Question

1)Which of the following is true of enzyme characteristics? (a) enzymes catalyze reactions when a substrate binds to the allosteric site (b) enzymes catalyze reactions by increasing the activation energy (c) enzymes do not exhibit specificity and a single enzyme can catalyze various different reactions (d) enzymes lower the activation energy of specific reactions, speeding up the reaction rate

2) Microbial growth is measured by what parameter? (a) increased cell size (b) increased size of cellular components (c) increase in total number of cells (d) a & b

3)During aerobic cell respiration, most of the energy is produced during… (a) Krebs cycle (b) glycolysis (c) fermentation (d) electron transport chain

4)Which of the following is the best definition of generation time? (a) the length of time it takes for lag phase to occur (b) the length of time it takes a population of cells to double (c) the minimum length of time it takes a cell to divide (d) the length of time a culture stays in stationary phase

5)Bacteria make exoenyzmes in order to… (a) make structures within the bacterium (b) synthesize large molecules of carbohydrates, proteins, and nucleic acids (c) hydrolyze large molecules to smaller ones so that they can be transported into the bacterium (d) none of the above; bacteria do not make exoenyzmes

6)Which of the following is NOT true of using a spectrophotometer to measure bacterial growth? (a) measurement is based on turbidity of the broth culture (b) this method accounts for both dead and viable cells (c) this method uses the transmission of light through the broth culture to estimate concentration of cells (d) this method requires serial dilutions prior to measurement

answer followings

Answer 1

1) Which of the following is true of enzyme characteristics?

Answer = (d) enzymes lower the activation energy of specific reactions, speeding up the reaction rate.

Explaination:

The enzymes lower the activation energy for reactions after binding to the substrate.

The enzymes decrease the barrier to start the reaction in lowering the activation energy and increases the rate of reaction.

The enzymes change the formation of the transition state by lowering the activation energy and stabilising the highly energetic unstable transition state. Due to this mechanism, the speed of the reaction increases.

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2) Microbial growth is measured by what parameter?

Answer = (c) increase in total number of cells.

Explanation:

The microbial growth is very difficult to measure. They are basically measured by a cell counting method in which the total number of cells in culture are measured by direct or indirect methods. The unit of microbial growth measurement is cells/ml.

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3) During aerobic cell respiration, most of the energy is produced during…

Answer = (d) electron transport chain

Explanation:

During glycolysis, 2 ATP molecules are formed. SImilarly during Kreb's cycle, 2 ATP molecules are formed and during electron transport chain, total 32 ATP molecules are formed by converting electrons to ATP.

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4) Which of the following is the best definition of generation time?

Answer =  (b) the length of time it takes a population of cells to double.

Explanation:

The generation time is a time taken by the organism to double in number during a specific time period.

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5) Bacteria make exoenyzmes in order to…

Answer = (c) hydrolyze large molecules to smaller ones so that they can be transported into the bacterium.

Explanation:

The exoenzymes are the enzymes produced by bacteria within the cells and then released outside the cell for the process of extracellular digestion. Very large macromolecules cannot be pass through the cell envelope, so the exoenzymes break down such macromolecules into smaller micromolecules and then transported to the cell.

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6) Which of the following is NOT true of using a spectrophotometer to measure bacterial growth?

Answer = (d) this method requires serial dilutions prior to measurement.

Explanation:

We can measure the bacterial growth of culture directly, there is no need of serial dilution everytime. If the culture is very much turbid, then the serial dilutions can be made but it is not compulsory.