Frogs have a third eye lid that covers their eyes so they can keep them open underwater. The eyelid is called the nictitating membrane and also helps the eyes to stay moist when they are not in the water.

Hence, the correct option is (D).

Pericardiectomy is the surgical removal of part or most of the pericardium. This operation is most commonly done to relieve constrictive pericarditis or to remove a pericardium that is calcified and fibrous.

Hence, the correct option is (B).

tRNA or Transfer Ribonucleic acid which transfers the amino acid to mRNA and acts as connecting link between them. Also the tRNA is known as the soluble RNA as they are soluble in 1M-Nacl. Hence they are also known as soluble RNA.
Hence, the correct option is (A).

The dividing cells of the vascular cambium consist of long, narrow fusiform initials, from which the tracheary elements are derived, and ray initials, from which ray parenchyma is formed. The vascular cambium is composed of two kinds of cells, ray initials and fusiform initials.
Hence, the correct option is (B).

Prototroph is the nutritionally wild strain that is unable to grow in the minimal medium unless additional nutrients were added to the medium. Phenotype is the kind of organism produced by the reaction of a given genotype to the environment. The holotype is one of the original types used to describe a new species.

Hence, the correct option is (D).

If a pulse crop possesses premature yellowing of leaves and decrease in yield then application of magnesium and iron to promote the synthesis of chlorophyll may become most beneficial to overcome the problem and to obtain maximum seed yield.  Magnesium is an important part of the ring structure of the chlorophyll molecule and its deficiency causes chlorosis and premature I leaf abscission. In iron deficiency also, the leaves become chlorotic because iron is required for the synthesis of some of the chlorophyll-protein complexes in the chloroplast.
Hence, the correct option is (D).

Aspergillus niger is the microorganism used for the production of citric acid in industries.

Aspergillus is defined as a group of conidial fungi—that is, fungi in an asexual state. Some of them, however, are known to have a teleomorph in the Ascomycota. With DNA evidence, all members of the genus Aspergillus are members of the Ascomycota.

Hence, the correct option is (D).

Indicator species are animals, plants, or microorganisms used to monitor changes in our environment. For example, they can tell us about the impact of pollution on an ecosystem, or how well an impaired environment is being managed or restored. Indicator species can also provide warning signals for upcoming changes or shifts to an ecosystem, such as climate change. Mollusca, Lichens, Greasewood, etc are indicator species.

Hence, the correct option is (D).

Pteridophytes (ferns and lycophytes) are free-sporing vascular plants that have a life cycle with alternating, free-living gametophyte and sporophyte phases that are independent at maturity. The body of the sporophyte is well-differentiated into roots, stems and leaves. The root system is always adventitious. The stem is either underground or aerial. The leaves may be microphylls or megaphylls.

Hence, the correct option is (A).

The bundle of his cardiac muscle fibers that conducts the electrical impulses that regulate the heartbeat, from the atrioventricular node in the right atrium to the septum between the ventricles and then to the left and right ventricles.

Hence, the correct option is (B).