1. Which of the following can weaken the immune system and increase susceptibility to infections?

A. Regular exercise
B. Balanced diet
C. Chronic stress
D. Adequate sleep

Correct answer: C

Rationale: Chronic stress can weaken the immune system by increasing the production of stress hormones like cortisol, which can suppress immune function over time. Prolonged stress can also lead to inflammation, making the body more vulnerable to infections. It is important to manage stress levels through relaxation techniques, exercise, and seeking support to maintain a healthy immune system.

2. What is the electron configuration of an atom?

A. The arrangement of electrons in an atom's orbitals.
B. The number of protons in an atom's nucleus.
C. The number of neutrons in an atom's nucleus.
D. The number of electrons in an atom's valence shell.

Correct answer: A

Rationale: The electron configuration of an atom refers to the arrangement of electrons in the atom's orbitals. This arrangement determines the atom's chemical properties and behavior. The number of protons in an atom's nucleus (option B) is known as the atomic number, while the number of neutrons in an atom's nucleus (option C) contributes to the atom's mass number. The number of electrons in an atom's valence shell (option D) is important for understanding the atom's reactivity and bonding behavior.

3. During which stage of meiosis II are sister chromatids separated, resulting in four genetically unique daughter cells?

A. Prophase I
B. Prophase II
C. Anaphase I
D. Anaphase II

Correct answer: D

Rationale: Rationale: - Prophase I occurs in meiosis I, not meiosis II. During Prophase I, homologous chromosomes pair up and exchange genetic material in a process called crossing over. - Prophase II is the stage where the nuclear envelope breaks down, and spindle fibers start to reappear, preparing the cell for division. Sister chromatids are still attached during Prophase II. - Anaphase I is the stage in meiosis I where homologous chromosomes are separated and pulled to opposite poles of the cell. - Anaphase II is the stage in meiosis II where sister chromatids are separated and pulled to opposite poles of the cell, resulting in four genetically unique daughter cells. This is the stage where the final separation of genetic material occurs, leading to the formation of haploid daughter cells.

4. What is the shape of the DNA molecule?

A. Linear
B. Circular
C. Double helix
D. Straight chain

Correct answer: C

Rationale: Rationale: The shape of the DNA molecule is a double helix. This structure was first described by James Watson and Francis Crick in 1953. The double helix shape consists of two strands that are twisted around each other in a spiral. This shape allows DNA to be compactly stored within the cell nucleus and provides stability to the molecule. The other options (A) Linear, (B) Circular, and (D) Straight chain do not accurately describe the shape of the DNA molecule.

5. What is the scientific term for the monthly cycle in females that prepares the body for potential pregnancy?

A. Ovulation cycle
B. Menstrual cycle
C. Implantation cycle
D. Gestation cycle

Correct answer: B

Rationale: The correct answer is B: 'Menstrual cycle.' The menstrual cycle is the scientific term for the monthly process in females that prepares the body for potential pregnancy. During this cycle, the lining of the uterus thickens to prepare for a fertilized egg, and if no fertilization occurs, the uterus sheds this lining in the form of menstrual bleeding. Ovulation cycle refers specifically to the release of an egg from the ovary, implantation cycle is the process of a fertilized egg attaching to the uterine wall, and gestation cycle is the period of pregnancy from conception to birth. Therefore, the menstrual cycle is the most appropriate term for the monthly process described in the question.

6. What is the main idea of the passage?

A. Petra is a modern city built for tourism.
B. Petra's historical significance lies in its architectural achievements.
C. Petra's prosperity was linked to its strategic location on trade routes.
D. Petra's obscurity remains a mystery despite its rediscovery.

Correct answer: C

Rationale: B mentions Petra's architecture, but not its connection to trade. A and D are factually incorrect and not supported by the passage. Choice C accurately identifies Petra's rise and fall as tied to its position on the Silk Road, making it the main idea.