BT102 Midterm Solved Papers Set 2

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.

Q3. Name two basic dyes?

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

Q4. Difference between viable count and direct count?

Viable count: Viable count is a method used in cell culture to determine the number of living cells in a culture. This is different from other cell counting techniques because it makes a distinction between live and dead cells Direct count: Direct counting methods include microscopic counts using a hemocytometer or a counting chamber. The hemocytometer works by creating a volumetric grid divided into differently sized cubes for accurately counting the number of particles in a cube and calculating the concentration of the entire sample.

Q5. Define pilli and also its functions?

➢ Longer than fimbriae Used for attachment to: Host cells Bacteria ➢ Used for DNA transfer from on bacterium to another:

➢ Also function in twitching Motility ➢ Gliding Motility is also the function of the pili.

6. write the name of three steps of glucose respiration.

Respiration of glucose takes place in three general steps:

• Glycolysis: Oxidation of glucose to pyruvic acid
• Krebs cycle: Oxidation of acetyl CoA to CO2
• Electron Transport Chain: Coenzymes that carry electrons from Krebs cycle or glycolysis are oxidized to create ATP.

• Respiration is further divided into two types:

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?

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 fluorochromes 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 .

A buffer is a solution that can maintain a nearly constant pH if it is diluted, or if relatively small amounts of strong acids or bases are added. A buffer solution can be made by mixing a weak acid with one of its salts OR mixing a weak base with one of its salts.

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. O 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?

Formation of spores takes place within a vegetative cell and the process is called sporulation or sporogenesis. It is initiated when nutrients become unavailable.

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.

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. Heat can activate the spore when appropriate moisture and nutrients are present in the environment. Germination: Spore starts swelling and losing its coats etc. It becomes metabolically active. Outgrowth: New components are made.

14. Give the characteristic of microaerophlis.(2)

Q5. Difference Between simple staining and differential staining (2 marks)

Simple staining: A single stain is used. Stain is washed off. A mordant is added, sometime. Microbes seen under the microscope. Examples of simple stain: Methylene Blue and crystal violet Differential staining: Differential stains react differently with different kinds of bacteria. Most common is Gram staining. 1884, by Hans Christian Gram Crystal Violet is added. It is primary stain Crystal violet is washed off. Iodine is added to enhance binding. Iodine is mordant. The slide is washed off with alcohol. Decolorizing agent Examples of differential staining: Fuchsin or safranin

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).

Refractive Index: Ability of a medium to bend the light

• Light rays move in a straight line through a single medium
• To increase contrast, we stain the specimen.

17. Parts of flagella.

A flagellum consists of the following 3 parts as shown in the accompanying diagram below:

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

19. what is chemotaxic and phototaxic

Movement of organism in response a chemical is called chemotaxix. Movement of organism in response to light stimulus is called phototaxix.

Q20. What is endospore?

A resistant dormant structure formed within a bacterial cell to pass unfavorable conditions. Specialized resting cells Highly durable, dehydrated forms of bacteria Formed inside a bacterium Survive extremes of temperatures; resistant to heat; needs to be autoclaved in order to be killed. Survive lack of water; can survive in high salt concentrations. Clostridia spores can survive in honey and that is one reason, honey is not recommended for infants, because spore can cause tetanus in babies. Survive radiation danger Survive in the toxic environment as well. Mostly formed by Gram positive bacteria Genus Clostridium Genus Bacillus One gram negative: Coxiella burnetii also has it. Formation of spores takes place within a vegetative cell and the process is called sporulation or sporogenesis. It is initiated when nutrients become unavailable.

21. Write name of three passive movements. Simple diffusion, Facilitated diffusion. Osmosis

22. Metachromatic granules

Also called volutin, they stain red with certain dyes such as methylene blue. That is why they are called metachromatic (stain in different color as methylene blue gives blue color but the color on these granules is red). • Large inclusions • These inclusions contain inorganic phosphates. Inorganic phosphates are used up in ATP synthesis. • Characteristics of Corynebacterium diphtheria: This bacterium can be identified by the presence of these granules in it.