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 Multiple Choice QuestionsMultiple Choice Questions


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

  • Bradyrhizobium

  • Clostridium

  • Frankia

  • Frankia



Nitrogen is the most critical element. The atmosphere is the greatest reservoir of nitrogen. Molecular nitrogen cannot be utilised directly by plants. It has to be fixed or converted into compounds prior to utilisation. 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 the 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.
Bradyhizobium is symbiont in plants of parasponia and soybean.

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



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

  • Neutrophils

  • Basophils

  • Eosinophils

  • Eosinophils



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

Monocytes are 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.



What will happen if the secretion of parietal cells of gastric glands is blocked with an inhibitor?

  • Gastric juice will be deficient in chymosin

  • Gastric juice will be deficient in pepsinogen

  • In the absence of HCl secretion, inactive pepsinogen is not converted into the active enzyme pepsin

  • In the absence of HCl secretion, inactive pepsinogen is not converted into the active enzyme pepsin


In the absence of HCl secretion, inactive pepsinogen is not converted into the active enzyme pepsin

Gastric glands are numerous microscopic tubular glands formed by the epithelium of the stomach.The parietal cells (oxynitic cells) are large and most numberous on the side walls of gastric glands. They secrete hydrochloric acid and castle intrinsic factor. The peptic cells (zymogen) cells of gastric glands secrete gastric digestive enzymes as proenzymes - pepsinogen and proennin and a small amount of gastric amylase and gastric lipase. The hydrochloric acid maintains a strongly acidic pH of about 1.5 to 2.5 in the stomach. HCl converts pepsinogen and prorennin to pepsin and rennin respectively.

The secretion of intestinal glands is called succus entericus. It contains many enzymes, maltase, lactase, sucrase, enterokinase, nucleotidase etc. The enterokinase coverts proenzyme trypsinogen into active trypsin.



What is the vital capacity of our lungs?

  • Inspiratory reserve volume plus tidal volume

  • Total lung capacity minus expiratory reserve volume

  • Inspiratory reserve volume plus expiratory reserve volume

  • Inspiratory reserve volume plus expiratory reserve volume


Inspiratory reserve volume plus expiratory reserve volume

Vital capacity is the sum of inspiratory reserve volume, tidal volume and expiratory reserve volume. It is about 4800 mL.

Total lung capacity is the sum of vital capacity and residual volume, ie, vital capacity minus residual volume.

Tidal volume is the amount of air, which normally passes into and out of the lungs during each cycle of quite breathing. It is about 800 mL in an adult person.

Inspiratory reserve volume is the extra volume of air that can be inhaled into lungs during deepest possible inspiration.



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

  • Pteris

  • Funaria

  • Polytrichum

  • Polytrichum



In Pteris (also Dryopteris) the spore germinates to produce the prothallus. The prothallus is 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, 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 relatively small, thin leafy shoot which develops first. The female branch arises later as a lateral outgrowth from the base of parent male shoot. 



Senescence as an active development cellular process in the growth and functioning of a flowering plant is indicated in 

  • vessel and tracheid differentiation

  • leaf abscission

  • annual plants

  • annual plants


leaf abscission

Senescence can be defined as the sum of deteriorative processes, which naturally terminate the functional life of an organism. Senescence is not confined only to the whole plant, it may be limited to a particular plant organ such as leaf and flower or cells such as phloem and xylem. Abscission is the natural shedding of leaves, foliage branches, fruits, floral parts etc. According to Leopold (1967) abscission is a Senescence phenomenon. Senescence as an active development cellular process in growth and functioning of a flowering plant is indicted in leaf abscission.

Whole plant senescence also known as overall senescence occur in annulas (eg, rice, wheat, gramme, mustard) biennials (eg, henbane or perennials.)



Vascular tissue in flowering plants develop from

  • phellogen

  • plerome

  • periblem

  • periblem



Histogen theory for shoot apical meristem has been proposed by Hastein (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 one producing the cortex and plerome is the innermost resulting in the certain cylinder (ie, vascular tissue).

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



Trichoderma harzianum has proved a useful microorganism for 

  • bioremediation of contaminated soils

  • reclamation of wastelands

  • gene transfer in higher plants

  • gene transfer in higher plants


gene transfer in higher plants

Some common fungal inhabitants of soil help to combat diseases caused by soil-borne fungi. Trichoderma lignorum and Gliocladium fimbriatum are found in damp soils. They have an inhibitory effect on the growth of the mycelium of pythium. They serve to suppress fungi causing damping off disease of the seedings and thereby influence favourably the growth of crops.



Keeping in view the 'fluid mosaic model' for the structure of cell membrane, which one of the following statements is correct with respect to the movement of lipids and proteins from one lipid monolayer to the other (described as flip-flop moment)?

  • Both lipids and proteins can flip-flop

  • While lipids and proteins can flip -flop

  • While proteins can flip-flop, lipids cannot

  • While proteins can flip-flop, lipids cannot


While lipids and proteins can flip -flop

singer and Nicolson (1972) suggested the widely accepted fluid mosaic model of biological membranes. According to this model, the plasma membrane contains a bimolecular lipid layer, both surface of which are interrupted by protein molecules. Some proteins are attached to the polar surface of the lipid (ie, called extrinsic protein) while, other (called intrinsic proteins) either partially entirely to stick but on both sides (called transmembrane proteins). The Movement of lipid molecules from one lipid monolayer to another monolayer is called flip-flop movement. Flip-flop movement is rarely found in lipid molecules whereas it remain absent in protein molecules.



The C-4 plants are photosynthetically more efficient than C-3 plants because

  • the CO2 compensation point is more

  • CO2 generated during photorespiration is trapped and recycled through PEP carboxylase

  • the CO2 efflux is not prevented 

  • the CO2 efflux is not prevented 


the CO2 efflux is not prevented 

Chloroplasts in bundle sheath cells are larger and always contain grana whereas chloroplasts in mesophyll cells are smaller. The C4 - plants are photosynthetically more efficient than c3 -plants because they more chloroplasts.