Q1. Colour blindness is
(a) More common among women
(b) Very rare in women
(c) Very rare in men
(d) Found to the same extent in both the sexes
(UPSC Prelims 1981)
Answer: (b) Very rare in women
Explanation: Colour blindness is a sex-linked genetic disorder, typically carried on the X chromosome. Since males have only one X chromosome, they are more likely to be affected. Females, having two X chromosomes, are less likely to express the condition unless both carry the gene.
Q2. Retina in the eyes acts as a in the camera
(a) Lens
(b) Shutter
(c) Film
(d) None of these
(UPSC Prelims 1982)
Answer: (c)
Explanation: The retina functions like the film in a camera, capturing light signals and converting them into electrical impulses that are sent to the brain. It plays a vital role in visual perception.
Q3. When one enters a dark room, he is not able to see anything but after some time his vision improves. This is because
(a) The retina of the eye comes forward
(b) The retina of the eye moves backward
(c) The pupil of the eye contracts
(d) The pupil of the eye dilates
(UPSC Prelims 1983)
Answer: (d) The pupil of the eye dilates
Explanation: In low light, the pupil dilates to allow more light to enter the eye, improving vision gradually. This adjustment helps the retina detect faint light, enabling better visibility in darkness.
Q4. Sex chromosomes transmit which of the following diseases ?
(a) Myopia
(b) Colour blindness
(c) Longsightedness
(d) Night blindness
(UPSC Prelims 1985)
Answer: (b) Colour blindness
Explanation: Colour blindness is a sex-linked genetic disorder, typically carried on the X chromosome. It is more common in males, who have only one X chromosome, making them more susceptible to X-linked conditions.