Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

Skeletal muscles appear striated due to presence of two characteristic proteins in alternating dark and light bands. Which of the following is a correct match of the protein with its light refractive property and colour

  • Protien  Colour Property
    Myosin Light Anisotropic
  •  

    Actin Dark Anisotropic
  • Myosin Dark Isotropic
  • Actin  Light Isotropic

D.

Actin  Light Isotropic

Each actin (thin) filament is a polymerised protein made up of two 'F' (fibrous) actin strands helically wound to each other. Each 'F' actin is a polymer of monomeric 'G' (globular) actins. It is light in colour & shows isotropic property.


22.

Which one of the following is correct regarding the excretion

  • Large amount of water from renal filtrate is reabsorbed in DCT and a less amount is reabsorbed by PCT.

  • The descending limb of loop of Henle is completely impermeable to salts.

  • Malpighian corpuscle is found in medulla region of kidney.

  • The colour of urine is pale yellow and is slightly alkaline in nature.


B.

The descending limb of loop of Henle is completely impermeable to salts.

In descending limb of loop of Henle, the water is reabsorbed from filtrate flowing in it due to increasing osmolarity of interstitial fluid. Sodium and other solutes are not reabsorbed here. The filtrate becomes hypertonic to blood plasma. All nephrons have their renal Malphigian corpuscles in the cortex.

Cortical nephrons have their loop of Henle in the renal medulla near its junction with the renal cortex, while the loop of Henle of juxtamedullary nephrons is located deep in the renal medulla; they are called juxtamedullary because their renal corpuscle is located near the medulla (but still in the cortex).


23.

Which of the following is an incorrect statement

  • Blood group 'O' person have A and B antigens on RBCs.

  • Eosinophils resist infections and are associated with allergic infection.

  • RBC's contain carbonic anhydrase.

  • T wave of normal ECG represent of depolarization of ventricle.


D.

T wave of normal ECG represent of depolarization of ventricle.

The T wave represents the repolarization (or recovery) of the ventricles. The end of the T-wave marks the end of systole. The P-wave represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria. The QRS complex represents the depolarisation of the ventricles, which initiates the ventricular contraction


24.

Assertion: Glycerides are important nutrients for body.

Reason: Glycerides are hydrolysed into glycerol and fatty acids which are further absorbed in intestine by the formation of chylomicron.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

Glycerides, mainly triglycerides are a principle form of fats present in our food. During digestion, fats are digested to form monoglycerides and free fatty acids. They first become dissolved in the central lipid portions of bile micelles which are soluble in chyme.

In this form, the monoglycerides and free fatty acids are carried to the surfaces of the microvilli of the intestinal cell brush border and then penetrate into the interior of the epithelial cells, which is possible because the lipids are also soluble in the epithelial cell membrane. This leaves the bile micelles still in the chyme, where they function again and to help absorb still more monoglycerides and fatty acid.

After entering the epithelial cell, the fatty acids and monoglycerides are taken up by the cell's smooth endoplasmic reticulum; here they are mainly used to form new triglycerides that are subsequently released in the form of chylomicrons through the base of the epithelial cell, to flow upward through the thoracic lymph duct and empty into the circulating blood. Thus, chylomicrons help in transport of glycerides through blood circulation to various body parts.


25.

The opening between the right atrium and the right ventricle is guarded by the valve named

  • bicuspid valve

  • mitral valve

  • tricuspid valve

  • semilunar valve.


D.

semilunar valve.

The opening between the right atrium and right ventricle is guarded by a valve formed of three muscular flaps or cusps, the tricuspid valve.


26.

Assertion: In angiosperms, transport of food and water is more efficient than gymnosperms and pteridophytes.

Reason: In angiosperms longitudinally arranged sieve elements and vessels with perforated end walls are present.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion

Vessels are much elongated tubes which are closed at either end and are formed by the union of several short, wide and thickened cells called vessel elements. The end walls of vessel elements are transverse or oblique.

Gymnosperms & pteridophytes lack these two vascular structures i.e. vessels and sieve elements. In angiosperms presence of vessels & sieve elements in addition to all other vascular tissues make their food & water transport more efficient


27.

Assertion: Blood in cockroach is colourless haemolymph with no respiratory pigment.

Reason: Respiration in cockroach occurs through diffusion in haemolymph.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


C.

If assertion is true but reason is false

The colourless blood or haemolymph of cockroach has a clear plasma and numerous white corpuscles called haemocytes. Being devoid of any respiratory pigment, it does not serve for gaseous exchange.


28.

Assertion: Plant growth as a whole is indefinite.

Reason: Plants retain the capacity of continuous growth throughout their life.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


A.

If both assertion and reason are true and reason is the correct explanation of assertion

Unlike animals, plants do not stop growing after reaching maturity. They continue to grow and bear new roots, leaves, branches, flowers, etc. While roots, sterns and their branches have indefinite growth, other organs like leaves, flowers and fruits show limited or definite growth. They appear and fall off periodically and sometimes repeatedly.

In lower plants, growth is diffused as every cell can divide and enlarge. Higher plants possess specific areas which take part in the formation of new cells.


29.

Assertion: Protons or hydrogen ions produced by photolysis of water accumulate in the lumen of thylakoids.

Reason: Photolysis of water takes place in inner membrane of thylakoid.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


B.

If both assertion and reason are true but reason is not the correct explanation of assertion

The first step in photosynthesis is the light-driven oxidation (splitting or photolysis) of water. It provides the electrons for the photosynthetic electron transport chains as well as protons for the establishment of a proton gradient. It occurs on the lurnenal side of the thylakoid membrane. During photolysis, water is oxidised to oxygen, protons and electrons. Protons accumulate in the lumen.


30.

Which of the following is a correct match

  • Frog - External ears

  • Earthworm - Muscular gizzard, typhlosole

  • Human - Fat globule, 10 pairs of cranial nerves

  • Cockroach - Chilopoda


B.

Earthworm - Muscular gizzard, typhlosole

Frogs do not have external ears. Instead, they have an eardrum of sorts, called a tympanum, which is just behind each eye.

Typhlosole are internal folds of the intestine or intestinal inner wall. Typhlosole occurs in bivalve mollusks, lampreys and some annelids and echinoderms. The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms and some fish. This specialized organ constructed of thick, muscular walls is used for grinding up food; often rocks are instrumental in this process. In certain insects and mollusks, the gizzard features chitinous plates or teeth.

Humans have 12 pairs of cranial nerves. Cockroach belongs to class insecta of phylum arthropoda.