Biomoulecules

All amino acids are linked to form the heteropolymers, protein by

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Translation and post-translation processes. There are twenty two amino acids that combine to form proteins by the natural method of translation involving, DNA, RNA and ribosomes. Apart from the twenty amino acids there are non-protein amino acids formed by the modification of the ones formed by translation. Such post-translation modifications are needed to regulate the functioning of proteins. Options A, B and C are incorrect as they are related only to the formation of protein amino acids.

Enzymes are useful to plants because

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Because enzymes work as biocatalysts in metabolic process.

Enzyme present in biological washing powder to remove protein food stains are ____.

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Protease. Proteases are protein-digesting enzymes. Options B, C and D are incorrect as they cannot breakdown protein.

The basic unit of nucleic acid is

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Nucleic acids (DNA and RNA) comprise of polynucleotides,pentose sugar and phosphoric acid.

Collagen is

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Collagen is a major fibrous protein of connective tissue occuring as white fibres produced by fibroblast.

The catalytic efficiency of two different enzymes can be compared by the

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K m ( Michealis Menton constant). It is defined as that substrate concentration at which under optimum conitions the rate of an enzyme catalysed reaction reaches half the maximum rate. km is inversely proportional to affinity of enzyme for its substrate.

Which of the following readily gives energy for metabolic activities inside the cell.

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ATP. Adenosine triphosphate is the energy-rich molecule found in all living organisms. Option A - Incorrect. Nicotinamide adenine dinucleotide is a coenzyme found in all living cells. Option B - Incorrect. Flavin adenine dinucleotide is a cofactor involved in many metabolic reactions. Option D - Incorrect. Nicotinamide adenine dinucleotide phosphate is a coenzyme used in many anabolic reactions.

The presence of different kinds of amino acids is due to ____.

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The presence of different kinds of amino acids is due to the kind of 'R' group attached. Each amino acid molecule has an amino group, an acidic group , a hydrogen atom and a variable group called the 'R' group. The varieties of amino acids are due to the different variable groups, starting with a simple H-atom, forming the amino acid glysine and so on.

In double helix of DNA, the two DNA stands are

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The two chains comprising the DNA are spirally coiled around a common axis to form a regular, right handed double helix.

Which is wrong about nucleic acids ?

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Length of one helix is 34 A(angstrom) in B-DNA

Cellulose, the most important constitutent of plant cell wall is made of

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Cellulose is the structural polysaccharide of plant cell walls. They are long chain polymers of -glucose units. The adjacent -glucose units are joined by beta 1,4 glycosidic bond linkages.

Which enzyme converts glucose into alcohol ?

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Zymase is an enzyme complex (" mixture ") that catalyzes glycolysis, the fermentation of sugar into ethanol and carbon dioxide.

The primary structure of a protein is due to

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Peptide bonds. Proteins become functional by attaining configurations like primary, secondary, tertiary and quaternary structures. The primary structure holds the sequence of the different amino acids by covalent or peptide bonds. The two ends of the amino acid are referred to as the carboxyl terminus (C-terminus) and the amino terminus (N-terminus). A peptide bond is formed between the carboxyl group of one amino acid and the amino group of the adjacent amino acid. Options A, C and D are incorrect.

Lactose is composed of

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Lactose is a disaccharide that consists of -D-galactose and -D-glucose molecules bonded through beta 1,4 glycosidic linkage. Lactose makes up around 2-8% of the solids in milk. The name comes from the Latin word for milk, plus the -ose ending used to name sugars.

Most diverse macromolecules, found in the cell both physically and chemically are

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Proteins are polymers of amino acids. There are 20 amino acids which can be arranged in different orders in a polypeptide chain to form a wide array of proteins.

The enormous diversity of protein molecules is mainly due to the diversity of

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There are only 20 amino acids. These can be arranged in different order in the polypeptide chain to form a diverse array of proteins.

The structural protein that behaves as an enzyme is ____.

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The structural protein that behaves as an enzyme is ribozyme. Catalytic RNA molecules are ribozymes. The ribosome is a ribozyme. Options B, C and D are incorrect as they are structural proteins but are not enzymes.

Milk protein is -

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Milk protein is Casein.

Chemical reactions ordinarily occur as a result of ____ between reacting particles.

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Chemical reactions ordinarily occur as a result of collision between reacting particles. The molecules possess kinetic energy which will be enhanced by collision and result in chemical reaction. Options B, C and D are incorrect.

All metabolic pathways are catalysed by ____.

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Enzymes. All metabolic activities are carried out by the biocatalysts named enzymes. Option A - incorrect. Hormones are not catalysts but chemical messengers required for growth, differentiation and regulation of metabolic activities. Option C - incorrect. Alkaloids are secondary metabolites of plants and has little significance in the metabolism of plants. Option D - incorrect. Pheromones are chemicals that act as signals especially for mating or marking the territory of an organism.

Carbohydrates, the most abundant bio-molecules on earth, are produced by:

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Some bacteria(such as Rhodopseudomonas), algae and green plant cells produce carbohydrates.

DNA synthesis can be specifically measured by estimating the incorporation of radiolabelled

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Thymine is used to assess the rate of DNA synthesis, since thymine is unique to DNA.

An enzyme brings about

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A substance that modifies the transition state to lower the activation energy is termed as ____.

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A substance that modifies the transition state to lower the activation energy is termed a catalyst. Options A and D are incorrect. Option C - The term biocatalyst is for metabolic reaction.

Find out the wrongly matched pair.

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Cellulose is a polysaccharide and homopolymer that consists of a long unbranched chain of glucose units.

Antiparallel strands of a DNA molecule means that

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Antiparallel strands of DNA have two strands having phosphate groups at same positions in space.

In which one of the following groups, all the three are examples of polysaccharides?

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Polysaccharides are complex carbohydrates formed by polymerization of a large number of units called monosaccharides, starch is a glucosan polysaccharide and is the major reserve food of animals. Cellulose is the structural polysaccharide of plant cell wall. Sucrose is a disaccharide formed of one unit of D-glucose and one unit of D-fructose. Maltose is a disaccharide formed of two molecules of glucose held together, lactose is disaccharide formed through condensation of D-glucose and D-galactose. Glucose and fructose are monosaccharides.

The Watson-Crick model of DNA is known as

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"B-type DNA. Right-handed-double coiled normal type with 10 base pairs per turn. A - incorrect. Right-handed, single turn of helix with 11 base pairs per turn. C - incorrect. Right-handed, single turn of helix with 9 basepairs per turn. D - incorrect. Right-handed, single turn of helix with 8 base pairs per turn."

RNA does not possess

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In RNA, pyrimidine thymine is replaced by uracil.

The polysaccharides made up of exclusively glucose monomers are ____.

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Starch, cellulose, glycogen. All three are homopolymers of glucose. Different arrangements of the glucose units produce these three different polymers. Cellulose molecules are straight and with hydrogen bond form water insoluble fibres. Starch molecules are coiled while glycogen is highly branched. Options A, B and D are incorrect as chitin is not a hompolymer of glucose but a homopolymer of subunits of N-acetyl-glucosamine, a derivative of glucose which has an amino group (containing nitrogen).

Class 11th Biology - 9 Biomolecules MCQs
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Class 11th Biology - 9 Biomolecules MCQs