NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions


A mature pollen grain of Pinus has

  • 2 cells

  • 3 cells

  • 4 cells

  • 5 cells


4 cells

In Pinus, the microspore nucleus divides by a periclinal wall and forms a very small prothallial cell and large central cell. The central cell cuts off a second prothallial cell and antheridial cell. The nucleus of the antheridial cell divides to form generative cell and tube cell. Thus, the pollen grain of Pinus is shed at four cell stage when it consists of two vegetative prothallial cells, a generative cell and a tube cell.


Darwin’s finches are an excellent example of

  • Adaptive Radiation

  • Seasonal migration

  • Brood parasitism

  • Connecting links


Adaptive Radiation


During the propagation of a nerve impulse, the action potential results from the movement of

  • K+ ions from extracellular fluid to intracellular fluid

  • Na+ ions from intracellular fluid to extracellular fluid

  • K+ ions from intracellular fluid to extracellular fluid

  • Na+ ions from extracellular fluid to intracellular fluid


Na+ ions from intracellular fluid to extracellular fluid


Na+ ions from extracellular fluid to intracellular fluid


In mitochondria, enzyme cytochrome oxidase is present in

  • Outer membrane

  • Perimitochondrial space

  • Inner Membrane

  • Matrix


Inner Membrane

Mitochondria contains various enzymes as follows:

(i) Outer membrane Acetyltransferase, glycerophosphatase, phospholipase-A,monoamine oxidase, etc.

(ii) Inner membrane Cytochrome oxidase,dehydrogenase, succinate NADH, dehydrogenase, ATPase, etc.

(iii) Perimitochondrial space Adenylate kinase, nucleoside diphosphokinase, etc.

(iv) Matrix Pyruvate dehydrogenase, citrate synthase, aconitase, isocitrate dehydrogenase, fumarase, c-ketoglutarate dehydrogenase, malate dehydrogenase, etc.


In which one of the following, the male and female gametophytes don’t have free-living independent existence?

  • Pteris

  • Funaria

  • Polytrichum

  • Cedrus



In Pteris (also Dryopteris), the spore germinates to produce the prothallus. The prothallus is a small, green, flat, surface loving, thallus-like object. It is monoecious and bears sex organs on the ventral side. The antheridia (male sex organs) arise among the rhizoids towards the posterior side of the prothallus and are emergent. The archegonia develop in central cushion behind the apical notch. In these plants, o male and female gametophytes do not have free-living independent existence.

All species of Polytrichum are dioecious. The antheridia and archegonia are borne on different gametophore. The plant body is an erect leafy shoot but is not the entire gametophyte.

The leafy shoot arises from protonema (the juvenile stage). The leafy gametophore of Funaria reproduces sexually by the formation of antheridia and archegonia. The antheridia are formed at the summit of a relatively small, thin, leafy shoot, which develops first. The female branch arises later as a lateral outgrowth from the base of parent male shoot.


Nitrogen-fixation in root nodules of Alnus is brought about by

  • Bradyrhizobium

  • Clostridium

  • Frankia

  • Azorhizobium



Nitrogen is the most critical element. The atmosphere is the greatest reservoir of nitrogen. Molecular nitrogen cannot be utilized directly by plants. It has to be fixed or converted into compounds prior to utilization, Symbiotic nitrogen fixation is accomplished by Rhizobium species, which occurs on the roots of leguminous plants. Certain non-leguminous plants also form nodules to fix nitrogen. The best known example in temperate region is alder (Alnus sp.). The bacteria involved in nodule formation is an Actinomycetes, the Frankia.

Clostridium is anaerobic, saprotrophic, free-living nitrogen-fixing bacteria.

Bradyrhizobium is symbiont in plants of parasponia and soyabean.

The Azorhizobium forms both stem and root nodules in Sesbania (aquatic plant).


Quantasome are present in

  • Chloroplast

  • Mitochondria

  • Golgi body

  • Lysosome



Quantasomes are the photosynthetic units present in the thylakoids of the chloroplast. Each of the quantasomes contains about 250-300 chlorophyll molecules.


Green potatoes are toxic due to

  • Phytoalexins

  • Solanin

  • Triazine

  • Hormones



Solanin is a glycoalkaloid poison or natural nerve toxin produced in the green part of the potato. It is a bitter poisonous crystalline alkaloid, which helps the plant to defend against predators,insects, diseases, etc Ingestion of it may cause vomiting, diarrhoea, headache and even paralysis of central nervous system.


The plant of Triticum aestivum is

  • Haploid

  • Diploid

  • Tetraploid

  • Hexaploid



The common bread wheat (Triticum aestivum) is an allohexaploid, which has two copies of each of the genomes A, B and D. Its somatic complement is represented by AABBDD.


Vascular tissues in flowering plants develop from

  • Phellogen

  • Plerome

  • Periblem

  • Dermatogen





Histogen theory for shoot apical meristem has been proposed by Hanstein (1870). It advocates that there are three distinct meristematic zones (layers) called dermatogen periblem and plerome.

The dermatogen is the outermost histogen giving rise to the epidermis, periblem is the middle on producing the cortex and plerome is the innermost resulting in central cylinder (i.e., vascular tissue).

Cork cambium (phellogen) is the secondary lateral meristem found in the outer cortical region. Its cells divide periclinally cutting off cells towards the outside (forming cork or phellem) and inside (forming secondary cortex or Phelloderm).