1. What is the protective fluid that surrounds the brain and spinal cord?

A. Blood
B. Cerebrospinal fluid
C. Myelin sheath
D. Insulin

Correct answer: B

Rationale: The correct answer is B: Cerebrospinal fluid. This fluid acts as a cushion for the brain and spinal cord, providing protection from impacts. Blood is essential for transporting nutrients and oxygen, but it does not directly surround or protect these vital nervous system structures. Myelin sheath is a fatty substance that insulates nerve fibers, not the fluid surrounding the nervous system. Insulin is a hormone involved in regulating blood sugar levels and is not related to protecting the brain and spinal cord.

2. Identify the antonym of the word "pensive":

A. joyous
B. thoughtful
C. curious
D. introspective

Correct answer: A

Rationale: "Joyous" is the opposite of "pensive," which means thoughtful and slightly melancholy.

3. Define "acceleration" in terms of motion.

A. Change in velocity over time
B. Speed in a straight line
C. Distance covered in a given time
D. Force applied to an object

Correct answer: a

Rationale: Acceleration measures the rate of change of velocity with respect to time.

4. The number of protons in the nucleus of an atom determines its:

A. Mass number
B. Atomic number
C. Isotope
D. Valence electron count

Correct answer: B

Rationale: The atomic number (Z) equals the number of protons in the nucleus and uniquely identifies an element. Mass number (A) includes both protons and neutrons, isotopes have different neutron numbers, and valence electrons are involved in bonding, not atomic identity.

5. In nuclear transmutation, a target nucleus is bombarded with a particle to create:

A. A heavier isotope of the same element
B. A lighter isotope of the same element
C. An entirely new element
D. A chain reaction of nuclear fission

Correct answer: C

Rationale: In nuclear transmutation, a target nucleus is bombarded with a particle to create an entirely new element. During this process, the target nucleus absorbs the incoming particle, resulting in changes to its atomic number and sometimes its mass number. These changes can lead to the creation of a different element altogether. This is a fundamental concept in nuclear chemistry and is used in various applications, including the creation of new isotopes for research or medical purposes. Options A and B are incorrect because transmutation involves creating a different element, not just a heavier or lighter isotope of the same element. Option D, a chain reaction of nuclear fission, is also incorrect as it refers to a different process where a nucleus splits into smaller fragments, releasing energy and more neutrons to sustain the chain reaction.

6. What is a mutation?

A. A change in the DNA sequence
B. A type of protein
C. A normal part of the DNA replication process
D. A harmless variation in DNA

Correct answer: A

Rationale: Rationale: A mutation is defined as a change in the DNA sequence. Mutations can occur due to various factors such as errors during DNA replication, exposure to mutagens (e.g., chemicals, radiation), or spontaneous changes. These changes can result in alterations to the genetic information carried by an organism, which can have different effects ranging from harmless variations to causing genetic disorders or diseases. Mutations are a fundamental aspect of genetic diversity and evolution. Options B, C, and D do not accurately describe what a mutation is.