The H-zone in the skeletal muscle fibre is due to from Biology N

Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Which of the following are homosporous pteridophytes?

I. Selaginella

II. Lycopodium

III. Salvinia

IV. Equisetum

  • I and IV only

  • II and III only

  • II and IV only

  • III and IV only


2.

Identify the given structure

  • Adenylic acid

  • Uracil

  • Cholesterol

  • Adenosine


3.

Cornea transplant in humans is almost never rejected. This is because

  • it is composed of enucleated cells

  • it is a non-living layer

  • its cells are least penetrable by bacteria

  • it has no blood supply


4.

Pseudostratified epithelium is found in

  • seminiferous tubule

  • Fallopian tube

  • trachea

  • kidney tubules


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5.

The given figure shows schematic plan of blood circulation in humans with labels A to D. Identify the labels along with their functions and select the correct option.

  • C- Vena Cava - takes blood from body parts to right atrium, Pco2 = 45 mm Hg

  • D- Dorsal aorta - takes blood from heart to body parts, Po= 95 mm Hg

  • A- Pulmonary vein - takes impure blood from body parts to heart, Po2 = 60 mm Hg

  • B- Pulmonary artery - takes blood from heart to lungs, Po2= 90 mm Hg.


6.

Which one of the following is not a mammalian character?

  • Presence of milk producing glands

  • Skin is unique in possessing hair

  • Presence of external ears called pinnae

  • Homodont type of dentition


7.

Retrogressive metamorphosis occurs in

  • Hemichordata

  • Cephalochordata

  • Urochordata

  • Vertebrata


8.

One hormone hastens maturity period in juvenile conifers, a second hormone controls xylem differentiation, while the third hormone increases the tolerance of plants to various stresses. They are respectively

  • Gibberellin, Auxin, Ethylene

  • Auxin, Gibberellin, Cytokinin

  • Gibberellin, Auxin, ABA

  • Auxin, Gibberellin, ABA


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9.

The H-zone in the skeletal muscle fibre is due to

  • the central gap between actin filaments extending through myosin filaments in the A-band

  • extension of myosin filaments in the central portion ofthe A-band

  • the absence of myofibrils in the central portion of A-band

  • the central gap between myosin filaments in the A-band.


A.

the central gap between actin filaments extending through myosin filaments in the A-band

Each muscle fibre has many parallely arranged myofibrils. Each myofibril contains many serially arranged units called sarcomere which are the functiorial units. Each sarcomere has a central 'A' band made of thick myosin filaments, and two half 'T' bands made of thin actin filaments on either side of it marked by Z' lines. In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments. This central part of thick filament, not overlapped by thin filaments is called the 'H' zone.


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10.

The volume of 'anatomical dead space' air is normally

  • 230 mL

  • 210 mL

  • 190 mL

  • 150 mL


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