Biology 1610 Exam 1

List the characteristics of life:

List the characteristics of life:

Reproduction, growth & development, energy use, order, regulation (homeostasis), response to the environment, evolution

What is the smallest unit that displays all characteristics of life?

The cell

Biology

Scientific study of life

Describe why Darwin’s descent with modification explains the unity and diversity of life on Earth.

Species accumulate differences from their ancestors as they adapt to different environments over time, via natural selection, leading to diversity, but there can be unifying traits from a common ancestor that are shared by their descendants

What is an example that demonstrates unity of life on Earth?

Common Ancestry

According to Darwin, which evolutionary process resulted in the diversity of life on Earth?

Natural Selection

As you move to higher levels of organization (cell to a tissue) or from a genus to a family, emergent properties arise. What are emergent properties?

New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.

What are some examples of emergent properties?

The specific organization of molecules in a chloroplast necessary for photosynthesis to take place, and the lack of brain function after head trauma, despite the presence of necessary brain tissue.

The Biosphere

Earth, all ecosystems

Ecosystems

All the organisms in a given area as well as the abiotic factors with which they interact

Communities

All the organisms that inhabit a particular area

Populations

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

Organisms

Individual living things

Organs and Organ Systems:

A group of systems that work together in performing vital body functions

Tissues

An integrated group of cells with a common structure, and function

Cells

Life’s fundamental unit of structure and function

Organelles

Any of several membrane-enclosed structures with specialized functions in eukaryotic cells

Molecules

Two or more atoms held together by bonds

Describe the process of science and the steps involved.

It involves making observations, asking questions, developing hypotheses, making predictions, testing those hypotheses via observation or experimentation, and drawing conclusions

What do you expect to observe if your hypothesis is supported?

If your results are what you predicted, then your hypothesis is supported. If not, you develop a new hypothesis and repeat the same steps.

Define hypothesis

A testable explanation for a set of observations based on the available data and guided by inductive reasoning. A hypothesis must lead to predictions that can be tested by making additional observations or by performing experiments

A useful hypothesis must be able to achieve two goals:

Falsifiable and testable

What is the difference between a hypothesis and scientific theory?

A scientific theory is much broader in scope than a hypothesis. A scientific theory is general enough to spin off many new, testable hypotheses. A scientific theory, compared to any one hypothesis, is generally supported by a much greater body of evidence.

Experimental Group

Being exposed to treatment. Control group is omitted from treatment.

Control Group

Scientists design experiments to test the effect of one variable by cancelling out the effects of unwanted variables.

Independent Variable

The factor that is being manipulated by the researcher.

Dependent Variable

The factor that is being measured in an experiment.

Why is it so important to control variables in an experiment?

Researchers usually “control” unwanted variables, not by eliminating them, but by cancelling their effects using control groups.

You are studying the effects of artificial sweetener on mice. Four groups of mice consume different amounts of sweetener in their food. How much sweetener would the control group receive? Explain your answer

None, they are the group that does not get exposed to treatment.

Describe the difference between the movement of energy and the movement of chemicals in an ecosystem.

Energy flows through an ecosystem. When light energy is transformed into chemical energy (photosynthesis), most energy is lost as heat. Must have constant inflow of light energy to replace energy lost as heat into an ecosystem from sunlight, which is converted to chemical energy via photosynthesis. Chemicals cycle in ecosystems. Matter is never created, nor destroyed, only changes form.

What is the independent variable in the mouse experiment?

Color of mouse and color of habitat, state of moon.

What is the dependent variable of the mouse experiment?

Percentage of mouse models attacked

What axis is the dependent variable plotted on?

The y-axis

What axis is the independent variable plotted on?

The x-axis

In a chemical reaction, all of the atoms in the reactants must be present in the products. The reactions must be “balanced.” Matter is conserved in a chemical reaction. Chemical reactions rearrange matter; they do not create or destroy matter. Balance the following equation: 4 NH3 + 5 O2 → __ NO + __ H2O

4 NH3 + 5 O2 → 4 NO + 6 H2O

In __________ __________, chemical bonds are broken and reformed, leading to new arrangements of atoms.

chemical reactions

The starting molecules in the process are called ________, and the final molecules are called ________.

reactants, products

Anion

A negatively charged ion

Cation

A positively charged ion

What type of chemical bonds form anions and cations?

