1. Which type of cell has a nucleus but lacks membrane-bound organelles?

A. Plant cell
B. Prokaryotic cell
C. Animal cell
D. Fungal cell

Correct answer: B

Rationale: The correct answer is B: Prokaryotic cell. Prokaryotic cells are characterized by having a nucleus, known as the nucleoid, which contains genetic material but lacks a membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Plant and animal cells (options A and C) are eukaryotic cells that have a nucleus and membrane-bound organelles. Fungal cells (option D) are also eukaryotic cells with a nucleus and organelles. Understanding the difference between prokaryotic and eukaryotic cells is essential in biology to grasp the diversity of cell structure and function.

2. The "fight-or-flight" response is triggered by the hormone released from the:

A. Thyroid gland
B. Adrenal glands
C. Pituitary gland
D. Pancreas

Correct answer: B

Rationale: The correct answer is B: Adrenal glands. The "fight-or-flight" response is a physiological reaction that occurs in response to a perceived threat or danger. When this response is triggered, the adrenal glands release adrenaline, also known as epinephrine, into the bloodstream. This hormone prepares the body for action by increasing heart rate, dilating airways, and redirecting blood flow to essential organs. The thyroid gland (option A) primarily regulates metabolism, the pituitary gland (option C) controls many other hormone glands, and the pancreas (option D) is responsible for regulating blood sugar levels through the production of insulin and glucagon, but they are not directly involved in the fight-or-flight response.

3. Which element has the lowest electronegativity value?

A. Oxygen
B. Fluorine
C. Helium
D. Chlorine

Correct answer: C

Rationale: Electronegativity is the tendency of an atom to attract electrons towards itself in a bond. Noble gases like helium have very low electronegativity because their outer electron shell is already full and stable.

4. Which organ plays a significant role in immune cell production and maturation?

A. Liver
B. Kidneys
C. Bone marrow
D. Spleen

Correct answer: C

Rationale: The correct answer is C: Bone marrow. The bone marrow is the primary site for the production and maturation of immune cells, including white blood cells, which are crucial for the body's immune response. Stem cells in the bone marrow differentiate into various types of immune cells, such as T cells, B cells, and natural killer cells, which play essential roles in fighting infections and diseases. While the liver and kidneys have other important functions in the body, such as filtering toxins and metabolizing substances, they are not directly involved in immune cell production and maturation. The spleen acts as a reservoir for blood and is involved in filtering blood and storing red blood cells but is not the primary site for immune cell production.

5. The process of splitting a heavy nucleus into smaller nuclei, releasing a vast amount of energy, is called:

A. Nuclear fusion
B. Nuclear fission
C. Radioactive decay
D. Chain reaction

Correct answer: B

Rationale: Rationale: Nuclear fission is the process of splitting a heavy nucleus into smaller nuclei, releasing a vast amount of energy. This process is commonly used in nuclear power plants and nuclear weapons. A) Nuclear fusion is the process of combining two light nuclei to form a heavier nucleus, releasing energy in the process. This process powers the sun and other stars. C) Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. D) Chain reaction is a self-sustaining reaction in which the products of one reaction event stimulate further reaction events. This can occur in both nuclear fission and nuclear fusion reactions.

6. Which nitrogenous bases pair with each other in DNA?

A. A-G and T-C
B. A-T and C-G
C. -A and T-T
D. C-C and G-G

Correct answer: B

Rationale: Rationale: In DNA, nitrogenous bases pair with each other in a specific manner known as complementary base pairing. Adenine (A) always pairs with Thymine (T), and Cytosine (C) always pairs with Guanine (G). This pairing is essential for maintaining the structure and function of DNA. Therefore, option B is the correct answer as it correctly identifies the nitrogenous bases that pair with each other in DNA.