UNIT 3

BIOTECHNOLGY

EXERCISE

A. Choose the correct answer for each of the following statements.

i. The additional circular pieces of DNA present in bacterial cell are

called:

(a) RNA (b) chromatid (c) plasmid (d) nucleotide

ii. The branch of science in which living organisms are used for the

welfare of humans is called:

(a) Biochemistry (b) Biotechnology (c) Microbiology (d)

Genetics

iii. Plasmid and attached foreign gene with it are collectively called:

(a) Recombinant cell (b) Recombinant DNA (c) Recombinant

plasmid (d) Recombinant chromosome

iv. The organism whose genes are modified is called:

(a) GM organism (b) transgenic organism (c) recombination

organism (d) all of these

v. A Gene is inserted into a bacterium by:

(a) digestion (b) genetic engineering (c) fermentation

(d) biodegradation

B. Match the words of column A with suitable words of column B.

Column A Column B Answer

1. Plasmid DNA 1. Bacterium

2. Diabetes Stimulating hormone 2. Insulin

3. Growth hormone Insulin 3. Stimulating hormone

4. Double helix Bacterium 4. DNA

5. GMOs Modified genes 5. Modified organisms

C. Answer the following short questions

1. Define biotechnology.

Ans. Biotechnology:

“ The use of living organisms or their products for the welfare

of mankind is called biotechnology.”

❖ The ultimate goal of this field is to improve the yield of products from the

living organisms by making modifications in their DNA.

2. Write some important products of biotechnology.

Ans. Products of biotechnology:

Biotechnology has a very important role in our life. We are using different

products of biotechnology. Some of the important products of biotechnology are:

• Bakery products, yogurt, cheese, bread and vinegar.

• Food crops modified by biotechnology.

• Different medicines e.g. insulin for diabetes, vaccines and antibiotics.

• Biodiesel, washing detergents, sugars, plastics etc.

3. What are genetically modified organisms?

Ans. Genetically modified organisms (GMO):

The organisms whose genes are modified are called genetically modified

organism (GMOs) or transgenic organism.

Genetic modification is basically the change in the genetic organization of an

organism using biotechnological techniques. This change can be produced by

removal, addition or modification of gene. This process is used in crops to develop

many characteristics in plants.

For Example: increased productivity, improved nutritional quality, novel products

and disease resistant plants etc.

4. What is DNA replication? Explain.

Ans. DNA Replication:

DNA replication is the process by which a double- stranded

DNA molecule is copied to produce two identical DNA molecules.

The molecule of DNA which is replicated is called parent DNA while, the

molecules produced in this process are called daughter DNA.

A parent DNA molecule after replication gives rise to two daughter DNA

molecules.

Steps involved in DNA replication:

1. The first step in DNA replication is the unwinding of the double helical

structure of the DNA molecule. The two strands separate from each other.

2. In the second step, each of these strands produces a new strand using all the

four types of nucleotides present in the nucleus. In this way, one DNA

molecule produces two daughter DNA molecules.

5. Draw a labeled diagram of bacterium.

D. Give detailed answers to the following

questions.

1. Explain the process of introducing gene into bacteria.

Ans. The process of gene introducing into the bacterium is as under:

i. The first step is the identification and isolation of gene (gene of interest)

from donor organism.

ii. An enzyme called restriction enzyme is used to cut the gene from the DNA

of donor organism.

iii. The isolated gene is then attached with plasmid DNA taken from bacterium.

The attached gene and plasmid DNA are collectively called recombinant

DNA.

iv. The recombinant DNA is then introduced into a bacterium, the bacterium

starts dividing and produces a bacterial colony.

Thus, every bacterium of the colony contains the desired gene and hence they

produce the desired product (protein).

2. Describe the role of biotechnology in agriculture and health.

Ans. Role of biotechnology in agriculture:

Biotechnology has played an important role in improving our agriculture

yield. Herbicides (weed killing chemicals) and pesticides (insect killing chemicals)

are used to eliminate weeds and insects and thus protect crops. Using

biotechnology, scientist insert weed resistant and pest resistant gene into plants.

Cultivation of such genetically modified crops improves the quality of crops and

makes them safe for human use. Proteins in cereals and legumes maybe transferred

to provide the amino acids needed by human beings for a balanced diet.

Biotechnology improves the taste, texture and appearance of the food.

Examples:

The major crops that have been modified are maize, wheat, rice, potato, corn,

soybean etc.

Role of biotechnology in Health;

Biotechnological techniques are also used for curing diseases and improving

health. Identification of causes of diseases, production of medicines and correction

of genetic defects etc. are the major contribution of biotechnology.

