BT102 Midterm Solved Past Paper

Midterm paper pattern · Mcqs = 20 · SQs (2marks) = 2 · SQs(3marks) = 2 · LQs (5marks) = 2 · Total marks = 40

Q1. What is flagellum? Give its functions?

Long filamentous structure that propels bacteria is called flagellum. It helps bacteria to move.

Q2. What is phosphorylation?

The addition of an inorganic phosphate group to a chemical compound is called phosphorylation. e.g addition of P to ADP for synthesis of ATP during metabolic reactions.

Name two basic dyes?

In basic dye the color is in the positive ion. e.g 1-Crystal violet 2-Methylene 3-blue Malachite green 4-Safranin

Q3. Differentiate direct count and viable count?

4. Direct microscopic count: This method uses a hemocytometer which takes a specific volume of sample and the number of microbes can directly be counted under a light microscope. The number of microbes in one ml of original sample may be determined by multiplying with appropriate number. No incubation is required, so this method is quicker and it also gives a total count (viable as well as dead microbes). There is an auto version of this method where the cells are counted electronically. The name of the instrument is Coulter counter.

Q5. Define pilli and also its functions?

These are hair-like structure composed of pilin, usually one to ten in number.

•  Longer than fimbriae
•  Used for attachment to: Host cells Bacteria
•  Used for DNA transfer from
•  on bacterium to another:
•  Conjugation (Sex pili)
•  Also function in twitching Motility
•  Gliding Motility is also the function of the pili.

Q6. Respiration of glucose?

• Electron Transport Chain: Coenzymes that carry electrons from Krebs cycle or glycolysis are oxidized to create ATP.

Aerobic Respiration: If in the electron transport chain, the final electron acceptor is oxygen, it is called an aerobic respiration.

Anaerobic Respiration: If in the electron transport chain, the final electron acceptor is any inorganic compound other than oxygen, it is called an anaerobic respiration. This final electron acceptor may be a nitrate ion, a sulfate ion, or a carbonate ion.

Q7. what is fluorochromes?

1. Fluorochromes are substances that absorb short wavelength of light and emit longer wavelength (visible light spectrum). The fluorochromes are used in fluorescent microscopy. These are attached to antibodies that are specific to organisms. So, if an organism is present in the specimen, we can use specific antibodies to determine the presence of those organisms by use of fluorochrome tagged antibodies.

Q8. what is buffer?

1. Buffers are used to maintain desired pH o Peptones and amino acids are used as buffers

o Phosphates are also used for buffers

Q9. What is resolution?

1. Resolution is the ability of the lenses to distinguish between two closely lying objects as separate. See the accompanying diagram for visual concept of resolution.
2. Light microscope resolving power is 0.2 μm.

o n = refractive index, 1.5 for immersion oil o Resolution (d) in the formula given in the diagram is directly proportional to the wavelength of the light used. As resolution is the smallest distance between two closely lying points, use of light with smaller wavelength gives better resolution. That is why it is find blue filters for blue light as illumination for the microscope, as blue light has the shortest wavelength in the visible spectrum. 

Q10. What is sporulation?

11. Why solid medium is good than liquid medium for the growth of bacteria

Solidification of the medium is done for purifying organisms from each other as solid medium provides surface for individual colonies to grow well separated from each other. A well isolated colony is assumed to be the progeny of a single cell. Purification of organisms is done by streaking the organisms. Secondly, the solid media are used to study the colony characteristics.

12. What is function of cell wall. Cell wall is the most important layer in bacteria. It is rigid layer just outside the plasma membrane.

city (ability of the organism to cause the

13. Stages of Germination spore.3

• Spore germinates when it finds a conducive environment for its growth. Germination has 3 phases or stages:

Activation: It prepares the spore for germination.

environment. Germination: Spore starts swelling and loosing its coats etc. ically active. Outgrowth: New components are made.

14. Give the characteristic of microaerophlis.(2)

15. Differentiate between differential and simple staining.(2)

• Simple Staining: only one stain is used. Methylene Blue staining
• Differential Staining: A couple of stains used. Gram Staining

16. . What is refractive index

It is the ratio of the velocity of light in a vacuum to its velocity in a specified medium. Refractive Index: Ability of a medium to bend the light. Refractive index as that of the glass (1.5).

17. Parts of flagella. A flagellum consists of the following 3 parts as shown in the accompanying diagram below:

• Filament: It is made of a protein called flagellin, which makes H antigen that can be used for serovar identification in gram negative bacteria. • Hook: A different protein • Basal Body: The most complex

Q18. Define Ribosome?

Ribosomes are non-membranous organelles present in both prokaryotes and eukaryotes and involved in protein synthesis. Their composition in prokaryotes is as follow

• 70S ribosomes (when two units are combined into one unit) n ribosomes and inhibit protein synthesis • Streptomycin attach to 30S

Q19. Write down type of bacteria?

20. what is agar ? what are the characteristics

Agar is Solidifier of a medium. ar is derived from a sea weed. by bacteria during the growth. 0C and solidifies at 43 0C plates or slants.