NEET biology

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Question
CBSEENBI11002850

Which type of white blood cells are concerned with the release of histamine and the natural anticoagulant heparin?

  • Neutrophils

  • Basophils

  • Eosinophils

  • Monocytes

Solution

B.

Basophils

The basophils are probably like mast cells of connective tissue. They release heparin histamine and serotonin. Their nucleus is usually three-lobed and their granules take basic stain strongly.

Monocytes are the largest of all types of leucocytes. Their nucleus is bean-shaped. They are motile and phagocytic in nature. They engulf bacteria and cellular debris. Generally, they will change into macrophages after entering tissue spaces. Eosinophils have a two-lobed nucleus. They are non-phagocytic and help in dissolving a blood clot.  Their number increases in people with allergic conditions such as asthma or high fever.

Neutrophils are most numerous of all leucocytes They eat harmful germs and are, therefore, phagocytic in nature. Their nucleus is many lobed and strain weakly with both and basic stains.

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Question
CBSEENBI11002851

Which one of the following in birds, indicates, their reptilian ancestry?

  • Scales on their hindlimbs

  • Four-chambered heart

  • Two special chambers crop and gizzard in their digestive tract

  • Eggs with a calcareous shell

Solution

C.

Two special chambers crop and gizzard in their digestive tract

Nearly a century ago TH Huxley called birds 'glorified reptiles' thereby meaning that birds have evolved from some reptilian ancestor. Both birds and reptiles lay the same type of eggs, which are deposited outside water. Eggs are large and telolecithal. The ovum is surrounded by albumen, an egg membrane and a thick hard calcareous shell, which are all secreted by special gland located int he walls of oviduct. 

Birds like mammals have completely four chambered heart with double circulation, in which there is no mixing of pure and impure bloods. Whereas the ventricle is imperfectly divided in reptiles, resulting in partial mixing of bloods.

All birds have horny epidermal scales confined to the lower parts of their legs and feet, which are exactly like the epidermal scales of the reptiles. Besides birds are covered by feathers, which are homologous  to the reptilian horny scales as they have a similar origin and develop from similar germ buds.

Question
CBSEENBI11002852

Select incorrect pair

  • Porifera – Choanocytes

  • Coelenterata – Nematocysts

  • Annelida – Segmentation

  • Monera – Eukaryote

Solution

D.

Monera – Eukaryote

Kingdom - Monera includes all prokaryotes (autotrophic of heterotrophic) viz, mycoplasmas, bacteria, Actinoomycetes (mycelial bacteria) and photosynthetic vyanobacterial while all unicellular eukaryotic organisms like flagellates, diatoms, dinoflagellates, slime moulds, sarcondina etc. are included in Kingdom - Protista.

Question
CBSEENBI11002853

Bilateral symmetry, metameric segmentation, coelom and open circulatory system are the features of

  • Annelida

  • Arthropoda

  • Mollusca

  • Echinodermata

Solution

C.

Mollusca

The members of phylum-Arthropoda show bilateral symmetry, three germ layers in body wall, external metamerism, jointed and paired appendages, haemoocel and open type of circulatory system with dorsal heart.

Question
CBSEENBI11002854

Universal donor is

  • O Rh+­

  • O Rh­

  • AB Rh+­

  • AB Rh­

Solution

B.

O Rh­

With regard to transfusion of whole blood or packed red blood cells, individuals with O type negative blood are often called universal donors and those with type AB positive blood are called universal recipients. The person with blood group O­ do not have any type of antigen present on the surface of the RBC so the recipient will not form any antibody against it.