Ionic bonds

In an ionic bond between Chloride and Sodium, Chloride ion is the anion, and sodium ion is the cation to form NaCI

Explain why an anion is negatively charged?

Anions have more electrons than protons.

Why is a Cation positively charged?

Cations have more protons than electrons.

What determines the chemical behavior of an atom?

Determined by the number of electrons in the atom’s valence shell

Carbon-13 and Carbon-14 are examples of _________ of carbon. These atoms differ in the number of neutrons in the nucleus.

Isotopes

Name the 4 elements that make up approximately 96% of us.

Oxygen, carbon, nitrogen, and hydrogen

The atom’s first electron shell, which is innermost and closest to the nucleus, can hold ______ electrons.

Two

The second and subsequent shells can hold more, or up to _______ electrons

Eight

The third shell can hold up to _______ electrons.

Eight.

Phosphorus has 15 electrons, how many electrons does it have in the outer valence shell?

5 electrons in the valence shell.

Rank the bonds strongest to weakest (in water).

Covalent, ionic, hydrogen

How is a covalent bond formed?

When two atoms share a pair of valence electrons.

How is an ionic bond formed?

If two atoms are so unequal in their attraction for valence electrons that one atom strips an electron completely from the other.

How is a hydrogen bond formed?

When a hydrogen atom that is already covalently bonded to one electronegative atom is attracted to another electronegative atom.

What is meant by electronegativity?

The attraction of a particular atom for the electrons of a covalent bond.

Which atom is typically the most electronegative?

Oxygen

What is a nonpolar covalent bond?

Electrons that are shared equally, and therefore their polarity

What is a polar covalent bond?

Occurs when one atom is bonded to a more electronegative atom, and the electrons are not shared.

What is an example of a polar covalent bond?

The bond between the oxygen and hydrogen atoms of a water molecule.

What bonds are formed in water?

Polar covalent bonds

What bonds are formed in Carbon Dioxide?

Non-polar covalent bonds

What bonds are formed in Oxygen?

Non-polar covalent bonds

How do CO2 emissions affect marine life and ecosystems?

CO2 dissolves in seawater, creating carbonic acid, which lowers the pH of the ocean, causing ocean acidification. Ocean acidification decreases the concentration of carbonate, which is required for calcification by many marine organisms. Additionally, CO2 emissions create acid precipitation that damages life in streams and lakes and adversely affects life on land by altering soil chemistry.

What is a hydrophobic substance?

Not soluble in water.

What are some examples of hydrophobic substances?

Non-polar molecules, like fat, and vegetable oil.

What is a hydrophilic substance?

Any substance that is soluble in water.

What are some examples of hydrophilic substances?

Polar molecules, and cotton

What is cohesion?

Hydrogen bonds holding water together.

What is adhesion?

Water molecules holding onto another substance.

What is a real-life example of cohesion?

High surface tension is produced because it is difficult to stretch or break the surface of water allowing an insect to remain on the surface.

What is a real-life example of adhesion?

Water clings to paper because paper is polar and forms hydrogen bonds with water.

What is high specific heat?

The amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1 degree C.

What is important about water’s specific heat?

It’s unusually high at 1 cal/gC, meaning a large body of water can absorb and store a huge amount of heat from the sun in the daytime and during the summer while warming up only a few degrees. As this water generally cools during the night and during winter, it warms the air, contributing to milder climates in coastal regions.

Why does ice float?

As a result of hydrogen bonding, water expands as it solidifies. At 4 degrees C, water acts like other liquids, expanding as it warms and contracting as it cools. However below 4 degrees C, water begins to freeze as more and more hydrogen molecules are moving too slowly to break the hydrogen bonds. Hydrogen bonds keep the molecules far enough apart to make ice about 10% less dense than water. At 4 degrees C, it is this lower density of ice that allows it to float.

