Solutions of worksheet 3, Ch 5, Class 7

Ans 1. Across: (2) Neutral      (4) Basic      (5) Red

           Down: (1)Indicator      (3)turmeric    (5)Acidic    (6)Heat

Ans 2. Solution A - Acidic, Solution B - Basic, solution C - Neutral

Ans3. The effect of antbite is neutralized by rubbing moist baking soda

Ans 4. (a)-III,  (b) -v,   (c)- (iv), (d)- (i),  (e)- (ii)

Ans5. (a)sour, acid

           (b) natural

           (c) magenta(dark pink)

           (d) react with, salt

Solution key of worksheet 2, Ch 5, Class7

1. Acid

2. Acetic acid, Citric acid

3. contain acid

4. in curd

5. Hydrochloric acid

6. By trating with bases like quick lime, slaked lime

7. milk of magnesia

8. neutralization

9. bitter, sour

10. magenta, green

11. otherwise they will harm water bodies

12. base or neutral

13. Acid rain

       

14. (a)

15. (b)

16  (d)

17. (d)

18. (d)

19. (a)

20. acid+base are reactants and salt+water are products

INTRODUCTION TO BIOTECHNOLOGY (CLASS XI)

FAO statement on biotechnology defines biotechnology as:
"any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use".

The wide concept of "biotech" or "biotechnology" encompasses a wide range of procedures for modifying living organisms according to human purposes

In 1917, Chaim Weizmann first used a pure microbiological culture in an industrial process, that of manufacturing corn starch using Clostridium acetobutylicum, to produce acetone

Biotechnology has also led to the development of antibiotics. In 1928, Alexander Fleming discovered the mold Penicillium.

The commercial viability of a biotechnology industry was significantly expanded on June 16, 1980, when the United States Supreme Court ruled that a genetically modified microorganism could be patented in the case of Diamond v. Chakrabarty.^[12] Indian-born Ananda Chakrabarty, working for General Electric, had modified a bacterium (of the genus Pseudomonas) capable of breaking down crude oil, which he proposed to use in treating oil spills.

The MOSFET (metal-oxide-semiconductor field-effect transistor) was invented by Mohamed M. Atalla and Dawon Kahng in 1959. Two years later, Leland C. Clark and Champ Lyons invented the first biosensor in 1962. Biosensor MOSFETs were later developed, and they have since been widely used to measure physical, chemical, biological and environmental parameters.

Biotechnology has applications in four major industrial areas, including health care (medical), crop production and agriculture, non-food (industrial) uses of crops and other products (e.g. biodegradable plastics, vegetable oil, biofuels), and environmental uses.

one application of biotechnology is the directed use of microorganisms for the manufacture of organic products (examples include beer and milk products). Another example is using naturally present bacteria by the mining industry in bioleaching. Biotechnology is also used to recycle, treat waste, clean up sites contaminated by industrial activities (bioremediation), and also to produce biological weapons.

DELETED PORTION OF BIOTECHNOLOGY FOR THE SESSION 2020-2021

http://cbseacademic.nic.in/web_material/CurriculumMain21/revisedsyllabi/Deduction/DELETEDBio_Technology_2020-21.pdf

WORKSHEET 1, PHYSICAL AND CHEMICAL CHANGES, CLASS 7

1. Classify the following changes as physical or chemical changes – 

     (i) Burning of sugar

     (ii) Melting of butter

     (iii) Souring of milk 

     (iv) Drying of wet hair 

     (v) Mixing lime with water 

     (vi) Burning of coal 

     (vii) Growth of plants to trees 

     (viii) Spoiling of food 

     (ix) Bursting of crackers 

     (x) Cutting of vegetables 

Q.2. Name the following: 

    (i) Common name of copper sulphate. 

    (ii) The gas evolved when vinegar is reacted with baking soda. 

    (iii) Any 3 alloys from your daily life.

    (iv) Two factors which cause rusting. 

    (v) An example of a chemical change in which there is a change of colour. 

Q.3. Metal X burns with a dazzling white flame to form a compound Y. Compound Y reacts with water to form Z which in turn turns red litmus paper blue. 

   (i) Identify X, Y and Z 

  (ii) Write down the chemical reactions involved. 

Q.4. Metal A change the colour of copper sulpahte solution when added to it. 

   (i) Name metal A. 

   (ii) Write down the reaction involved in this change. 

   (iii) What type of change is this?

Q.5. Complete the following reactions – 

   (i) __________ + Carbon dioxide ➡️Calcium carbonate + __________.

   (ii) Carbon + oxygen➡️ _____________ 

   (iii) Magnesium oxide + _____________➡️ Magnesium hydroxide.

   (iv) Magnesium + _____________ ➡️Magnesium oxide.

Q.6. Fill in the blanks: 

   (i) Dissolving sugar in water is a ___________ change. 

   (ii) The process of depositing a layer of zinc on iron is called ____________.

   (iii) Crystals of pure substances are obtained from their solutions by __________.

    (iv) Hydrated iron oxide is called ___________

Q.7.Which of the following is a physical but irreversible change? 

   (a) burning of a matchstick 

   (b) melting of an ice cream 

   (c) crushing of glass 

   (d) lighting of an electric bulb

Q.8. Observe the following two changes. Change A: Biogas is produced by decomposition of animal and plant waste by anaerobic bacteria. Change B: Biogas is burnt as other fuels. Which of these is a chemical change?

    (a) Change A 

    (b) Change B  

    (c) Both (a) and (b)

    (d) None of these

TYPES OF MICROBIAL CULTURE

1. BATCH CULTURE:

A technique used to grow microorganisms or cells. A limited supply of nutrients for growth is provided; when these are used up, or some other factor becomes limiting, the culture declines. Cells, or products that the organisms have made, can then be harvested from the culture

2. FED BATCH CULTURE: 

Fed-batch culture is, in the broadest sense, defined as an operational technique in biotechnological processes where one or more nutrients (substrates) are fed (supplied) to the bioreactor during cultivation and in which the product(s) remain in the bioreactor until the end of the run.^[1] An alternative description of the method is that of a culture in which "a base medium supports initial cell culture and a feed medium is added to prevent nutrient depletion".^[2] It is also a type of semi-batch culture. In some cases, all the nutrients are fed into the bioreactor. The advantage of the fed-batch culture is that one can control concentration of fed-substrate in the culture liquid at arbitrarily desired levels (in many cases, at low levels).

3. CONTINUOUS CULTURE:

The continuous culture of micro-organisms is a technique of increasing impor- tance in microbiology. The essential feature of this technique is that microbial growth in a continuous culture takes place under steady-state conditions; that is, growth occurs at a constant rate and in a constant environment.

Continuous culture: may be chemostat or turbidostat