Biology Exam 1

Attached to the 3" carbon of nucleic acids

hydroxyl

Is used to make a water molecule during dehydration

hydroxyl group

In 1-2 complete sentences, explain the differences between a hypothesis and a prediction.

A hypothesis uses reasoning to form a logical explanation for observations made about naturally occurring phenomena. Predictions describe possible outcomes of an experiment that may or may not support a hypothesis.

For the three items above for MTF 9 (Questions 39, 40, and 41), explain why each statement is true or false. Provide your answers complete sentences. Note: Students commonly find themselves trapped in circular reasoning with these kinds of questions. Simply stating that a true answer is "true because it's true." is not an acceptable.

Both DNA and RNA contain pentose sugars. TRUE: DNA contains deoxyribose, RNA contains ribose sugars, and both of those are types of a 5-carbon sugar called a pentose. Polymers of carbohydrates contain glycosidic linkages formed by dehydration reactions. TRUE: Water forms during the synthesis of polysaccharides when the OH from one monosaccharide and the H of another monosaccharide form a polymer. When water is forms during a synthesis reaction it is called dehydration. Peptide bonds form between carbon and nitrogen atoms in nucleic acids. FALSE: Peptide bonds form between the carbon and nitrogen atoms in amino acids. Nucleic acids are linked together by phosphodiester bonds.

Researchers have attempted to identify the lowest oxygen level that can sustain animal growth by studying the breadcrumb sponge, Halichondria panicea. The researchers were interested in how the breadcrumb sponge consumes oxygen at different oxygen levels. An entry level lab tech submits the following experimental design proposals: A. The best experiment would be to put one sponge in a tank at a certain oxygen level. Then put another sponge (matched for age and sex) into a separate tank at a different oxygen level. Measure and compare the oxygen consumption rates between the two sponges. B. The best experiment to do would be to put some sponges in a tank at a certain oxygen level. Then put some other sponges (matched for age and sex) into other tanks at different oxygen levels. Measure and compare the oxygen consumption rates between the sponges. Which proposal is most appropriate and why? Explain your answer in 2-3 complete sentences.

Experiment A is not appropriate because it DOES NOT have multiple individuals per tank, so the researchers will be more confident that whatever results they obtain are reproducible within the breadcrumb sponges that they studied. Experiment B is appropriate because it 1) directly addresses the question--how does oxygen level affect sponge oxygen consumption rate? and 2) it needs to have multiple individuals per tank, so the researchers will be more confident that whatever results they obtain are reproducible within the breadcrumb sponges that they studied.

Household ammonia, or ammonium hydroxide, is a mixture of ammonia (NH3) and water (H2O). Given this information, identify if the next four statements are TRUE or FALSE. Nitrogen and hydrogen have the same valence.

False

Household ammonia, or ammonium hydroxide, is a mixture of ammonia (NH3) and water (H2O). Given this information, identify if the next four statements are TRUE or FALSE. The nitrogen atom in ammonia has a partial positive charge.

False

Identify if the next five items regarding macromolecules are TRUE or FALSE Saturated fats have single hydrogen bonds, which make them solid at room temperature.

False

Identify if the next five items regarding macromolecules are TRUE or FALSE Unsaturated fats have more polar groups than do saturated fats.

False

Identify if the next five items regarding macromolecules are TRUE or FALSE Unsaturated fats tend to be liquid at room temperature because they have few oxygen atoms.

False

Identify if the next four items regarding pH is TRUE or FALSE. A single unit change on the pH scale is equivalent to a 100% change in hydrogen ion concentration

False

Identify if the next four items regarding pH is TRUE or FALSE. The pH scale is a measure of oxygen ion concentration

False

Identify if the next four items regarding water molecules are TRUE or FALSE: Ice is less dense than liquid water primarily due to polar covalent bonds between water molecules

False

Identify if the next four items regarding water molecules are TRUE or FALSE: Liquid water has low density and low surface tension due primarily to hydrogen bonds.

False

Identify if the next four items regarding water molecules are TRUE or FALSE: Oxygen donates its electrons to hydrogen.

False

Identify if the next three items regarding polymers are TRUE or FALSE. Peptide bonds form between carbon and nitrogen atoms in nucleic acids.

False

Pesticides are chemicals that humans spray on crops to kill the insects that eat those plants. However, a certain species of beetle has evolved a resistance to the pesticides and is not killed by them. Given this information, identify if the next three items are TRUE or FALSE. In order for natural selection to occur, beetles that live the longest have the greatest fitness.

False

Pesticides are chemicals that humans spray on crops to kill the insects that eat those plants. However, a certain species of beetle has evolved a resistance to the pesticides and is not killed by them. Given this information, identify if the next three items are TRUE or FALSE. The beetles are resistant to the pesticide because few mutations have occurred.

False

T/F A researcher applies varying amounts of fertilizer (0, 10, 15, 25, 50 units) to 50 potted pepper plants. All other variables that may affect the outcome (watering, temperature, sunlight, plant size, etc.) are kept the same from pot to pot. At the end of the growing season, the peppers grown on each plant are weighed to determine which fertilizer level produces the largest number of peppers per plant. The amount of fertilizer is a controlled variable.

