STD 11 - 19. Chemical coordination and integration — NEET STD 11 Science — Question

Assertion: The most distinctive feature of echinoderms is the presence of water vascular system.
Reason: Water vascular system helps in locomotion, capture and transport of food and respiration.

Number of chromosomes in Down's syndrome are

Statement I: Earthworms are known as friends of farmers.
Statement II: Earthworms make burrows in the soil and make it porous which helps in respiration and penetration of the developing plant roots.

During the course of development, cells in various regions of embryo become variable in morphology and eventually perform diverse functions. This process is known as

A pregnant female delivers a baby who suffers from stunted growth, mental retardation, low intelligence quotient and abnormal skin.This is the result of

Which one of the following statements are correct ?
(A) At the posterior pole of the eye, lateral to the blind spot, there is a yellowish pigmented spot called macula lutea with a central pit called the fovea.
(B) Fovea is the point where the visual acuity is the lowest.
(C) The space between cornea and lens is called aqueous chamber and contain a thick watery fluid called aqueous humor.
(D) The space between lens and retina is called vitreous chamber and is filled with transparent gel called vitreous chamber.
(E) The photopigments in human eye are composed of opsin, a protein and retinal, an ketone of vitamin A.
(F) The action potentials are transmitted by the optic nerve to the visual cortex area of the brain, where the neural impulses are analyzed and the image is formed on the retina.
(G) The canal of outer ear is called external auditory meatus.
(H) Pinna collects the vibrations in the air which produce sound.
(I) Tectorial membrane is commonly known as ear drum.
(J) The very fine hairs and wax-secreting glands are present in the skin of pinna and meatus,
(K) The tympanic membrane is composed of connective tissues covered with skin inside and with mucus membrane outside.
(L) The malleus ossicle is attached to tympanic membrane and stapes ossicle is attached to oval window of cochlea.
Choose the correct option given below :-

Mammals have the ability to produce a concentrated urine. Which statement not match with production of concentrated urine ?
(i) The Henle's loop and vasa recta play a significant role in this.
(ii) Concentration of urine occurs by counter current mechanism.
(iii) The proximity between the Henle's loop and vasa recta, as well as the counter current in them increases osmolarity from cortex to medulla.
(iv) Osmolarity increasing from 300 mOsmol L' in the cortex to about 1200 mOsmol L' in the inner medulla.
(v) Osmolarity gradient from cortex to medulla is mainly caused by NaCl and urea.
(vi) Presence of osmolarity gradient helps in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine).
(vii) Human kidneys can produce urine nearly four times concentrated than the initial filtrate formed.