In balancing selection, two or more alleles are kept in balance, and therefore are maintained in a population over the course of many generations. Which of the following example can support balancing natural selection?

A- Sickle cell allele kept in balance because heterozygotes have greater chance of survival if infected by the malarial parasite, compared with normal homozygotes

B. One morph has selective advantage over another morph

C. One homozygote has greater chance of survival than other genotype results in purity of population

D. many species of invertebrates exist as different colored forms, identical in all respects except color. Visually searching predators often develop a search image for one color form, usually the commoner

#Question id: 361

#Unit 1. Molecules and their Interaction Relevant to Biology

Calculate the percentage of histidine that has its imidazole side chain protonated at pH 7.3. The pKa values for histidine are pK1 = 1.8, pK2 (imidazole) = 6.0, and pK3 = 9.2.

#Question id: 362

#Unit 1. Molecules and their Interaction Relevant to Biology

A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?

#Question id: 363

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the pH of a mixture of 0.042 M NaH2PO4 and 0.058 M Na2HPO4? If 1.0 mL of 10.0 M NaOH is added to a liter of the buffer prepared, how much will the pH change? (pKa = 6.86)

#Question id: 364

#Unit 1. Molecules and their Interaction Relevant to Biology

 A solution contains 0.0000001 (10-7) moles of hydrogen ions [H+] per liter. Which of the following best describes this solution?

#Question id: 365

#Unit 1. Molecules and their Interaction Relevant to Biology

Water is a polar molecule: the oxygen atom with its unshared electrons carries a partial negative charge (δ−) of ___________, and the hydrogen atoms each carry a partial positive charge (δ+) of __________, where e is the charge of the electron.

#Question id: 366

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the pH of a solution with a hydroxyl ion (OH-) concentration of 10-10 M?