NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT states, 'The members of subphylum Vertebrata possess notochord during the embryonic period. The notochord is replaced by a cartilaginous or bony vertebral column in the adult.'

The NCERT defines common chordate features: 'Other common features observed in the chordates are the dorsal, hollow nerve cord and paired pharyngeal gill slits.' While other options can be found in some chordates, they are not universal to all chordates, unlike the dorsal, hollow nerve cord and pharyngeal gill slits.

According to the NCERT, 'Gnathostomata has two super classes, Pisces and Tetrapoda. Classes Chondrichthyes and Osteichthyes bear fins for locomotion and are grouped under Pisces.'

The NCERT explicitly states, 'Thus all vertebrates are chordates but all chordates are not vertebrates.'

The NCERT states, 'Besides the basic chordate characters, vertebrates have a ventral muscular heart with two, three or four chambers, kidneys for excretion and osmoregulation and paired appendages which may be fins or limbs.' Protochordates (Urochordata and Cephalochordata) also possess notochord, gill slits, and post-anal tail at some stage but lack a complex ventral muscular heart and kidneys for osmoregulation as distinguishing features of vertebrates.

The NCERT states 'Vertebrates have a ventral muscular heart with two, three or four chambers' and earlier, common to all Chordates (which includes Vertebrates) is 'a closed circulatory system'.

The NCERT mentions, 'Some of the vertebrates do not possess jaws (Agnatha) whereas most of them possess jaws (Gnathostomata). Agnatha is represented by the class, Cyclostomata.' Therefore, Gnathostomata is distinguished from Cyclostomata by the presence of jaws.

The NCERT states, 'vertebrates have... paired appendages which may be fins or limbs.'

Referring to Table 4.4 and 4.2, the standard electrode potential (E$^{\text{o}}$) for the reduction of M$^{2+}$ to M are: Ti (-1.63 V), V (-1.18 V), Cr (-0.90 V), Mn (-1.18 V), Fe (-0.44 V), Co (-0.28 V), Ni (-0.25 V), Cu (+0.34 V), Zn (-0.76 V). Titanium has the most negative E$^{\text{o}}$ value of -1.63 V, indicating the strongest tendency to get oxidized (i.e., its M$^{2+}$ ion is hardest to reduce).

A high positive standard electrode potential for the reduction of M$^{3+}$ to M$^{2+}$ (like Co$^{3+}$ + e$^{-}$ $\to$ Co$^{2+}$ with E$^{\text{o}}$ = +1.81 V or +1.97 V) indicates that the M$^{3+}$ ion has a strong tendency to gain an electron and be reduced. Therefore, Co$^{3+}$ acts as a strong oxidizing agent.