Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

At metaphase, chromosomes are attached to the spindle fibres by their

  • satellites

  • Secondary constrictions

  • Kinetochores

  • Kinetochores


C.

Kinetochores

Kinetochores ar small disc -shaped proteinous structures present at the surface of the centromere. These structures serve as the sites of attachment of spindle fibres to the chromosomes that are moved into position at the centre of the cell.

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2.

The cells lining the blood vessels belong to  the category of 

  • smooth muscle tissue

  • squamous epithelium

  • columnar epithelium

  • columnar epithelium


B.

squamous epithelium

The squamous epithelium is made up of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary

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3.

Which one of the following is a possibility for most of us in regard to breathing, by making a conscious effort?

  • One can breathe out air totally without oxygen

  • One can breathe out air through eustachian tubes by closing both the nose and the mouth

  • One can consously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all

  • One can consously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all


B.

One can breathe out air through eustachian tubes by closing both the nose and the mouth

A eustachian tube connects the middle ear cavity with the pharynx. The eustachian the pressure on either side of the eardrum (tympanic membrane).

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4.

Which one of the following statements is totally wrong about the occurrence of the notochord, while the other three are correct? 

  • It is present only in larval tail in Ascidians

  • It is replaced by a vertebral coloumn in adult frog

  • It is absent throughout life in humans from the very beginning

  • It is absent throughout life in humans from the very beginning


C.

It is absent throughout life in humans from the very beginning

The notochord is a flexible, rod -shaped body found in the embryo of all chordates. It is composed of cells derived from the mesoderm. It represents the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body (e.g. Amphibians), while in most vertebrates including humans it becomes the vertebral body of the vertebral column.

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5.

Frogs differ from humans in possessing

  • paired cerebral hemispheres

  • chymotrypsin

  • trypsin

  • trypsin


C.

trypsin

In frogs, the blood cells are RBC (Red Blood cells), WBC (White blood cells) or leucocytes and platelets. RBCs, also called erythrocytes, are nucleated and contain red coloured pigment namely haemoglobin.Human possesses enucleated RBC in a mature state.

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6.

Some vascular bundles are described as open because these

  • are surrounded by pericycle but no endodermis

  • are capable of producing secondary xylem and phloem

  • Possess conjunctive tissue between xylem and phloem

  • Possess conjunctive tissue between xylem and phloem


B.

are capable of producing secondary xylem and phloem

In open vascular bundle, cambium is present between xylem and phloem of the same vascular bundle, eg, dicot stems.Due to the presence of cambium, secondary growth in stem occurs and secondary permanent tissues (secondary xylem, secondary phloem and vascular rays) are formed.

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7.

The pathogen Microsporum responsible for ringworm disease in humans belongs to the same kingdom of organisms as that of 

  • Taenia, a tapewarm

  • Wuchereria, a filarial worm

  • Rhizopus, a mould

  • Rhizopus, a mould


C.

Rhizopus, a mould

Many fungi belonging to the genera-Microsporum, Trichophyton and Epidermophyton are responsible for ringworms which is one of the most common infectious diseases in man. Microsporum is a member of the class- Deuteromycetes (Fungi imperfecti) of Kingdom - Fungi, Rhizopus (bread mould) is a member of the class - Zygomycetes (conjugation fungi) of Kingdom - Fungi.

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8.

In mitochondria, protons accumulate in the 

  • outer membrane

  • inner membrane

  • intermembrane space

  • intermembrane space


C.

intermembrane space

During the passage of two electrons from one an electron carrier (NADH) to another on ETC, enough energy is liberated that pumps out three pairs of protons (H+) from the matrix (inner chamber) to the outer chamber (intermembrane space) of mitochondria.The accumulation of protons in intermembrane space results in their higher concentration than in the matrix creating a proton gradient (ΔpH) and electric potential across the membrane.

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9.

Function of copanion cells is 

  • providing energy to sleve elements for active transport

  • Providing water to phloem

  • loading of sucrose into sieve elements by passive transport

  • loading of sucrose into sieve elements by passive transport


D.

loading of sucrose into sieve elements by passive transport

The companion cells are specialised parenchyma cells, which are closely associated with sieve tube elements. The sieve tube elements and companion cells help in maintaining the pressure gradient in the sieve tubes. they also function in the loading of sucrose into sieve elements actively.

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10.

One of the constituents of the pancreatic juice while poured into the duodenum in humans, is

  • Trypsinogen

  • chymotrypsin

  • trypsin

  • trypsin


A.

Trypsinogen

Trypsinogen is the precursor form or zymogen of the pancreatic enzyme trypsin. It is found in pancreatic juice, along with amylase. lipase and chymotrypsinogen. It is activated by enteropeptidase which is found in the intestinal mucosa, to form trypsin.

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