Grade 11 Botany Solution

Introduction To Biology (Biomolecules)

Short questions:

1. Discusses types of carbohydrates?

Ans: Carbon hydrogen and oxygen is the main constituent of the carbohydrates. Where hydrogen and oxygen are present in the ratio of 2:1 as in water.

Carbohydrate divides in 3 types.

I) Monosaccharides: It is the simplest form of the carbohydrate. The general formula is cnh2non. For e.g. Glucose, fructose, etc. They are soluble in water and usually sweet in taste.

II) Disaccharides: They are formed by two molecules of the monosaccharides. For e.g. Maltose, sucrose, lactose. They are also soluble in water and sweet in taste.

III) Polysaccharides

They are formed by the large number of monosaccharides and having several million molecular weights. They are insoluble in water and not sweet in taste. The common polysaccharides are starch, glycogen and cellulose. Starch is the reserved food material in plant.


2. Describe the important of water in our life.

Ans: Water is the mother liquor of all forms of life. It is the vital essence, miracle of nature, and the great sustainer of life. The essentiality of water for living system is quite evident a without water, there is no life. In human adult total body water accounts for about 70% of the lean body mass. In plant, it makes about 70%-90% of the living matter of active cells. In many hydrophytes and fruits, water appears in even high percentage. A greater portion of water is found in free form that means the water which is available for the metabolic process.


Function of water

I) Water is a universal solvent.

II) It is used as a raw material in photosynthesis.

III) It also helps in transpiration due to torpor pressure.

IV) It also maintains the turgidity of cells and their organelles.



3. What are the roles of Macro and micro element in plant life?

Ans: The macronutrients are consumed in larger quantities and are present in plant tissue in quantities from 0.2% to 4.0% (on a dry matter weight basis). Micro nutrients are present in plant tissue in quantities measured in parts per million, ranging from 5 to 200 ppm, or less than 0.02% dry weight. The macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg)

Nitrogen: Nitrogen is a major constituent of several of the most important plant substances. For example, nitrogen compounds comprise 40% to 50% of the dry matter of protoplasm, and it is a constituent of amino acids, the building blocks of proteins, Nitrogen deficiency most often results in stunted growth, slow growth, and chlorosis.

Sulphur: Sulphur is a structural component of some amino acids and vitamins, and is essential in the manufacturing of chloroplasts. It is immobile and deficiency therefore affects younger tissues first. Symptoms of deficiency include yellowing of leaves and stunted growth.

Calcium: Calcium regulates transport of other nutrients into the plant and is also involved in the activation of certain plant enzymes. Calcium deficiency results in stunting.

Magnesium: The outstanding role of Magnesium in plant nutrition is as a constituent of the chlorophyll molecule. As a carrier, it is also concerned in numerous enzyme reactions as an effective activator. Those elements which required in low amount and have certain function.

The micronutrients are: boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni)

Iron: Iron is necessary for photosynthesis and is present as an enzyme cofactor in plants. Iron deficiency can result in interveinal chlorosis and necrosis.

Copper: It is important for photosynthesis. Symptoms for copper deficiency include chlorosis. It is involved in many enzyme processes.

Manganese: It is necessary for photosynthesis, including the building of chloroplasts. Manganese deficiency may result in coloration abnormalities, such as discolored spots on the foliage.

Sodium: It is involved in the regeneration of phosphoenolpyruvate in CAM and C4 plants. It can also substitute for potassium in some circumstances.



4. Discuss the protein as important biomolecule.

Ans: Proteins are the macromolecules of amino acids. The amino acids are the building blocks of protein. Several amino acids join together by the peptide bond to form a proteins hence the protein is also known as poly peptides. Protein found in every part of the body. It mainly found in skin, muscles, and in glands. Proteins can be classified into three types. They are

I) Simple protein: Those proteins formed by amino acids only, e.g. Albumin

II) Conjugate protein: Protein which contain amino group as well as some prosthetic group in addition, e.g. Hemoglobin.

III) Derived proteins: These proteins are formed due to other unbiological activities. Such as denaturation. E.g. Proteoses



5. Describe the double heilix structure of DNA?

Ans: J.D. Watson and F. Crick (1953) combined the physical and chemical bata generated by early work and purposed a double helix model for DNA molecule. This model is widely accepted. According to this model, the DNA molecule consists of two strands which are connected together by hydrogen bonds and helically twisted. Each step on the one strand consists of a nucleotide of purine base which alternate with that of pyrimidine base. Thus, a strand of a DNA molecule is a polymer of four nucleotide i.e. A, G, T, C. The two strand join together to form double helix. Bases of two nucleotide form hydrogen bond i.e. A combines with T by two H-bond (A=T) and G combines with C by three hydrogen bond. However, the sequence of bonding is such that for every A.T.G.C. On one strand there would be T.A.C.G. on the other strand. Therefore, the two strands are complementary to each other. The two strands of double helix run in antiparallel direction, i.e. they have opposite polarity.

                     Fig: Structure of DNA (Watson and Crick Model)


The hydrogen bonds between the two strands are such that maintain a distance of 20A0. The double helix coils in right hand direction. The turning of double helix results in the formation of a deep and wide groove called major groove. The major groove is the site if bonding of specific protein. The distance between two strands forms a minor groove. The DNA model also suggested a copying mechanism of the genetic material. DNA replication is the fundamental and unique event underlying growth and reproduction in all living organism ranging from the smallest viruses to the most complex of all creatures including man. DNA replicates by semiconservative mechanism.



