Question 1

A researcher exposed flies to increasing concentrations of caffeine and measured their heart rates. The data showed average heart rates of 150, 165, 180, and 210 bpm for control, low, medium, and high caffeine concentrations, respectively. Which of the following best describes the overall trend in the data?

Accepted Answer

Heart rate increases as caffeine concentration increases.

Question 2

Which of the following statements about elements and compounds is correct?

Accepted Answer

A compound consists of two or more elements in a fixed ratio and has properties different from its constituent elements.

Question 3

Which four elements make up approximately 96% of living matter?

Accepted Answer

Carbon, hydrogen, oxygen, and nitrogen

Question 4

A radioactive isotope has a half-life of 10 years. If you start with 100 grams, how much will remain after 30 years? Use the formula $$N = N_0$ 	imes (\frac{1}{2}$$)^{t/T_{1/2}$$}$$ where $$N_0 is $$the initial amount, $$t is $$time, and $$T_{1/2} is $$half-life.

Accepted Answer

$$12.5$$ grams

Question 5

Which of the following best explains why sodium chloride (NaCl) forms a crystal lattice in nature?

Accepted Answer

Because sodium and chlorine form ions that are held together by ionic bonds, resulting in a repeating crystal structure.

Question 6

Which of the following is true about isotopes?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 7

A student crosses two heterozygous pea plants (Rr x Rr) for flower color. What is the expected ratio of purple to white flowers, and what are the expected numbers for each phenotype out of 80 plants?

Accepted Answer

Ratio: 3:1; Purple: 60, White: 20

Question 8

Which of the following best describes a polar covalent bond?

Accepted Answer

Electrons are shared unequally due to differences in electronegativity.

Question 9

Which of the following is a trace element required by humans in minute quantities?

Accepted Answer

Iron

Question 10

Which statement about chemical reactions is correct?

Accepted Answer

Chemical reactions involve the making and breaking of chemical bonds.

Question 11

Which of the following best explains why elements with a full valence shell are chemically inert?

Accepted Answer

They do not need to gain, lose, or share electrons to achieve stability.

Question 12

Which of the following is the correct formula for calculating the chi-square value in a genetics experiment?

Accepted Answer

$$\$$chi^2$$ = \sum \frac{(O - E)^2$}{E}$$

Question 13

Which of the following is true about hydrogen bonds?

Accepted Answer

They are weak attractions between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 14

Which of the following best describes the role of van der Waals interactions in biological systems?

Accepted Answer

They are weak attractions that collectively can be strong, such as in gecko toe hairs adhering to surfaces.

Question 15

Which of the following is true about the molecular shape and its biological function?

Accepted Answer

Molecular shape determines how biological molecules specifically recognize and respond to one another.

Question 16

Which of the following is an example of a chemical reaction important in biology, and what are its reactants and products?

Accepted Answer

Photosynthesis: Reactants are carbon dioxide and water; products are glucose and oxygen.

Question 17

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation is positively charged, and an anion is negatively charged.

Question 18

Which of the following statements about electronegativity is correct?

Accepted Answer

Electronegativity is the attraction of an atom for the electrons in a covalent bond.

Question 19

Which of the following best explains why morphine and endorphins have similar effects in the brain?

Accepted Answer

They have similar molecular shapes that allow them to bind the same receptors.

Chemical Foundations of Life and Experimental Design in Biology

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