Why is water a good solvent?

Due to its polarity, water can dissolve ionic compounds and many compounds made up of non-ionic polar molecules, as well as molecules such as proteins if they have polar and ionic regions on their surface.

Which types of molecules are soluble in water.

Polar molecules

Which types of molecules are not soluble in water?

Non-polar molecules, like fats are not.

Make an electron distribution diagram of water. Which element is most electronegative? Why is water considered a polar molecule? Label the regions that are more positive or more negative.

Water is considered a polar molecule because oxygen is more electronegative than hydrogen, and therefore the shared electrons are pulled more toward oxygen.

A water molecule can be broken apart by releasing _____ and _________ ions.

H+ and OH- ions

What does the pH scale measure?

It measures the concentration of H+ ions in a solution. The more H+ the solution, the more acidic.

A fluid with a pH between 0 and 6.9 would be considered ____. Would this fluid have more H+ or OH- ions?

pH 0-6.9 is an acid, so more H+

A fluid with a pH between 7.1 and 14 would be considered ____. Would this fluid have more H+ or OH- ions?

pH 7.1-14 is a base, so more OH-

What is the concentration of H+ and OH- in pure water at 25 degrees C? What is the pH?

10^-7 M (at 25°C), they are equal in concentration. pH = 7

Chemical groups known as ______ _______ affect molecular function through their direct involvement in ______ _______.,

Functional groups, chemical reactions

List and draw a few examples of common groups.

Hydroxyl = OH

Carboxyl = COOH

Methyl = CH3

Amino = NH2

Which molecule is most similar to carbon in terms of its valence electrons?

Silicon, both have 4 valence electrons and can form 4 covalent bonds.

The most important large molecules found in all living things fall into just four main classes. Name them and an example of each:

Carbohydrates (glycogen), lipids (phospholipids, steroids), proteins (hemoglobin), nucleic acids (DNA, RNA).

What macromolecule is this image showing?

Protein

These are examples of what kind of structures?

Alpha helices and beta sheets are examples of a protein’s secondary structure

What protein structures does this model show?

Primary, secondary, and tertiary structure

What is a polymer?

A long-chain like molecule, consisting of many similar or identical building blocks (monomers) linked by covalent bonds.

What is a monomer?

Smaller molecules that serve as the building blocks of polymers

What type of reaction bonds two monomers together? Explain the process:

Monomers are connected in a dehydration reaction. During a dehydration reaction, two monomer molecules are covalently bonded to each other, with the loss of a water molecule. In this reaction, each monomer contributes part of the water molecule that is released during the reaction. This reaction is repeated as monomers are added to the chain one by one, making a polymer.

Which reaction breaks down large molecules (polymers) to monomers? Explain the process.

During hydrolysis, a polymer is broken down with water added between the monomers. The reactants are the polymer and water, and the products are the resultant monomers.

Which polymers have sugars?

Carbohydrates (glucose and cellulose), and Nucleic acids (DNA and RNA)

Which polymers contain phsophorus?

Common in Nucleic acids (DNA, ATP), and phospholipids

Which polymers contain nitrogen?

Common in proteins (amino acids) and nucleic acids (DNA).

Write out the correct monomer: polymer pairing

Amino acid: proteins, Monosaccharides: polysaccharides, Nucleotides: nucleic acids

Are lipids consider polymers? Why or why not?

No, because they are not comprised of repeating subunits (such as monosaccharides or amino acids).

What are examples of polysaccharides we discussed in class? What is their primary function and where are they commonly found?

Starch-energy storage in plants,

Glycogen-energy storage in animals (liver),

Cellulose (most abundant compound on earth)- structural support plants (cell wall), non-digestible dietary

Chitin- structural support (exoskeleton) insects and cell wall fungis

What are some characteristics of lipids?

All lipids mix poorly, if at all, with water. Hydrocarbons are hydrophobic. They also are a great source of long-term energy storage.