Examples:

➢ Insulin is useful for diabetics.

➢ Vaccines are used against many infectious diseases.

➢ Growth hormones are used for stimulating growth.

3. Describe the role of biotechnology in meeting the nutritional needs of

human beings.

Ans. Role of biotechnology in meeting the nutritional needs:

Biotechnology plays a vital role in meeting the nutritional needs of human

population. Biotechnology has a great importance in human life. We can succeed

in meeting our food problems through biotechnology. We can enhance food

production and nutrition by improvements in livestock and plants using different

techniques of biotechnology such as tissue culture and genetic engineering etc.

Tissue Culture:

Tissue culture is an important technique of biotechnology. We can get the types of

crops and other plants, which give more production using this technique.

Genetic Engineering:

Genetic engineering is used in animals for better production of milk and meat.

For example:

Neeli Ravi buffalo is produced for better production of milk and Nancy sheep for

production of more meat. Such animals are very helpful in meeting the nutritional

needs.

UNIT 5 CHEMICAL REACTIONS

Exercise

A. Fill in the blanks to complete the following equations.

i. 2KClO3 2KCL + 3O2

ii. 3H2 + N2 2NH3

iii. 2Na + 2H2O 2NaOH + H2

iv. NaOH + HCL NaCl + H2O

v. Mg + Cl2 MgCl2

B. Choose the correct answer for each of the following statements.

i. Substances on the left hand side of a chemical reaction are called

a) electrons b) groups c) products d) reactants

ii. The reaction in which there is only one reactant, which must be a compound, is:

a) decomposition b) displacement c) synthesis d)

double displacement

iii. Number of atoms of reactants is equal to number of products in a balanced

chemical equation:

a) sometimes b) often c) always d)

never

iv. The reaction between sodium and chlorine to form sodium chloride is:

a) displacement b) decomposition reaction c) addition

reaction d) double displacement reaction

v. The heat evolved or absorbed during a chemical reaction is called:

a) heat of reaction b) exothermic c) heat energy d)

endothermic

C. Give short answers of the following

i. What are the characteristics of chemical reactions?

Ans. Characteristics of Chemical Reactions:

Following are the characteristics of chemical reactions:

1. Evolution of gas.

2. Formation of precipitate.

3. Change in color.

4. Change in temperature.

5. Change in state.

ii. Define chemical reaction and its types.

Ans. Chemical Reaction:

The process of formation or breakdown of a chemical compound is called a

chemical reaction.

➢ Those substances which combine with each other are called reactants

while,

➢ Those substances which are produced as a result of chemical reaction are

called products.

Examples of Chemical Reaction:

1. 2H2+ O2 2H2O

Reactant Product

2. CaCO3 CaO + CO2

Reactant Product

Types of Chemical Reactions:

Chemical reactions can be categorized into four basic types:

1) Addition or synthesis reaction.

2) Decomposition reaction.

3) Single displacement reaction.

4) Double displacement reaction.

iii. Explain each type of chemical reaction with one example each.

Ans. 1) Addition or Synthesis Reaction:

These chemical reactions occur when two or more substances react together to

form only one product.

Example: 2H2 + O2 2H2O

2) Decomposition Reaction:

Decomposition reactions have only one reactant which breaks up to form two or

more products. These reactions are endothermic as they require heat.

Example: CaCO3 CaO + CO2

3) Displacement Reaction:

These chemical reactions occur when a more reactive element displaces a less

reactive one from its compound.

Example: Zn + 2HCl H2 + ZnCl2

4) Double Displacement Reaction:

Double displacement reactions involve the exchange of ions between two

compounds. Double displacement reaction can be represented as,

Example: HCl + NaOH NaCl + H2O

iv. Exothermic reactions are very important in our daily life. Give two

reasons.

Ans. Exothermic reactions are extremely important in our daily life because,

❖ The life on earth is possible due to the exothermic reactions taking place in

the sun.

❖ The heat released by the burning of fuels is also used for cooking food,

running vehicles and operating factories.

v. What is balanced chemical equation? Why chemical equations need to be

balanced?

Ans. Balanced Chemical Equation:

A balanced chemical equation occurs when the number of different atoms of

elements in the reactant side is equal to the number of product side.

Balancing of Chemical Equations:

A chemical equation needs to be balanced so that it follows the law of conservation

of mass. According to the law of conservation of mass, “matter can neither be

created nor destroyed during a chemical reaction”. Therefore, the number of atoms

in each element must be equal on both sides of a chemical reaction.

Various methods are used for balancing of chemical equation but the simplest

method for balancing is inspection or trial and error method.

