Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

Plasmodesmata are

  • lignified cemented layers between cells

  • locomotory structures

  • membranes connecting the nucleus with the plasmalemma

  • membranes connecting the nucleus with the plasmalemma


D.

membranes connecting the nucleus with the plasmalemma

The primary cell wall contains many small openings or pores situated in primary pit fields. The cytoplasm of adjacent cells communicates through the pores by means of cytoplasmic bridges called plasmodesmata. The plasmodesmata permit circulation of fluid and passage of solutes between cells.

513 Views

12.

Which one of the following are the correct pairing of a body part and the kind of muscle tissue that moves it?

  • Heart wall - Involuntary unstriated muscle

  • Biceps of upper arm - smooth muscle fibres

  • Abdominal wall - Smooth muscle

  • Abdominal wall - Smooth muscle


D.

Abdominal wall - Smooth muscle

Smooth muscles are plain, non- striated, involuntary or unstriped muscles due to the absence of striations. These occur in the walls of hollow internal organs, in capsules of lymph glands, spleen etc, in iris and ciliary body of eyes, skin dermis, penis and other accessory genitalia etc. 

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13.

The annular and spirally thickened conducting elements generally develop in the protoxylem when the root or stem is

  • maturing

  • elongating

  • widening

  • widening


C.

widening

Vessel or tracheae are made up of a row of cells, placed one above the other, with their intervening walls absent or variously pored. The walls of vessels are lignified and hard, but not very thick. The cell cavity or the lumen is wide. The thickening may be annuler, spiral, scalariform, reticulate and pitted. 

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14.

In barley stem, vascular bundles are

  • open and scattered

  • closed and scattered

  • open and in a ring

  • open and in a ring


B.

closed and scattered

The vascular bundles in Hordeum vulgare (barley) plant are scattered in ground tissue, many in number and vary in size-smaller towards the periphery and bigger towards the centre of the ground tissue, oval or rounded in outline, conjoint, collateral and closed.

654 Views

15.

The genetic defect-Adenosine Deaminase (ADA) deficiency may be cured permanently by

  • periodic infusion of genetically engineered lymphocytes having functional ADA cDNA

  • administering denosine deaminase activators

  • introducing bone marrow cells producing ADA into cells at early embryonic stages

  • introducing bone marrow cells producing ADA into cells at early embryonic stages


A.

periodic infusion of genetically engineered lymphocytes having functional ADA cDNA

severe combined immunodeficiency (SCID) caused by adenosine deaminase deficiency (AIDA) is the first genetic disorder to be treated with gene therapy. T-cell-directed gene transfer was useful in the treatment of ADA-SCID, whereas the retroviral-mediated gene transfer to haematopoietic stem cells was insufficient for the achievement of clinical benefits.

488 Views

16.

Oxygenic photosynthesis occurs in

  • Chromatium

  • Oscillatoria

  • Rhodospirillum

  • Rhodospirillum


B.

Oscillatoria

Oscillatoria is a photosynthetic cyanobacterium. In this, during photosynthesis water is electron donor and oxygen is a by -product, ie oxygenic photosynthesis occurs. Rhodospirillum and Chlorobium are non- oxygenic photosynthetic, purple non- sulphur and green sulphur bacteria. chromatium is a purple sulphur bacterium, also a non- oxygenic photosynthetic.

857 Views

17.

In a standard ECG, which one of the following alphabets is the correct representation of the respective activity of the human heart?

  • R-repolarisation of ventricles

  • S- start of systole

  • T -end of diastole

  • T -end of diastole


D.

T -end of diastole

In ECG, P-wave indicates impulse of contraction generated by SA-node and it spreads in atria causing atrial depolarization.

T-wave is the most constant and conspicuous wave having the tallest amplitude. It is the first positive deflection during ventricular depolarization.

S - wave is the next downward deflection constant but often inconspicuous.

T- wave is repolarisation wave of ventricular relaxation.

390 Views

18.

If a live earthworm is pricked with a needle on its outer surface without damaging its gut, the fluid that comes out is

  • excretory fluid

  • coelomic fluid

  • haemolymph

  • haemolymph


B.

coelomic fluid

The body cavity of an earthworm is true coelom (schizocoelous) as it is formed by the division of mesoderm. The coelom fluid, which contains different types of corpuscles. Thus, if the alive earthworm is prickled with a needle on its outer surface, the coelomic fluid will come out.

546 Views

19.

Middle lamella is mainly composed of 

  • hemicellulose

  • muramic acid

  • calcium pectate

  • calcium pectate


C.

calcium pectate

The middle lamella is cementing layer between the cells. It is made up of Ca and Mg pectates. The basic chemical unit of pectin is galacturonic acid, which has the capability of salt formation with calcium and magnesium (an acid-base reaction).

838 Views

20.

Which part of human brain is concerned with the regulation of body temperature?

  • Medulla oblongata

  • cerebellum

  • cerebrum

  • cerebrum


D.

cerebrum

In the human brain, the hypothalamus is a centre for hunger, thirst sweating, sleep. fatigue, temperature, anger, pleasure, love, hate and satisfaction.

Medulla oblongata contains centre for a heart beat, respiration, digestion, BP, involuntary functions, urination, etc.

Cerebellum regulates posture and balance.

The cerebrum is the centre for intelligence, emotion, will- power, memory consciousness, imagination, etc.

600 Views