False

T/F A researcher applies varying amounts of fertilizer (0, 10, 15, 25, 50 units) to 50 potted pepper plants. All other variables that may affect the outcome (watering, temperature, sunlight, plant size, etc.) are kept the same from pot to pot. At the end of the growing season, the peppers grown on each plant are weighed to determine which fertilizer level produces the largest number of peppers per plant. The dependent variable is the amount of sunlight and temperature.

False

T/F A researcher applies varying amounts of fertilizer (0, 10, 15, 25, 50 units) to 50 potted pepper plants. All other variables that may affect the outcome (watering, temperature, sunlight, plant size, etc.) are kept the same from pot to pot. At the end of the growing season, the peppers grown on each plant are weighed to determine which fertilizer level produces the largest number of peppers per plant. This is an example of a controlled experiment because several different amounts of fertilizers were used, not just one amount.

False

Water "beads up" on synthetic fabrics such as polyester but binds to cotton. Given this information, identify if the next four items are TRUE or FALSE. Cotton fibers are thinner than polyester, so water can bind to the fibers.

False

Water "beads up" on synthetic fabrics such as polyester but binds to cotton. Given this information, identify if the next four items are TRUE or FALSE. Water binds to cotton because cotton likely contains fewer covalent bonds than polyester.

False

Water "beads up" on synthetic fabrics such as polyester but binds to cotton. Given this information, identify if the next four items are TRUE or FALSE. Water binds to cotton because it is a naturally occurring substance.

False

Identify if the next four items regarding water molecules are TRUE or FALSE: NaCl is dissolves in water because the hydrogens on the water molecules form hydrogen bonds with Cl- ions.

Flase

A food development company is interested in making on-the-go powder-based snacks in which consumers can "just add water" before eating. During market tests there are complaints that the powder does not dissolve well in water. After modifying the on-the-go powder, a food scientist conducts a test and determines that the new formula makes a solution that is alkaline (basic). How does this new formula impact the pH of the solution when it is dissolved in water? Provide your answer in 1-2 complete sentences.

If the modification makes the solution more alkaline, then the pH of the solution will increase because the concentration of H+ is decreasing/OH- is decreasing.

Identify if the next three items regarding polymers are TRUE or FALSE. Polymers of carbohydrates contain glycosidic linkages formed by dehydration reactions

True

For the three items above in MTF 3 (Question 10, 11, and 12), explain why each statement is true or false. Provide your answers complete sentences. Note: Students commonly find themselves trapped in circular reasoning with these kinds of questions. Simply stating that a true answer is "true because it's true." is not an acceptable. Also, simply correcting a false statement by changing the wording is not enough of an explanation. You need to explain why.

In order for natural selection to occur some individual beetles in the population vary in resistance to the pesticide. TRUE: This statement is true because in order for natural selection to occur there must be some genetic variation within the population. In order for natural selection to occur, beetles that live the longest have the greatest fitness. FALSE: This statement is false because fitness is a measure of reproductive success and not longevity. Individuals can live a very long time and if they have no offspring, they have zero fitness. The beetles are resistant to the pesticide because few mutations have occurred. FALSE: This statement is false because although mutations are a source of variation, the number of mutations to do not influence the process of natural selection. For example, there could be hundreds of mutations that result in increased susceptibility to the pesticide, but the majority of the population will still be resistant because that trait is more likely to increase survival.

Rank the following bonds from most polar to least polar: H-F O-H Li-H C-H H-H

Most Polar H-F O-H Li-H C-H H-H Least Polar

Image description: A molecule with a phosphate group attached to a 5-carbon sugar, and a nitrogen ring.

The pentose in this molecule is called deoxyribose

Image description: A long chain of carbons with a single carbon double bond in the middle and a carboxyl group on one end.

This molecule is a type of lipid that is amphipaathic

Image description: A 6-carbon molecule in a ring shape with hydroxyl groups attached to several of the carbons.

This monomer is joined together with other monomers by a glycosidic linkage to make polysaccharides

Image description: A molecule with an carboxyl group, amino group, and a side chain with a hydroxyl and methyl group attached to a central carbon.

This monomer is joined together with other monomers by forming a covalent bond between a Carbon and Nitrogen molecule to make polypeptides

Household ammonia, or ammonium hydroxide, is a mixture of ammonia (NH3) and water (H2O). Given this information, identify if the next four statements are TRUE or FALSE. In water, there are polar covalent bonds between each hydrogen atom and the oxygen atom.

True

Household ammonia, or ammonium hydroxide, is a mixture of ammonia (NH3) and water (H2O). Given this information, identify if the next four statements are TRUE or FALSE. Nitrogen (N) is much more electronegative than hydrogen (H).

True

Household ammonia, or ammonium hydroxide, is a mixture of ammonia (NH3) and water (H2O). Given this information, identify if the next four statements are TRUE or FALSE. The hydrogen atoms in both ammonia and water have partial positive charges.

True

Identify if the next five items regarding macromolecules are TRUE or FALSE All nucleic acids are polar.

True

Identify if the next five items regarding macromolecules are TRUE or FALSE Some amino acid side chains are polar and some are non-polar.

