BT102 Midterm Questions and Answers

BT 102 Subjective · Midterms Past Papers · 2 marks

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.

3.

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?

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.

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 fluorochrome tagged antibodies.

Q8. What is buffer?

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?

Resolution is the ability of the lenses to distinguish between two closely lying objects as separate. Light microscope resolving power is 0.2 μm. 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.

Q11. 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.

Q12. What is function of cell wall?

Cell wall is the most important layer in bacteria. It is rigid layer just outside the plasma membrane.

1. It provides shape to the living organisms.
2. It protect from osmotic lysis.
3. It is also involve in pathogenocity.

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