31 Years NEET Previous Year Questions: Biomolecules - 1 - NEET MCQ

The correct option is D

Explanation of the correct option:

1. Secondary metabolites are substances that plants make but do not need for metabolic activities.
2. Amino acids refer to compounds having the primary nitrogen group and carboxyl groups.
3. Amino acids are essential for protein synthesis.
4. Glucose refers to a monosaccharide of simple sugar.
5. Glucose is required for the synthesis of energy.
6. As both are required for metabolic processes, they are not secondary metabolites.

Explanation of the incorrect options:

Option A:

1. Curcumin is a natural polyphenol product extracted from Rhizoma Curcuma longa.
2. Vinblastin is used as a chemotherapy drug.
3. Both the compounds are not involved in metabolic processes.

Option B:

1. Rubber is naturally produced, a waterproof, chemical compound formed due to the fluids of tropical trees.
2. Gums are referred to as polysaccharides and their derivatives.
3. Both the compounds are not involved in metabolic processes.

Option C:

1. Morphine and codeine are opioid drugs derived from the Opioid family.
2. Both compounds do not get involved in any metabolic process.

Final answer: Amino acids and glucose are not secondary metabolites in plants.

The correct option is A.

Explanation for the correct option:

1. Proteins are formed from amino acids.
2. Lysine is essential for muscle growth, bone strength maintenance, injury and surgery recovery, and hormone, antibody, and enzyme regulation. It also has antiviral properties.
3. Lysine is a type of basic amino acid.

Explanation for the incorrect options:

Option B:

1. Valine is essential for mental focus, muscle coordination, and emotional stability.
2. Valine supplements can help people with muscle growth, tissue repair, and energy.
3. Valine is a type of aliphatic amino acid.

Option C:

1. Tyrosine is essential for the production of thyroid hormones T3 and T4, as well as the synthesis of a class of neurotransmitters and melanin, which is a natural pigment found in our eyes, hair, and skin.
2. Tyrosine is a type of aromatic amino acid.

Option D:

1. Glutamic acid functions as a neurotransmitter and is primarily involved in brain development and function.
2. Glutamic acid is an amino acid that is acidic.

The correct option is A

Explanation of the correct option:

1. GLUT IV is the insulin-dependent glucose transporter.
2. Its function is to transport glucose to muscle and adipose tissues under anabolic conditions.

Explanation of the correct options:

Option B:

1. GLUT I is insulin-independent glucose transporter.
2. It is a uniporter.

Option C:

1. GLUT II is insulin-independent glucose transporter.
2. This transporter protein is bidirectional.

Option D:

1. GLUT III is insulin-independent transporter of glucose.
2. It helps in the transport of glucose into the neuron.

GLUT IV is insulin-dependent glucose transporter.

Carbohydrates (commonly called sugars) are chemically defined as polyhydroxy aldehyde or ketones. All sugar molecules have one carbonyl group (-CO-) in addition to the hydroxyl group (OH) on other carbon atoms. Here are the examples:

A typical fat molecule has one glycerol and three fatty acid molecules.

Structure of a typical fat molecule:

The correct option is D
Explanation of the correct option: 
Glycine is an amino acid with the chemical formula of NH2​‐CH2​‐COOH.Glycine is a Nitrogen-containing amino acid. 

Explanation of the incorrect options:
Option A:
Sucrose is a disaccharide formed by the glycosidic linkage between glucose and fructose. 
Option B:
Cellulose is a polysaccharide. It is formed by the linkage of beta 1,4 linkage of the glucose unit. It is an important component of the cell wall of the plant.
Option C:
The nitrogenous bases are purines and pyrimidines. The purines are adenine and guanine. The pyrimidines are thymine and cytosine. In RNA, the thymine is replaced by uracil. 

So, the correct answer is option A.

The correct option is A

Explanation of the correct option

1. Amino acid precursor tryptophan acts as a precursor for the synthesis of both melatonin and serotonin.
2. These are neurotransmitters.
3. It also helps in the generation of antipellagra vitamins and nicotinic acid.
4. Its products influences many bodily functions like sleep, mood, and behavior.

Explanation of the incorrect option

Option B:

1. Thyroxine is produced by thyroid gland and its precursor is thyroglobulin whereas the precursor of triiodothyronine is thyroxine.
2. These hormones help in maintaining body metabolism, weight regulation, and nail health and form an important part of the endocrine system.

Option C:

1. Pregnenolone is the pre-cursor of steroid hormones like estrogen and progesterone.
2. These hormones are released in the ovary and help in maintaining the ovarian and menstrual cycle.
3. These help in pregnancy and the maintenance of the fetus inside the womb.

Option D:

1. The main precursor for cortisone is cholesterol.
2. These are the glucocorticoid hormones.
3. Cortisone is the man-made or synthetic version of cortisol.
4. They help in managing pain, swelling, and joint swelling.

Final answer: The amino acid tryptophan is the precursor for the synthesis of melatonin and serotonin.

• Enzymes are biological catalysts which speed up the metabolic reaction by decreasing the activation energy.
• The energy required to start a chemical reaction is called activation energy.
• Enzymes bind to the reactant molecules which are called the substrate specifically, at a site on the enzyme molecule called the active site and forms enzyme-substrate complex thus, less energy is required.
• Lower the activation energy for a reaction faster the rate of reaction.

So, the correct answer is 'Lowering activation energy'.

• Insulin is a hormone consisting of 2 polypeptide chains. Each chain is composed of a specific sequence of amino acid residues connected by peptide bonds.
• In humans, chain A has 21 amino acids, and chain B has 30. Post-translational modifications result in the connection of these two chains by disulfide bridges. 

Structure of Insulin:

K_m increases but V_max remains the same in competitive inhibition.
This is because, on slightly increasing the substrate concentration, the effect of the inhibitor is removed. 

DNA and RNA are the chain of polynucleotide which are joined by the phosphodiester bonds. The two nucleotide is linked by the phosphodiester bond. It is formed by the linkage between the 3' carbon atom of one sugar molecule and the 5' carbon atom of another.

Succus entericus is the clear to pale yellow watery secretions from the glands lining the small intestine walls. It contains hormones, digestive enzymes, mucus, and bicarbonate. It doesn't contain a nuclease enzyme.

A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids.

• Agrobacterium tumefaciens is a plant pathogenic bacterium that carries Ti plasmid.
• It can transfer a particular segment of the tumor-inducing (Ti) plasmid into the nucleus of infected cells.
• The transferred T-DNA is then integrated into the host genome and transcribed with it.
• This ability of Agrobacterium tumefaciens to transfer the T-DNA in the host genome is explored in genetic engineering to transfer the desired DNA segment, carrying the gene of interest, into the genome of selected organisms. 

Inhibitions of succinic dehydrogenase by malonate is an example of competitive inhibition. Thus it is a reversible reaction.
On increasing the substrate (succinate) concentration the effect of inhibitor is removed and Vmax remains the same. 

Hence option B is correct.

The correct option is B Sucrose

• A reducing sugar is any sugar that is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group.
• All monosaccharides are reducing sugars, along with some disaccharides, oligosaccharides, and polysaccharides.
• Of the given option, sucrose is the only non-reducing sugar. It is disaccharide composed of glucose and fructose.