TLS Online TPP Program

#Question id: 9159


Which of the following investigations would shed the most light on the future distribution of organisms in temperate regions that are faced with climate change?

#Unit 9. Diversity of Life Forms
  1. Remove, to the mineral soil, all of the organisms from an experimental plot, and monitor the colonization of the area over time in terms of both species diversity and abundance.

  2. Look at the climatic changes that occurred since the last ice age and how species redistributed as glaciers melted, then make predictions on future distribution in species based on past trends.

  3. Compare and contrast the flora and fauna of warm/cold/dry/wet climates to shed light on how they evolved to be suited to their present-day environment.

  4. Quantify the impact of man's activities on present-day populations of threatened and endangered species to assess the rate of extirpation and extinction.
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TLS Online TPP Program

#Question id: 378

#Unit 1. Molecules and their Interaction Relevant to Biology

Which of the following statements about buffers is true?

TLS Online TPP Program

#Question id: 379

#Unit 1. Molecules and their Interaction Relevant to Biology

A compound has a pKa of 7.4. To 100 mL of a 1.0 M solution of this compound at pH 8.0 is added 30 mL of 1.0 M hydrochloric acid. The resulting solution is pH:

TLS Online TPP Program

#Question id: 380

#Unit 1. Molecules and their Interaction Relevant to Biology

The Henderson-Hasselbalch equation:

TLS Online TPP Program

#Question id: 381

#Unit 1. Molecules and their Interaction Relevant to Biology

Consider an acetate buffer, initially at the same pH as its pKa (4.76). When sodium hydroxide (NaOH) is mixed with this buffer, the:

TLS Online TPP Program

#Question id: 382

#Unit 1. Molecules and their Interaction Relevant to Biology

The molar ratio of sodium acetate to acetic acid in a buffer solution with a pH OF 5.76 is 10:1. Assuming the total buffer concentration is 2.2 X 10-2 mol/L, how many grams of sodium acetate (m.w. 82) and how many grams of acetic acid (m.w. 60) should be used in preparing a litre of the solution?

TLS Online TPP Program

#Question id: 383

#Unit 1. Molecules and their Interaction Relevant to Biology

Three buffers are made by combining a 1 M solution of acetic acid with a 1 M solution of sodium acetate in the ratios shown below

1 M acetic acid              

1 M sodium acetate  

Buffer 1: 10 mL

 90 mL

Buffer 2: 50 mL

50 mL

Buffer 3: 90 mL

10 mL

 Which of these statements is true of the resulting buffers?