True

Identify if the next five items regarding macromolecules are TRUE or FALSE Some types of lipids act as signaling molecules that travel through the body

True

Identify if the next four items regarding pH is TRUE or FALSE. A solution with a pH of 10.5 has a higher concentration of hydroxide (OH-) ions than a solution with a pH of 1.5

True

Identify if the next four items regarding pH is TRUE or FALSE. An increase in hydrogen ion concentration means a decrease in pH scale units

True

Identify if the next four items regarding pH is TRUE or FALSE. Something with a pH of 5 would be considered acidic.

True

Identify if the next four items regarding water molecules are TRUE or FALSE: Electron pairs are unevenly shared between the oxygen atom and the two hydrogen atoms.

True

Identify if the next four items regarding water molecules are TRUE or FALSE: The tendency of water molecules to stick together with other water molecules is referred to as cohesion.

True

Identify if the next three items regarding polymers are TRUE or FALSE. Both DNA and RNA contain pentose sugars.

True

Pesticides are chemicals that humans spray on crops to kill the insects that eat those plants. However, a certain species of beetle has evolved a resistance to the pesticides and is not killed by them. Given this information, identify if the next three items are TRUE or FALSE. In order for natural selection to occur some individual beetles in the population vary in resistance to the pesticide.

True

T/F A researcher applies varying amounts of fertilizer (0, 10, 15, 25, 50 units) to 50 potted pepper plants. All other variables that may affect the outcome (watering, temperature, sunlight, plant size, etc.) are kept the same from pot to pot. At the end of the growing season, the peppers grown on each plant are weighed to determine which fertilizer level produces the largest number of peppers per plant. The independent variable is the amount of fertilizer

True

T/F A researcher applies varying amounts of fertilizer (0, 10, 15, 25, 50 units) to 50 potted pepper plants. All other variables that may affect the outcome (watering, temperature, sunlight, plant size, etc.) are kept the same from pot to pot. At the end of the growing season, the peppers grown on each plant are weighed to determine which fertilizer level produces the largest number of peppers per plant. The type of fertilizer is a controlled variable.

True

Water "beads up" on synthetic fabrics such as polyester but binds to cotton. Given this information, identify if the next four items are TRUE or FALSE. Polyester is nonpolar, whereas cotton is polar.

True

Water "beads up" on synthetic fabrics such as polyester but binds to cotton. Given this information, identify if the next four items are TRUE or FALSE. Water beads up on polyester because it is less polar than cotton.

True

When the pH of an aqueous solution decreases, it can interfere with the cohesive properties of water. Explain how and why this occurs in 1-2 complete sentences.

When the pH decreases a solution becomes more acidic, this means that the hydrogen ion concentration has increases. Hydrogen ions are positively charged and when they increase in abundance in an aqueous solution the partially negative charge in the oxygen in a water molecule will surround those ions rather than be attracted to other water molecules. Cohesion is the attraction of water molecules to other water molecules, so adding an acid will decrease the number of hydrogen bonds between water molecules making it less cohesive.

Found on the N-terminus of amino acids

amino

Found on the C-terminus of amino acids

carboxyl group

A current trend among professional athletes is to wear copper-infused fabrics. An athletic clothing brand is advertising that the copper-infused fabric "maximizes muscle movement and energy flow in the body." You've been hired by the clothing company to evaluate the effectiveness of this fabric on athletic performance. Given this information, identify if the next three items are a HYPOTHESIS or a PREDICTION. Copper-infused fabrics are more effective in professional athletes because of the greater amount of stress they put on muscles and connective tissue.

hypothesis

A current trend among professional athletes is to wear copper-infused fabrics. An athletic clothing brand is advertising that the copper-infused fabric "maximizes muscle movement and energy flow in the body." You've been hired by the clothing company to evaluate the effectiveness of this fabric on athletic performance. Given this information, identify if the next three items are a HYPOTHESIS or a PREDICTION. Copper-infused fabrics decrease fatigue in athletes by reducing inflammation in muscle cells after intense physical activity.

hypothesis

Can make molecules insoluble in water

methyl

Found commonly in fatty acid tails

methyl group

Bonds to the 5" carbon of nucleic acids

phosphate

Abundant in the molecules that make up the cell membrane

phosphate group

A current trend among professional athletes is to wear copper-infused fabrics. An athletic clothing brand is advertising that the copper-infused fabric "maximizes muscle movement and energy flow in the body." You've been hired by the clothing company to evaluate the effectiveness of this fabric on athletic performance. Given this information, identify if the next three items are a HYPOTHESIS or a PREDICTION. Athletes who wear copper-infused fabrics are more satisfied with their athletic performance.

prediction

A current trend among professional athletes is to wear copper-infused fabrics. An athletic clothing brand is advertising that the copper-infused fabric "maximizes muscle movement and energy flow in the body." You've been hired by the clothing company to evaluate the effectiveness of this fabric on athletic performance. Given this information, identify if the next three items are a HYPOTHESIS or a PREDICTION. Basketball players report less pain or fewer injuries when wearing the copper-infused fabrics.

prediction