Question 1

Carbon is an important element for biology because _____.

Accepted Answer

Carbon is an important element for biology because it can form a variety of carbon skeletons and functional groups that can be built on them, allowing for endless possibilities in molecular structures and the ability to create a diverse range of organic molecules, including carbohydrates, lipids, proteins, and nucleic acids.

Question 2

Which of the functional groups below acts like an acid in solution?

Accepted Answer

Carboxyl groups contain a -COOH functional group which can donate a proton (H+) in solution, making it acidic.

Question 3

Why would the spontaneous formation of formaldehyde and hydrogen cyanide not take place on Earth today as much as on the prebiotic Earth?

Accepted Answer

The atmospheric conditions on Earth have changed since the prebiotic era. Specifically, the presence of oxygen in Earth's atmosphere today would prevent the spontaneous formation of formaldehyde and hydrogen cyanide. Oxygen readily reacts with both compounds, preventing their accumulation in the atmosphere.

Question 4

Why is carbon so important in biology?

Accepted Answer

Carbon is important in biology because it has the unique ability to form up to four covalent bonds, which allows it to form stable and diverse compounds with other elements. This property allows carbon to form the backbone of important biological molecules, such as proteins, carbohydrates, lipids, and nucleic acids.

Question 5

You've been asked to analyze a reaction that took place at 300 K.∆H was -150 and ∆S was +0.4.Is the reaction endothermic or exothermic?

Accepted Answer

The reaction is exothermic because ∆H is negative.

Question 6

The first chemicals that provided potential energy on Earth may have been formaldehyde and hydrogen cyanide.While these were produced by sunlight-driven reactions,they also occur around deep-sea vents.If the first organisms on Earth evolved around these vents,the first life on Earth was _____.

Accepted Answer

Formaldehyde and hydrogen cyanide are chemicals that can be found around deep-sea vents, indicating a chemosynthetic source of potential energy. Therefore, the first life on Earth was likely chemosynthetic, obtaining energy from chemicals rather than the Sun or other organisms.

Question 7

The Q10 rule states that within their survivable range the rates of biochemical processes of many ectothermic organisms approximately double with every 10-degree (C)rise in temperature.Why would this be true?

Accepted Answer

As temperature increases, molecules have more kinetic energy and move faster, leading to more frequent collisions and faster reactions. Therefore, warmer molecules interact faster, which is the main reason behind the Q10 rule.

Question 8

During chemical evolution,which of the following occurred in the molecules involved?

Accepted Answer

During chemical evolution, molecules became more complex, which means their entropy (disorder) decreased, while their potential energy increased due to the formation of more complex chemical bonds.

Question 9

_____ atoms give organic molecules their overall shape;_____ atoms determine the overall chemical behavior of organic molecules.

Accepted Answer

Carbon atoms give organic molecules their overall shape due to their ability to form four covalent bonds and create branched or ring-shaped structures. Hydrogen, nitrogen, and oxygen atoms determine the overall chemical behavior of organic molecules due to their electronegativity and ability to form hydrogen bonds, which impact properties such as polarity, reactivity, and solubility.

Question 10

Which of the following tends to make chemical reactions spontaneous?

Accepted Answer

Spontaneous reactions are favored by an increase in entropy, meaning the products are more disordered than the reactants.

Quiz 2: Water and Carbon: the Chemical Basis of Life