural protein that also makes up hair and the outer layer of skin. Collagen, as mentioned in option A, is found in the dermis of the skin and is responsible for providing strength and elasticity to the skin. Melanin, as in option C, is a pigment that gives color to the skin, hair, and eyes, but it does not contribute to the structure of nails. Sebum, as in option D, is an oily substance produced by the sebaceous glands in the skin to moisturize and protect the skin, but it is not a component of nails.

3. When unpolarized light passes through a polarizing filter, the intensity of the transmitted light is:

A. Completely absorbed
B. Reduced by half
C. Unaffected
D. Doubled

Correct answer: B

Rationale: When unpolarized light passes through a polarizing filter, the intensity of the transmitted light is reduced by half. This is because a polarizing filter only allows light waves oscillating in one plane to pass through while blocking the other perpendicular plane. Unpolarized light consists of waves oscillating in all possible planes, so when it passes through the polarizer, only half of the light waves aligned with the filter's polarization direction can transmit through. As a result, the intensity of the transmitted light is reduced by half as only a portion of the original light waves can pass through the filter.

4. Which hormone, produced by the adrenal glands, prepares the body for a "fight or flight" response by increasing heart rate, dilating airways, and mobilizing energy stores?

A. Cortisol
B. Aldosterone
C. Epinephrine
D. Insulin

Correct answer: c

Rationale: The correct answer is C: Epinephrine. 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 to pump more blood to muscles, dilates airways to improve oxygen intake, and mobilizes energy stores to provide immediate fuel for physical activity. Cortisol is a hormone involved in stress response and metabolism regulation, but it does not directly trigger the rapid physiological changes associated with 'fight or flight.' Aldosterone regulates salt and water balance, while insulin regulates blood sugar levels, neither of which are directly involved in preparing the body for a rapid response to danger or stress.

5. 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.

6. What information can be obtained directly from the element's atomic number?

A. Its atomic mass
B. Its position on the periodic table
C. Its position on the periodic table
D. Its chemical properties

Correct answer: B

Rationale: The atomic number of an element represents the number of protons in the nucleus of an atom. This number determines the element's unique identity and its position on the periodic table. The atomic mass (option A) is not directly determined by the atomic number but is a weighted average of the isotopes of an element. The position on the periodic table (option C) is directly related to the atomic number, as elements are arranged in order of increasing atomic number. The chemical properties of an element (option D) are influenced by the number of protons in the nucleus, which is determined by the atomic number.