1. Which hormone, produced by the pancreas, regulates blood sugar levels by promoting the uptake of glucose into cells?

A. Insulin
B. Glucagon
C. Cortisol
D. Thyroxine

Correct answer: A

Rationale: The correct answer is A: Insulin. Insulin is a hormone produced by the pancreas that plays a crucial role in regulating blood sugar levels by promoting the uptake of glucose into cells. When blood sugar levels are high, insulin is released to help cells take in glucose for energy production or storage. Glucagon (option B) is another hormone produced by the pancreas but functions in the opposite way to insulin, increasing blood sugar levels by promoting the release of stored glucose from the liver. Cortisol (option C) and Thyroxine (option D) are hormones produced by the adrenal glands and thyroid gland, respectively, but they do not primarily regulate blood sugar levels like insulin. Therefore, the correct choice is A: Insulin.

2. 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.

3. Why are isotopes of the same element chemically similar?

A. They have the same number of protons.
B. They have the same number of electrons.
C. Their chemical properties are identical.
D. They share the same electron configuration.

Correct answer: A

Rationale: They have the same number of protons. This determines the element's identity and its interactions with other elements, leading to similar chemical behavior, even if the number of neutrons differs.

4. What is the main component of stomach acid?

A. Hydrochloric acid
B. Bicarbonate
C. Bile salts
D. Enzymes

Correct answer: A

Rationale: Rationale: Stomach acid, also known as gastric acid, is primarily composed of hydrochloric acid. Hydrochloric acid plays a crucial role in the digestive process by helping to break down food and kill bacteria in the stomach. Bicarbonate is a base that helps neutralize stomach acid in the small intestine. Bile salts are produced by the liver and stored in the gallbladder, aiding in the digestion and absorption of fats. Enzymes are proteins that help catalyze chemical reactions in the body, including the breakdown of food molecules during digestion.

5. What is the work done by a force of 20 N acting on an object that moves 5 meters in the direction of the force?

A. 100 Joules (J)
B. 25 Joules (J)
C. 4 Joules (J)
D. Work cannot be determined without knowing the object's mass.

Correct answer: A

Rationale: Work is defined as the force applied multiplied by the distance moved in the direction of the force. Work = force x distance = 20 N x 5 m = 100 J.

6. Decomposers in an ecosystem play a vital role by:

A. Photosynthesizing and producing organic matter
B. Breaking down dead organisms and returning nutrients to the environment
C. Preying on herbivores and controlling their populations
D. Fixing nitrogen from the atmosphere and making it available to plants

Correct answer: B

Rationale: Rationale: Decomposers are organisms that break down dead organic matter, such as dead plants and animals, into simpler substances. By doing so, they help to recycle nutrients back into the environment, making them available for other organisms to use. This process is essential for the functioning of ecosystems, as it ensures that nutrients are not lost but instead are continuously cycled through the ecosystem. Photosynthesis (option A) is the process by which plants and some other organisms convert light energy into chemical energy in the form of glucose, and it is not a role of decomposers. Preying on herbivores (option C) is a role typically carried out by predators, not decomposers. Fixing nitrogen from the atmosphere (option D) is a process carried out by nitrogen-fixing bacteria, not decomposers.