1. Acne vulgaris, commonly known as acne, is primarily caused by

A. Dry skin (Dry skin can worsen acne but isn't the primary cause)
B. Clogged pores and excess oil production
C. Bacterial infection alone (Bacteria play a role but not the sole cause)
D. Vitamin deficiency

Correct answer: B

Rationale: The correct answer is B: 'Clogged pores and excess oil production.' Acne vulgaris, or acne, is primarily caused by a combination of factors including excess sebum (oil) production by the skin's sebaceous glands and the accumulation of dead skin cells, leading to clogged pores. This environment provides a breeding ground for acne-causing bacteria, contributing to inflammation and the formation of pimples. While factors like dry skin, bacterial infections, and even vitamin deficiencies can exacerbate acne, they are not the primary cause. Thus, B is the most accurate option for the primary cause of acne.

2. Which type of wave does not require a medium for propagation?

A. Transverse wave
B. Longitudinal wave
C. Mechanical wave
D. Electromagnetic wave

Correct answer: D

Rationale: Electromagnetic waves, like light and radio waves, can travel through a vacuum, unlike mechanical waves (sound, water waves) that require a medium to vibrate and transmit energy.

3. How does the structure of centromeres contribute to chromosome movement during mitosis?

A. The centromere provides a binding site for spindle fibers, allowing chromosomes to be attached and manipulated.
B. The centromere serves as a dividing point between sister chromatids, ensuring their separation during anaphase.
C. The centromere maintains chromosome stability by preventing chromosomal breaks and rearrangements.
D. The centromere plays a role in DNA replication, ensuring accurate copying of the genetic material.

Correct answer: A

Rationale: Rationale: A) The centromere provides a binding site for spindle fibers, which are microtubules that help move chromosomes during cell division. This attachment allows the chromosomes to be pulled towards opposite poles of the cell during mitosis. Therefore, the structure of centromeres directly contributes to chromosome movement during mitosis by facilitating the attachment and manipulation of chromosomes by the spindle fibers. B) While the centromere does serve as a dividing point between sister chromatids, ensuring their separation during anaphase, this function is more related to the segregation of chromosomes rather than their movement. C) The centromere does play a role in maintaining chromosome stability by ensuring proper chromosome segregation, but it is not primarily responsible for preventing chromosomal breaks and rearrangements. D) The centromere is not directly involved in DNA replication. Its main function is

4. What is the general formula for an alcohol?

A. CnH2n
B. CnH2n+2
C. CnH2n-1
D. CnH2nO

Correct answer: D

Rationale: The general formula for an alcohol is $C_nH_{2n}O$, indicating the presence of a hydroxyl group (-OH).

5. What is the muscular sac in the female body that nourishes and protects a developing fetus during pregnancy?

A. Ovary
B. Fallopian tube
C. Uterus
D. Vagina

Correct answer: C

Rationale: The correct answer is C: Uterus. The uterus, also known as the womb, is a muscular sac in the female reproductive system where a fertilized egg implants and develops into a fetus during pregnancy. It provides nourishment, support, and protection to the developing fetus until birth. The ovaries produce eggs, the fallopian tubes transport eggs to the uterus, and the vagina is the birth canal and the organ of sexual intercourse, but the uterus is specifically responsible for nurturing and protecting the developing fetus.