6. Describe the type and function of RNA.

Ans: The RNA is usually single stranded except viruses such as TMV, yellow mosaic virus, reovirus etc. RNA is found both in the nucleus and in the cytoplasm. The single strand of the RNA is folded either at certain regions or entirely to form hairpin shaped structure. The RNA does not possess equal purine-pyrimidine ratio, as is found in the DNA.

                                               Fig: Structure of RNA.

Like DNA, the RNA is also the polymer of four nucleotides each one contains D-ribose, phosphoric acid and a nitrogenous base. The bases are two purines (A,G) and two pyrimidines (C,U). Thyamine is not found in RNA. Pairing between bases occurs as A-U and G-C.

 If the RNA is involved in genetic mechanism, it is called genetic RNA as found in plant, animal, and bacterial viruses. The DNA acts as genetic material and RNA follows the order of DNA, In such cells the RNA dose not have genetic role. Therefore, it is called non-genetic RNA. The non- genetic RNA is of three types:

1. M-RNA(messenger RNA): it constitutes about 5% - 10% of the total RNA present in the cell, m-RNA  carries the genetic information from DNA for Protein synthesis.

2. R- RNA(Ribosomal RNA): It makes about 80% of the total RNA in the cell. It is the major component of ribosomal.

3. T RNA (Transfer RNA): it is also known as soluble RNA. It forms about 10% - 15% of the total RNA. It used to transfer amino acid molecule to the site of protein synthesis.

A nucleotide is made up of three molecules. These are

A) Pentose sugar: the pentose sugar is ribose.

B) Nitrogenous bases:  i) Purine = Adenine And Guanine ii) Pyrimidine=Cytosine And Uracil

C) Phosphoric Acid


7. Write about the circular DNA?

Ans: Circular DNA is a form of DNA that is found in viruses, bacteria and archaea as well as in eukaryotic cells in the form of either mitochondrial DNA or plastid DNA. This form of DNA does not contain histones. While the individual strands of a linear double helix represent two distinct and separable molecules, this need not be true for circular DNA. Most bacterial chromosomes contain a circular DNA molecule - there are no free ends to the DNA. Free ends would otherwise create significant challenges to cells with respect to DNA replication and stability.



8. Describe the structure of amino acid.

Ans: Amino acids are building blocks of proteins. They are micromolecule having carbon, hydrogen and oxygen group. Each amino acid is a nitrogenous compound having an acidic carboxyl (-COOH) and a basic amino (-NH2)group. About 20 amino acids are occurring naturally. According to the body which synthesis amino acid it can be divided into two types, i.e. Essential and non-essential.

      Essential protein

  Non-essential protein

1. These amino acids are cannot synthesized by our body.

2. These amino acids must supply through diet.

3. These include Isoleucine, leucine, lysine, threonine, valine.

1. These amino acids are can synthesized by our body.

2. These amino acid are abundant on our body.

3. These include glutamic acid, aspartic acids, glycine, tyrosine, arginine, ornithine, taurine, histidine, serine, proline, asparagine, alanine.


9. Write the function of amino acid?

Ans: Amino acids are building blocks of proteins. They are micro molecule having carbon, hydrogen and oxygen group. Each amino acid is a nitrogenous compound having an acidic carboxyl (-COOH) and a basic amino (-NH2) group. About 20 amino acids are occurring naturally. According to the body which synthesis amino acid it can be divided into two types, i.e. Essential and non-essential. They mainly help in protein synthesis.


10. Discuss the carbohydrate as an important bio molecule.

Ans: Carbohydrates are the macronutrient that we need in the largest amounts. About 40% - 65% of calories should come from carbohydrate. We need this amount of carbohydrate because:

Carbohydrates are the body’s main source of fuel.

Carbohydrates are easily used by the body for energy.

All of the tissues and cells in our body can use glucose for energy.

Carbohydrates are needed for the central nervous system, the kidneys, the brain, the muscles (including the heart) to function properly.

Carbohydrates can be stored in the muscles and liver and later used for energy.

Carbohydrates are important in intestinal health and waste elimination.

Carbohydrates are mainly found in starchy foods (like grain and potatoes), fruits, milk, and yogurt. Other foods like vegetables, beans, nuts, seeds and cottage cheese contain carbohydrates, but in lesser amounts.


11. Discuss the nucleic acid as important biomolecules.

Ans: The DNA is the biological molecule that stores all the genetic information of the cell (in some viruses RNA may function as the molecule that stores the genetic information). In addition, DNA functions as the molecule that carries on the genetic information from parent to offspring.

RNA is made when the complex biochemical decodification machinery of the cell acts on the DNA to extract the information needed for a particular function. RNA is a key factor for protein synthesis. RNA is responsible for transferring the information contained in the DNA to make a particular protein needed in a specific process for a specific function. Messenger RNA (mRNA) is the nucleic acid that brings information (from the nucleus to the cytoplasm) about which protein to make, and transfer RNA (tRNA) is responsible for transporting amino acids to the ribosome’s to make the required proteins. There is also regulatory RNA that is RNA molecules capable of regulating gene expression by different mechanisms such as interference or blocking.



12 what are the different between fat and oil?




1.solid at room temperature

1.liquid at room temperature. in saturated fatty acid. in un saturated fatty acid.

3.usually present in animal.

3.obtained from all plants some animal.


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