D. Give detailed answers to the following questions.

I. Explain the steps for balancing of chemical equations with two examples.

Ans. The following steps are involved in balancing chemical equation.

STEP 1: Write unbalanced chemical equation. The symbol and formulae of the

reactants and products must be correct.

STEP 2: Count the numbers of atoms of each element on both sides.

STEP 3: If the number of atoms are different on both sides, write the required

number as a coefficient of the symbol or formulae.

STEP 4: Work with one element at a time.

STEP 5: Always start with a relatively small number.

STEP 6: Start with atoms they appear only once in the reactants and products.

Usually leave the di-atomic elements like nitrogen, hydrogen and oxygen etc. until

last.

Example 1:

CH4+ O2 CO2 + H2O

Reactant Product

C = 1 C = 1 Balanced

H = 4 H = 2 Unbalanced

O = 2 O = 3 Unbalanced

There are 4 H in CH4 at left side and only 2H in H2O on right side. So, we will

double the co-efficient of H2O to balance hydrogen atoms on both sides.

CH4 + O2 CO2 + 2H2O

The carbon atoms are same on both sides so, they are already balanced.

Finally, we can see that the number of oxygen atoms is 2 on the reactants side

while 4 on the product side, so we will add 2 as a co-efficient of O2 at left side to

balance the oxygen atoms on both sides.

CH4+ 2O2 CO2 + 2H2O

While checking the work, the final balanced equation is written as below:

CH4 + 2O2 CO2 + 2H2O

Example 2

Fe + H2O Fe3O4 + H2

There is only one Fe atom on the left side while 3 Fe atoms on the right side. So,

we have to add co-efficient '3’ with Fe at left side to balance the Fe atoms on both

sides of the equation

3Fe + H2O Fe3O4 + H2

As there is one oxygen atoms on left side and 4 oxygen atoms on right side of the

equation. So, we will add co-efficient '4’ with H2O on left side to balance oxygen

atoms on both sides.

3Fe + 4H20 Fe3O4 H2

Finally, we have to balance the hydrogen atoms on both sides. So, we will add co-

efficient '4’ with H2 at right side to balance hydrogen atoms on both sides.

3Fe + 4H2O Fe3O4+ 4H2

ii. (a) Define Law of conservation of mass. Explain with the help of two

examples.

(b) When a pile of wood is burnt, the ash left behind is less as compared to

wood. How Law of conservation of mass is applicable in this situation?

Ans. Law of Conservation Of Mass:

This law was put forward by a French chemist Lavoisier in 1785.

Definition:

“Mass can neither be created nor destroyed during a chemical

reaction.”

During a chemical reaction, total mass of products is equal to the total mass of

reactants.

Mass of reactant = Mass of product

Example1:

When a piece of iron is left in moist air, its surface gradually turns brown, the iron

gets rusted and gains mass.

4Fe + 3O2 2Fe2O3

(Iron) (oxygen) (iron oxide)

Example 2:

When coal burns, it leaves behind ash. The ash is lighter than coal. But the mass of

coal and O2 will be equal to that of ash and the liberated carbon dioxide.

C + O2 CO2 + ash

(b) When we burn a log of wood, the carbon and other atoms present in it turn into

oxide i.e. carbon turned into carbon dioxide. Oxygen comes from atmosphere. If

we measure the mass of hot carbon and oxygen present in a closed system and

mass of released carbon dioxide. It will be balanced to the ash and the log of wood.

Thus, the law of conservation of mass is applicable.

iii. Define heat of reaction. Differentiate between exothermic and endothermic

chemical reactions with examples.

Ans. Heat of Reaction:

Heat is either released or absorbed in almost all chemical reactions. “The heat

evolved or absorbed during a chemical reaction is called heat of reaction.”

There are two types of reaction with respect to energy changes:

1. Exothermic Reaction 2. Endothermic Reaction

Difference between Exothermic reaction and Endothermic reaction

Exothermic Reaction Endothermic Reaction

1. Exo means outside

and therm means

heat.

1. Endo means inside and

therm means heat.

2. All those chemical

reactions in which

heat is released

during chemical

reaction is called

Exothermic

2. All those chemical

reactions in which heat is

absorbed during chemical

reaction is called

endothermic reaction.

reaction

3. Exothermic refers

to the reactions in

which heat is

released into the

surrounding.

3. Endothermic refers to

those reactions in which

heat is absorbed from the

surrounding.

4. For example:

Burning of natural

gas, heat released

during respiration

etc.

4. For example

Melting ice, plants

absorbing heat by sun

during photosynthesis

etc.