Question 1

Which structure in the human eye is primarily responsible for the greatest refraction of light as it enters the eye, and why does this occur?

Accepted Answer

The cornea, because there is a large difference between the refractive index of air and cornea.

Question 2

A patient is unable to see objects clearly at a distance but can read a book up close. Which condition does this describe, and what is the underlying cause?

Accepted Answer

Myopia, caused by the image being focused in front of the retina.

Question 3

During accommodation for near vision, which changes occur in the lens and ciliary muscles?

Accepted Answer

Lens becomes thicker and ciliary muscles contract.

Question 4

Which of the following best explains why photoreceptors are located at the back of the retina?

Accepted Answer

To prevent damage from intense light and receive nutrients from the choroid.

Question 5

What is the functional difference between rods and cones in the retina?

Accepted Answer

Cones are responsible for color vision and high acuity, while rods are sensitive to low light and motion.

Question 6

A person suffers retinal detachment, depriving the retina of nutrients and oxygen. What is the most likely consequence?

Accepted Answer

Permanent loss of vision in the affected area.

Question 7

Which equation correctly represents Chargaff's rule for base pairing in DNA?

Accepted Answer

$$A = T$$, $$G = C$$

Question 8

During DNA replication, which enzyme is responsible for breaking the phosphodiester bonds at specific sequences?

Accepted Answer

Restriction enzyme

Question 9

In the central dogma of molecular biology, what is the correct sequence of events?

Accepted Answer

DNA replication → RNA transcription → protein synthesis

Question 10

Which process involves the formation of mRNA from a DNA template?

Accepted Answer

Transcription

Question 11

A scientist wants to produce human insulin using bacteria. Which genetic engineering technique is most relevant?

Accepted Answer

Transgenic organism creation via recombinant plasmid insertion

Question 12

During mitosis, which phase is characterized by the alignment of chromosomes along the metaphase plate?

Accepted Answer

Metaphase

Question 13

What is the ploidy of human somatic cells and gametes, respectively?

Accepted Answer

Somatic cells: diploid (2n); Gametes: haploid (n)

Question 14

Which of the following is a source of genetic variation during meiosis?

Accepted Answer

Crossing over between non-sister chromatids of homologous chromosomes

Question 15

Which bond forms between the sugar and phosphate groups in a nucleotide chain?

Accepted Answer

Phosphodiester bond

Question 16

Which of the following best describes the quaternary structure of a protein?

Accepted Answer

The assembly of multiple polypeptide chains into a functional protein complex.

Question 17

Collagen is an example of which type of protein, and what is its primary function?

Accepted Answer

Fibrous protein; provides support and strength in connective tissue

Question 18

Which test is used to identify reducing sugars, and what is the expected color change if reducing sugars are present?

Accepted Answer

Benedict's test; blue to brick-red

Question 19

Haemoglobin is a globular protein with a quaternary structure. How many oxygen molecules can one haemoglobin molecule bind?

Accepted Answer

Four

Question 20

Which of the following statements about G-protein coupled receptors is correct?

Accepted Answer

They are embedded in the cell surface membrane and involved in signal transduction.

Anatomy & Physiology: Eye Structure, Vision, and Photoreceptors

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