Biology
Garima feels difficulty in seeing in dim light and during nights. Which of the following could not be the cause of her condition ?
- Deficiency of vitamin A.
- Non-formation of the pigment visual purple.
- Excessive synthesis of pigment iodopsin.
- Rods do not synthesize the pigment rhodopsin.
Answer
Excessive synthesis of pigment iodopsin
Reason — Night vision depends on rod cells and their pigment rhodopsin (visual purple). Iodopsin is present in cone cells and is concerned with bright-light and colour vision. Therefore, excessive synthesis of iodopsin cannot cause difficulty in seeing in dim light or at night.
Related Questions
The spiral organ possessing sensory cells for hearing is:
- Ampulla
- Semicircular Canal
- Vestibule
- Organ of Corti
Which of the following structures equalises the air pressure on either side of the tympanum ?
- Auditory tube
- Eustachian tube
- Vestibular canal
- Tympanic canal
When a person comes out of a cinema hall after a noon show, he experiences a dazzling effect for a short period of time. It happens due to degeneration of (P) …………… and regeneration of (Q) …………… pigments. Which of the following options is correct for P and Q ?
P - Iodopsin, Q - Rhodopsin
P - Rhodopsin, Q - Iodopsin
P - Visual violet, Q - Visual purple
P - Iodopsin, Q - Visual violet
Thomas was travelling in the train from Ranchi to Kanyakumari. It was a long journey. On getting down from the train, he felt that he is still moving. What could be the possible reasons for this experience ?
P: The semicircular canals, which maintain dynamic balance, take some time to return to normal after continuous motion.
Q: The parts of membranous labyrinth (utriculus and succulus) responsible for static balance take time to become active.
R: He was tired, so he felt dizzy.
S: The fluid in the semi-circular canals was still shaky.
- P and Q
- Q and R
- P and S
- P and R