1. Maintaining good muscle strength and flexibility as we age becomes important to avoid:

A. Headaches
B. Falls
C. Anxiety
D. Common cold

Correct answer: B

Rationale: The correct answer is B: 'Falls.' Maintaining good muscle strength and flexibility as we age is crucial for preventing falls, which become more common with age and can lead to serious injuries such as fractures. Strong muscles and good flexibility help in maintaining balance and stability, reducing the risk of falls. Headaches, anxiety, and the common cold are not directly related to muscle strength and flexibility, making them less likely to be avoided by focusing on these aspects of physical health.

2. Which of the following is NOT a mechanism that can directly cause evolution by natural selection?

A. Mutations in genes
B. Differential survival and reproduction based on traits
C. Inheritance of acquired characteristics (like strong muscles from working out)
D. Competition for resources in an environment

Correct answer: C

Rationale: Rationale: A) Mutations in genes can introduce new genetic variations into a population, which can be acted upon by natural selection. B) Differential survival and reproduction based on traits is a key component of natural selection, as individuals with advantageous traits are more likely to survive and pass on their genes to the next generation. C) Inheritance of acquired characteristics, also known as Lamarckism, is not a mechanism of evolution by natural selection. Traits acquired during an individual's lifetime (such as strong muscles from working out) are not passed on to offspring. D) Competition for resources in an environment can drive natural selection by favoring individuals with traits that help them better compete for limited resources. Therefore, the correct answer is C) Inheritance of acquired characteristics (like strong muscles from working out), as it is not a mechanism that can directly cause evolution by natural selection.

3. Dense irregular connective tissue, found in tendons and ligaments, provides:

A. Flexibility
B. Lubrication
C. Insulation
D. Tensile strength

Correct answer: D

Rationale: The correct answer is D: 'Tensile strength.' Dense irregular connective tissue is composed of tightly packed collagen fibers arranged in a random pattern, providing resistance to tension forces. This structural arrangement is ideal for tendons and ligaments, as they need to withstand pulling and stretching forces. 'Flexibility' (A) is more characteristic of elastic fibers, 'Lubrication' (B) is provided by synovial fluid in joints, and 'Insulation' (C) is typically associated with adipose tissue. Therefore, tensile strength is the primary function of dense irregular connective tissue in tendons and ligaments.

4. Which preposition best completes the sentence: "She borrowed money _____ her friend."

A. of
B. from
C. on
D. for

Correct answer: B

Rationale: "From" indicates the source of the borrowed money.

5. What do isotopes of the same element have in common?

A. Identical number of protons and neutrons.
B. Identical chemical properties.
C. Identical number of electrons.
D. Identical mass number.

Correct answer: A

Rationale: Identical number of protons and neutrons - Isotopes have the same atomic number but different mass numbers due to varying neutron counts.

6. 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.