Bio 100 Chap. 2 AQ

What must the probe sent to Europa be able to do in order to effectively detect life on this world? Select the TWO answers that are correct.

1) It must be able to detect as little as a picomole of organic material in a sample. 2) It must be able to detect as few as 100 cells in a milliliter of water.

Why is the phospholipid bilayer important to cell survival? Select the TWO answers that are correct.

1) It separates the cellular environment from the external environment. 2) It acts as a barrier for some, but not all, molecules on either side of it.

How do triglycerides and phospholipids differ? Select the TWO answers that are correct.

1) Phospholipids have two fatty acid tails, whereas triglycerides have three. 2) Phospholipids have a hydrophilic phosphate group in place of one fatty acid tail.

Based on the information in the podcast, ocean planets are prime targets in the search for life. However, in the book chapter scientists are also searching Mars for life, even though Mars is not an ocean planet. Why is Mars still considered to be a good candidate in the search for extraterrestrial life? Select the TWO answers that are correct.

1) There are signs that Mars once had liquid water on its surface. 2) Some photos suggest that there are underground stores of water on Mars.

How do RNA and DNA molecules differ? Select the TWO answers that are correct.

1) Uracil is used in RNA, whereas thymine is used in DNA. 2) RNA is single-stranded, whereas DNA is double-stranded.

What hypotheses have been proposed to explain how prions evolve? Select the TWO answers that are correct.

1) When the environment changes, one of the less common variants in a prion population may be able to better spread and become the dominant type of prion. 2) Changes in the environment change the shape of some prions, possibly producing a variant that is better able to tolerate the change than the original type of prion.

What characteristics make a particular molecule organic? Select the TWO answers that are correct.

1) a carbon backbone 2) a carbon-hydrogen bond

Which substances have an alkaline pH? Select the TWO answers that are correct.

1) baking soda 2) drain cleaner

One argument explaining why viruses are not living is that viruses depend on the cells of other living creatures in order to multiply. Which characteristics of life does this argument use? Select the TWO answers that are correct.

1) growth 2) reproduction

What characteristics make a world a prime candidate to potentially harbor life? Select the TWO answers that are correct.

1) the presence of liquid water 2) being geologically active

What determines the identity of a particular atom? Select the TWO answers that are correct.

1) total number of electrons in orbitals 2) number of protons and number of neutrons in the nucleus

Glucose (a monosaccharide) has the molecular formula C6H12O6. How many carbon atoms are in each glucose molecule?

6

Which of the following are most likely to dissolve in olive oil?

A nonpolar molecule

Which statement describes a hydrogen bond between two water molecules?

A weak bond between the slightly negative oxygen atom of one water molecule and the slightly positive hydrogen atoms of another water molecule.

What is the relationship between acids, bases, and hydroxide ions?

Acids contain relatively few hydroxide ions, whereas bases contain excess hydroxide ions.

A cell is unable to take up or make sugars. Which molecules will it be unable to take up or make?

Carbohydrates and nucleic acids

Identify the smallest subunits of life that can also sometimes be considered living organisms on their own.

Cells

What happened when researchers added 475 molecules of water to their experiment?

Complete ice crystals formed.

The bond between the oxygen atom and a hydrogen atom in a water molecule is a(n) ___________ bond)

Covalent

As an acidic compound dissolves in water, the pH of the water _______.

Decreases

Which part of an atom forms covalent bonds with other atoms?

Electrons in the outermost energy shell

Humans' ability to shiver is an attempt to increase the body's internal temperature and maintain _______.

Homeostasis

In terms of bond strength, which of the following is the weakest?

Hydrogen

The "stickiness" of water results from the ______________ bonding of water molecules.

Hydrogen

What makes ice less dense than liquid water?

Hydrogen bonds between water molecules expand when solid.

Which part of the cell membrane acts as a barrier to hydrophilic molecules entering the cell?

Hydrophobic tails

Olive oil is _______________ because _____________________.

Hydrophobic; it does not interact with water

Polar bears rely on Arctic ice sheets and icebergs on the surface of water as a part of their habitat. How would the habitat of polar bears be affected if solid water was more dense than liquid water?

Ice would sink rather than float, so there would be no ice sheets or ice bergs.

Why do salt crystals form in a pan of seawater from which the water has been evaporated?

In the absence of water, sodium and chloride form ionic bonds and aggregate into crystals.

When an atom loses an electron, what happens?

It becomes positively charged.

How are lipids unique when compared to other macromolecule groups?

Lipids do not contain monomers and they are comprised of compounds.

What are the four types of organic molecules that make up all living things on Earth?

Lipids, nucleic acids, carbohydrates, proteins

What are prions?

Misfolded proteins that can cause disease and spread by causing normal proteins to misfold as well.

The ability to _____ is not a generally recognized characteristic of most (if not all) living organisms?

Obtain energy directly from sunlight

The cell membrane is made of _______.

Phospholipids and proteins

Which trait is NOT a functional characteristic of all living things?

Protect self from predators

Where are the protons, neutrons, and electrons located in an atom?

Protons and neutrons are located in the nucleus, and electrons are located in orbitals.

This is the QUIZ PART. _____ make up the nucleus of an atom, whereas _____ surround the nucleus.

Protons and neutrons; electrons

Which of the following does NOT give researchers hope that life may exist on Mars?

Rovers have captured images of bacterial cells within rocks.

Which of the following statements about carbon is FALSE?

Soil samples containing carbon must contain life.

Coffee or tea with sugar dissolved in it is an example of a water-based solution. Coffee in this case is the __________________, sugar is the _________________, and this means that the sugar molecules must be __________________.

Solvent; solute; hydrophilic

What is another possible application for the experimental techniques scientists used for this research?

Studying the way other chemicals transition from solid to liquid to gas

Which of the characteristics of life does a virus display, even though its characterization as being alive is controversial?

The abilities to reproduce and grow

Why is the phospholipid bilayer considered semipermeable?

The bilayer is a barrier to some, but not all, substances on either side of it.

How does the molecular structure of a water molecule affect its polarity?

The oxygen has a partial negative charge and the hydrogens have a partial positive charge, yielding a weakly polar water molecule that can form hydrogen bonds.

How do prions cause disease?

They cause properly folded proteins to fold incorrectly, creating more prions which collect in nerve tissue and cause brain damage.

This is AFTER the quiz (y'know the American Activities). How does light interact differently with water and with ice?

Water and ice absorb different frequencies of light.

How does water dissolve table salt?

Water is a polar molecule that disrupts ionic bonds between sodium and chloride.