Practice free NEET NEET multiple-choice questions online with instant answers and detailed explanations. No login required.
Octopus, also known as Devil fish, belongs to which phylum?
The NCERT text lists 'Octopus (Devil fish)' as an example under Phylum Mollusca.
The distinct head region in molluscs is equipped with:
The NCERT text states, 'The anterior head region has sensory tentacles.' for molluscs.
Which of the following classes of enzymes is responsible for catalyzing the breaking of C-C, C-halide, or P-N bonds by hydrolysis?
According to the NCERT text, 'Hydrolases: Enzymes catalyzing hydrolysis of ester, ether, peptide, glycosidic, C-C, C-halide or P-N bonds.' Therefore, Hydrolases are responsible for this type of reaction.
An enzyme's activity is significantly reduced when a chemical whose molecular structure closely resembles the substrate competes for the enzyme's active site. This phenomenon is known as:
The NCERT text states: 'When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor. Due to its close structural similarity with the substrate, the inhibitor competes with the substrate for the substrate-binding site of the enzyme.'
Which of the following components of an enzyme is an organic compound, tightly bound to the apoenzyme, and part of the active site, as seen in peroxidase and catalase?
The NCERT text specifies: 'Prosthetic groups are organic compounds and are distinguished from other cofactors in that they are tightly bound to the apoenzyme. For example, in peroxidase and catalase, which catalyze the breakdown of hydrogen peroxide to water and oxygen, haem is the prosthetic group and it is a part of the active site of the enzyme.'
Enzymes isolated from thermophilic organisms are known for their:
The NCERT text mentions: 'However, enzymes isolated from organisms who normally live under extremely high temperatures (e.g., hot vents and sulphur springs), are stable and retain their catalytic power even at high temperatures (upto 80°-90°C). Thermal stability is thus an important quality of such enzymes isolated from thermophilic organisms.'
During an enzyme-catalyzed reaction, what is the transient structure formed when the substrate is bound to the enzyme's active site?
The NCERT text states: 'During the state where substrate is bound to the enzyme active site, a new structure of the substrate called transition state structure is formed.'
Which enzyme class catalyzes reactions involving the transfer of a group 'G' (other than hydrogen) between two substrates, S and S' (e.g., S - G + S' → S + S' - G)?
According to the NCERT text: 'Transferases: Enzymes catalyzing a transfer of a group, G (other than hydrogen) between a pair of substrate S and S’ e.g., S - G + S’ → S + S’ - G'.
The activity of an enzyme declines both below and above its optimum temperature. At low temperatures, the enzyme is in a temporarily inactive state, while at high temperatures, it is denatured. This is because:
The NCERT text clarifies: 'Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat.'
What is the primary effect of an enzyme on the activation energy of a chemical reaction?
The NCERT text explains: 'Enzymes eventually bring down this energy barrier making the transition of ‘S’ to ‘P’ more easy.' The 'energy barrier' refers to the activation energy.
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The bank mixes NEET previous year questions (PYQs) with practice questions, each tagged with its exam appearances where applicable.